AP-238 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 analgesic acyl piperazine compounds first synthesized and reported in Japan in the 1970s. AP-238 has analgesic potency 4-5 times 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 accordance with these studies, results from the intravenous self-administration experiments in rats showed that ap-238 has a marked reinforcing effect with tolerance and dependence quickly developing In addition, the morphine antagonist naloxone reverses the effect of ap-238 and precipitates withdrawal symptoms in ap-238 treated rats further indicating a mechanism of analgesia mediated via selective agonist activity at μ-opioid receptors.
- Synonyms: AP238
- Formal Name: 1-(4-cinnamyl-2,6-dimethylpiperazin-1-yl)propan-1-one
- CAS number: NA
- Molecular Formula: C18H26N2O
- Molecular Weight: 322.9
- Purity: ≥99%
- Formulation: A crystalline solid