Oxybutynin: past, present, and future

Oxybutynin chloride is primarily indicated for the treatment of overactive bladder syndrome (OAB). It remains the most widely prescribed compound for OAB in the world. OAB is defined as the presence of urinary urgency, usually accompanied by daytime urinary frequency and nocturia, with or without urgency urinary incontinence, in the absence of infection or other identifiable etiology. This is a significant problem for men and women said to affect over 33 million adults in the USA, with the prevalence increasing with age. These symptoms can alter quality of life, with both physical and psychological impairment, as well as cause significant financial burden including the cost of sanitary supplies and decreased work productivity. Both pharmacological and non-pharmacological methods may be employed to aid in the treatment of OAB. The mainstay of treatment for OAB relies on pharmacological management, most specifically treatment with antimuscarinic medications. These medications are thought to prevent involuntary bladder contractions and/or urgency by inhibiting the muscarinic receptors within the urothelium and detrusor muscle. Currently, there are six different medications approved by the US Food and Drug Administration (FDA) for the treatment of OAB, with more than nine formulations including immediate- and extended-release tablets, transdermal patch and gel, vaginal ring, and suppository. This review will focus specifically on oxybutynin chloride, which has been used to treat OAB for four decades in numerous formulations.