MCHB-1 is a benzimidazole derived drug which was researched as an analgesic but never developed for medical use. It acts as a potent agonist of the CB₂ receptor, with an EC₅₀ of 0.52nM at CB₂, and ~30x selectivity over CB₁ (Ki of 110nM at CB₁ vs 3.7nM at CB₂). It has been sold online as a designer drug, first being identified in Germany in December 2013.