Effects of ketamine on precipitated opiate withdrawal.

Objective: N-methyl-D-aspartate antagonists were shown to be effective in suppressing the symptoms of opiate withdrawal. Intravenous anesthetic, ketamine, is the most potent N-methyl-D-aspartate antagonist available in clinical practice. The present study was designed to evaluate the effects of subanesthetic ketamine infusion, as little human data are available on ketamine in precipitated opiate withdrawal.

Materials And Methods: A total of 58 opiate-dependent patients were enrolled in a randomized, placebo-controlled, double-blind study. Patients underwent rapid opiate antagonist induction under general anesthesia. Prior to opiate antagonist induction patients were given either placebo (normal saline) or subanesthetic ketamine infusion of 0.5 mg/kg/h. Further evaluations were divided into three phases: anesthetic, early postanesthetic (48 hours), and remote at 4 months after procedure. Cardiovascular, respiratory, renal, and gastrointestinal responses to opiate antagonist induction were monitored during anesthesia phase. Changes in plasma cortisol concentrations were measured as stress-response markers. Evaluations during early postanesthetic phase were based on Subjective and Objective Opiate Withdrawal Scales. Remote effects were assessed according to questionnaire based on Addiction Severity Index.

Results: Altogether, 50 patients were included in the final analysis. Ketamine group presented better control of withdrawal symptoms, which lasted beyond ketamine infusion itself. Significant differences between Ketamine and Control groups were noted in anesthetic and early postanesthetic phases. There were no differences in effects on outcome after 4 months.

Conclusion: In this study, subanesthetic ketamine infusion was an effective adjuvant in the correction of acute precipitated opiate withdrawal although it had no long-term effects on treatment of opiate dependence.