Intravenous Ketamine-induced Affective Switch in a Patient of Major Depressive Disorder with Suicidal Ideation: A Case Report

In treatment-resistant unipolar and bipolar depression, there is increasing evidence to support the fast, although the short-lived antidepressant effect of ketamine, a non-competitive glutamate N-methyl-D-aspartate receptor antagonist. Ketamine has been shown to cause transient mood elevation or euphoria, dissociative symptoms and psychotomimetic effects when administered in unipolar or bipolar depression. Still, it has not been shown to cause an affective switch resulting in persistent hypomania/mania or a manic-like state. We report the case of a 47-year-old man who developed a switch to mania while receiving a sub-anaesthetic dosage of ketamine intravenously for his third episode of recurrent, non-psychotic severe major depression with suicidal ideation. This case indicates that a polarity switch should be acknowledged as a possible side effect when using ketamine for depression.