Can Quetiapine Prolong the Antidepressant Effect of Ketamine?: A 5-Year Follow-up Study

In this follow-up study (n=16), the long-term effects of ketamine on the mood of depressed patients was assessed. After receiving at least one dose of ketamine, patients who had been taking the neuroleptic (antipsychotic medication) quetiapine had a significantly longer time to relapse than patients taking other neuroleptics at the 5 year follow-up. Quetiapine may prolong the antidepressant effects of ketamine.


Purpose: Ketamine, a noncompetitive, high-affinity antagonist of the N-methyl-D-aspartate-type glutamate receptor, has a rapid effect in patients with treatment-resistant disorder, but many patients who respond to intravenous ketamine relapse within several days. The objective of this study was to examine the long-term outcome of patients’ mood 5 years after ketamine treatment.

Methods: Sixteen electroconvulsive therapy referrals received at least 1 intravenous ketamine treatment in addition to their stable antidepressant medications. Depression was evaluated using the Inventory of Depressive Symptomatology-Clinician-Rated, Hamilton Rating Scales for Depression, and Montgomery-Åsberg Depression Rating Scale. Anxiety was measured using the Hamilton Rating Scale.

Results: Of 16 patients treated, 6 achieved complete remission, 3 partially responded, and 7 did not respond. At baseline, all patients were treated with antidepressants, 14 patients were also treated with neuroleptics, of whom 5 patients were treated with quetiapine. The time to relapse in the 5 patients taking quetiapine was significantly longer than in patients who were taking other neuroleptics (965.83 ± 824.68 vs 80.5 ± 114.3, Z = 7.001, P = 0.0001). At the 5-year follow-up, 3 of the patients taking quetiapine maintained their remission. Overall levels of depression and anxiety at all times were improved in comparison to baseline.

Conclusions: Our follow-up results suggest that the combination of quetiapine and ketamine can prolong time to relapse after ketamine treatment in patients with treatment-resistant disorder.”

Authors: Revital Amiaz, Rachel Saporta, Adam Noy, Haim Berkenstadt & Mark Weiser

Study details

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Study characteristics

16 Humans