Solifenacin is a urinary antispasmodic of the antimuscarinic class. It is used in the treatment of overactive bladder with or without urge incontinence. Solifenacin is a competitive cholinergic receptor antagonist. The binding of acetylcholine to these receptors, particularly the M3 receptor subtype, plays a critical role in the contraction of smooth muscle. By preventing the binding of acetylcholine to these receptors, solifenacin reduces smooth muscle tone in the bladder, allowing the bladder to retain larger volumes of urine and reducing the number of micturition, urgency and incontinence episodes. Solifenacin should not be taken by people with a history of previous hypersensitivity to it, urinary retention, gastric retention, uncontrolled or poorly controlled closed-angle glaucoma, or severe liver disease. Solifenacin is metabolized in the liver by the cytochrome P450 enzyme CYP3A4.
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