SC14D9C

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14D-9

Solicitation/Recommendation Statement

Under Section 14(d)(4) of the Securities Exchange Act of 1934

ZOGENIX, INC.

(Name of Subject Company)

ZOGENIX, INC.

(Name of Person Filing Statement)

Common Stock, $0.001 par value per share

(Title of Class of Securities)

98978L204

(CUSIP Number of Class of Securities)

Stephen J. Farr, Ph.D.

President and Chief Executive Officer

Zogenix, Inc.

5959 Horton Street, Suite 500

Emeryville, CA 94608

(510) 550-8300

(Name, Address and Telephone Number of Person Authorized to Receive Notices and

Communications on Behalf of the Person Filing Statement)

With copies to:

Scott Shean

Latham & Watkins LLP

650 Town Center Dr

20th Floor

Costa Mesa, CA 92626

Telephone: (714) 540-1235

☒ Check the box if the filing relates solely to preliminary communications made before the commencement of a tender offer.

The information set forth under Items 1.01, 7.01 and 9.01 of the Current Report on Form 8-K filed by Zogenix, Inc. (the “Company” or “Zogenix”) on January 19, 2022 (including all exhibits attached thereto and incorporated therein by reference) is incorporated herein by reference.

(i) On January 19, 2022, Dr. Stephen J. Farr, the Company’s President and Chief Executive Officer, provided the electronic communication attached hereto as Exhibit 99.1 to the Company’s employees.

(ii) On January 19, 2022, the Company presented the slides attached hereto as Exhibit 99.2 to its employees at a town hall meeting.

(iii) On January 19, 2022, the Company provided the questions and answers attached hereto as Exhibit 99.3 to its employees.

(iv) On January  19, 2022, the Company provided the electronic communications attached hereto as Exhibit 99.4 to its partners, suppliers and vendors.

(v) On January 19, 2022, the Company provided the electronic communications attached hereto as Exhibit 99.5 to its physicians.

(vi) On January 19, 2022, the Company provided the electronic communications attached hereto as Exhibit 99.6 to its patient advocacy groups.

(vii) On January  19, 2022, the Company provided the electronic communications attached hereto as Exhibit 99.7 to its analysts.

(viii) On January 19, 2022, the Company provided the electronic communications attached hereto as Exhibit 99.8 to its investors.

(ix) On January 19, 2022, the Company provided the electronic communications attached hereto as Exhibit 99.9 to its consultants and temporary employees.

(x) On January  19, 2022, the Company provided the electronic communications attached hereto as Exhibit 99.10 to its newly hired employees.

***

Additional Information and Where to Find It

The tender offer described above has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of the Company. The solicitation and the offer to buy shares of the Company’s common stock will only be made pursuant to a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials, that UCB S.A. (“Parent”) intends to cause Zinc Merger Sub, Inc. (“Merger Sub”) to file with the SEC. In addition, the Company will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and the Company with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by the Company under the “Investors” section of the Company’s website at www.zogenix.com. INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT OF THE COMPANY AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

Forward-Looking Statements

The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. These forward-looking statements include without limitation statements regarding the planned completion of the transactions contemplated by the Agreement and Plan of Merger dated as of January 18, 2022 by and among the Company, Merger Sub and Parent. Additional statements include, but are not limited to, statements regarding: The Company’s expectations regarding the potential benefits of FINTEPLA; the Company’s expectations regarding the potential commercial launch of FINTEPLA; and the Company’s expectations regarding potential applications of its products to treat rare/orphan diseases

Risks and uncertainties that could cause results to differ from expectations include: (i) uncertainties as to the timing of the tender offer and the subsequent Merger; (ii) the risk that the tender offer or the subsequent Merger may not be completed in a timely manner or at all; (iii) uncertainties as to the percentage of the Company’s stockholders tendering their shares in the tender offer; (iv) the possibility that competing offers or acquisition proposals for the Company will be made; (v) the possibility that any or all of the various conditions to the consummation of the tender offer or the subsequent Merger may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); (vi) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement; (vii) the risk that the milestone specified in the CVR Agreement is not achieved; (viii) the effect of the announcement or pendency of the transactions contemplated by the Merger Agreement on the Company’s ability to retain and hire key personnel, its ability to maintain relationships with its customers, suppliers and others with whom it does business, or its operating results and business generally; (ix) risks related to diverting management’s attention from the Company’s ongoing business operations; (x) the risk that stockholder litigation in connection with the transactions contemplated by the Merger Agreement may result in significant costs of defense, indemnification and liability; and (xi) risks and uncertainties pertaining to the Company’s business, including the risks and uncertainties detailed in the Company’s Annual Report on Form 10-K for the year ended December 30, 2020 and its other filings with the SEC, as well as the tender offer materials to be filed by Merger Sub and Parent and the Solicitation/Recommendation Statement to be filed by the Company in connection with the tender offer. Risks and uncertainties that contribute to the uncertain nature of the forward-looking statements regarding the Company’s business may include: FINTEPLA may not achieve broad market acceptance as a treatment option of Dravet syndrome, which would limit Zogenix’s ability to generate revenues; Zogenix may not be successful in executing its sales and marketing strategy for the commercialization of FINTEPLA in the U.S. and Europe, including due to the costs and procedures related to the REMS certification process or controlled access program; the COVID-19 pandemic may continue to disrupt Zogenix’s business operations, impairing the ability to commercialize FINTEPLA in Europe and Zogenix’s ability to generate product revenue in Europe and conduct its development programs; unexpected adverse side effects or inadequate therapeutic efficacy of fenfluramine that could limit regulatory approval or commercialization, or that could result in recalls or product liability claims; later developments with FDA that may be inconsistent with the already completed meetings; additional data from Zogenix’s ongoing studies may contradict or undermine the data previously reported; and the potential for the FDA to delay timing of review of the sNDA due to the FDA’s internal resource constraints or other reasons.

You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement and the Company undertakes no obligation to revise or update these statements to reflect events or circumstances after the date hereof, except as required by law.

EX-99.1

Exhibit 99.1

Dear Z-Team Colleagues,

A few moments ago, UCB and Zogenix issued a joint press release announcing the companies had entered into an agreement for UCB to acquire Zogenix. UCB shares our focus and passion for helping people living with neurological and rare diseases. For more than 30 years, they have provided therapies that have helped transform the epilepsy landscape and improve the lives of millions of people worldwide.

The value placed on our company by UCB is entirely due to the Z-Team – past and present – in successfully building our business and creating our well-earned reputation among patients, caregivers, healthcare providers, and our peer companies.

I am sure this announcement for many of you may come as a surprise and expect you will have questions after processing the news and its implications. We will be hosting an all-employee Zogenix Update on Wednesday at 8:30 AM PST, when I will share more of my thoughts and details around this news. I encourage you to read the attached press release and to attend the Zoom meeting, which will appear shortly as an invite in your Outlook calendar.

Headquartered in Brussels, Belgium, UCB is a global biopharmaceutical company focusing on neurology and immunology. Their neurology product portfolio includes marketed therapies in epilepsy, Parkinson’s disease, and Restless Legs Syndrome. The company also has an innovative pipeline in advanced development for the treatment of Myasthenia Gravis and other serious rare neurological diseases, as well as research partnerships with Roche in Alzheimer’s and Novartis in Parkinson’s disease focused on disease modification. UCB has approximately 8,000 employees worldwide, with products registered in more than 40 countries. Its U.S. operations are based in Atlanta, Georgia. Their mission – “Inspired by Patients. Driven by Science” – perfectly aligns with our own to transform the lives of patients with serious diseases.

As some of you are aware, we have always been active in evaluating opportunities to grow our own business including through partnerships with companies that can extend our global reach. To this end, a dialogue with UCB commenced in late summer last year around a potential partnering relationship. These discussions subsequently evolved into an interest from UCB to acquire the whole company. Given we are a public company, the Board determined UCB’s offer, in addition to their global footprint as a leading neurology and rare disease company, was the best next phase of our evolution and consistent with their responsibilities for unlocking value for shareholders.

