AM404, also known as N-arachidonoylaminophenol,[1] is an active metabolite of paracetamol (acetaminophen), responsible for all or part of its analgesic action.[2]


AM404 was originally reported to be an endogenous cannabinoid reuptake inhibitor, preventing the transport of anandamide and other related compounds back from the synaptic cleft, much in the same way that common SSRI antidepressants prevent the reuptake of serotonin. Recent work on the mechanism of AM404 has suggested that the inhibition of fatty acid amide hydrolase (FAAH) by AM404 is likely responsible for all of its attributed "reuptake" properties, since intracellular FAAH hydrolysis of anandamide changes the intra/extracellular anandamide equilibrium.[3]

AM404 is also a TRPV1 agonist and inhibitor of cyclooxygenase COX-1 and COX-2, thus attenuating prostaglandin synthesis. AM404 is thought to induce its analgesic action through its activity on the endocannabinoid, COX, and TRPV systems, all of which are present in pain and thermoregulatory pathways.[4]

See also