Arena Pharmaceuticals, Inc. Announces Update On Partnership With Merck & Co., Inc. In Development Of Niacin Receptor Agonists

SAN DIEGO, Sept. 25 /PRNewswire-FirstCall/ -- Arena Pharmaceuticals, Inc. announced today that an investigational niacin receptor agonist that was being developed under its partnership with Merck & Co., Inc. to develop drugs for the treatment of atherosclerosis and other disorders is no longer in development for the treatment of atherosclerosis.

Merck made the decision to discontinue development of MK-0354 following completion of a randomized, double-blind, placebo-controlled Phase 2 clinical trial that evaluated patients with dyslipidemia. Although MK-0354 is no longer being developed for the treatment of atherosclerosis, preclinical studies are underway to explore other possible indications for this compound. Also, exploration of additional investigational niacin receptor agonists for the treatment of atherosclerosis and related disorders will continue under the partnership.

"The data from the clinical trials of MK-0354 have provided valuable information and add to our understanding of the niacin receptor as we continue to evaluate its therapeutic potential," said Jack Lief, President and Chief Executive Officer of Arena. "We are pleased that, together with Merck, we will continue to conduct research to assess the therapeutic potential of MK-0354 and other niacin receptor agonists."

"We look forward to further evaluating the therapeutic potential of niacin receptor agonists through our partnership with Arena," said Kathleen Metters, Ph.D., Senior Vice President, Basic Research, Merck Research Laboratories.

About Atherosclerosis

Atherosclerosis is characterized by the collection of fatty material deposits, such as cholesterol, along artery walls. This fatty material thickens, hardens, and may eventually block the arteries, adversely affecting blood flow and increasing the risk of heart attack and stroke over time. Atherosclerosis accounts for nearly three out of every four deaths from cardiovascular disease. In 1999, U.S. community hospitals billed $26.2 billion for coronary atherosclerosis care. HDL cholesterol, commonly known as the "good" cholesterol, can help clear the fatty deposits from the walls of blood vessels and transport cholesterol to the liver for processing and removal from the body. Drugs that can influence the levels of HDL cholesterol, or "good" cholesterol, may potentially provide clinical benefits to patients by reducing the risk of heart attack and stroke. The niacin receptor, a G protein-coupled receptor, or GPCR, is believed to have potential in regulating plasma lipid profiles, including HDL.

About Arena Pharmaceuticals

Arena is a clinical-stage biopharmaceutical company focused on discovering, developing and commercializing oral drugs in four major therapeutic areas: cardiovascular, central nervous system, inflammatory, and metabolic diseases. Arena's most advanced product candidate, lorcaserin, is being investigated in a Phase 3 clinical trial program for the treatment of obesity. Arena's broad pipeline of novel compounds targeting G protein-coupled receptors, an important class of validated drug targets, includes compounds being evaluated for other serious diseases and disorders independently and with our partners, Merck & Co., Inc. and Ortho-McNeil, Inc.

Arena Pharmaceuticals(R) and Arena(R) are registered service marks of the company. CART(TM) is an unregistered service mark of the company. "APD" is an abbreviation for Arena Pharmaceuticals Development.

Forward-Looking Statements

Certain statements in this press release are forward-looking statements that involve a number of risks and uncertainties. Such forward-looking statements include statements about future testing and exploration of MK-0354 and other niacin receptor agonists, the continuation of the collaboration with Merck and expected activities thereunder, and other statements about Arena's strategy and ability to develop compounds and commercialize drugs. For such statements, Arena claims the protection of the Private Securities Litigation Reform Act of 1995. Actual events or results may differ materially from Arena's expectations. Factors that could cause actual results to differ materially from the forward-looking statements include, but are not limited to, Arena's planned clinical trials and studies may not proceed at the time or in the manner Arena expects or at all; the results of preclinical studies or clinical trials may not be predictive of future results; the timing, success and cost of Arena's research and development; Arena's ability to partner lorcaserin, APD125 or other of its compounds or programs; Arena's ability to obtain additional financing; Arena's ability to obtain and defend its patents; and the timing and receipt of payments and fees, if any, from Arena's collaborators. Additional factors that could cause actual results to differ materially from those stated or implied by Arena's forward-looking statements are disclosed in Arena's filings with the Securities and Exchange Commission. These forward-looking statements represent Arena's judgment as of the time of this release. Arena disclaims any intent or obligation to update these forward-looking statements, other than as may be required under applicable law.

Contacts: Jack Lief Carolyn Wang President and CEO WeissComm Partners Media Relations David Walsey 415.946.1065 Director, Corporate Communications Arena Pharmaceuticals 858.453.7200, ext. 1682 www.arenapharm.com

Arena Pharmaceuticals, Inc.

CONTACT: Jack Lief, President and CEO, or David Walsey, Director,Corporate Communications, both of Arena Pharmaceuticals, Inc.,+1-858-453-7200, ext. 1682; or Carolyn Wang, Media Relations of WeissCommPartners, +1-415-946-1065, for Arena Pharmaceuticals, Inc.

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