Please keep in mind that we are still early in the stages of this process with UCB. We will now focus on obtaining transaction-related regulatory approvals before the deal is complete and the transition period begins. We anticipate the transaction to close during the second quarter of 2022. Until then, it is business as usual, and all of us should remain focused on our day- to-day responsibilities as we execute on our 2022 corporate objectives.

I want to emphasize that we will be providing regular updates as more information becomes available. Following the all-employee meeting, each Executive Team member will schedule department meetings to address your questions. We will send an FAQ document which should be helpful in answering your questions and providing information on the transaction. We commit to updating you at our weekly Morning Check-In’s, and a column on the ZONE will be established to help keep you informed. Again, after this announcement, there is still much to be discussed and decided between the two companies.

WE are Zogenix and I know our collective and individual commitment to our patients and their families will never change. You are an amazing team and I thank you deeply for all you do and the dedication with which you do it. I look forward to seeing you at our all-employee call.

Best regards,

Steve

*    *     *

Additional Information and Where to Find It

The tender offer in the transaction described above has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of Zogenix, Inc. (the “Company”). The solicitation and the offer to buy shares of the Company’s common stock will only be made pursuant to a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials that UCB S.A. (the “Parent”) intends to cause Zinc Merger Sub, Inc. (“Merger Sub”) to file with the Securities and Exchange Commission (“SEC”). In addition, the Company will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and the Company with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by the Company under the “Investors” section of the Company’s website at www.zogenix.com.

INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT OF THE COMPANY AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

Forward-Looking Statements

The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. These forward-looking statements include without limitation statements regarding the planned completion of the transactions contemplated by the Agreement and Plan of Merger dated as of January 18, 2022 by and among the Company, Merger Sub and Parent. Risks and uncertainties that could cause results to differ from expectations include: (i) uncertainties as to the timing of the Offer and the subsequent Merger; (ii) the risk that the Offer or the subsequent Merger may not be completed in a timely manner or at all; (iii) uncertainties as to the percentage of the Company’s stockholders tendering their shares in the Offer; (iv) the possibility that competing offers or acquisition proposals for the Company will be made; (v) the possibility that any or all of the various conditions to the consummation of the Offer or the subsequent Merger may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); (vi) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement; (vii) risk that the milestone specified in the CVR Agreement is not achieved, (viii) the effect of the announcement or pendency of the transactions contemplated by the Merger Agreement on the Company’s ability to retain and hire key personnel, its ability to maintain relationships with its customers, suppliers and others with whom it does business, or its operating results and business generally; (ix) risks related to diverting management’s attention from the Company’s ongoing business operations; (x) the risk that stockholder litigation in connection with the transactions contemplated by the Merger Agreement may result in significant costs of defense, indemnification and liability; and (xi) risks and uncertainties pertaining to the Company’s business, including the risks and uncertainties detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 and its other filings with the SEC, as well as the tender offer materials to be filed by Merger Sub and Parent and the Solicitation/Recommendation Statement to be filed by the Company in connection with the tender offer.

You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement and the Company undertakes no obligation to revise or update these statements to reflect events or circumstances after the date hereof, except as required by law.

EX-99.2

Zogenix + UCB January 19, 2022 Exhibit 99.2

Forward-Looking Statements The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. These forward-looking statements include without limitation statements regarding the planned completion of the transactions contemplated by the Agreement and Plan of Merger dated as of January 18, 2022 by and among the Company, Merger Sub and Parent. Risks and uncertainties that could cause results to differ from expectations include: (i) uncertainties as to the timing of the Offer and the subsequent Merger; (ii) the risk that the Offer or the subsequent Merger may not be completed in a timely manner or at all; (iii) uncertainties as to the percentage of the Company’s stockholders tendering their shares in the Offer; (iv) the possibility that competing offers or acquisition proposals for the Company will be made; (v) the possibility that any or all of the various conditions to the consummation of the Offer or the subsequent Merger may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); (vi) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement; (vii) risk that the milestone specified in the CVR Agreement is not achieved, (viii) the effect of the announcement or pendency of the transactions contemplated by the Merger Agreement on the Company’s ability to retain and hire key personnel, its ability to maintain relationships with its customers, suppliers and others with whom it does business, or its operating results and business generally; (ix) risks related to diverting management’s attention from the Company’s ongoing business operations; (x) the risk that stockholder litigation in connection with the transactions contemplated by the Merger Agreement may result in significant costs of defense, indemnification and liability; and (xi) risks and uncertainties pertaining to the Company’s business, including the risks and uncertainties detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 and its other filings with the SEC, as well as the tender offer materials to be filed by Merger Sub and Parent and the Solicitation/Recommendation Statement to be filed by the Company in connection with the tender offer. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement and the Company undertakes no obligation to revise or update these statements to reflect events or circumstances after the date hereof, except as required by law.

Transaction Overview Deal Terms Deal Structure, Value Tender Offer for UCB to acquire Zogenix transaction value of approximately $1.9 billion Consideration $26.00 per share in cash $2.00 per share Contingent Value Right (CVR) * Process Transaction unanimously approved by BOD of both companies Subject to customary closing conditions and transaction-related regulatory approvals Expected to close in Q2 Moving Forward UCB to lead combined company after close UCB and Zogenix have shared values in improving the lives of patients suffering from severe diseases As a leader in the field of epilepsy, UCB places great value on FINTEPLA development and commercial success A UCB-Zogenix combination further enhances UCB’s epilepsy & rare disease offerings and capabilities The transaction creates immediate value to Zogenix shareholders * Contingent Value Right. $2.00 CVR on retention of Orphan Drug Designation upon approval of LGS in Europe

UCB Background Global biopharmaceutical company focused on treating severe immunological and neurological disease Founded in 1928, headquartered in Brussels, Belgium US Operations based in Atlanta, Georgia Over 8,000 employees globally Annual sales of >€5 billion in 2020 Over 30 years dedicated to improving the lives of people living with epilepsy and has four approved anti-epileptic therapies Expanded rare disease focus - acquisition of Ra Pharmaceuticals and zilucoplan in 2019 www.ucb.com

Strategic Rationale for Combination We have collectively built an organization we can be proud of – a company that develops and markets transformative treatments for people living with rare diseases UCB shares our commitment to addressing the unmet needs of people living with neurological and rare diseases where few treatment options exist UCB recognizes the potential of FINTEPLA to broaden and build on their role as a world leader in epilepsy by adding a specific treatment for rare forms of epilepsy UCB expects to utilize our experience and capabilities in rare disease health ecosystems Complements UCB’s existing medicines and expands clinical development pipeline of epilepsy and rare disease therapies Committed to developing and commercializing therapies with the potential to transform the lives of patients and their families living with rare diseases

What This Means for Your Equity Stock Upon closing, holders of stock will receive $26.00 per share in cash plus one CVR entitling you to $2.00 per share upon FINTEPLA approval in Europe as an orphan medicine (by Dec 2023) Options Upon closing, all options (vested and unvested) will vest and be automatically exchanged for transaction consideration In the case of in-the-money options (<$26), you will receive $26 in cash less the applicable exercise price, plus one CVR In the case of options with an exercise price between $26 and $28, you will receive in cash the difference between $28 and the applicable exercise price under the CVR agreement All options with an exercise price of >$28 will be cancelled on closing RSUs/PSUs Upon closing, all RSUs and PSUs will vest and will receive the same per share cash and CVR consideration as stock; you will be paid through payroll, net of withholding taxes

What Else This Means for You Bonuses 2021 bonuses and sales incentives will be paid to eligible employees in Q1 2022 Approved corporate goal achievement in 2021 is 101% Salary 2022 Salary increases will be communicated in Q1 2022 For employees continuing with the combined company, salaries will be comparable to their Zogenix salary for at least 12 months after closing Equity Eligible non-executive employees will receive their ordinary course 2022 annual awards in the form of cash-settled RSUs More details on this will be available in the coming weeks Severance A severance plan will be shared by HR

