Orexigen Therapeutics, Inc. Initiates Second Phase IIb Empatic(TM) Trial on Schedule

SAN DIEGO, July 9 /PRNewswire-FirstCall/ -- Orexigen(R) Therapeutics, Inc. announced today that it has begun randomizing patients in ZB-202, a second Phase IIb clinical trial for Empatic(TM), one of the Company's two late-stage obesity product candidates. The trial is designed to build on highly encouraging safety and efficacy results from a previous Phase IIb trial of Empatic, which demonstrated robust weight loss at 48 weeks ranging from approximately 11 percent to 15 percent in obese patients completing the trial and a discontinuation rate due to adverse events that was not significantly different than placebo.

"Initiation of ZB-202 is an important milestone for our Empatic program and the final anticipated step before moving into Phase III development," said Gary Tollefson, M.D., Ph.D., Orexigen President and CEO. "Empatic continues to be an important component of the Company's obesity program. Along with Contrave(R), now in Phase III clinical trials, these product candidates both have the potential to target a large, distinct and complementary segment within the obesity market."

Orexigen is the only company currently developing two late-stage product candidates to address the full spectrum of obesity ranging from mild-to-moderate and moderate-to-severe obesity. Obesity has become a national epidemic, with more than 70 million Americans classified as obese and 300,000 deaths a year attributable to obesity, according to the Centers for Disease Control (CDC). Obesity is associated with a number of significant medical conditions, including diabetes, hypertension, high cholesterol and coronary artery disease, among others. Research has shown that obesity has a greater impact on the development of chronic conditions in the U.S. than poverty, nicotine or alcohol abuse. Obesity also places a significant financial burden on the economy with mortality and morbidity costs estimated to exceed $100 billion annually.

Empatic combines zonisamide and bupropion, two existing drugs that have been independently approved by the U.S. Food and Drug Administration (FDA) to treat other central nervous system disorders. Orexigen has developed a proprietary sustained release (SR) formulation of zonisamide that has demonstrated a better tolerability profile than the legacy, immediate release (IR) formulation. These two drugs were selected based on their complementary activity in reducing appetite, increasing the body's burning of calories and sustaining weight loss.

The Company's other late-stage obesity product candidate, Contrave(R), is a combination of bupropion SR and naltrexone in a proprietary SR formulation that also appears to result in improved tolerability compared to the legacy naltrexone IR formulation. Contrave currently is being studied in four Phase III clinical trials that are fully enrolled. The program continues on schedule with initial results anticipated in late 2008 or early 2009 and the filing of a New Drug Application (NDA) with the FDA projected for late 2009.

Phase IIb Empatic Trial Details

ZB-202 is a randomized, double-blind, placebo-controlled trial involving approximately 720 generally healthy, nondiabetic obese patients at 20 sites nationwide. The primary endpoint for this trial is percent change in body weight after 24 weeks of blinded therapy. Patients will be randomized to one of six treatment groups including two of the Empatic doses associated with weight loss in the previous Phase IIb trial. The efficacy of Empatic will be compared against zonisamide monotherapy, bupropion monotherapy and placebo. Trial results are expected in the second half of 2009.

About Orexigen Therapeutics

Orexigen(R) Therapeutics, Inc. is a biopharmaceutical company focused on the development of pharmaceutical product candidates for the treatment of central nervous system disorders, including obesity. The Company's late-stage product candidates targeting obesity are Contrave(R), which is in Phase III clinical trials, and Empatic(TM), which is in Phase IIb clinical development. Orexigen is developing other proprietary drugs for use in other central nervous system disorders. Further information about the Company and its pipeline can be found at http://www.Orexigen.com.

Forward-Looking Statements

Orexigen cautions you that statements included in this press release that are not a description of historical facts are forward-looking statements. Words such as "believes," "anticipates," "plans," "expects," "indicates," "will," "intends," "potential," "suggests," "assuming," "designed" and similar expressions are intended to identify forward-looking statements. These statements are based on the Company's current beliefs and expectations. These forward-looking statements include statements regarding the efficacy and safety of the various formulations of Empatic, the potential to obtain regulatory approval for, and effectively treat obesity with, Empatic and Contrave and the enrollment, timing and completion of clinical trials of Contrave and Empatic. The inclusion of forward-looking statements should not be regarded as a representation by Orexigen that any of its plans will be achieved. Actual results may differ from those set forth in this release due to the risk and uncertainties inherent in the Company's business, including, without limitation: the progress and timing of the Company's clinical trials; the potential that earlier clinical trials may not be predictive of future results; the ability for Empatic to receive regulatory approval on a timely basis or at all; the potential for adverse safety findings relating to Empatic to delay or prevent regulatory approval or commercialization, or result in product liability claims; Orexigen and its licensors may not be able to obtain, maintain and successfully enforce adequate patent and other intellectual property protection of its product candidates; and other risks described in the Company's filings with the Securities and Exchange Commission (SEC), including those detailed under the heading "Risk Factors" in the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2008 filed with the SEC on May 9, 2008. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and Orexigen undertakes no obligation to revise or update this news release to reflect events or circumstances after the date hereof. All forward- looking statements are qualified in their entirety by this cautionary statement. This caution is made under the safe harbor provisions of Section 21E of the Private Securities Litigation Reform Act of 1995.

CONTACT: Liz Frank, +1-212-301-7216, for Orexigen Therapeutics, Inc.

Web site: http://www.Orexigen.com/

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