Psychedelic Effects of Ketamine in Healthy Volunteers
Andrew t. Bowdle, Allen d. Radant, Deborah s. Cowley, Evan d. Kharasch, Rick j. Strassman, Peter p. Roy-Byrne
Anesthesiology January 1, 1998 DOI: 10.1097/00000542-199801000-00015 (opens in new tab)
Summary
AI-generated from the abstractSubanesthetic doses of ketamine produce a unique spectrum of subjective psychedelic effects in healthy volunteers. The relationship between steady-state venous plasma ketamine concentrations and the intensity of these effects is highly linear across the range of 50 to 200 ng/ml. Ketamine produced dose-related psychedelic effects, with linear regression coefficients for visual analog scale scores ranging from 0.93 to 0.99. Hallucinogen rating scale scores were similar to those found in a previous study with psychedelic doses of N,N-dimethyltryptamine, an illicit LSD-25-like drug.
Study at a glance
| Characteristics | Single-blinded crossover protocol Peer reviewed |
|---|---|
| Sample size | 10 |
| Population | Psychiatrically healthy volunteers |
| Intervention | Ketamine |
| Dose | 0, 50, 100, 150, and 200 ng/ml target plasma concentrations |
| Duration | 30 min per concentration step, with assessments after 20 min at each step; one hour after infusion discontinuation |
| Keywords | Ketamine ketamine levels Ketamine concentrations Potent psychedelic compounds Dose-response relationship direct Linear relationship |
| Citations | 371 |
| Key finding | Subanesthetic doses of ketamine produce dose-related psychedelic effects, with a highly linear relationship between steady-state plasma concentrations and effect intensity between 50 and 200 ng/ml. |
Abstract
Background Ketamine has been associated with a unique spectrum of subjective "psychedelic" effects in patients emerging from anesthesia. This study quantified these effects of ketamine and related them to steady-state plasma concentrations. Methods Ketamine or saline was administered in a single-blinded crossover protocol to 10 psychiatrically healthy volunteers using computer-assisted continuous infusion. A stepwise series of target plasma concentrations, 0, 50, 100, 150, and 200 ng/ml were maintained for 30 min each. After 20 min at each step, the volunteers completed a visual analog (VAS) rating of 13 symptom scales. Peripheral venous plasma ketamine concentrations were determined after 28 min at each step. One hour after discontinuation of the infusion, a psychological inventory, the hallucinogen rating scale, was completed. Results The relation of mean ketamine plasma concentrations to the target concentrations was highly linear, with a correlation coefficient of R = 0.997 (P = 0.0027). Ketamine produced dose-related psychedelic effects. The relation between steady-state ketamine plasma concentration and VAS scores was highly linear for all VAS items, with linear regression coefficients ranging from R = 0.93 to 0.99 (P < 0.024 to P < 0.0005). Hallucinogen rating scale scores were similar to those found in a previous study with psychedelic doses of N,N-dimethyltryptamine, an illicit LSD-25-like drug. Conclusions Subanesthetic doses of ketamine produce psychedelic effects in healthy volunteers. The relation between steady-state venous plasma ketamine concentrations and effects is highly linear between 50 and 200 ng/ml.