Antidepressant, mood stabilizing and procognitive effects of very low dose sublingual ketamine in refractory unipolar and bipolar depression.

Intravenous ketamine (0.5 mg/kg) produces robust, rapid and long-lasting antidepressant effects, but is unpractical. Sublingual administration of ketamine renders better bioavailability (~30%) and less conversion to norketamine than oral administration.