Watson Announces Positive Results From Study Of Oxybutynin Topical Gel For Overactive Bladder Treatment
Overactive Bladder Treatment
Watson Pharmaceuticals announced positive results from its Phase 3 study of oxybutynin topical gel (OTG) in patients with overactive bladder (OAB).
The study met its primary endpoint of a statistically significant reduction in incontinence episodes, and secondary endpoints of reduction in frequency and increases in void volume compared with placebo, while demonstrating a low incidence of side effects.
"We are extremely encouraged with the results from this trial which will support our NDA submission, and we are on track to file with FDA in the second quarter of 2008," said Paul Bisaro, Watson's President and Chief Executive Officer. "Additionally, we have the potential to introduce the first gel formulation for the treatment of overactive bladder in 2009."
"Offering patients the ease and comfort of a daily gel for the treatment of OAB may provide greater patient acceptability and persistence on treatment," said Peter K. Sand, M.D., director of the Evanston Continence Center, Evanston Northwestern Healthcare, Northwestern University, Feinberg School of Medicine and Professor of Obstetrics and Gynecology and Director of the Division of Urogynecology, Evanston, IL.
It is well recognized that transdermal delivery of oxybutynin is a safe and effective treatment for OAB. By delivering oxybutynin transdermally, first-pass gastric and hepatic metabolism is bypassed, which is believed to result in lower anticholinergic side effects such as dry mouth and constipation. These side effects result in a significant level of patient non-compliance among existing oral OAB treatments, according to Dr. Sand. "Watson's oxybutynin gel is an elegant topical formulation that is clear, odorless and fast drying and will offer healthcare providers a unique treatment option for OAB patients," said Dr. Sand.
The Phase 3 multi-center, double blind, placebo-controlled study evaluated the efficacy and safety of OTG in 789 patients with overactive bladder. The primary objective of the study was to demonstrate that daily treatment of a 1g dose (approximately 1 mL) of OTG for 12 weeks was superior to placebo for the relief of OAB symptoms. Changes from baseline to endpoint were calculated from a three-day patient urinary diary and included a reduction in incontinence episodes and urinary frequency, and an increase in void volume. Additionally, 216 patients participated in a 14-week, open label, safety-extension study for a total of 26 weeks. During the double-blind portion of the trial, highly statistically significant improvements relative to placebo were seen on all of these endpoints.
Secondary endpoints also included a patient assessment of incontinence-specific, quality-of-life measures using multiple validated instruments including the Incontinence Impact Questionnaire (IIQ) and the King's Health Questionnaire, which indicated a significant positive effect of OTG treatment on quality-of-life total and subscale scores at endpoint in comparison with placebo.
OTG was well tolerated in the study. No serious adverse events related to the treatment were reported. Dry mouth (6.9%) and application site pruritis (2.1%) were the only treatment-related side effects reported at levels greater than 2%. Treatment-related adverse events that resulted in study discontinuation during the double-blind period were low ( 1.8%) and the similar for both the treatment and placebo groups.
Phase 1 studies have demonstrated that the steady-state plasma levels of oxybutynin show little fluctuation during the 24-hour dosing interval, and absorption of oxybutynin is similar when applied to the abdomen, thigh, or upper arm/shoulder.
OTG is protected by two patents, which cover methods of treatment and certain articles of manufacture for treating overactive bladder, with the latest patent expiring in 2020. An additional patent application is pending with the U.S. Patent and Trademark Office and various foreign jurisdictions.