Muscarinic antagonists are used to treat overactive bladder, urinary incontinence, and bladder spasms. These medications work by blocking the action of acetylcholine, a chemical that causes muscles to contract, which helps to relax the bladder muscles and reduce urinary urgency and frequency. Muscarinic antagonists come in different forms, including oral pills and extended-release tablets. Examples include oxybutynin, tolterodine (Detrol), and solifenacin (Vesicare). You can choose the form that best fits your needs.