APINACA (AKB48, N-(1-adamantyl)-1-pentyl-1H-indazole-3-carboxamide) is a drug that acts as a reasonably potent agonist for the cannabinoid receptors, with a Ki of 304.5nM and a EC50 of 585nM at CB1. It had never previously been reported in the scientific or patent literature, and was first identified by laboratories in Japan in March 2012 as an ingredient in synthetic cannabis smoking blends, along with a related compound APICA. Structurally, it closely resembles cannabinoid compounds from a University of Connecticut patent (WO 2003/035005), but with a simple pentyl chain on the indazole 1-position, and APINACA falls within the claims of this patent despite not being disclosed as an example.
^Uchiyama, N.; Kawamura, M.; Kikura-Hanajiri, R.; Goda, Y. (2012). "URB-754: A new class of designer drug and 12 synthetic cannabinoids detected in illegal products". Forensic Science International. 227 (1–3): 21–32. doi:10.1016/j.forsciint.2012.08.047. PMID23063179.
^Uchiyama, N.; Kawamura, M.; Kikura-Hanajiri, R.; Goda, Y. (2012). "Identification of two new-type synthetic cannabinoids, N-(1-adamantyl)-1-pentyl-1H-indole-3-carboxamide (APICA) and N-(1-adamantyl)-1-pentyl-1H-indazole-3-carboxamide (APINACA), and detection of five synthetic cannabinoids, AM-1220, AM-2233, AM-1241, CB-13 (CRA-13), and AM-1248, as designer drugs in illegal products". Forensic Toxicology. 30 (2): 114. doi:10.1007/s11419-012-0136-7.