Auxilium Pharmaceuticals’s Data Presented at the 5th International AIDS Society Conference Suggests Low Testosterone Frequently Goes Undetected in HIV-Positive Men

MALVERN, PA--(Marketwire - July 21, 2009) - Auxilium Pharmaceuticals, Inc. (NASDAQ: AUXL), a specialty biopharmaceutical company, today announced that new data from the two-part HYHYHI Study (Hypogonadal Hypotestosteronism in HIV-Seropositive Men) were presented as a poster today at the 5th International AIDS Society (IAS) Conference in Cape Town, South Africa. This retrospective chart review, supported by the Company, evaluated the challenges associated with diagnosing low testosterone in men with HIV/AIDS. The study also compared the difference in testosterone levels achieved after 12 months of treatment with either Testim® 1% (testosterone gel) or AndroGel®, two commonly used FDA-approved testosterone replacement products.

Results from the study showed that when using the more sensitive Free Testosterone test (FT < 50pg/ml) as a measurement, approximately 64 percent of the 396 men in the study were diagnosed with Low Testosterone (Low T), whereas only 35 percent of these men in the study would have been diagnosed with Low T when the more commonly used Total Testosterone (TT < 300ng/ml) was used. Dr. Gary Blick, M.D., A.A.H.I.V.S., medical and research director of CIRCLE Medical, stated that men with HIV/AIDS often have lower levels of Free T due to an increase in the protein SHBG (sex hormone-binding globulin), which can restrict the amount of testosterone available for the body to use.

Patients using Testim for at least six months achieved median Total T levels of 682 ng/dL (80% increase from baseline) and Free T levels of 102 pg/mL (69% increase from baseline). Those using AndroGel over a similar time period achieved Total T levels of 450 ng/dL (17% increase from baseline) and Free T levels of 87 pg/mL (47% increase from baseline). The study also showed that 5.3 percent of patients using Testim switched to another treatment, versus 15.2 percent of those using AndroGel. Additionally, 2.7 percent of patients using Testim titrated to a higher dose, versus 24.1 percent of those using AndroGel.

“The incidence of low testosterone in men with HIV/AIDS may be even higher than previously estimated,” said Dr. Blick. “Results from this study suggest the use of free testosterone may provide a more sensitive method of diagnosing Low T in men living with HIV/AIDS and allow them to begin treatment with a testosterone replacement therapy, such as Testim, in order to restore normal testosterone levels.”

About the Study

The HYHYHI study, designed and conducted by Dr. Blick, was a retrospective chart review of men with HIV/AIDS screened for Low T and treated with testosterone replacement therapy. Data were collected from two U.S. sites and included 400 men diagnosed with HIV/AIDS and screened for Low T, defined as Total T < 300 ng/dL and/or Free T < 50 pg/mL. Free testosterone is the unbound form of the androgen that can actively interact with cells. Total testosterone measures both free testosterone and testosterone (T) that is bound to plasma proteins. Patients using AndroGel (n=92) or Testim (n=75) for at least 6 months were randomly selected for this study. Their charts were reviewed for testosterone levels, lipid measurements and PSA determinations, as well as symptomatic improvements. The most common presenting symptoms of Low T in the study included fatigue, decreased focus/concentration, depression, decreased libido, decreased peripheral muscle, increased abdominal girth, and erectile dysfunction.

Previous estimates suggest that between 30 and 50 percent of men with HIV/AIDS are estimated to have low testosterone levels due to their body’s inability to produce sufficient quantities of testosterone. Testosterone is one of the most important circulating hormones in men, affecting the brain, muscle, kidneys, bone marrow, bones, liver and skin. “Low T can cause a multitude of significant symptoms, including depression, marked fatigue, poor focus and concentration, decreased late day energy and endurance, loss of muscle mass, increased abdominal fat and bone loss, in addition to erectile dysfunction and decreased sexual libido,” continued Dr. Blick. “Recognition of these symptoms and proper diagnostic testing will allow patients to be initiated on appropriate treatment.”

About Testim

Testim is a proprietary, clear, topical gel containing 1% testosterone, the same type of hormone that is produced by the human body. When applied once-daily to the upper arms and shoulders, clinical studies have shown that Testim will restore and maintain testosterone levels. Once Testim is absorbed through the skin, it enters the bloodstream and helps return testosterone to normal levels. The efficacy of Testim has been demonstrated in 16 clinical studies involving approximately 1,800 patients, including the largest placebo-controlled study ever conducted to evaluate the benefits and risks of testosterone replacement therapy. Auxilium estimates that approximately 76 million tubes, or daily applications, of Testim have been used since the product was launched in 2003. For information regarding the safety and use of Testim, please see the prescribing information at http://www.testim.com.