Next Steps: Timing and Integration Planning Timing to Close Transaction is expected to close in the second quarter Until then, Zogenix and UCB continue to operate as separate, independent companies Business as usual; remain focused on day-to-day operations and continue work towards 2022 corporate & department goals, including US approval and launch of FINTEPLA in LGS and advancing MT-1621 program to NDA and MAA submissions Integration Planning Still early and many decisions are yet to be made An Integration Planning Team will be formed and comprised of Zogenix and UCB leadership, which will plan how our organizations will come together No decisions concerning organizational structure will be finalized before the close We are committed to transparency and keeping you informed

Commitment to Transparency FAQs will be sent to employees today and posted on the ZONE Executive team members have scheduled meetings with each of their own departments for today and tomorrow UCB Head of Global Human Resources, Neurology & Rare and UCB Head of US Neurology & Rare are in Emeryville meeting the Zogenix ET and will hold group meetings with employees today and tomorrow The ZONE will be updated daily or as new information is available Updates at Monday morning check-in (assuming there is anything new to share) Support Programs have been planned to take place between signing and closing

Message From Jean-Christophe Tellier   Dear all,   Many thanks for giving me the opportunity to say hello to all of you on what is an important day for both companies. Unfortunately, I'm not able to join you live during your meeting, but I'm sure we will have occasions in the future to do so.   I'm excited that UCB and Zogenix have agreed to enter into an agreement for UCB to acquire Zogenix because I believe we share your passions to drive, discover and develop differentiated solutions to help patients suffering from very severe forms of epilepsy. So, this is today an important milestone for UCB and I'm looking forward to working with you to create even more value for these patients.   Like you, we saw the potential in Fintepla® and I'm convinced that in working with UCB we can deliver even more for Fintepla® and create even more value for patients in need. I know that this is a very important change for you and I expect that you are leaving today feeling a lot of mixed emotions. But we will get to know each other and I hope that through the dialogue you will be able to know more about us, you will be able to get more confidence, and we will be able to answer your questions along the road.   Now a few words about UCB. We are a purpose-driven company. Everything we do is with the aim to create value for patients and their families now and in the future. Our purpose is really embedded into our strategy. Patients and individual experiences are at the heart of everything we do and I understand that we have this in common.   We believe very strongly that a successful future must deliver value for all: people living with severe diseases, their family, colleagues, community, planet, stakeholders and shareholders. Because at the end, it doesn't make sense to create value for patients if this is at the expense of others. So, yes, sustainability is an integrate part of our strategy. We have a highly collaborative environment, we want everyone to thrive at UCB, to contribute to our journey, to be part of our communities. So, yes, we are looking forward to welcoming you in our organisation after the closing. So, once again, welcome and looking forward to seeing you in the near future at Emeryville. Thank you.

Additional Information and Where to Find It The tender offer described above has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of Zogenix, Inc. (the “Company”). The solicitation and the offer to buy shares of the Company’s common stock will only be made pursuant to a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials that UCB S.A. (the “Parent”) intends to cause Zinc Merger Sub, Inc. (“Merger Sub”) to file with the Securities and Exchange Commission (“SEC”). In addition, the Company will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and the Company with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by the Company under the “Investors” section of the Company’s website at www.zogenix.com. INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT OF THE COMPANY AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

EX-99.3

Exhibit 99.3

Zogenix FAQs

Contents

General Information		3
1.	What was announced?	3
2.	Who is UCB?	3
3.	Why is this good for Zogenix? How does it fit into our strategy?	3
4.	How do the values of the two companies align?	4
5.	When do you expect to close the transaction?	4
6.	Can we expect updates from UCB during this period before the deal closes?	4
7.	Can Zogenix employees interact with UCB employees?	4
8.	Who is on the integration planning team?	5
Impact to Employees		5
9.	How will the transaction with UCB affect the employees of Zogenix? Will there be layoffs?	5
10.	When will I know if my position is being eliminated? Can you provide detail on the level of layoffs you expect at Zogenix?	5
11.	Is there a severance program for affected employees?	5
12.	If my position is retained (or they offer me a comparable position) but I do not want to work for UCB/move to Atlanta, can I “take a package” instead?	5
13.	If I receive another job offer before this transaction closes, can I accept that job and still receive severance?	6
14.	Will I receive a retention bonus?	6
15.	Will I receive my 2021 bonus and a salary increase?	6
16.	What will happen to my stock options after the close?	6
17.	What happens to my existing restricted stock unit award(s) and performance stock unit awards after the close?	7
18.	What happens to any other Zogenix shares that I own?	7
19.	What happens if I voluntarily resign prior to the closing of the transaction?	7
20.	What happens if I exercise my currently vested stock options before the transaction is effective?	7
21.	What will happen to my benefits? If I continue employment with UCB, will my compensation and benefits package be the same as the package I currently have?	8
22.	Will there be new opportunities in terms of jobs and relocation? Will I be asked to relocate?	8

Business Operations		8
23.	What may I say to partners, suppliers, and others that I have contact with in the normal course of business? What may I say if they ask about the future of Zogenix?	8
24.	What should I do if I’m contacted by the media, the financial community, or other third parties about the transaction?	9
25.	Does this impact the commercial launch of Fintepla?	9
26.	Will this transaction impact any existing supply chain, patient services or commercialization agreements with our current partners?	9
27.	We have many job openings. Are we still hiring during this interim period?	9
28.	How does this effect MT 1621?	9
•	This announcement has no impact on our NDA and MAA target dates of Q4 2022 and Q1 2023 respectively; nor does it impact Zogenix’s commitment to this program	9
29.	Where will the combined company be headquartered and who will lead it?	10
30.	What will happen to our current office facilities?	10
31.	If I have additional questions, who can I ask?	10
Technical Questions		10
32.	What is a tender offer?	10
33.	What is a Contingent Value Right?	11

Thank you for your patience and understanding throughout this process. We appreciate and understand your desire for more information. While we are not able to answer every question at this time, we will attempt to answer as many as we can, and we are committed to transparency and communication during the process. For now, it is very important that we all remain focused on running our business and serving our patients and their families.

General Information

1. What was announced?

• We announced that Zogenix has agreed to be acquired by UCB in a transaction valued at $1.9 billion.

• Upon the closing of the transaction, Zogenix shareholders will receive $26.00 per share in cash. In addition, shareholders will receive one Contingent Value Right (CVR) per share. Each CVR entitles the holder to receive $2.00 in cash for each CVR held if (and only if), no later than December 31, 2023 the European Commission approves the therapeutic indication for seizures associated with Lennox-Gastaut syndrome for Fintepla as an orphan medicinal product after the EMA has recommended that fenfluramine for the treatment of Lennox-Gastaut syndrome not be removed from the EU’s register of orphan medicinal products. (the “Milestone”).

• This is an important milestone for our company, and we are confident it will help position Fintepla for successful global launches and enhance Fintepla’s ability to reach patients around the world.

2. Who is UCB?

• Like Zogenix, UCB shares a focus on neurology and a passion for helping patients. They are a global leader in neuroscience research and development with a strong, established portfolio of commercialized therapies across three neurology disease areas – Epilepsy, Parkinson’s Disease & Restless Legs Syndrome.

• UCB is headquartered in Brussels, Belgium and has more than 8,000 employees worldwide, with products registered in more than 40 countries. Its U.S. operations are based in Atlanta, Georgia.

3. Why is this good for Zogenix? How does it fit into our strategy?

• At Zogenix, we have made tremendous strides in advancing the treatments for rare diseases to address significant unmet patient needs.

• UCB shares our confidence in Fintepla’s tremendous potential, and we are confident their global scale and resources and proven product launch experience will help bring Fintepla to more patients around the world.

• In addition, both companies share a commitment to serving patients with high unmet needs, and to discovering, developing, and commercializing novel therapies to improve the lives of those suffering from rare, complex, and debilitating conditions.

• From a financial perspective, the transaction creates substantial and immediate value for Zogenix shareholders, as well as further potential upside upon the achievement of the Milestone.

4. How do the values of the two companies align?

• UCB’s patient focus in neurology and rare disease is closely aligned to Zogenix’s, and they share our commitment to serving patients with unmet needs.

• Both organizations have highly experienced and talented employees dedicated to improving the lives of patients suffering from complex diseases.

