Physostigmine antagonizes ketamine.

In a random cross-over double-blind trial, the effects of intravenous physostigmine salicylate (2.0 mg) and placebo were observed in seven healthy volunteers 10 minutes after the intravenous administration of 1.5 mg/kg of ketamine. Recovery time was significantly shorter after physostigmine than after placebo. Nystagmus and blurred vision, which followed ketamine anesthesia, disappeared more rapidly when physostigmine was given. This study confirms previous observations that physostigmine counteracts some of the manifestation of ketamine aftereffects which resemble the so-called central anticholinergic syndrome. Nausea and vomiting were significantly more frequent after physostigmine administration.