The effectiveness of ketamine as an antidepressant has been mitigated by concerns of possible abuse and suggestions that the antidepressant effects might be dependent on opiate receptor stimulation. However, results from a case series published in JAMA Psychiatry support the efficacy of combined naltrexone and ketamine treatment for depressive symptoms.  

Investigators conducted an 8-week open-label pilot study of 5 patients with current major depressive disorder and alcohol use disorder. Patients received a single dose of injectable naltrexone (380 mg) 2 to 6 days prior to the first ketamine treatment, followed by 4 weeks of ketamine infusions (0.5 mg/kg once a week). Patients were assessed at baseline and at 4 hours after each infusion with the Montgomery Åsberg Depression Rating Scale. The primary outcome measure was a 50% or higher improvement from baseline Montgomery Åsberg Depression Rating Scale score. All patients were abstinent from alcohol for 5 days or longer prior to the initial ketamine infusion.

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Combined treatment with naltrexone and ketamine was associated with a significant reduction in depressive symptoms. Three of 5 patients (60%) met response criteria following initial ketamine dose, and 5 of 5 patients (100%) met response criteria by the fourth dose, although 1 patient left the trial following 2 ketamine infusions. Symptoms improved by 57% to 92%, depending on the patient. In addition, 4 of 5 patients (80%) reported a reduction in alcohol craving and consumption per the Obsessive Compulsive Drinking Scale. Combined treatment was safe and well tolerated. No serious adverse events were reported in the trial.

These results challenge existing data that pretreatment with naltrexone may interfere with the antidepressant properties of ketamine. Research with a larger cohort is necessary to further investigate the efficacy of combination treatment with naltrexone and ketamine for depression.

Reference

Yoon G, Petrakis IL, Krystal JH. Association of combined naltrexone and ketamine with depressive symptoms in a case series of patients with depression and alcohol use disorder [published online January 9, 2019]. JAMA Psychiatry. doi: 10.1001/jamapsychiatry.2018.3990