Efficacy and safety of transdermal and oral oxybutynin in children with neurogenic detrusor overactivity.

Abstract

We evaluated the efficacy and safety of transdermal and oral oxybutynin in children with neurogenic detrusor overactivity. Children with neurogenic detrusor overactivity 6 to 15 years old and previously receiving oxybutynin were assigned randomly at a 3:1 ratio to treatment with transdermal or oral oxybutynin. Initial dosages (transdermal 1.3, 2.9 or 3.9 mg daily; oral 5, 10 or 15 mg daily), based on pre-study dosages, were adjusted after 2 weeks and then maintained for 12 weeks. The primary efficacy end point was change from baseline to last observation in average urine volume collected by clean intermittent catheterization. A total of 57 patients were randomized to receive transdermal (41) or oral (16) oxybutynin. Safety data were available for 55 patients and efficacy data were available for 52. Mean +/- SD urine volume increased from 95 +/- 64 ml to 125 +/- 74 ml (p <0.001) with transdermal oxybutynin and from 114 +/- 75 ml to 166 +/- 92 ml (p = 0.002) with oral oxybutynin. Transdermal oxybutynin resulted in significant improvement in all measured urodynamic parameters. Similar trends and a significant increase in maximal cystometric bladder capacity were observed in the smaller oral oxybutynin group. There were 12 treatment related adverse events noted with transdermal oxybutynin (mild skin reaction) and 1 with oral oxybutynin (vasodilatation). The ratio of N-desethyloxybutynin-to-oxybutynin plasma concentrations was substantially lower with transdermal (1.4) than with oral (6.7) oxybutynin. Transdermal oxybutynin was a well tolerated and effective alternative to oral oxybutynin in treating neurogenic detrusor overactivity in children who previously tolerated oxybutynin.