Acute antidepressant effects of intramuscular versus intravenous ketamine

Conventional antidepressants take two weeks before their therapeutic action begins. Recent studies have reported on the rapid antidepressant effect of ketamine when given as an intravenous (I.V.) infusion. Little is known about its intramuscular (I.M.) use in depression. Hence this study was conducted to compare the safety, tolerability and efficacy of I.M. versus. I.V. ketamine in Major Depression (ICD-10).

It was a randomized open label parallel group study in a tertiary care teaching hospital. Study sample consisted of 27 subjects having major depression divided randomly into three groups of nine subjects each. Ketamine administered to each group in the dose of 0.5 mg/kg as an I.V. infusion, as 0.5 mg/kg I.M. or 0.25 mg/kg I.M. respectively. Depression rated on the Hamilton Depression Rating Scale (HAM-D) before the injection, two hours later, the next day, and after three days. Data analyzed using the Statistical Package for Social Sciences (SPSS).

Mean age of the sample was 36.81 years (SD 11.815). Two hours after the injection, HAM-D fell by 58.86%, 60.29% & 57.36% in each group respectively. The improvement was sustained for next three days. Adverse effects noticed were rare, of mild nature and transient, lasting less than an hour.

Intramuscular ketamine in the dose of 0.25 mg/kg is as effective and safe as 0.5 mg/kg given either I.M. or I.V., substantially alleviating depressive symptoms within a few hours and sustained for 3 days.