FDA Approves Oxybutynin Gel 10% for Overactive Bladder

Laurie Barclay, MD

February 02, 2009

February 2, 2009 — On January 27, Watson Pharmaceuticals, Inc, announced that the US Food and Drug Administration (FDA) has approved oxybutynin chloride gel 10% (Gelnique) for the treatment of overactive bladder (OAB). The new formulation of this antispasmodic agent may offer OAB patients an effective and novel alternative to currently available options for treatment of urge urinary incontinence, urgency, and frequency.

"Based on the results of a clinical trial, which showed strong efficacy and excellent tolerability, and considering its unique delivery system, we expect that Gelnique will be used as a first-line therapy for the treatment of OAB," Paul Bisaro, chief executive officer of Watson Pharmaceuticals, said in a news release.

Transdermal release of oxybutynin via the gel formulation bypasses liver metabolism required for the orally administered formulation of oxybutynin, thereby reducing adverse effects such as dry mouth and constipation. Gelnique is a quick-drying, clear, colorless, fragrance-free, hydroalcoholic gel containing 100 mg/g oxybutynin chloride.

The dose is 1 g (approximately 1 mL) applied once daily to the thigh, abdomen, upper arm, or shoulder. Delivery of a consistent dose of oxybutynin transdermally during a 24-hour period allows good efficacy as well as tolerability.

The manufacturer anticipates that the antispasmodic agent will be made available to patients in the second quarter of 2009 and will be actively marketed to physicians in the interim.

Data from a phase 3, randomized, double-blind, placebo-controlled, parallel group, 12-week trial led to FDA approval of the agent. Among 789 participants with signs and symptoms of OAB, those receiving a 1-g, once-daily dose of oxybutynin chloride gel had better relief of OAB symptoms than did those assigned to placebo, with fewer incontinence episodes, less urinary frequency, and increased urine void volume.

Oxybutynin chloride gel was well tolerated, with few adverse events and no treatment-related serious adverse events. Treatment-related adverse events occurring in more than 2% of patients and with a greater frequency than placebo were dry mouth, occurring in 6.9% of patients, and application-site reactions, which occurred in 5.4% of patients.

Further pharmacodynamic testing showed that absorption of oxybutynin chloride gel was not significantly affected by showering 1 hour later or by applying sunscreen 30 minutes before or after the agent's application.

US prevalence of OAB is 33 million. Although it affects both men and women, more severe symptoms tend to occur earlier in life in women. Symptoms may include urinary urgency, urge incontinence, urinary frequency, and nocturia. These symptoms are often associated with a significant decrease in health-related quality of life, increased risk for depression, and even disability.

Oxybutynin chloride gel is contraindicated in patients with or at risk for urinary or gastric retention, uncontrolled narrow-angle glaucoma, or known hypersensitivity to the agent. It should be used with caution in patients with hepatic or renal impairment, clinically significant bladder outflow obstruction, myasthenia gravis, gastrointestinal obstructive disorders, ulcerative colitis, intestinal atony, gastroesophageal reflux, and concurrent use of drugs that can cause or exacerbate esophagitis.

Oxybutynin chloride gel can be transferred to another person by vigorous skin-to-skin contact with the application site. Patients should avoid open fire or smoking until the gel has dried.

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