Solifenacin is a competitive muscarinic acetylcholine 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. It is FDA approved for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency. Common adverse reactions include constipation, Xerostomia. Inhibitors of CYP3A4 may increase the concentration of Solifenacin. Vice versa, CYP3A4 Inducers decrease concentration.