• In addition, both companies share a commitment to discovering, developing, and commercializing novel therapies to improve the lives of those suffering from rare, complex, and debilitating neurologic conditions.

• UCB’s values are closely aligned with those of Zogenix: Patients at the heart, Innovation, Passion for Performance, Entrepreneurship, Integrity, Care, Accountability, & Embracing Difference compared to our Zogenix values of Compassion, Courage, Collaboration & Excellence.

5. When do you expect to close the transaction?

• We expect to close the transaction in the second quarter of 2022, subject to customary closing conditions and the receipt of transaction-related regulatory approvals. Regulatory delays or other events could cause this timeline to be extended.

• Until the transaction closes, Zogenix and UCB will continue to operate as separate and independent companies, and it is business as usual at Zogenix.

• The most important thing you can do is remain focused on your day-to-day responsibilities as we continue preparing for Fintepla’s U.S. launch for Lennox-Gastaut Syndrome.

6. Can we expect updates from UCB during this period before the deal closes?

• Until the transaction closes, Zogenix and UCB will continue to operate as separate, independent companies and it is business as usual at Zogenix.

• Any updates you receive regarding the transaction will come from Zogenix’s leadership team.

• We will keep you informed as quickly and as transparently as we can as we move through this process and encourage you to regularly check The Zone for updates.

7. Can Zogenix employees interact with UCB employees?

• Until the transaction closes, Zogenix and UCB will continue to operate as separate, independent companies, and it is business as usual at Zogenix.

• Until then, discussions with UCB team members must be directed through an integration planning team.

• It is very important that you do not engage with UCB employees unless a member of Zogenix executive leadership team explicitly directs you to do so.

8. Who is on the integration planning team?

• We are working through those details now. We will keep you informed as quickly and as transparently as possible as we move through this process and encourage you to regularly check The Zone for updates.

Impact to Employees

9. How will the transaction with UCB affect the employees of Zogenix? Will there be layoffs?

• Zogenix and UCB will continue to operate as separate, independent companies prior to the closing of the transaction, and Zogenix will continue its normal business activities. You will continue reporting to your current manager. Your job responsibilities will remain unchanged prior to the closing of the transaction.

• It’s important to note that in all its public statements, UCB has specifically said that it values the strong presence that Zogenix has established in the marketplace and believes the proposed acquisition can add another potential growth dimension for its Neurology & Rare segment, through our reach into this important market. Our job is to ensure that our customers and patients continue to receive the highest possible standards of service and support. After the closing of the transaction, UCB will evaluate the organization and make decisions on the appropriate future structure.

10. When will I know if my position is being eliminated? Can you provide detail on the level of layoffs you expect at Zogenix?

• UCB has specifically said that it values the strong relationships and presence that Zogenix has established in the marketplace. UCB will need to take the appropriate time to assess the Zogenix organization and make employment-related decisions. For now, it is very important that we all remain focused serving our patients and their families who depend on FINTEPLA to treat Dravet Syndrome and ensuring continued success of Zogenix.

11. Is there a severance program for affected employees?

• Yes. Zogenix maintains a severance policy that provides employees who are involuntarily terminated with severance benefits based on level and years of service. UCB has agreed to honor the Zogenix severance policy for any involuntary terminations that occur during the first year following the closing of the transaction. Details of the severance program will be communicated to Zogenix employees soon.

12. If my position is retained (or they offer me a comparable position) but I do not want to work for UCB/move to Atlanta, can I “take a package” instead?

• Details of the severance program will be communicated to Zogenix employees soon.

13. If I receive another job offer before this transaction closes, can I accept that job and still receive severance?

• You will need to be an employee at Zogenix/UCB at the time a severance package is offered to be eligible for a severance package.

14. Will I receive a retention bonus?

• It is still early in the process, and there are many decisions that have yet to be made. Details regarding roles, salaries, and benefits will be worked out following the close. As soon as these details are finalized, we will update you. Any available integration planning updates will be shared on The Zone.

15. Will I receive my 2021 bonus and a salary increase?

• Zogenix employees will be eligible to receive their 2021 corporate bonuses, or field sales incentive bonuses in accordance with our approved bonus plans, and employees will also be eligible to receive a 2022 salary increase.

16. What will happen to my stock options at the closing?

• Each stock option that is outstanding (i.e., options that have not been exercised or forfeited) on the closing date of the transaction, whether vested or unvested, with an exercise price that is less than $26.00 per share, will be cancelled, terminated, and converted into the right to receive:

• A cash payment determined by multiplying: (1) $26.00 minus the applicable exercise price per share of such option, and (2) the number of shares of common stock underlying such option, plus

• One CVR for each share subject to such stock option.

For example, if you currently have an option to purchase 100 shares at an exercise price of $20.00 per share, you will receive a cash payment at closing of $600 ($26.00 - $20.00) times 100), less applicable withholding taxes, plus 100 CVRs.

• Each stock option that is outstanding (i.e., options that have not been exercised or forfeited) on the closing date of the transaction, whether vested or unvested, with an exercise price that is at least $26.00 per share but less than $28.00 per share, will be cancelled, terminated, and converted into the right to receive a cash payment if the Milestone is achieved and the CVRs are paid out determined by multiplying: (1) $28.00 minus the applicable exercise price per share of such option, and (2) the number of shares of common stock underlying such option.

• Any stock option that has a per share exercise price that is equal to or greater than $28.00 will be cancelled without consideration upon the closing of the transaction.

• If you leave the Company for any reason before the closing of the transaction, all your unvested options will immediately terminate. All your options that have vested as of your separation date will continue to be exercisable for 90 days following your last day of employment. If the transaction closing date occurs during this 90-day period, your vested options will be cancelled, terminated, and converted into the right to receive the consideration indicated above.

• You may also exercise your stock options as outlined below in Question 21. However, no option exercises will be permitted for three days prior to the closing of the transaction.

Every situation is unique, and you should consult with your personal tax advisor to confirm the tax treatment specific to your personal situation.

17. What happens to my existing restricted stock unit award(s) and performance stock unit awards at closing?

• Many employees have restricted stock unit awards (“RSUs”) and performance stock unit awards (“PSUs”) that remain outstanding. Upon the closing of the transaction, the RSUs and PSUs will be cancelled, terminated, and converted into the right to receive:

• a cash payment determined by multiplying: (1) $26.00, and (2) the number of shares of common stock underlying such RSU or PSU award (with the PSU award treated as being fully earned for this purpose with respect to all share subject to the award), less applicable taxes, plus one CVR for each share of common stock underlying such RSU or PSU award.

If your employment terminates for any reason before the closing of the transaction, any RSUs or PSUs that were granted prior to January 1, 2022 and that have not vested as of your termination date will be forfeited and will not be subject to acceleration.

Every situation is unique, and you should consult with your personal tax advisor to confirm the tax treatment specific to your personal situation.

18. What happens to any other Zogenix shares that I own?

• In the coming weeks, a “Tender Offer” will commence during which UCB will offer to acquire all outstanding shares of Zogenix stock. At the time the Tender Offer is commenced, you will be provided with an opportunity to tender each share you own in exchange for $26.00 per share, without interest, plus one CVR. You may also sell your shares prior to the closing of the transaction during an open trading window (see Question 19).

Every situation is unique, and you should consult with your personal tax advisor to confirm the tax treatment specific to your personal situation.

19. What happens if I voluntarily resign prior to the closing of the transaction?

• If you voluntarily terminate your employment at any time prior to the closing of the transaction, you will not be entitled to any severance pay or benefits and your unvested equity awards will terminate just like any standard termination prior to this announcement.

20. What happens if I exercise my currently vested stock options before the transaction is effective?

• You may exercise your vested stock options in accordance with our normal procedures for exercising options, which require pre-clearance. If you are planning to sell your shares, including doing a same-day sale, you may do so only in an open trading window and so long as you are not in possession of material non-public information and follow our procedures for selling. Our trading window is currently closed. Although we typically open the trading window for most employees two business days after the public release of earnings data for the fourth quarter of 2021, given current circumstances we may not open the trading window, or we may be required to close the trading window early and without advance notice.

