Case series: Clinical response of ketamine infusion in patients with treatment-resistant depression

Treatment-resistant depression (TRD) is one of the most debilitating conditions that does not respond to conventional pharmacotherapy. Ketamine is a recently used effective treatment option in depressive disorders with a novel mechanism of action. Still, studies estimating the improvement of depressive symptoms in TRD with multiple doses of ketamine are limited. Hence, we report 5 TRD cases that received six open-label intravenous (IV) infusions of ketamine. Five cases of TRD, diagnosed by a clinician defined as the persistence of significant depressive symptoms despite being treated with two different antidepressant regimens, each used for more than 6 weeks were evaluated to identify the need for ketamine infusion and were administered six open-label IV infusions of ketamine which were done at the rate of 0.5 mg/kg body weight, thrice weekly, on alternative days for 2 weeks, following standard protocol. The Montgomery–Åsberg Depression Rating Scale (MADRS) scores were administered by the clinician before the infusion and were repeated after 2 weeks post-infusion. The response was recorded and was seen as a more than 50% decrease in MADRS scores and our cases showed significant improvement clinically. Our low infusion rate and serial dosing trial with ketamine support the efficacy of this drug in TRD. Approximately 30% of patients with major depressive disorder are treatment-resistant. New treatment strategies are needed to address that portion of cases. Subanesthetic doses of IV ketamine have a rapid antidepressant effect in TRD, this signifies the potential of ketamine to be used in this regard.