AM 1221

AM-1221 is a drug that acts as a potent and selective agonist for the cannabinoid receptor CB₂, with a K_i of 0.28 nM at CB₂ and 52.3 nM at the CB₁ receptor, giving it around 180x selectivity for CB₂. The 2-methyl and 6-nitro groups on the indole ring both tend to increase CB₂ affinity while generally reducing affinity at CB₁, explaining the high CB₂ selectivity of AM-1221. However, despite this relatively high selectivity for CB₂, its CB₁ affinity is still too strong to make it useful as a truly selective CB₂ agonist, so the related compound AM-1241 is generally preferred for research purposes.