Oxybutynin topical gel in the treatment of overactive bladder

Overactive bladder (OAB), often accompanied by urinary incontinence, is most prevalent among the elderly, but also affects many middle-aged men and women in the US. OAB may severely impair quality of life, and its overall economic costs to society are substantial. Although antimuscarinic agents relieve OAB symptoms effectively, treatment persistence generally is low. This has been attributed in part to the occurrence of dry mouth and other anticholinergic adverse events. High plasma concentrations of N-desethyloxybutynin (DEO), an active metabolite of oxybutynin, have been identified as the major cause of anticholinergic adverse effects associated with oral oxybutynin. Transdermal formulations of oxybutynin generate much lower DEO plasma concentrations compared with oral formulations. In a placebo-controlled US Phase III study in patients with OAB, the recently approved oxybutynin topical gel (OTG) was efficacious and well tolerated. Dry mouth occurred in 6.9% of patients treated with OTG and 2.8% of patients on placebo. Incidences of other anticholinergic events were low and similar for OTG and placebo. OTG rarely caused application site skin reactions. OTG provides significant benefits to patients with OAB, particularly those who are sensitive to anticholinergic adverse effects.