Tolterodine (also known as PNU-200583E) is a tartrate salt of tolterodine that is a potent and competitive muscarinic receptor antagonist. Tolterodines is an antimuscarinic medication used to treat urinary incontinence symptoms. While older antimuscarinic treatments for overactive bladder specifically target M3 receptors, tolterodine acts on both the M2 and M3 subtypes of muscarinic receptors. Tolterodine targets the bladder more than other parts of the body, so even though it acts on all types of receptors, it has fewer side effects than oxybutynin (which is selective for M3 and M1, but more so in the parotid than in the bladder).