Potent CB1 receptor antagonist/inverse agonist (Ki = 141 nM) with greater than 70-fold selectivity over CB2 receptors (Ki > 10 μM). Structurally dissimilar from SR 141716A and AM 251. Shows weak binding to both 5-HT2 (Ki = 6.4 μM) and muscarinic receptors (Ki = 2.1 μM). Purity 98%. MW (observed): 383.4