Exhibit (a)(1)(I)

This announcement is neither an offer to purchase nor a solicitation of an offer to sell Shares (as defined below), and the provisions herein are subject in their entirety to the provisions of the Offer (as defined below). The Offer is made solely by the Offer to Purchase, dated October 3, 2016, and the related Letter of Transmittal and any amendments or supplements thereto, and is being made to all holders of Shares. The Offer is not being made to (nor will tenders be accepted from or on behalf of) holders of Shares in any jurisdiction in which the making of the Offer or the acceptance thereof would not be in compliance with the securities, “blue sky” or other laws of such jurisdiction. In those jurisdictions where applicable laws require the Offer to be made by a licensed broker or dealer, the Offer will be deemed to be made on behalf of Purchaser (as defined below) by one or more registered brokers or dealers licensed under the laws of such jurisdiction to be designated by Purchaser.

Notice of Offer to Purchase for Cash

All Outstanding Shares of Common Stock

of

TOBIRA THERAPEUTICS, INC.

a Delaware corporation

at

$28.35 net per share plus one non-transferable

contractual contingent value right for each share, which represents

the right to receive contingent payments of up to $49.84 in cash

in the aggregate per share, if any, upon the achievement of certain milestones

pursuant to the Offer to Purchase

dated October 3, 2016

by

SAPPHIRE ACQUISITION CORP.

a wholly owned subsidiary of

ALLERGAN HOLDCO US, INC.

and an indirect wholly owned subsidiary of

ALLERGAN plc

Sapphire Acquisition Corp., a Delaware corporation (“Purchaser”), a wholly owned subsidiary of Allergan Holdco US, Inc., a Delaware corporation (“Parent”) and an indirect wholly owned subsidiary of Allergan plc, an Irish public limited company (“Allergan”), is offering to purchase all outstanding shares of common stock, par value $0.001 per share (the “Shares”), of Tobira Therapeutics, Inc., a Delaware corporation (“Tobira”), at a purchase price of $28.35 per Share, net to the seller in cash (the “Closing Amount”), without interest and less any applicable withholding taxes, plus one nontransferable contractual contingent value right (“CVR”) per Share, which represents the right to receive contingent payments of up to $49.84 in cash in the aggregate, if any, if certain specified milestones are achieved, upon the terms and subject to the conditions set forth in the Offer to Purchase, dated October 3, 2016 (the “Offer to Purchase”), and in the related Letter of Transmittal (the “Letter of Transmittal” which, together with the Offer to Purchase and other related materials, as each may be amended or supplemented from time to time, constitutes the “Offer”).

Each CVR represents the right to receive the following cash payments, if any, in each case without interest and less any applicable withholding taxes, with each payment conditioned upon the achievement of the applicable milestone in accordance with the terms of the Contingent Value Rights Agreement to be entered into at or prior to the Offer Acceptance Time between Parent and a trustee mutually agreeable to Parent and the Company (the “CVR Agreement”) as follows: (i) $13.68 per CVR payable by Parent if, on or before December 31, 2028, the first human is enrolled in a qualifying Phase 3 trial of cenicriviroc (“CVC”), which trial includes, as one of its primary outcome measures, an evaluation of improvement in fibrosis of at least one stage with no worsening of steatohepatitis (or a substantially similar measure with respect to such evaluation or a similar disease characteristics), (ii) $4.53 per CVR payable by Parent if, on or before December 31, 2028, a new drug application is submitted to the United States Food and Drug Administration (the “FDA”), for approval of any pharmaceutical product or combination of co-administered products containing CVC as an active ingredient for the treatment of non-alcoholic steatohepatitis with fibrosis or fibrosis due to non-alcoholic steatohepatitis (“NASH”, and any such product, a “Product”), (iii) $13.56 per CVR payable by Parent if there has been, on or before December 31, 2028, the first sale in the United States in an arm’s length transaction to a third party of a Product whose approved label includes an indication for the treatment of NASH following regulatory approval for marketing of such Product by the FDA (“First Commercial Sale”), and (iv) $18.07 per CVR payable by Parent if, within any four consecutive calendar quarters during the three consecutive year period commencing with the first calendar quarter immediately following the date of the First Commercial Sale, there are worldwide net sales (gross amounts received for sales of the Product, less certain permitted deductions) of a Product exceeding $1 billion (such potential cash payments, together with the Closing Amount, are referred to collectively herein as the “Offer Price”).

