Transdermal therapy for overactive bladder: present and future.

Transdermal delivery of certain pharmacologic agents offers distinct advantages, including the ability to bypass the gastrointestinal environment, fewer side effects, and increased bioavailability. For many patients with overactive bladder (OAB), transdermal therapy is more convenient than oral therapy, and the altered drug metabolism offers the advantages of an improved side-effect profile and enhanced steady-state plasma concentrations. The "newness" of transdermal delivery to physicians treating OAB is a potential limitation; however, much insight can be gained from the successful use of transdermal systems for delivery of other therapies, such as agents for chronic pain, hormone replacement therapy, and contraceptives. The transdermal oxybutynin system for OAB reduces the level of oxybutynin metabolites, resulting in a low incidence of anticholinergic side effects, and provides efficacy similar to that of standard doses of currently available oral preparations. However, there is room for improvement of the transdermal system, especially with respect to providing increased efficacy over currently available oral medications and reducing and treating local skin reactions at the application site.