An Overview of Ketamine for Treatment-Resistant Depression
A 2017 series of articles by researcher Chittaranjan Andrade in the Journal of Clinical Psychiatry reviews the last 10 years of research on ketamine, the anesthetic drug that in smaller doses (0.5 mg/kg of body weight) can bring about rapid antidepressant effects. Ketamine is typically delivered intravenously (though it can also be delivered via inhaler, injected under the skin or into muscles, and least effectively by mouth). Ketamine can improve depression in less than an hour, but its effects usually fade within 3 to 5 days. Repeating infusions every few days can extend ketamine’s efficacy for weeks or months.
Andrade cited a 2016 meta-analysis of nine ketamine studies by T. Kishimoto and colleagues in the journal Psychological Research. The meta-analysis found that compared to placebo, ketamine improved depression beginning 40 minutes after IV administration. Its effects peaked at day 1 and were gone 10–12 days later. Remission rates were better than placebo starting after 80 minutes and lasting 3–5 days.
Several studies have found that ketamine also reduces suicidality.
Andrade reported that both effectiveness and side effects seem to be dose-dependent within a range from 0.1 mg/kg to 0.75 mg/kg.
Side effects of ketamine are typically mild and transient. A 2015 study by Le-Ben Wan and colleagues (also in the Journal of Clinical Psychiatry) that Andrade cited reported that in 205 sessions of ketamine administration, the most common side effects were drowsiness, dizziness, poor coordination, blurred vision, and feelings of strangeness or unreality. The feelings of unreality (dissociative effects) diminish with repeated infusions. Heart and blood pressure may also temporarily increase as a result of ketamine administration.
One study found that ketamine could speed up and add to the effects of the selective serotonin reuptake inhibitor (SSRI) antidepressant escitalopram (Lexapro). A meta-analysis of 10 randomized controlled trials found that ketamine did not improve the effects of electroconvulsive therapy.
Ketamine has some history as a recreational club drug (sometimes known as ‘K’ or ‘special K’), and can be misused or abused.
While there have been many studies of ketamine’s antidepressant effects, Andrade concludes that none is of a standard to justify US Food and Drug Administration approval for the drug. It is hoped that larger, more rigorous trials will be completed in the next few years. However, ketamine is already being used widely to treat treatment-resistant unipolar and bipolar depression.
