Published in:
01-09-2003 | Adis Drug Profile
Transdermal Oxybutynin
For Overactive Bladder
Published in: Drugs & Aging | Issue 11/2003
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▴ Oxybutynin binds to the M3 muscarinic receptors on the detrusor muscle of the bladder, preventing acetylcholinergic activation and relaxing the muscle.
▴ The transdermal system delivers oxybutynin over a 3- to 4-day period after application to intact skin. Peak plasma concentrations of oxybutynin and the major active metabolite, N-desethyloxybutynin, are reached 24–48 hours after a single application and therapeutic concentrations are maintained throughout the dosage interval.
▴ In a large, randomised, double-blind trial, trans-dermal oxybutynin 3.9 mg/day significantly decreased the median number of incontinence episodes per week compared with placebo (−19 vs −15, p = 0.0165) in patients with overactive bladder. In addition, the micturition frequency was reduced and average voided volume was increased by trans-dermal oxybutynin treatment.
▴ Significant reductions in incontinence episodes following transdermal oxybutynin treatment were also observed in two further studies and the clinical efficacy was similar to that of oral tolterodine or oral oxybutynin.
▴ Transdermal oxybutynin was well tolerated in clinical trials. Application site reactions were the most common adverse effect; however, the majority were mild to moderate in severity. Adverse events associated with anticholinergic drugs (e.g. dry mouth) were less frequently reported in patients treated with transdermal oxybutynin than in those receiving orally administered oxybutynin or tolterodine.