Preliminary evaluation of a new controlled-release oxybutynin in urinary incontinence

SUMMARY

Objective: To conduct a preliminary evaluation of a new oral formulation of controlled-release (CR) oxybutynin tablet taken once-daily in patients with urinary urge incontinence.

Research design and methods: A single-centre, open-label, 8-week study was conducted. Patients with urodynamically-confirmed detrusor instability, micturition frequency (> 8 voids/day) and/or urinary incontinence (> 2 incontinence periods/day) were enrolled. The study duration was 8 weeks: patients received IR oxybutynin (2.5-5 mg bid) for 2 weeks, followed by a 2-week washout/baseline period to avoid carryover effects, and oral CR oxybutynin (15 mg OD) for 4 weeks. Daily void frequency, fluid intake, urinary incontinence episodes, and spontaneously reported adverse events were recorded in a daily diary for five consecutive days in each treatment period.

Results: Of 12 enrolled patients, 9 patients completed the study and were evaluable for efficacy; all patients were evaluable for safety. Compared to baseline/washout, CR oxybutynin reduced UI episodes/day by 45% (p = 0.13) and micturitions/day by 15% (p = 0.07). Treatment with IR oxybutynin (mean dose: 6.7 ± 2.5mg/day) reduced UI episodes/day from baseline by 7% (p = 0.58) and voids/day by 6% (p = 0.29). Fluid intake remained consistent at approximately 2 litres/day during all study periods. The most common adverse event was dry mouth.

Conclusion: Based on the reductions in daily frequency of incontinence and micturition following 4-weeks treatment, CR oxybutynin (15 mg OD) was at least as effective as the patients' previous dose of IR oxybutynin (mean dose: 6.7 ± 2.5 mg/day). These improvements were achieved without restriction of fluid intake. Initial 15mg doses of CR oxybutynin appear to be well tolerated.

Key Words::

• Bladder
• Cholinergic antagonist
• Drug delivery systems
• Pharmacology
• Urinary incontinence