• If, prior to the expiration of the Tender Offer, you elect to exercise your stock options and hold the shares, you may choose to tender your shares to UCB after the close.

• If you do not exercise your vested stock options prior to the expiration of the Tender Offer, your options will be cancelled in exchange for the consideration described in Question 15 above.

• However, no option exercises will be permitted for three days prior to the closing of the transaction.

Every situation is unique, and you should consult with your personal tax advisor to confirm the tax treatment specific to your personal situation.

21. What will happen to my benefits? If I continue employment with UCB, will my compensation and benefits package be the same as the package I currently have?

• The Zogenix benefit plans will continue at least through the closing of the transaction. We understand that UCB offers a comparable range of employee benefit programs and will do what we can to provide more information about their benefits programs at some future point.

• If any positions are eliminated as a result of the closing of the transaction and impacted individuals are a current participant in a Zogenix healthcare insurance plan, COBRA coverage will be available. COBRA is generally available for up to 18 months after termination of employment if you are eligible to receive severance benefits. Information about COBRA would be provided in such circumstances.

22. Will there be new opportunities in terms of jobs and relocation? Will I be asked to relocate?

• While it is possible, it is still early in the process, and there are many decisions that have yet to be made.

• Between now and close, the integration planning team comprised of Zogenix and UCB leadership will determine how our organizations will come together.

• However, decisions regarding organizational structure will not be finalized before the close. This means that details regarding roles, salaries and benefits will be worked out following close.

• We are committed to keeping you informed, and we will provide additional details on our integration planning as decisions are made.

Business Operations

23. What may I say to partners, suppliers, and others that I have contact with in the normal course of business? What may I say if they ask about the future of Zogenix?

• Our Executive Team and Corporate Communications are reaching out to our partners, suppliers, and key vendors. For those people that you are in contact with during the normal course of business, you can share the press release that was distributed to all employees and is also available on our company website. You may only communicate that we will not know any further information until the closing of the transaction.

24. What should I do if I’m contacted by the media, the financial community, or other third parties about the transaction?

• Should you be contacted by members of the media or financial community or other third parties regarding this transaction, please refer all inquiries directly to Mike Smith, EVP, Chief Financial Officer.

25. Does this impact the commercial launch of Fintepla?

• This announcement has no impact on our PDUFA target action date, which the FDA set for March 25, 2022.

• We remain on track to launch Fintepla for Lennox-Gastaut Syndrome in the US, upon approval, in April 2022. All commercial and operational readiness activities for the launch will continue as planned.

• Importantly, we are confident that UCB’s global scale and resources and proven product launch experience will help position Fintepla for successful global launches and enhance its ability to reach more patients around the world.

26. Will this transaction impact any existing supply chain, patient services or commercialization agreements with our current partners?

• There are no changes to our current contracts, and we expect them to remain in effect following the transaction.

• It is business as usual with our current partners and our plans to produce, distribute and commercialize Fintepla remain the same.

• Our patient services offered through Zogenix Central will continue offering exceptional support to the patient community.

27. We have many job openings. Are we still hiring during this interim period?

• It is important to note that both Zogenix and UCB recognize the need to hire additional staff for a successful launch of Fintepla in US and Europe, as well as to advance our development programs forward. Until the transaction closes, we will be pausing any non-critical hiring. Please consult with your department’s executive team member for any hiring needs and/or decisions.

28. How does this transaction impact the MT 1621 program?

• This transaction has no impact on our NDA and MAA target dates of Q4 2022 and Q1 2023 respectively; nor does it impact our commitment to this program.

• We urge all team members to stay focused on their roles and continue their work to bring this important therapy to patients who need it

29. Where will the combined company be headquartered and who will lead it?

• No decisions concerning organizational structure will be finalized before the close.

• Following the close, Jean-Christophe Tellier, UCB’s CEO, will lead the combined company. We will continue to keep you informed as we move through this process and encourage you to regularly check the Zone for updates.

30. What will happen to our current office facilities?

• Please keep in mind that these are still early days of our relationship with UCB, and many details remain to be worked out.

• Between now and close, we will form an integration planning team comprised of Zogenix and UCB leadership that will begin planning how our organizations will come together.

• However, decisions regarding organizational structure will not be finalized before the close. We will take the time needed to carefully assess and discuss these important issues.

• We will continue to keep you informed as we move through this process and encourage you to regularly check the intranet site for updates.

31. If I have additional questions, who can I ask?

• We encourage you to speak with your manager or any member of the executive team.

• Here is a contact list for any other questions:

• Communication with vendors – Finance

• Equity – stockadmin@zogenix.com

• Benefits – HR@zogenix.com

Technical Questions

32. What is a tender offer?

• A tender offer is an offer made by an entity directly to a company’s shareholders to purchase their stock for cash, stock, or a combination of both. In this case, UCB is making an offer to purchase all shares of Zogenix for a cash payment at closing in the amount of $26.00 per share plus one CVR per share.

• Shareholders are given the opportunity to “tender,” or sell their stock for a set price within a stated time limit.

• A tender offer must comply with the rules and regulations of the Securities and Exchange Commission, which include certain minimum offering periods, withdrawal rights, manner of publication and other requirements.

• Further details on the tender offer will be made available in documents filed with the Securities and Exchange Commission, which are expected to be filed by Zogenix and UCB later this week.

33. What is a Contingent Value Right?

• A Contingent Value Right (CVR) refers to a promise of value to be provided in the future, typically in the form of a cash payment. A CVR ensures that the shareholders get certain benefits if a specific event occurs after the closing of an acquisition.

* * *

Additional Information and Where to Find It

The tender offer described above has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of Zogenix, Inc. (the “Company”). The solicitation and the offer to buy shares of the Company’s common stock will only be made pursuant to a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials that UCB S.A. (the “Parent”) intends to cause Zinc Merger Sub, Inc. (“Merger Sub”) to file with the Securities and Exchange Commission (“SEC”). In addition, the Company will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and the Company with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by the Company under the “Investors” section of the Company’s website at www.zogenix.com.

INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT OF THE COMPANY AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

Forward-Looking Statements

The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. These forward-looking statements include without limitation statements regarding the planned completion of the transactions contemplated by the Agreement and Plan of Merger dated as of January 18, 2022 by and among the Company, Merger Sub and Parent. Risks and uncertainties that could cause results to differ from expectations include: (i) uncertainties as to the timing of the Offer and the subsequent

Merger; (ii) the risk that the Offer or the subsequent Merger may not be completed in a timely manner or at all; (iii) uncertainties as to the percentage of the Company’s stockholders tendering their shares in the Offer; (iv) the possibility that competing offers or acquisition proposals for the Company will be made; (v) the possibility that any or all of the various conditions to the consummation of the Offer or the subsequent Merger may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); (vi) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement; (vii) risk that the milestone specified in the CVR Agreement is not achieved, (viii) the effect of the announcement or pendency of the transactions contemplated by the Merger Agreement on the Company’s ability to retain and hire key personnel, its ability to maintain relationships with its customers, suppliers and others with whom it does business, or its operating results and business generally; (ix) risks related to diverting management’s attention from the Company’s ongoing business operations; (x) the risk that stockholder litigation in connection with the transactions contemplated by the Merger Agreement may result in significant costs of defense, indemnification and liability; and (xi) risks and uncertainties pertaining to the Company’s business, including the risks and uncertainties detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 and its other filings with the SEC, as well as the tender offer materials to be filed by Merger Sub and Parent and the Solicitation/Recommendation Statement to be filed by the Company in connection with the tender offer.

You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement and the Company undertakes no obligation to revise or update these statements to reflect events or circumstances after the date hereof, except as required by law.

EX-99.4

Exhibit 99.4

January 19, 2022

Dear [Valued Supplier / Vendor / Partner],

As you are a valued partner to Zogenix, I am writing to update you about some important news about Zogenix. Today we announced Zogenix has entered into an agreement to be acquired by UCB S.A., a global leader in developing and commercializing innovative therapies in neurology and immunology. The news release, which includes more information regarding the transaction, can be found at https://www.prnewswire.com/news-releases/ucb-to-acquire-zogenix-301463511.html.

