The Forefront for Novel Therapeutic Agents Based on the Pathophysiology of Lower Urinary Tract Dysfunction: Ameliorative Effect of Solifenacin Succinate (Vesicare^®), a Bladder-Selective Antimuscarinic Agent, on Overactive Bladder Symptoms, Especially Urgency Episodes

Abstract

Overactive bladder (OAB) syndrome is a common condition that is most often observed in the elderly. Pharmacological treatment with muscarinic receptor antagonists has been most widely used for OAB. An antimuscarinic agent, solifenacin, showed the highest affinity for the muscarinic M₃ receptor, which mediates urinary bladder contraction. In preclinical studies, solifenacin exhibited a highly bladder-selective profile compared with other antimuscarinic agents. Solifenacin was also shown to increase bladder capacity without affecting residual urine in an OAB model of rats. Urgency is now considered to result from overactivation of afferent nerves from the urinary bladder. It has been reported that afferent nerves are located adjacent to the urothelium, and stimulation of muscarinic receptors expressed on the urothelium may contribute to the activation of afferent nerves via non-neuronal ATP release. Solifenacin produces its inhibitory effect on bladder afferent activity partly via the suppression of non-neuronal ATP release. Clinically, solifenacin ameliorates all symptoms in OAB patients; and in particular, it produces a significant decrease in urgency episodes, which is the principal symptom of OAB. The pharmacological profile of solifenacin is therefore considered to contribute to its beneficial effects of high efficacy against OAB symptoms with good tolerability.