Maintenance Intramuscular Ketamine-Assisted Psychotherapy, a Retrospective Chart Review of Efficacy, Adverse Events, and Dropouts from a Community Practice

The use of ketamine and ketamine-assisted psychotherapy (KAP) for treatment of depression has grown dramatically, though much of these data are short term. The clinical profile of maintenance treatment remains poorly characterized. We assessed maintenance KAP for efficacy, tolerability, and reasons for dropout. This observational study retrospectively analyzed electronic health records from an addiction psychiatry practice offering intramuscular ketamine with contemporaneous psychotherapy for the treatment of depression. All patients receiving treatment between January 2016 and September 2022 were included, yielding 1,114 sessions from 70 patients. The response was quantified via the clinical global impression-severity scale. Side effects and reasons for dropout were extracted from charts. Comorbidities include an anxiety disorder (79%) or substance use disorder (49%). The induction yielded 82% response, maintained above 80% after six months (sessions q21 days, 1.13 mg/kg mean dose). Many (38%) remained in treatment for at least one year. Nausea management accounted for nearly all as-needed medication use. Antihypertensives were seldom utilized. Chronic side effects were notable for one case of ketamine use disorder, resulting in residential treatment. Dropouts cited logistical reasons half the time and side effects only 9.7% of the time. KAP yielded robust improvements in mood, anxiety, and substance use. Maintenance sessions effectively extended benefit and were largely well tolerated.