HU-243 (AM-4056) is a synthetic cannabinoid drug that is a single enantiomer of the hydrogenated derivative of the commonly used reference agonist HU-210. It is a methylene homologue of canbisol. It is a potent agonist at both the CB1 and CB2 receptors, with a binding affinity of 0.041 nM at the CB1 receptor, making it marginally more potent than HU-210, which had an affinity of 0.061 nM in the same assay.