Alvimopan dihydrate (ADL 8-2698 dihydrate) is a potent, selective, orally active and reversible μ-opioid receptor antagonist, with an IC 50 of 1.7 nM. Alvimopan dihydrate is highly selective for μ-opioid receptor ( Ki =0.47 nM) over κ- and δ-opioid receptors ( Kis =100, 12 nM, respectively). Alvimopan dihydrate can be used for the research of postoperative ileus [1] [2] [3].

Alvimopan inhibits the binding of loperamide-stimulated [35 S]GTPγS to membranes containing the cloned human μ-opioid receptor with an IC 50 of 1.7 nM [1].

Alvimopan (0.1-1.0 mg/kg; p.o.) partially antagonizes the slowing of small intestinal transit of 113 Sn-labelled microspheres produced by morphine in rats [3]. Alvimopan (3 mg/kg; p.o.) has no effect on noxious colorectal distension (CRD)-induced visceromotor behavioural responses (VMR) in conscious rats [3].