Bucinnazine (AP-237, 1-butyryl-4-cinnamylpiperazine) is an opioid analgesic drug that was widely used in China to treat pain in cancer patients as of 1986.

[5] In accordance with these studies, results from the intravenous self-administration experiments in rats showed that bucinnazine has a marked reinforcing effect with tolerance and dependence quickly developing.

[1] In addition, the opioid receptor antagonist naloxone reverses the effect of bucinnazine and precipitates withdrawal symptoms in bucinnazine treated rats further indicating a mechanism of analgesia mediated via selective agonist activity at μ-opioid receptors.

2-methyl-AP-237 has been sold on the grey market as a designer opioid, first identified by a police forensic laboratory in Slovenia in March 2019.

[6][7][8] In 2023, the United States Department of Justice took criminal action against two individuals for selling 2-methyl-AP-237 under the false pretenses that such product was intended for 'research purposes' only.