Ketamine’s possible role as an antidepressant was first reported in 2000.Berman et al reported a rapid antidepressant effect after single infusion of Ketamine. 4 further studies have now reported similar immediate effects. These studies also showed that the benefits are not sustained. Investigations with serial infusions ( 6 thrice weekly infusions) have been promising.Dissociatiev side effects were of shorter duration. Studies have used 0.5mg/kg over 40 minutes as the infusion dose. Doses above 0.3mg/kg would require anesthesia monitoring in many places and this will limit the use of this treatment. Would a lower rate of infusion without anaesthetists involved be safe and effective?
Keith G Rasmussen and team report the results of their open label study addressing the above question.They treated depressed adult patients (with two antidepressant failures) of serial ketamine infusions (twice weekly for up to two weeks) with each patient treated until remission criteria were met or there were four infusions without remission.Infusion rate was 0.3 mg/kg per hour for 100 minutes.
Half of the patients (5/10) met criteria for remission after infusion showing transient antidepressant effect. Among the remitters, one patient required one infusion, three required two infusions, and one required four infusions. Two of these five sustained the remitted state during four weeks of follow-up. During this time, all these patients were receiving antidepressant medications.80% of the completers responded to ketamine infusions.
Limitations: This is an open label study. Sample size is too small. Concomitant medication adjustments were common during the ketamine treatment phase making attributions of benefit less clear.
Conclusion: Ketamine continue to show transient antidepressant effects. Safety in elderly individuals with depression, safety questions about bladder toxicity, whether oral administration will have similar effects are key considerations for future research.It is currently considered as experimental treatment in non psychotic depression only.This study provides preliminary evidence to support safety and efficacy of ketamine infusion without anaesthetist supervision.
Summary of the article:
Rasmussen KG, Lineberry TW, Galardy CW, Kung S, Lapid MI, Palmer BA, Ritter MJ, Schak KM, Sola CL, Hanson AJ, Frye MA. J Psychopharmacol. 2013 May;27(5):444-50.