Stockholders of record who tender directly to Computershare Trust Company, N.A. (the “Depositary”) will not be obligated to pay brokerage fees, commissions or similar expenses or, except as otherwise provided in the Letter of Transmittal, stock transfer taxes with respect to the purchase of Shares by Purchaser pursuant to the Offer. Stockholders who hold their Shares through a broker, dealer, commercial bank, trust company or other nominee should consult with such institution as to whether it charges any service fees or commissions.

THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT THE END OF THE DAY, ONE MINUTE AFTER 11:59 P.M., EASTERN TIME, ON OCTOBER 31, 2016, UNLESS THE OFFER IS EXTENDED OR EARLIER TERMINATED.

The Offer is being made pursuant to the Agreement and Plan of Merger, dated as of September 19, 2016 (as it may be amended from time to time, the “Merger Agreement”), by and among Parent, Purchaser and Tobira. The Merger Agreement provides, among other things, that following the consummation of the Offer and subject to the satisfaction or waiver of certain conditions, Purchaser will be merged with and into Tobira (the “Merger”), with Tobira continuing as the surviving corporation in the Merger and a wholly owned subsidiary of Parent. Because the Merger will be governed by Section 251(h) of the General Corporation Law of the State of Delaware (“DGCL”), no stockholder vote will be required to consummate the Merger. In the Merger, each Share outstanding immediately prior to the effective time of the Merger (other than Shares held (i) in the treasury of Tobira or by Parent, Purchaser or any other direct or indirect wholly owned subsidiary of Parent, which Shares shall be canceled and shall cease to exist or (ii) by stockholders who validly exercise appraisal rights under Delaware law with respect to such Shares) will be automatically canceled and converted into the right to receive the Offer Price, without interest thereon and less any applicable withholding taxes. As a result of the Merger, Tobira will cease to be a publicly traded company and will become wholly owned by Parent. Except as expressly set forth in the CVR Agreement, under no circumstances will interest be paid on the purchase price for Shares, regardless of any extension of the Offer or any delay in making payment for Shares. The Merger Agreement is more fully described in the Offer to Purchase.

The Offer is conditioned upon, among other things, (a) the absence of a termination of the Merger Agreement in accordance with its terms (the “Termination Condition”) and (b) the satisfaction of:

(i) the Minimum Tender Condition (as described below);

(ii) the HSR Condition (as described below); and

(iii) the Governmental Impediment Condition (as described below).

The Offer is not subject to a financing condition. The Minimum Tender Condition requires that the number of Shares validly tendered (excluding Shares tendered pursuant to guaranteed delivery procedures but not yet received) in accordance with the terms of the Offer and not validly withdrawn on or prior to the end of the day, one minute after 11:59 p.m., Eastern Time, on October 31, 2016 (the “Expiration Date,” unless Purchaser shall have extended the period during which the Offer is open in accordance with the Merger Agreement, in which event “Expiration Date” shall mean the latest time and date at which the Offer, as so extended by Purchaser, shall expire), together with any Shares then owned by Parent and its affiliates, equals one Share more than 50% of the sum of (i) the total number of Shares outstanding at the time of the expiration of the Offer, plus (ii) the total number of Shares that the Company would be required to issue upon conversion, settlement, exchange or exercise of all options, warrants, rights or securities outstanding at the time of the expiration of the Offer that are convertible, exchangeable or exercisable into Shares (whether then outstanding or for which the conversion, settlement, exchange or exercise date has already occurred, but in any event without duplication). The HSR Condition requires that any applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and the rules and regulations promulgated thereunder (the “HSR Act”), shall have expired or otherwise been terminated. Under the HSR Act, each of Allergan and Tobira expects to file on October 3, 2016, a Premerger Notification and Report Form with the Federal Trade Commission (the “FTC”) and the Antitrust Division of the U.S. Department of Justice (the “Antitrust Division”) in connection with the purchase of Shares in the Offer. The Offer may not be consummated until the expiration of a thirty (30)-calendar-day waiting period following the filing, unless the waiting period is earlier terminated by the FTC and the Antitrust Division. If the thirty (30)-calendar-day waiting period expires on a Saturday, Sunday, or legal public holiday, the waiting period is automatically extended to the end of the next day that is not a Saturday, Sunday, or legal public holiday. If within the thirty (30)-calendar-day waiting period either the FTC or the Antitrust Division issues a request for additional information and documentary material, the waiting period with respect to the Offer would be extended until thirty (30) calendar days following the date of substantial compliance by Parent with that request, unless the FTC or the Antitrust Division terminates the additional waiting period before its expiration. The Governmental Impediment Condition requires that there be no judgment issued by any governmental body of competent jurisdiction or law or other legal prohibition in effect preventing or prohibiting the consummation of the Offer or the Merger. The Offer is also subject to other conditions as described in the Offer to Purchase (collectively, the “Offer Conditions”). See Section 15 — “Conditions of the Offer” of the Offer to Purchase.

