Ketamine – Wikipedia

Ketamine is a cyclohexanone -derived general anesthetic and NMDA receptor antagonist with analgesic and hallucinogenic properties, used medically for anesthesia, depression, and pain management. [19][20] Ketamine exists as its two enantiomers, S – (esketamine) and R – (arketamine), and has antidepressant action likely involving other mechanisms …

https://en.wikipedia.org/wiki/Ketamine