NESS-0327 is a drug used in scientific research which acts as an extremely potent and selective antagonist of the cannabinoid receptor CB<sub>1</sub>. It is much more potent an antagonist, and more selective for the CB<sub>1</sub> receptor over CB<sub>2</sub>, than the more commonly used ligand rimonabant, with a K<sub>i</sub> at CB<sub>1</sub> of 350fM (i.e. 0.00035nM) and a selectivity of over 60,000x for CB<sub>1</sub> over CB<sub>2</sub>. Independently, two other groups have described only modest nanomolar CB<sub>1</sub> affinity for this compound (125nM and 18.4nM). Also unlike rimonabant, NESS-0327 does not appear to act as an inverse agonist at higher doses, instead being a purely neutral antagonist which blocks the CB<sub>1</sub> receptor but does not produce any physiological effect of its own.