The evolution of transdermal therapy for overactive bladder.

Oxybutynin chloride has been effectively used for treating overactive bladder syndrome for more than three decades. The evolution of different delivery systems led first to intravesical administration, anal suppositories, and then to the commercial development of an extended-release oral formulation of oxybutynin chloride to improve its tolerability while maintaining efficacy. These modes of delivery were associated with decreased antimuscarinic side effects and N-desethyloxybutynin serum levels by avoiding first-pass metabolism in the upper gut and liver. The development of transdermal delivery has carried this evolution even further, with serum levels of desethyloxybutynin < or = oxybutynin and dry mouth rates of 7%, with little constipation. The new development of a transdermal oxybutynin gel has decreased these application site reactions to low levels while maintaining good efficacy.