Watson Pharmaceuticals, Inc. (NYSE: WPI), a leading specialty pharmaceutical company, announced that its New Drug Application (NDA) for silodosin, a novel alpha(1)- adrenoreceptor antagonist, has been accepted for filing by the U.S. Food and Drug Administration (FDA). Watson is seeking marketing approval of silodosin from the FDA for the treatment of the signs and symptoms associated with benign prostatic hyperplasia (BPH), or enlarged prostate. Watson anticipates that the FDA will take action on its application in the fourth quarter 2008.

Silodosin was designed to decrease urinary resistance and improve dysuria (difficulty or pain in urination) associated with BPH. In clinical trials, silodosin demonstrated a very low level of the most highly-reported cardiovascular and blood pressure-related side effects associated with existing BPH treatments, including dizziness and first-dose syncope (fainting).

“This filing highlights Watson’s capabilities in new drug development and our commitment to this product, providing solutions to the millions of men with BPH symptoms,” said Paul Bisaro, Watson’s President and Chief Executive Officer. “Watson is expanding the portfolio it offers to urologists and their patients, focusing on symptom management that makes a big difference in their day-to-day lives.”

Watson submitted the filing for silodosin with data from two Phase 3 multi-center (88 sites), randomized, double-blind, placebo-controlled trials that evaluated a total of 923 patients with signs and symptoms of BPH for 12 weeks. The trials demonstrated that a once daily 8mg dose of silodosin given for 12 weeks provided significant relief of BPH symptoms, compared with placebo, as measured by the International Prostate Symptom Score (IPSS), the primary endpoint. Secondary endpoints included improvements of maximum urine flow and quality of life. As expected, the most common side effects seen in the two studies greater than 2% were retrograde ejaculation (reduced semen) and dizziness.

Silodosin is highly uroselective for the alpha (1A) receptors located in the prostate and bladder neck. Blocking these receptors relaxes the smooth muscles, resulting in an improvement in urine flow and a reduction in BPH symptoms. The selective binding of silodosin to the alpha (1A) receptors is substantially greater than the binding to the cardiovascular-associated alpha (1B) receptors and thereby maximizes target organ activity while minimizing the potential for blood pressure effects.

The compound was originally developed by Kissei Pharmaceutical Co., Ltd., in Japan and licensed to Watson for the United States, Canada and Mexico. Kissei successfully launched Urief(R) (silodosin) in Japan in May of 2006 at a twice daily dosing of 4mg. Urief(R) is marketed in cooperation with Daiichi Sankyo Pharmaceutical Co., Ltd.

BPH, or an enlarged prostate, is a condition found only in men and is characterized by a non-cancerous enlargement of the prostate gland. Symptoms of BPH include urinary difficulty, urinary frequency and an inability to complete bladder emptying. The number of BPH patients has been increasing with the expansion of the elderly population. In the United States, BPH affects more than half of men in their 60’s and as many as 90 percent of men by the age of 85. According to IMS data, BPH symptoms were the primary reason patients visited their urologists in 2006.