Oxybutynin for treatment of urge urinary incontinence and overactive bladder: an updated review

Urge urinary incontinence (UUI) and overactive bladder are common conditions often associated with profound impairment of the health and quality of life of the patient. Antimuscarinic medications have been the mainstay of treatment for these disorders. Oxybutynin hydrochloride, one of the most widely used antimuscarinic agents, has attracted considerable interest from both clinicians and pharmacologists over the last three decades. Although efficacy of this drug has been proven to be high, its use is limited by antimuscarinic adverse effects, possibly related to its active metabolite N-desethyloxybutynin (N-DEO). The extended-release form of oxybutynin uses a push-pull osmotic release system which has significantly improved its tolerability and safety profile. A transdermal transport system has also been developed, bypassing the first-pass metabolism in the liver and gut. This system is associated with significant reduction in the production of the primary metabolite and additional improvement in the tolerability profile of the drug. Intravesical instillation of oxybutynin has been reported although the efficacy and safety of this delivery system has yet to be determined. This article comprehensively reviews the contemporary literature on the pharmacology, clinical efficacy and adverse reactions of oxybutynin in its various delivery forms, and compares them to other frequently used medications for UUI and overactive bladder.