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The board of directors of Tobira (which we refer to as the “Tobira Board”), among other things, has (i) determined that the Merger Agreement and transactions contemplated thereby are fair to and in the best interests of Tobira and its stockholders, (ii) declared it advisable to enter into the Merger Agreement, (iii) approved the execution, delivery and performance by Tobira of the Merger Agreement and the consummation of the transactions contemplated thereby, including the Offer and the Merger, (iv) resolved that the Merger shall be effected under Section 251(h) of the DGCL and (v) resolved to recommend that the stockholders of Tobira accept the Offer and tender their Shares to Purchaser pursuant to the Offer.

The Merger Agreement contains provisions to govern the circumstances in which Purchaser is required or permitted to extend the Offer and in which Parent is required to cause Purchaser to extend the Offer. Specifically, the Merger Agreement provides that: Purchaser must (and Parent must cause Purchaser to) extend the Offer (i) for the minimum period required by any law, any interpretation or position of the SEC or its staff or any rules and regulations of the NASDAQ Stock Market applicable to the Offer, (ii) for periods of up to ten (10) business days each until any waiting period (and extension thereof) applicable to consummate the Offer under the HSR Act and any foreign antitrust or competition-related law has expired or been terminated and (iii) for additional periods of up to ten (10) business days per extension at the request of Tobira if, as of the then scheduled Expiration Date, any Offer Condition has not been satisfied or waived, in order to permit the satisfaction of such Offer Condition. Additionally, Purchaser may, in its discretion extend the Offer on one or more occasions, if, as of the then scheduled Expiration Date, any Offer Condition has not been satisfied or waived, to the extent waivable by Purchaser or Parent, for an additional period of up to ten (10) business days per extension, in order to permit the satisfaction of such Offer Condition. Purchaser will not be required, or permitted without the Company’s consent, to extend the Offer beyond January 19, 2017 (or April 19, 2017, in the event that the End Date is extended pursuant to the terms of the Merger Agreement) (the “End Date”). Further, Purchaser is not required to extend the Offer beyond the then existing Expiration Date for more than three (3) consecutive additional periods not to exceed a total of thirty (30) business days if, as of the applicable Expiration Date, all Offer Conditions have been satisfied or waived except for the Minimum Condition.

Subject to the terms and conditions of the Merger Agreement and applicable law, Purchaser expressly reserves the right to (i) increase the Offer Price, (ii) waive any Offer Condition and (iii) make any other changes in the terms and conditions of the Offer that are not inconsistent with the Merger Agreement. However, without the consent of Tobira, Parent and Purchaser are not permitted to (i) decrease the Closing Amount or amend the terms of the CVR or the CVR Agreement, (ii) change the form of consideration payable in the Offer, (iii) decrease the maximum number of Shares sought to be purchased in the Offer, (iv) impose conditions or requirements to the Offer in addition to the Offer Conditions, (v) amend, modify or waive the Minimum Condition, the Termination Condition, the HSR Condition or the Governmental Impediment Condition, (vi) otherwise amend or modify any of the other terms of the Offer in a manner that adversely affects any holder of Shares in its capacity as such or (vii) terminate the Offer or accelerate, extend or otherwise change the Expiration Date except as provided in the Merger Agreement.

