Alvimopan monohydrate (ADL 8-2698 monohydrate) is a potent, selective, orally active and reversible μ-opioid receptor antagonist, with an IC 50 of 1.7 nM. Alvimopan monohydrate has selectivity for μ-opioid receptor ( K i =0.47 nM) over κ- and δ-opioid receptors ( K i s=100, 12 nM, respectively). Alvimopan monohydrate can be used for the research of postoperative ileus In Vitro Alvimopan inhibits the loperamide-stimulated [ 35 S]GTPγS binding to membranes containing the cloned human μ-opioid receptor, with an IC 50 of 1.7 nM. MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo Alvimopan (0.1-1.0 mg/kg; p.o.) partially antagonizes the slowing of small intestinal transit of 113 Sn-labelled microspheres in rats. Alvimopan (3 mg/kg; p.o.) has no effect on the visceromotor behavioural responses (VMR) induced by noxious colorectal distension (CRD) in conscious rats. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:μ Opioid Receptor/MOR