Effect of controlled-release oxybutynin on neurogenic bladder function in spinal cord injury

Objective: This study evaluated the effects and tolerability of extended-release oxybutynin chloride on the frequency of voiding and catheterization and urodynamic capacity in spinal cord injury (SCI) patients with defined detrusor hyperreflexia. Methods: This was a 12-week, prospective, close-titration study of extended-release oxybutynin (oxybutynin XL). SCI patients with urodynamically defined detrusor hyperreflexia were recruited for this study. Following a 7-day washout period, patients were evaluated via video-urodynamic study and then treatment was initiated at a dosage of 10 mg per day. Dosage was increased in weekly intervals to a maximum of 30 mg per day. Micturation frequency diaries and urodynamics were completed at baseline and repeated at week 12. Tolerability information was collected at each follow-up visit. Results: Ten patients (mean age = 49 years) with complete or incomplete SCI were enrolled. Participants reported clinical improvement (decreased urinary frequency and fewer incontinence episodes) with oxybutynin therapy following titration to 3 0 mg per day. All patients chose a final effective dosage of greater than 10 mg, with 4 patients taking the maximum of 3 0 mg per day. Mean cystometric bladder capacity increased from 2 74 mL to 3 80 mL (P = 0.008). No patient experienced serious adverse events during the 12-week study. Conclusion: Oxybutynin XL is safe and effective in patients with detrusor hyperreflexia secondary to SCI. The onset of clinical efficacy occurs within I week, and daily dosages up to 30 mg are well tolerated.