8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15 (d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported):  March 16, 2009

United Therapeutics Corporation

(Exact Name of Registrant as Specified in Charter)

Delaware (State or Other Jurisdiction of Incorporation)	000-26301 (Commission File Number)	52-1984749 (I.R.S. Employer Identification Number)
1110 Spring Street
Silver Spring, MD		20910
(Address of Principal Executive Offices)		(Zip Code)

Registrant’s telephone number, including area code:

(301) 608-9292

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 7.01.  Regulation FD Disclosure.

On March 16, 2009, United Therapeutics Corporation (the “Company”) issued a press release regarding a probable delay of the U.S. Food and Drug Administration’s pending review of the Company’s New Drug Application for inhaled treprostinil.  A copy of the press release is attached hereto as Exhibit 99.1.

The information contained in this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to liability under that section, nor shall it be deemed incorporated by reference into any filing under the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

Item 9.01.  Exhibits

(d)  Exhibits

Exhibit No.	Description of Exhibit
99.1	Press release dated March 16, 2009

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SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	UNITED THERAPEUTICS CORPORATION
Dated: March 16, 2009	By:	/s/ Paul A. Mahon
	Name:	Paul A. Mahon
	Title:	General Counsel

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Exhibit Index

Exhibit No.	Description of Exhibit
99.1	Press release dated March 16, 2009

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EX-99.1

Exhibit 99.1

For Immediate Release

Contact: Andrew Fisher
(202) 483-7000
Afisher@unither.com

UNITED THERAPEUTICS ANNOUNCES PROBABLE DELAY IN
APPROVAL TIMELINE FOR INHALED TREPROSTINIL (TYVASO)

Conference Call to be Held at 9:00 a.m. Eastern Time on March 16, 2009

Silver Spring, MD, March 16, 2009:  United Therapeutics Corporation (NASDAQ: UTHR) announced today that, based on its most recent interactions with the U.S. Food and Drug Administration (FDA), the FDA’s pending regulatory review of the New Drug Application (NDA) for Tyvaso™ (inhaled treprostinil) will likely extend beyond its originally anticipated April 30, 2009, action date.  The probable delay relates to questions received from the FDA concerning human factors testing and the instructions for use (IFU) of the OptiNeb® portable nebulizer that delivers Tyvaso.

“In response to FDA comments related to our originally submitted instructions for the Optineb nebulizer, we provided the FDA with a revised IFU.  Following our most recent discussion with the FDA, we have agreed to conduct human factors testing to validate that the revised IFU results in the proper use of the device by a naïve user.  This relatively small study in normal subjects will test the new IFU in its ability to guide patients to accomplish such tasks as proper device assembly, drug administration, disassembly and cleaning, among other things,” said Roger Jeffs, Ph.D., United Therapeutics’ President and Chief Operating Officer.  “We are working to get the human factors testing conducted and submitted to the FDA as rapidly as possible, but it is a challenge to complete the study and have it properly reviewed by the FDA in advance of the April 30th action date.”

Martine Rothblatt, Ph.D., United Therapeutics’ Chairman and Chief Executive Officer, said, “Given the need to conduct this additional study, we are of the opinion that additional review time is likely.  Accordingly, we felt it was our responsibility to inform our shareholders in advance of any formal notice from the FDA.  We hope that any delay related to this issue will be limited to just a few months.  However, in deference to the regulatory process, we will not be providing further information or status updates on any other aspect of our Tyvaso NDA until we receive a definitive written response from the FDA.”

Conference Call

A half-hour teleconference will be held on Monday, March 16, 2009, at 9:00 a.m. Eastern Time to answer questions relating to the probable delay.  The teleconference is accessible by dialing 877-852-6578, with international callers dialing 719-325-4820.  A rebroadcast of the teleconference will be available for one week and can be accessed by dialing 888-203-1112, with international callers dialing 719-457-0820, and using passcode: 4242990.

The teleconference is also being web cast and can be accessed via United Therapeutics’ website at http://ir.unither.com/events.cfm.

About United Therapeutics

United Therapeutics Corporation is a biotechnology company focused on the development and commercialization of unique products to address the unmet medical needs of patients with chronic and life-threatening cardiovascular and infectious diseases and cancer.

Forward-looking Statements

Statements included in this press release concerning the probability or likelihood of a delay in the FDA’s pending review of our NDA for Tyvaso, the reasons for such delay, the expected duration of such delay and our intention to not comment further on the status of Tyvaso’s regulatory review until a definitive written response has been received from the FDA are “forward-looking statements” within the meaning of the safe harbor contained in the Private Securities Litigation Reform Act of 1995.  These forward-looking statements are qualified by the cautionary statements, cautionary language and risk factors set forth in our periodic reports and documents filed with the Securities and Exchange Commission, including our most recent Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, and current reports on Form 8-K, which could cause actual results to differ materially from anticipated results.  We are providing this information as of March 16, 2009, and assume no obligation to update or revise the information contained in this press release whether as a result of new information, future events or any other reason. [uthr-g]

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