Arena Pharmaceuticals, Inc.
May 7, 2008

Arena Pharmaceuticals Announces First Quarter 2008 Financial Results

SAN DIEGO, May 7 /PRNewswire-FirstCall/ -- Arena Pharmaceuticals, Inc. (Nasdaq: ARNA) today reported financial results for the first quarter ended March 31, 2008.

Total revenues in the first quarter of 2008 were $2.6 million, compared to $4.9 million in the first quarter of 2007, and included $2.0 million in revenue under Arena's contract manufacturing agreement with Siegfried Ltd and $0.6 million in patent reimbursements from Arena's collaborations with Merck & Co., Inc. and Ortho-McNeil Pharmaceutical, Inc. Arena reported a net loss allocable to common stockholders in the first quarter of 2008 of $55.0 million, or $0.75 per share, compared to a net loss allocable to common stockholders in the first quarter of 2007 of $32.4 million, or $0.53 per share.

"In the first quarter of 2008, we purchased certain pharmaceutical manufacturing assets from Siegfried and secured Siegfried as a supplier of lorcaserin for our planned NDA submission in 2009 and for the potential partnering and commercialization of the drug candidate. Additionally, lorcaserin passed the month-12 ESMB review of echocardiographic data, APD125, our insomnia drug candidate, entered a Phase 2b trial and APD791, our drug candidate for arterial thrombosis, entered a Phase 1b trial," stated Jack Lief, Arena's President and Chief Executive Officer. "This is a productive start to the year, and we look forward to the results from our ongoing clinical trials and advancing our pipeline of innovative therapeutics."

Research and development expenses totaled $47.6 million in the first quarter of 2008, compared to $35.8 million in the first quarter of 2007. This increase in research and development expenses is primarily attributable to increased clinical development costs related to the Phase 3 clinical program for lorcaserin hydrochloride, Arena's drug candidate for the treatment of obesity. Research and development expenses included $1.0 million in non-cash, share-based compensation expense in each of the quarters ended March 31, 2008 and 2007. General and administrative expenses totaled $8.9 million in the first quarter of 2008, compared to $4.9 million in the first quarter of 2007. This increase in general and administrative expenses is primarily attributable to increases in patent costs and personnel-related expenses. Total patent costs, including patent costs related to partnered programs, increased by $1.7 million in the first quarter of 2008 compared to the first quarter of 2007. General and administrative expenses in the first quarter of 2008 included $1.4 million in non-cash, share-based compensation expense, compared to $0.9 million in the first quarter of 2007.

Cash, cash equivalents and short-term investments totaled $333.6 million at March 31, 2008. Approximately 73.8 million shares of common stock were outstanding at March 31, 2008.

Arena's First Quarter Highlights

Scheduled Earnings Call

Arena will host both a conference call and webcast to discuss the first quarter 2008 financial results and to provide a corporate update today, Wednesday, May 7, 2008, at 5:00 p.m. Eastern Time (2:00 p.m. Pacific Time). Jack Lief, President and Chief Executive Officer and Robert E. Hoffman, Vice President, Finance and Chief Financial Officer will host the conference call.

The conference call may be accessed by dialing 866.356.3095 for domestic callers and 617.597.5391 for international callers. Please specify to the operator that you would like to join the "Arena First Quarter Earnings Call." The participant code for the call is 65484912. The conference call will be webcast live under the investor relations section of Arena's website at http://www.arenapharm.com, and will be archived there for 30 days following the call. Please connect to Arena's website several minutes prior to the start of the broadcast to ensure adequate time for any software download that may be necessary.

Upcoming Corporate Presentations

Arena is scheduled to present at several investment and industry conferences through June 2008, including:

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 drug candidate, lorcaserin, is being investigated in a Phase 3 clinical trial program for the treatment of obesity. Arena's broad pipeline of novel compounds target G protein-coupled receptors, an important class of validated drug targets, and includes compounds being evaluated independently and with partners, including Merck & Co., Inc. and Ortho-McNeil Pharmaceutical, Inc.

Arena Pharmaceuticals® and Arena® are registered service marks 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 the protocol, design, scope, enrollment and other aspects of current and planned clinical trials and other studies of Arena's or its collaborators' product candidates and compounds; the future results of clinical trials; the tolerability, side effects, efficacy and potential of Arena's or its collaborators' product candidates and compounds; an NDA submission for lorcaserin and the potential partnering and commercialization of the drug candidate; expectations relating to the agreements and Arena's relationship with Siegfried; the advancement and content of Arena's pipeline; and other statements about Arena's outlook, strategy, internal and partnered programs, 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, clinical trials and studies may not proceed at the time or in the manner Arena expects or at all, the results of clinical trials or preclinical studies may not be predictive of future results, Arena's ability to partner lorcaserin, APD125, APD791 or other of its compounds or programs, the timing, success and cost of Arena's research, out-licensing endeavors and clinical trials, Arena's ability to obtain additional financing, Arena's ability to obtain and defend its patents, the timing and receipt of payments and fees, if any, from Arena's collaborators, and Arena's ability to redeem with common stock any outstanding shares of its series B convertible preferred stock. 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
President and CEO

Mary Claire Duch


WeissComm Partners

Media Relations
David Walsey
212.301.7228
Director, Corporate Communications



Arena Pharmaceuticals, Inc.


858.453.7200, ext. 1682



                         Arena Pharmaceuticals, Inc.
               Condensed Consolidated Statements of Operations
                   (In thousands, except per share amounts)

                                             Three months ended March 31,
                                               2008               2007
                                                     (unaudited)
    Revenues
    Contract manufacturing                    $2,019              $   -
    Collaborative agreements                     590              4,911
      Total revenues                           2,609              4,911

    Operating Expenses
    Cost of contract manufacturing             2,330                  -
    Research and development                  47,565             35,755
    General and administrative                 8,861              4,923
    Amortization of acquired technology          384                384
      Total operating expenses                59,140             41,062

    Interest and other income, net             2,066              4,256
    Net loss                                 (54,465)           (31,895)
    Dividends on redeemable convertible
     preferred stock                            (540)              (514)
    Net loss allocable to common
     stockholders                           $(55,005)          $(32,409)

    Net loss per share allocable to common
     stockholders, basic and diluted          $(0.75)            $(0.53)

    Shares used in calculating net loss per
     share allocable to common stockholders,
     basic and diluted                        73,605             60,734



                         Arena Pharmaceuticals, Inc.
                  Condensed Consolidated Balance Sheet Data
                                (In thousands)

                                          March 31, 2008   December 31, 2007
                                            (unaudited)         (Note)
    Assets
      Cash, cash equivalents and
       short-term investments               $333,636           $398,185
      Accounts receivable                      2,398              1,901
      Other current assets                     8,938              9,162
      Land, property and equipment, net       92,704             65,940
      Acquired technology and other
       non-current assets                     26,857             12,318
        Total assets                        $464,533           $487,506

    Liabilities and Stockholders' Equity
      Accounts payable, accrued expenses
       and accrued compensation              $38,345            $30,058
      Total deferred revenues                  4,049              4,049
      Total lease financing obligations
       and other long-term liabilities        72,067             63,100
      Redeemable convertible preferred
       stock                                  54,462             53,922
      Total stockholders' equity             295,610            336,377
        Total liabilities and stockholders'
         equity                             $464,533           $487,506

    Note: The Condensed Consolidated Balance Sheet Data has been derived from
          the audited financial statements as of that date.

SOURCE Arena Pharmaceuticals, Inc.