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

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.

This was a 12-week, prospective, dose-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.

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 30 mg per day. All patients chose a final effective dosage of greater than 10 mg, with 4 patients taking the maximum of 30 mg per day. Mean cystometric bladder capacity increased from 274 mL to 380 mL (P = 0.008). No patient experienced serious adverse events during the 12-week study.

Oxybutynin XL is safe and effective in patients with detrusor hyperreflexia secondary to SCI. The onset of clinical efficacy occurs within 1 week, and daily dosages up to 30 mg are well tolerated.