UCB has a successful track record in epilepsy and is committed to addressing unmet needs of people living with specific or rare forms of epilepsy, and other rare neurological diseases. UCB is headquartered in Brussels, Belgium, employs approximately 8,000 people worldwide and its U.S. operations are based in Atlanta, Georgia.

We expect the transaction to close in the second quarter of 2022, subject to regulatory approvals and other customary closing conditions. Until that time, both Zogenix and UCB will remain separate companies and your contacts at Zogenix will remain the same. We will communicate important updates as information becomes available.

In the meantime, please do not hesitate to reach out to your Zogenix contact if you have any questions. As always, thank you for your continued support. We recognize our partnership has played an important role in our success, and we looked forward to continuing it.

Sincerely,

[NAME]

*    *     *

Additional Information and Where to Find It

The tender offer described above has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of Zogenix, Inc. (the “Company”). The solicitation and the offer to buy shares of the Company’s common stock will only be made pursuant to a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials that UCB S.A. (the “Parent”) intends to cause Zinc Merger Sub, Inc. (“Merger Sub”) to file with the Securities and Exchange Commission (“SEC”). In addition, the Company will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and the Company with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by the Company under the “Investors” section of the Company’s website at www.zogenix.com. INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT OF THE COMPANY AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

Forward-Looking Statements

The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. These forward-looking statements include without limitation statements regarding the planned completion of the transactions contemplated by the Agreement and Plan of Merger dated as of January 18, 2022 by and among the Company, Merger Sub and Parent. Risks and uncertainties that could cause results to differ from expectations include: (i) uncertainties as to the timing of the Offer and the subsequent Merger; (ii) the risk that the Offer or the subsequent Merger may not be completed in a timely manner or at all; (iii) uncertainties as to the percentage of the Company’s stockholders tendering their shares in the Offer; (iv) the possibility that competing offers or acquisition proposals for the Company will be made; (v) the possibility that any or all of the various conditions to the consummation of the Offer or the subsequent Merger may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); (vi) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement; (vii) risk that the milestone specified in the CVR Agreement is not achieved, (viii) the effect of the announcement or pendency of the transactions contemplated by the Merger Agreement on the Company’s ability to retain and hire key personnel, its ability to maintain relationships with its customers, suppliers and others with whom it does business, or its operating results and business generally; (ix) risks related to diverting management’s attention from the Company’s ongoing business operations; (x) the risk that stockholder litigation in connection with the transactions contemplated by the Merger Agreement may result in significant costs of defense, indemnification and liability; and (xi) risks and uncertainties pertaining to the Company’s business, including the risks and uncertainties detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 and its other filings with the SEC, as well as the tender offer materials to be filed by Merger Sub and Parent and the Solicitation/Recommendation Statement to be filed by the Company in connection with the tender offer.

You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement and the Company undertakes no obligation to revise or update these statements to reflect events or circumstances after the date hereof, except as required by law.

EX-99.5

Exhibit 99.5

January 19, 2022

Dear [ESL],

As you are a valued partner to Zogenix, I am writing to update you about some important news about Zogenix. Today we announced Zogenix has entered into an agreement to be acquired by UCB S.A., a global leader in developing and commercializing innovative therapies in neurology and immunology. We believe this transaction will benefit patients and caregivers that we currently serve with Dravet syndrome, LGS, CDD, and TK2d. The news release, which includes more information regarding the transaction, can be found at https://www.prnewswire.com/news-releases/ucb-to-acquire-zogenix-301463511.html.

We strongly believe this transaction will allow more patients globally to benefit from our existing medicines and our potential future pipeline. As you may know, UCB has a successful track record in epilepsy and is committed to addressing unmet needs of people living with specific or rare forms of epilepsy, and other rare neurological diseases. UCB is headquartered in Brussels, Belgium, employs approximately 8,000 people worldwide and its U.S. operations are based in Atlanta, Georgia.

We expect the transaction to close in the second quarter of 2022, subject to regulatory approvals and other customary closing conditions. Until that time, both Zogenix and UCB will remain separate companies and your contacts at Zogenix will remain the same. We will communicate important updates as information becomes available.

In the meantime, please do not hesitate to reach out to us if you have any questions. Lastly, and as always, we want to truly thank you for your unwavering and continued support over the years. We believe our partnership has made a transformational impact on our patients’ lives and we looked forward to continuing working with you to make a bigger impact around the globe.

Sincerely,

[NAME]

*    *     *

Additional Information and Where to Find It

The tender offer described above has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of Zogenix, Inc. (the “Company”). The solicitation and the offer to buy shares of the Company’s common stock will only be made pursuant to a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials that UCB S.A. (the “Parent”) intends to cause Zinc Merger Sub, Inc. (“Merger Sub”) to file with the Securities and Exchange Commission (“SEC”). In addition, the Company will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and the Company with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by the Company under the “Investors” section of the Company’s website at www.zogenix.com.

INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT OF THE COMPANY AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

Forward-Looking Statements

The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. These forward-looking statements include without limitation statements regarding the planned completion of the transactions contemplated by the Agreement and Plan of Merger dated as of January 18, 2022 by and among the Company, Merger Sub and Parent. Risks and uncertainties that could cause results to differ from expectations include: (i) uncertainties as to the timing of the Offer and the subsequent Merger; (ii) the risk that the Offer or the subsequent Merger may not be completed in a timely manner or at all; (iii) uncertainties as to the percentage of the Company’s stockholders tendering their shares in the Offer; (iv) the possibility that competing offers or acquisition proposals for the Company will be made; (v) the possibility that any or all of the various conditions to the consummation of the Offer or the subsequent Merger may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); (vi) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement; (vii) risk that the milestone specified in the CVR Agreement is not achieved, (viii) the effect of the announcement or pendency of the transactions contemplated by the Merger Agreement on the Company’s ability to retain and hire key personnel, its ability to maintain relationships with its customers, suppliers and others with whom it does business, or its operating results and business generally; (ix) risks related to diverting management’s attention from the Company’s ongoing business operations; (x) the risk that stockholder litigation in connection with the transactions contemplated by the Merger Agreement may result in significant costs of defense, indemnification and liability; and (xi) risks and uncertainties pertaining to the Company’s business, including the risks and uncertainties detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 and its other filings with the SEC, as well as the tender offer materials to be filed by Merger Sub and Parent and the Solicitation/Recommendation Statement to be filed by the Company in connection with the tender offer.

You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement and the Company undertakes no obligation to revise or update these statements to reflect events or circumstances after the date hereof, except as required by law.

EX-99.6

Exhibit 99.6

January 19, 2022

Dear [PAG],

As you are a valued partner to Zogenix, we are writing to update you about some important news about Zogenix. Today we announced Zogenix has entered into an agreement to be acquired by UCB S.A., a global leader in developing and commercializing innovative therapies in neurology and immunology. We believe this transaction will benefit patients and caregivers that we currently serve with [Dravet syndrome/ LGS/ CDD// TK2d]. The news release, which includes more information regarding the transaction, can be found at https://www.prnewswire.com/news-releases/ucb-to-acquire-zogenix-301463511.html.

We strongly believe this transaction will allow more patients globally to benefit from our existing medicines and from our potential future pipleine. As you may know, UCB has a successful track record in epilepsy and is committed to addressing unmet needs of people living with specific or rare forms of epilepsy, and other rare neurological diseases. UCB is headquartered in Brussels, Belgium, employs approximately 8,000 people worldwide and its U.S. operations are based in Atlanta, Georgia.

We expect the transaction to close in the second quarter of 2022, subject to regulatory approvals and other customary closing conditions. Until that time, both Zogenix and UCB will remain separate companies and your contacts at Zogenix will remain the same. We will communicate important updates as information becomes available.

In the meantime, please do not hesitate to reach out to us if you have any questions. Lastly, and as always, we want to truly thank you for your unwavering and continued support over the years. We believe our partnership has made a transformational impact on our patients’ lives and we looked forward to continuing working with you to make a bigger impact around the globe.

