Esketamine

Esketamine (also (S)-ketamine or S(+)-ketamine) (brand name Ketanest S) is a general anaesthetic and a dissociative. It is the S(+) enantiomer of the drug ketamine, a general anaesthetic. Esketamine acts primarily as a non-competitive NMDA receptor antagonist, but is also a dopamine reuptake inhibitor. As of July 2014, it is in phase II clinical trials for treatment-resistant depression (TRD).

Pharmacology

Esketamine is approximately twice as potent as racemic ketamine. It is eliminated from the human body more quickly than arketamine (R(–)-ketamine) or racemic ketamine, although arketamine slows its elimination.

A number of studies have suggested that esketamine has a more medically useful pharmacological action than arketamine or racemic ketamine. Esketamine inhibits dopamine transporters eight times more than arketamine. This increases dopamine activity in the brain. At doses causing the same intensity of effects, esketamine is generally considered to be more pleasant by patients. Patients also generally recover mental function more quickly after being treated with pure esketamine, which may be a result of the fact that it is cleared from their system more quickly.