Zamifenacin (UK-76654) is a potent gut-selective muscarinic M3 receptor antagonist. Zamifenacin significantly reduces colonic motility in irritable bowel syndrome^[1]. IC50 & Target: Muscarinic M3 receptor^[1] In Vivo: Zamifenacin exhibits moderate oral bioavailability (mouse 26%, rat 64%, dog 100%) and C_max (mouse 92, rat 905, dog 416 ng/mL) following oral administration (mouse 13.2, rat 20 and, dog 5 mg/kg)^[2].
Zamifenacin exhibits terminal elimination half-lives (mouse 2.1, rat 6.0 and, dog 1.1 h) due to high plasma clearance (68, 35, and 39 mL/min/kg respectively combined with large volumes of distribution (12.5, 19.0, and 3.5 L/kg respectively) following intravenous administration (mouse 5.3, rat 5.0 and, dog 1.0 mg/kg)^[2].