Comparative EEG analysis of the effects of ketamine enantiomers and metabolites in rhesus macaques.
Journal of neurophysiology April 1, 2026 Yoshihiro Iwamura, Kantaro Nishigori, Masataka Yamaguchi et al.
At a dose matching the concentration found effective for depression in humans, the anesthetic (R,S)-ketamine increased gamma power in the EEG of rhesus macaques, replicating clinical findings. The enantiomer (R)-ketamine produced a similar rise in gamma power but had weaker effects on EEG features linked to side effects. Ketamine metabolites caused only mild EEG changes, suggesting they contribute little to ketamine's EEG effects. The results indicate (R)-ketamine may have a broader therapeutic range and lower risk of adverse effects than (R,S)-ketamine.