Serial infusions of low-dose ketamine for major depression.

Background: Single infusions of ketamine have been used successfully to achieve improvement in depressed patients. Side effects during the infusions have been common. It is not known whether serial infusions or lower infusion rates result in greater efficacy.

Methods: Ten depressed patients were treated with twice weekly ketamine infusions of ketamine 0.5 mg/kg administered over 100 min until either remission was achieved or four infusions were given. Side effects were assessed with the Young Mania Rating Scale (YMRS) and the Brief Psychiatric Rating Scale (BPRS). Patients were followed naturalistically at weekly intervals for four weeks after completion of the infusions.

Results: Five of 10 patients achieved remission status. There were no significant increases on the BPRS or YMRS. Two of the remitting patients sustained their improvement throughout the four week follow-up period.

Conclusions: Ketamine infusions at a lower rate than previously reported have demonstrated similar efficacy and excellent tolerability and may be more practically available for routine clinical care. Serial ketamine infusions appear to be more effective than a single infusion. Further research to test relapse prevention strategies with continuation ketamine infusions is indicated.