Efficacy and Safety of Oxybutynin Transdermal System in Spinal Cord Injury Patients With Neurogenic Detrusor Overactivity and Incontinence: An Open-label, Dose-titration Study

Objectives: To evaluate the efficacy and safety of oxybutynin transdermal system (oxybutynin-TDS) in spinal cord injury patients with neurogenic detrusor overactivity and incontinence despite use of clean intermittent catheterization (CIC). Methods: This multicenter, open-label, dose-titration study included patients ≥ 18 years old. During an 8-week dose-titration period, oxybutynin-TDS doses were adjusted every 2 weeks, depending on symptoms. The primary efficacy end point was a change in daily number of CIC periods without leakage, from baseline to 8 weeks or last observation. Outcome parameters included 3-day voiding diary, CIC volume, and urodynamic parameters. Changes from baseline were analyzed with paired t tests. Results: Of 24 study participants (mean age, 41.9 years), 18 (75.0%) completed the study. Final oxybutynin-TDS doses were 7.8, 9.1, and 11.7 mg/d for 4, 9, and 11 patients, respectively. Daily number of CIC periods without leakage increased significantly (mean change, 1.5 ± 2.2; P = .0036) from baseline (2.4 ± 1.8) to 8 weeks (3.9 ± 1.9). CIC volume (P = .0029), reflex volume (P = .0466), maximal cystometric bladder capacity (P = .0009), and residual urine volume (P = .0023) all increased significantly, whereas detrusor pressure at maximal bladder capacity decreased significantly (P = .0457). The most common adverse events were application site reaction (12.5% of patients), dry mouth (8.3%), and abnormal vision (8.3%). No patient discontinued treatment because of an adverse event. Conclusions: Oxybutynin-TDS was efficacious in spinal cord injury patients with neurogenic detrusor overactivity and was well tolerated at up to 3 times the standard dose.