Important Safety Information

Androgens are contraindicated in men with cancer of the breast or known or suspected cancer of the prostate. Testim is not indicated for women, has not been evaluated for use in women, and must not be used in women. Children and women should avoid skin contact with application sites on men. Testosterone may cause fetal harm. Men treated with androgens may be at an increased risk for the development of prostatic hyperplasia and prostatic carcinoma. Prior to any situation in which direct skin-to-skin contact is anticipated, patients should wash the application sites thoroughly with soap and water so as to remove drug residue.

About Auxilium

Auxilium Pharmaceuticals, Inc. is a specialty biopharmaceutical company with a focus on developing and marketing to urologists, endocrinologists, orthopedists and select primary care physicians. Auxilium markets Testim® 1%, a topical testosterone gel, for the treatment of hypogonadism through its approximately 190-person sales and marketing team. Auxilium has five projects in clinical development. XIAFLEX™ (collagenase clostridium histolyticum), formerly referred to as AA4500, has completed phase III clinical trials for the treatment of Dupuytren’s contracture, and the biologics license application is under review at the FDA for the treatment of Dupuytren’s contracture. XIAFLEX is in phase IIb of development for the treatment of Peyronie’s disease and is in phase II of development for treatment of Frozen Shoulder syndrome (Adhesive Capsulitis). Auxilium’s transmucosal film product candidate for the treatment of overactive bladder (AA4010) and its fentanyl pain product using its transmucosal delivery system are in phase I of development. The Company is currently seeking a partner to further develop these product candidates. Auxilium has rights to additional pain products and products for hormone replacement and urologic disease using its transmucosal film delivery system. Auxilium also has options to all indications using XIAFLEX for non-topical formulations. For additional information, visit http://www.auxilium.com.

SAFE HARBOR STATEMENT UNDER THE PRIVATE SECURITIES LITIGATION REFORM ACT OF 1995

This release contains “forward-looking-statements” within the meaning of The Private Securities Litigation Reform Act of 1995, including statements regarding the interpretation of data; the impact of symptom recognition and proper diagnostic testing on hypogonadal men; products in development for Peyronie’s disease, Frozen Shoulder syndrome, overactive bladder, pain, hormone replacement and urologic disease; and all other statements containing projections, statements of future performance or expectations, or statements of plans or objectives for future operations (including statements of assumption underlying or relating to any of the foregoing). You can identify these statements by the fact that they use words such as “believe,” “appears,” “may,” “could,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “should,” “plan,” “expect,” and other words and terms of similar meaning in connection with any discussion of projections, future performance or expectations, plans or objectives for future operations (including statements of assumption underlying or relating to any of the foregoing). Actual results may differ materially from those reflected in these forward-looking statements due to various factors, including further evaluation of clinical data, results of clinical trials, decisions by regulatory authorities as to whether and when to approve drug applications, and general financial, economic, regulatory and political conditions affecting the biotechnology and pharmaceutical industries and those discussed in Auxilium’s Annual Report on Form 10-K for the year ended December 31, 2008 under the heading “Risk Factors,” which is on file with the Securities and Exchange Commission (the “SEC”) and may be accessed electronically by means of the SEC’s home page on the Internet at http://www.sec.gov or by means of Auxilium’s home page on the Internet at http://www.Auxilium.com under the heading “For Investors -- SEC Filings.” There may be additional risks that Auxilium does not presently know or that Auxilium currently believes are immaterial which could also cause actual results to differ from those contained in the forward-looking statements. Given these risks and uncertainties, any or all of these forward-looking statements may prove to be incorrect. Therefore, you should not rely on any such factors or forward-looking statements.

In addition, forward-looking statements provide Auxilium’s expectations, plans or forecasts of future events and views as of the date of this release. Auxilium anticipates that subsequent events and developments will cause Auxilium’s assessments to change. However, while Auxilium may elect to update these forward-looking statements at some point in the future, Auxilium specifically disclaims any obligation to do so. These forward-looking statements should not be relied upon as representing Auxilium’s assessments as of any date subsequent to the date of this release.