Description
A µ-opioid receptor antagonist (Ki = 0.47 nM); selective over the κ- and δ-opioid receptors (Kis= 100 nM and 12 nM, respectively); inhibits µ-opioid receptor-mediated GTP binding to CHO cell membranes (IC50 = 1.7 nM); inhibits morphine-induced slowing of colorectal transit in mice with (ED50 = 0.41 mg/kg); reduces morphine-induced inhibition of GI transit in rats at 0.3 and 1 mg/kg, p.o