Sincerely,

[NAME]

* * *

Additional Information and Where to Find It

The tender offer described above has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of Zogenix, Inc. (the “Company”). The solicitation and the offer to buy shares of the Company’s common stock will only be made pursuant to a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials that UCB S.A. (the “Parent”) intends to cause Zinc Merger Sub, Inc. (“Merger Sub”) to file with the Securities and Exchange Commission (“SEC”). In addition, the Company will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and the Company with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by the Company under the “Investors” section of the Company’s website at www.zogenix.com.

INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT OF THE COMPANY AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

Forward-Looking Statements

The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. These forward-looking statements include without limitation statements regarding the planned completion of the transactions contemplated by the Agreement and Plan of Merger dated as of January 18, 2022 by and among the Company, Merger Sub and Parent. Risks and uncertainties that could cause results to differ from expectations include: (i) uncertainties as to the timing of the Offer and the subsequent Merger; (ii) the risk that the Offer or the subsequent Merger may not be completed in a timely manner or at all; (iii) uncertainties as to the percentage of the Company’s stockholders tendering their shares in the Offer; (iv) the possibility that competing offers or acquisition proposals for the Company will be made; (v) the possibility that any or all of the various conditions to the consummation of the Offer or the subsequent Merger may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); (vi) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement; (vii) risk that the milestone specified in the CVR Agreement is not achieved, (viii) the effect of the announcement or pendency of the transactions contemplated by the Merger Agreement on the Company’s ability to retain and hire key personnel, its ability to maintain relationships with its customers, suppliers and others with whom it does business, or its operating results and business generally; (ix) risks related to diverting management’s attention from the Company’s ongoing business operations; (x) the risk that stockholder litigation in connection with the transactions contemplated by the Merger Agreement may result in significant costs of defense, indemnification and liability; and (xi) risks and uncertainties pertaining to the Company’s business, including the risks and uncertainties detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 and its other filings with the SEC, as well as the tender offer materials to be filed by Merger Sub and Parent and the Solicitation/Recommendation Statement to be filed by the Company in connection with the tender offer.

You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement and the Company undertakes no obligation to revise or update these statements to reflect events or circumstances after the date hereof, except as required by law.

EX-99.7

Exhibit 99.7

SUBJECT: UCB to Acquire Zogenix in Transaction Valued at US$1.9 Billion

[NAME],

Tonight we announced that Zogenix has entered into an agreement to be acquired by UCB (Euronext: UCB) in a transaction valued at $1.9 billion. The press release we issued can be found at https://www.prnewswire.com/news-releases/ucb-to-acquire-zogenix-301463511.html.

Key highlights of the transaction include:

• Zogenix shareholders will receive $26.00 per share in cash and one Contingent Value Right per share, entitling them to receive an additional $2.00 per share the receipt of the approval of Fintepla for treatment of seizures associated with Lennox-Gastaut syndrome (LGS) with retention of Orphan Drug Designation on or before December 31, 2023. The transaction is structured as a tender offer and expected to close by the end of the second quarter of 2022.

• We believe this transaction delivers substantial and immediate value to our shareholders with the upfront consideration representing a 72% premium to Zogenix shares based on the 30-day volume weighted average closing stock price of Zogenix prior to signing.

• UCB a global biopharmaceutical company focused on bringing innovative therapies to address unmet needs of people living with epilepsy and other severe neurological and immunological and rare diseases,

• U.S. and EU launches for Fintepla in Dravet syndrome continues momentum and we remain on track for a U.S. PDUFA date for Fintepla in LGS in the second quarter of 2022.

We will be arranging one-on-one conversations over the next couple of days and would be happy to schedule a call.

As always, thank you for your continuing support of Zogenix.

Regards,

[NAME]

* * *

Additional Information and Where to Find It

The tender offer described above has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of Zogenix, Inc. (the “Company”). The solicitation and the offer to buy shares of the Company’s common stock will only be made pursuant to a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials that UCB S.A. (the “Parent”) intends to cause Zinc Merger Sub, Inc. (“Merger Sub”) to file with the Securities and Exchange Commission (“SEC”). In addition, the Company will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and the Company with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by the Company under the “Investors” section of the Company’s website at www.zogenix.com.

INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT OF THE COMPANY AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

Forward-Looking Statements

The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. These forward-looking statements include without limitation statements regarding the planned completion of the transactions contemplated by the Agreement and Plan of Merger dated as of January 18, 2022 by and among the Company, Merger Sub and Parent. Risks and uncertainties that could cause results to differ from expectations include: (i) uncertainties as to the timing of the Offer and the subsequent Merger; (ii) the risk that the Offer or the subsequent Merger may not be completed in a timely manner or at all; (iii) uncertainties as to the percentage of the Company’s stockholders tendering their shares in the Offer; (iv) the possibility that competing offers or acquisition proposals for the Company will be made; (v) the possibility that any or all of the various conditions to the consummation of the Offer or the subsequent Merger may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); (vi) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement; (vii) risk that the milestone specified in the CVR Agreement is not achieved, (viii) the effect of the announcement or pendency of the transactions contemplated by the Merger Agreement on the Company’s ability to retain and hire key personnel, its ability to maintain relationships with its customers, suppliers and others with whom it does business, or its operating results and business generally; (ix) risks related to diverting management’s attention from the Company’s ongoing business operations; (x) the risk that stockholder litigation in connection with the transactions contemplated by the Merger Agreement may result in significant costs of defense, indemnification and liability; and (xi) risks and uncertainties pertaining to the Company’s business, including the risks and uncertainties detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 and its other filings with the SEC, as well as the tender offer materials to be filed by Merger Sub and Parent and the Solicitation/Recommendation Statement to be filed by the Company in connection with the tender offer.

You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement and the Company undertakes no obligation to revise or update these statements to reflect events or circumstances after the date hereof, except as required by law.

EX-99.8

Exhibit 99.8

SUBJECT: UCB to Acquire Zogenix in Transaction Valued at $1.9 Billion

[NAME],

We’ve just announced that we have entered into an agreement to be acquired by UCB (Euronext: UCB) in a transaction valued at $1.9 billion. The press release with additional details regarding the transaction can be found at https://www.prnewswire.com/news-releases/ucb-to-acquire-zogenix-301463511.html.

Upon closing of the transaction, Zogenix shareholders will receive $26.00 per share in cash and one Contingent Value Right per share, entitling them to receive an additional $2.00 per share upon receipt of EU approval of FINTEPLA^® as an orphan drug for the treatment of seizures associated with Lennox-Gastaut syndrome (LGS) on or before December 31, 2023. The transaction is structured as a tender offer and is expected to close by the end of the second quarter of 2022.

UCB is a global biopharmaceutical company focused on the development and commercialization of innovative therapies to address unmet needs of people living with severe neurological and immunological diseases. As a recognized leader in epilepsy, UCB shares in our excitement for FINTEPLA and its potential to bring significant and differentiated value to patients suffering from Dravet syndrome and, if approved, LGS and potentially other rare epilepsies. Additionally, UCB believes the transaction enhances their future epilepsy pipeline and strategic priorities in rare/orphan diseases.

As always, thank you for your continuing support of Zogenix.

Regards,

[NAME]

* * *

Additional Information and Where to Find It

The tender offer described above has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of Zogenix, Inc. (the “Company”). The solicitation and the offer to buy shares of the Company’s common stock will only be made pursuant to a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials that UCB S.A. (the “Parent”) intends to cause Zinc Merger Sub, Inc. (“Merger Sub”) to file with the Securities and Exchange Commission (“SEC”). In addition, the Company will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and the Company with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by the Company under the “Investors” section of the Company’s website at www.zogenix.com.

INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT OF THE COMPANY AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

Forward-Looking Statements

The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. These forward-looking statements include without limitation statements regarding the planned completion of the transactions contemplated by the Agreement and Plan of Merger dated as of January 18, 2022 by and among the Company, Merger Sub and Parent. Risks and uncertainties that could cause results to differ from expectations include: (i) uncertainties as to the timing of the Offer and the subsequent Merger; (ii) the risk that the Offer or the subsequent Merger may not be completed in a timely manner or at all; (iii) uncertainties as to the percentage of the Company’s stockholders tendering their shares in the Offer; (iv) the possibility that competing offers or acquisition proposals for the Company will be made; (v) the possibility that any or all of the various conditions to the consummation of the Offer or the subsequent Merger may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); (vi) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement; (vii) risk that the milestone specified in the CVR Agreement is not achieved, (viii) the effect of the announcement or pendency of the transactions contemplated by the Merger Agreement on the Company’s ability to retain and hire key personnel, its ability to maintain relationships with its customers, suppliers and others with whom it does business, or its operating results and business generally; (ix) risks related to diverting management’s attention from the Company’s ongoing business operations; (x) the risk that stockholder litigation in connection with the transactions contemplated by the Merger Agreement may result in significant costs of defense, indemnification and liability; and (xi) risks and uncertainties

pertaining to the Company’s business, including the risks and uncertainties detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 and its other filings with the SEC, as well as the tender offer materials to be filed by Merger Sub and Parent and the Solicitation/Recommendation Statement to be filed by the Company in connection with the tender offer.

You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement and the Company undertakes no obligation to revise or update these statements to reflect events or circumstances after the date hereof, except as required by law.

EX-99.9

Exhibit 99.9

Subject: Zogenix Announcement Tonight

Hello Zogenix consultants and temporary staff,

Tonight we announced that Zogenix has entered into an agreement to be acquired by UCB, a global leader in developing and commercializing innovative therapies in neurology and immunology. The news release, which includes more information regarding the transaction, can be found at https://www.prnewswire.com/news-releases/ucb-to-acquire-zogenix-301463511.html.

UCB has a wealth of experience in epilepsy and is committed to addressing unmet needs of people living with specific or rare forms of epilepsy, as well as other rare neurological diseases. UCB is headquartered in Brussels, Belgium, employs approximately 8,000 people worldwide and its U.S. operations are based in Atlanta, Georgia.

We realize that you will have many questions about how this will impact your involvement with Zogenix. Please expect more communication from your Zogenix leaders in the coming days. For now, it is business as usual, and you should remain focused on your responsibilities as we continue executing on our current launch of Fintepla in Dravet syndrome and preparing for our important upcoming regulatory milestones for our late stage programs.

Regards,

[NAME]

Additional Information and Where to Find It

The tender offer described above has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of Zogenix, Inc. (the “Company”). The solicitation and the offer to buy shares of the Company’s common stock will only be made pursuant to a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials that UCB S.A. (the “Parent”) intends to cause Zinc Merger Sub, Inc. (“Merger Sub”) to file with the Securities and Exchange Commission (“SEC”). In addition, the Company will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and the Company with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by the Company under the “Investors” section of the Company’s website at www.zogenix.com. INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT OF THE COMPANY AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

Forward-Looking Statements

The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. These forward-looking statements include without limitation statements regarding the planned completion of the transactions contemplated by the Agreement and Plan of Merger dated as of January 18, 2022 by and among the Company, Merger Sub and Parent. Risks and uncertainties that could cause results to differ from expectations include: (i) uncertainties as to the timing of the Offer and the subsequent Merger; (ii) the risk that the Offer or the subsequent Merger may not be completed in a timely manner or at all; (iii) uncertainties as to the percentage of the Company’s stockholders tendering their shares in the Offer; (iv) the possibility that competing offers or acquisition proposals for the Company will be made; (v) the possibility that any or all of the various conditions to the consummation of the Offer or the subsequent Merger may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); (vi) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement; (vii) risk that the milestone specified in the CVR Agreement is not achieved, (viii) the effect of the announcement or pendency of the transactions contemplated by the Merger Agreement on the Company’s ability to retain and hire key personnel, its ability to maintain relationships with its customers, suppliers and others with whom it does business, or its operating results and business generally; (ix) risks related to diverting management’s attention from the Company’s ongoing business operations; (x) the risk that stockholder litigation in connection with the transactions contemplated by the Merger Agreement may result in significant costs of defense, indemnification and liability; and (xi) risks and uncertainties pertaining to the Company’s business, including the risks and uncertainties detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 and its other filings with the SEC, as well as the tender offer materials to be filed by Merger Sub and Parent and the Solicitation/Recommendation Statement to be filed by the Company in connection with the tender offer.

EX-99.10

Exhibit 99.10

Dear [NAME],

I am writing to share some important news about Zogenix.

[Today / Last night] we announced that Zogenix has entered into an agreement to be acquired by UCB, a global leader in developing and commercializing innovative therapies in neurology and immunology. The news release, which includes more information about the pending merger, can be found at https://www.prnewswire.com/news-releases/ucb-to-acquire-zogenix-301463511.html.

Zogenix is committed to developing and commercializing therapies with the potential to transform the lives of patients and their families living with rare diseases; a commitment exemplified by our recent successful approval and launch of Fintepla for Dravet syndrome and the advancement of our late-stage rare disease pipeline toward additional regulatory milestones. UCB has a wealth of experience in epilepsy and is committed to addressing unmet needs of people living with specific or rare forms of epilepsy, as well as other rare neurological diseases. UCB is headquartered in Brussels, Belgium and employs approximately 8,000 people worldwide.

Please note this news has no impact on your pending employment with Zogenix or on your start date. We look forward to welcoming you to our team.

In terms of next steps, the transaction is expected to close in the second quarter of 2022 subject to regulatory approvals and other customary closing conditions. Until that time, both Zogenix and UCB will remain separate companies and your contacts at Zogenix will remain the same. We will communicate important updates as information becomes available.

In the meantime, please do not hesitate to reach out to me if you have questions.

Sincerely,

[NAME]

Additional Information and Where to Find It

The tender offer described above has not yet commenced. This communication is not an offer to buy nor a solicitation of an offer to sell any securities of Zogenix, Inc. (the “Company”). The solicitation and the offer to buy shares of the Company’s common stock will only be made pursuant to a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials that UCB S.A. (the “Parent”) intends to cause Zinc Merger Sub, Inc. (“Merger Sub”) to file with the Securities and Exchange Commission (“SEC”). In addition, the Company will file with the SEC a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer. Once filed, investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and the Company with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, any such documents filed with or furnished to the SEC by the Company under the “Investors” section of the Company’s website at www.zogenix.com. INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS WHEN THEY BECOME AVAILABLE, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT OF THE COMPANY AND ANY AMENDMENTS THERETO,

AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

Forward-Looking Statements

The statements included above that are not a description of historical facts are forward-looking statements. Words or phrases such as “believe,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “seek,” “plan,” “expect,” “should,” “would” or similar expressions are intended to identify forward-looking statements. These forward-looking statements include without limitation statements regarding the planned completion of the transactions contemplated by the Agreement and Plan of Merger dated as of January 18, 2022 by and among the Company, Merger Sub and Parent. Risks and uncertainties that could cause results to differ from expectations include: (i) uncertainties as to the timing of the Offer and the subsequent Merger; (ii) the risk that the Offer or the subsequent Merger may not be completed in a timely manner or at all; (iii) uncertainties as to the percentage of the Company’s stockholders tendering their shares in the Offer; (iv) the possibility that competing offers or acquisition proposals for the Company will be made; (v) the possibility that any or all of the various conditions to the consummation of the Offer or the subsequent Merger may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); (vi) the occurrence of any event, change or other circumstance that could give rise to the termination of the Merger Agreement; (vii) risk that the milestone specified in the CVR Agreement is not achieved, (viii) the effect of the announcement or pendency of the transactions contemplated by the Merger Agreement on the Company’s ability to retain and hire key personnel, its ability to maintain relationships with its customers, suppliers and others with whom it does business, or its operating results and business generally; (ix) risks related to diverting management’s attention from the Company’s ongoing business operations; (x) the risk that stockholder litigation in connection with the transactions contemplated by the Merger Agreement may result in significant costs of defense, indemnification and liability; and (xi) risks and uncertainties pertaining to the Company’s business, including the risks and uncertainties detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 and its other filings with the SEC, as well as the tender offer materials to be filed by Merger Sub and Parent and the Solicitation/Recommendation Statement to be filed by the Company in connection with the tender offer.