*
Oxybutynin inhibits contraction of the detrusor muscle in the
overactive bladder by binding to
muscarinic M(3) receptors and blocking acetylcholinergic activation. *The transdermal
oxybutynin system, applied twice weekly, delivers continuous
oxybutynin over a 96-hour patch wear period. The transdermal route of administration avoids the extensive first-pass metabolism of
oxybutynin to its active metabolite,
N-desethyloxybutynin. *In two well designed trials in patients with
overactive bladder, transdermal
oxybutynin 3.9 mg/day decreased the number of incontinence episodes and increased average voided volume to a significantly greater extent than placebo. Urinary frequency was improved to a significantly greater extent with transdermal
oxybutynin than with placebo in one trial but not the other. *There was no significant difference between transdermal
oxybutynin and extended-release oral
tolterodine for any of these endpoints. *Health-related quality-of-life improvements with transdermal
oxybutynin were shown in patients with
overactive bladder in the open-label MATRIX trial, as demonstrated by significant improvements in all domains of the King's Health Questionnaire. *Transdermal
oxybutynin is generally well tolerated in patients with
overactive bladder. The majority of patients who discontinued transdermal
oxybutynin treatment in two pivotal trials did so because of application-site reactions. However, none discontinued treatment because of dry mouth.