Antimuscarinic agents have become standard pharmacological therapy for urinary incontinence. However, a substantial proportion of patients find the anticholinergic adverse effects, particularly dry mouth, difficult to tolerate. Recently, extended-release (ER) formulations of oxybutynin and tolerodine have been developed with the objectives of permitting once-daily dosing and reducing anticholinergic side effects without adversely affecting the efficacy of the compounds. At the WHO 2nd International Consultation on Incontinence (ICI) [Paris, France; July 2001] results from two studies showed oxybutynin ER ['Ditropan XL'] to be effective and well tolerated in patients with overactive bladder secondary to multiple sclerosis or spinal cord injury. Additionally, in a preliminary clinical comparison, changes in gastric pH altered the functionality of tolterodine ER ['Detrol LA'] but not oxybutynin ER. Specifically, a rise in pH resulted in a 'dumping phenomenon', or accelerated release of tolerodine soon after administration.