Any extension, delay, termination or amendment of the Offer will be followed as promptly as practicable by public announcement thereof, and such announcement in the case of an extension will be made no later than 9:00 a.m., Eastern Time, on the next business day after the previously scheduled Expiration Date. Without limiting the manner in which Purchaser may choose to make any public announcement, it currently intends to make announcements regarding the Offer by issuing a press release and making any appropriate filing with the SEC.

Acceptance and payment for Shares pursuant to and subject to the conditions of the Offer will occur on November 1, 2016 (the “Offer Closing”), unless we extend the Offer pursuant to the terms of the Merger Agreement. The date and time at which such Offer Closing occurs is referred to as the “Offer Acceptance Time”.

Because the Merger will be governed by Section 251(h) of the DGCL, Purchaser does not expect there to be a significant period of time between the Offer Closing and the consummation of the Merger.

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On the terms of and subject to the Offer conditions and the Merger Agreement, Purchaser shall, and Parent shall cause Purchaser to, accept for payment all Shares validly tendered and not withdrawn pursuant to the Offer promptly after the Expiration Date, and to pay for such Shares promptly after the Offer Acceptance Time. For purposes of the Offer, Purchaser will be deemed to have accepted for payment, and thereby purchased, Shares validly tendered and not properly withdrawn as, if and when Purchaser gives oral or written notice to the Depositary of its acceptance for payment of such Shares pursuant to the Offer. Upon the terms and subject to the conditions of the Offer, payment for Shares accepted for payment pursuant to the Offer will be made by deposit of the aggregate Closing Amounts for such Shares with the Depositary, which will act as paying agent for tendering stockholders for the purpose of receiving payments from Purchaser and transmitting such payments to tendering stockholders whose Shares have been accepted for payment. If Purchaser extends the Offer, is delayed in its acceptance for payment of Shares or is unable to accept Shares for payment pursuant to the Offer for any reason, then, without prejudice to Purchaser’s rights under the Offer and the Merger Agreement, the Depositary may retain tendered Shares on Purchaser’s behalf, and such Shares may not be withdrawn except to the extent that tendering stockholders are entitled to withdrawal rights as described in the Offer to Purchase and as otherwise required by Rule 14e-1(c) under the Exchange Act. Except as expressly set forth in the CVR Agreement, under no circumstances will Parent or Purchaser pay interest on the purchase price for Shares by reason of any extension of the Offer or any delay in making such payment for Shares.

No alternative, conditional or contingent tenders will be accepted. In all cases, payment for Shares accepted for payment pursuant to the Offer will only be made after timely receipt by the Depositary of (i) certificates evidencing such Shares (the “Share Certificates”) or confirmation of a book-entry transfer of such Shares (a “Book-Entry Confirmation”) into the Depositary’s account at The Depository Trust Company (“DTC”) pursuant to the procedures set forth in the Offer to Purchase, (ii) the Letter of Transmittal (or a manually signed facsimile thereof), properly completed and duly executed, with any required signature guarantees or, in the case of a book-entry transfer, an Agent’s Message (as described in the Offer to Purchase) in lieu of the Letter of Transmittal and (iii) any other documents required by the Letter of Transmittal. Accordingly, tendering stockholders may be paid at different times depending upon when Share Certificates or Book-Entry Confirmations with respect to Shares are actually received by the Depositary.

Shares tendered pursuant to the Offer may be withdrawn at any time prior to the Expiration Date and, unless theretofore accepted for payment by Purchaser pursuant to the Offer, may also be withdrawn at any time after December 2, 2016, which is the 60th day after the date of the commencement of the Offer.

