Disclosed herein are pharmaceutical compositions comprising a therapeutically effective amount of extended release solifenacin, or a pharmaceutically acceptable salt thereof, and a therapeutically effective amount of pilocarpine, or a pharmaceutically acceptable salt thereof. Also disclosed herein are methods of treating a patient suffering from overactive bladder, the method comprising identifying a patient in need thereof, and administering to the patient a therapeutically effective amount of extended release solifenacin, or a pharmaceutically acceptable salt thereof, and a therapeutically effective amount of pilocarpine, or a pharmaceutically acceptable salt thereof. Also disclosed herein are methods of alleviating a side effect of treatment for overactive bladder in a patient suffering therefrom, the method comprising identifying a patient in need thereof, and administering to the patient a therapeutically effective amount of extended release solifenacin, or a pharmaceutically acceptable salt thereof, and a therapeutically effective amount of pilocarpine, or a pharmaceutically acceptable salt thereof.
