Carbamazepine × Quetiapine

Carbamazepine is a potent CYP3A4 inducer. Quetiapine plasma levels fall by 75–85%, which can cause loss of therapeutic effect (psychosis or mania relapse).

Return of positive symptoms: hallucinations, delusions, agitation. In bipolar disorder: manic episode risk.

During carbamazepine therapy, increase quetiapine 4- to 5-fold with clinical monitoring. Alternative anticonvulsants without induction: sodium valproate, lamotrigine, or levetiracetam.