For a withdrawal to be proper and effective, a written, telegraphic or facsimile transmission notice of withdrawal must be timely received by the Depositary at one of its addresses set forth on the back cover page of the Offer to Purchase. Any such notice of withdrawal must specify the name of the person who tendered the Shares to be withdrawn, the number of Shares to be withdrawn and the name in which the Share Certificates are registered if different from that of the person who tendered such Shares. If Share Certificates evidencing Shares to be withdrawn have been delivered or otherwise identified to the Depositary, then, prior to the physical release of such Share Certificates, the serial numbers shown on such Share Certificates must be submitted to the Depositary and the signature(s) on the notice of withdrawal must be guaranteed by an Eligible Institution (as described in the Offer to Purchase), unless such Shares have been tendered for the account of an Eligible Institution. If Shares have been tendered pursuant to the procedure for book-entry transfer as set forth in the Offer to Purchase, any notice of withdrawal must also specify the name and number of the account at DTC to be credited with the withdrawn Shares.

Withdrawals of Shares may not be rescinded. Any Shares properly withdrawn will thereafter be deemed not to have been validly tendered for purposes of the Offer. However, withdrawn Shares may be re-tendered by again following one of the procedures described in the Offer to Purchase at any time prior to the Expiration Date.

Purchaser will determine, in its sole discretion, all questions as to the form and validity (including time of receipt) of any notice of withdrawal and Purchaser’s determination will be final and binding. None of Parent, Purchaser, the Depositary, the Information Agent or any other person will be under any duty to give notice of any defects or irregularities in any notice of withdrawal or incur any liability for failure to give any such notification.

The information required to be disclosed by paragraph (d)(1) of Rule 14d-6 of the General Rules and Regulations under the Exchange Act is contained in the Offer to Purchase and is incorporated herein by reference.

Tobira has provided Purchaser with Tobira’s stockholder list and security position listings for the purpose of disseminating the Offer to Purchase, the related Letter of Transmittal and other related materials to holders of Shares. The Offer to Purchase and related Letter of Transmittal will be mailed to record holders of Shares whose names appear on Tobira’s stockholder list and will be furnished to brokers, dealers, commercial banks, trust companies and similar persons whose names, or the names of whose nominees, appear on the stockholder list or, if applicable, who are listed as participants in a clearing agency’s security position listing for subsequent transmittal to beneficial owners of Shares.

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The receipt of cash and CVRs by a U.S. holder in exchange for Shares pursuant to the Offer or the Merger will be a taxable transaction for U.S. federal income tax purposes. The amount of gain or loss a U.S. holder recognizes, and the timing and

potentially character of a portion of such gain or loss, depends on the U.S. federal income tax treatment of the CVRs, with respect to which there is a significant amount of uncertainty. The installment method of reporting any gain attributable to receipt of a CVR generally will not be available with respect to the disposition of Shares pursuant to the Offer or the Merger because the Shares are traded on an established securities market. See Section 5— “Certain U.S. Federal Income Tax Considerations” of the Offer to Purchase for a more detailed discussion of the tax treatment of the Offer. Each holder of Shares should consult with its tax advisor as to the particular tax consequences to such holder of exchanging Shares for cash in the Offer or the Merger.

The Offer to Purchase and the related Letter of Transmittal contain important information. Holders of Shares should carefully read both documents in their entirety before any decision is made with respect to the Offer.

Questions and requests for assistance may be directed to the Information Agent at its address and telephone numbers set forth below. Requests for copies of the Offer to Purchase, the Letter of Transmittal, the notice of guaranteed delivery and other tender offer materials may be directed to the Information Agent. Such copies will be furnished promptly at Purchaser’s expense. Stockholders may also contact brokers, dealers, commercial banks or trust companies for assistance concerning the Offer. Except as set forth in the Offer to Purchase, neither Purchaser nor Parent will pay any fees or commissions to any broker or dealer or any other person for soliciting tenders of Shares pursuant to the Offer. Brokers, dealers, commercial banks, trust companies or other nominees will, upon request, be reimbursed by Purchaser for customary mailing and handling expenses incurred by them in forwarding the Offer materials to their customers.

The Information Agent for the Offer is:

MacKenzie Partners, Inc.

105 Madison Avenue

New York, New York 10016

212-929-5500 (Call Collect) or

CALL TOLL FREE 800-322-2885

Email: tenderoffer@mackenziepartners.com

October 3, 2016

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