Ketamine is characterised by 3 rings: an aryl ring, a cyclohexyl ring, and an amine ring (Figure one). The cyclohexane ring is normally intact because it is necessary for antagonism on the NMDA receptor. ACHs are chiral; the asymmetric carbon within the C2 situation has two optical isomers. Ketamine is promoted as being a racemate (i.Purity the pub