[Psychedelic effects of subanesthetic doses of ketamine]

To study the psychedelic effects in healthy volunteers when given subanesthetic dose of ketamine.

Thirteen male healthy volunteers aged 24-39 years were enrolled. All subjects received subanesthetic doses of ketamine using target control infusion. A stepwise series of target plasma concentrations (0, 100, 200, and 300 ng/ml) were maintained for 20 minutes each. Visual analogue scale (VAS) of mechanical pain by von Frey hair was evaluated, and then the volunteers completed a VAS rating of 13 symptom scales. Pictures were shown to them at the same time. Heart rate, mean blood pressure, and SpO2 were monitored throughout the infusion.

During the process of analgesia, ketamine produced dose-related analgesic effects. With the increase of ketamine dose, some psychedelic effects became more obvious and the memory impairment became worse stepwisely.

Target control infusion of subanesthetic doses of ketamine produce obvious psychedelic effects in healthy volunteers.