Watson Pharmaceuticals, Inc., a leading integrated global pharmaceutical company, and self-injection pharmaceutical products and topical gel-based medicines company, Antares Pharma, Inc have received the US Food and Drug Administration (FDA) approval for  Antares' topical oxybutynin gel 3% product for the treatment of overactive bladder (OAB) with symptoms of urge urinary incontinence, urgency, and frequency.  

Overactive bladder is a condition that affects more than 33 million Americans, and the market currently exceeds $2.0 billion annually.

Antares oxybutynin gel 3% is a topical, translucent hydroalcoholic gel containing oxybutynin, an antispasmodic, antimuscarinic agent. Applied once daily to the thigh, abdomen, upper arm or shoulder, an 84 mg (approx. 3 mL) dose delivers a consistent dose of oxybutynin through the skin over a 24-hour period, providing significant efficacy without sacrificing tolerability.

Antares' oxybutynin product is a clear, odorless topical gel available in a convenient, metered-dose pump that has demonstrated to be an effective and safe treatment for overactive bladder (OAB).  Because the active ingredient is delivered transdermally, it is not metabolized by the liver in the same way as orally administered oxybutynin.  This results in a low level of side effects, such as dry mouth and constipation. Under an exclusive licensing agreement, Watson anticipates launching the product in 2012.

"This significant achievement represents Antares' first NDA approval and is the culmination of a development program managed successfully by our clinical and regulatory team," said Paul K Wotton, Ph.D., Antares' president and CEO.  "Watson Pharmaceuticals' proven track record of commercializing transdermal products to urologists and other significant prescribers of OAB treatments makes them an ideal partner to execute a successful product launch."

"The addition of Antares' oxybutynin gel product will strategically enhance our overactive bladder product portfolio which currently includes Gelnique (oxybutynin chloride) gel 10%, and Oxytrol oxybutynin transdermal system," said Fred Wilkinson, Watson's executive vice president, global brands. "With the addition of Antares' new gel formulation, we look forward to offering patients the added convenience of a novel pump delivery system beginning in 2012."

The approval of Antares' oxybutynin gel 3% is based on a 12-week, multi-center placebo controlled Phase 3 clinical study conducted by Antares. Patients were randomized to either an 84 mg or 56 mg dose application of oxybutynin gel 3% versus placebo.  The FDA approved the 84 mg dose application.  Patients treated with 84 mg oxybutynin gel daily achieved steady state drug concentrations within three days and experienced a statistically significant decrease in OAB symptoms versus placebo, including the number of urinary incontinence episodes per week.  Statistically significant improvements in daily urinary frequency and urinary void volume were also seen with the 84 mg dose.

The product was well tolerated in the study.  The most frequently reported treatment-related adverse events (>3%) were dry mouth (12.1% versus 5% in placebo), application site erythema (3.7% versus 1.0% in placebo) and application site rash (3.3% versus 0.5% in placebo).

Additional pharmacokinetic studies showed that showering one hour or later, or the application of sunscreen 30 minutes before or after gel application had no affect on the overall systemic exposure of the drug.