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. It is one of the most potent compounds among a series of piperazine-amides first synthesized and reported in Japan in the 1970s. Bucinnazine has analgesic potency comparable to that of morphine but with a relatively higher therapeutic index.
The drug was initially claimed to be a non-narcotic analgesic. However, subsequent studies have shown bucinnazine and similar acyl piperazines to be potent and selective agonists of μ-opioid receptor (MOR) with relatively low affinity for the δ-opioid receptor and the κ-opioid receptor.
In addition, the morphine antagonist naloxone reverses the effect of bucinnazine.
Derivatives: 2-methyl-AP-237 has been sold on the black market as a designer opioid, first identified by a police forensic laboratory in Slovenia in March 2019.