Quetiapine may induce mania: A case report

Inducing manic or hypomanic symptoms is a well-documented risk during anti- depressive treatment with different classes of antidepressants. Recently, several case reports and a critical review have demonstrated a similar risk induced by atypical antipsychotics, such as olanzapine and risperidone. A serotonin (5-HT) receptor occupancy (5-HT2 and 5-HTD2) hypothesis has been proposed to explain olanzapine and risperidone effects on mood, but other mechanisms are likely involved in the manic switch that is associated with these 2 atypical antipsychotics. We report a case of possible induction of manic episode associated with quetiapine treatment in a patient with a schizofreniform disorder. The gradual onset of manic symptoms during quetiapine treatment and the rapid remission with discontinuation of the drug in a patient without a history of mania and without past or current substance abuse seems to support the possibility that quetiapine was responsible for inducing the manic episode. In our case manic symptoms appeared slowly at a moderate quetiapine dosage. This seems to support the hypothesis proposed for risperidone, with which quetiapine shares biochemical features; specifically, at high dosages, dopaminergic blockade action shows antimanic properties, while, conversely, at smaller dosages, the mania-inducing effects could result from the 5-HT2 antagonistic action, as well as the ensuing dopamine disinhibiting effects