Major
Amitriptyline × Carbamazepine
Tricyclic antidepressants (TCA)×Antiepileptics. Carboxamide derivatives
Mechanism
Carbamazepine induces CYP3A4 and CYP2D6; amitriptyline plasma levels fall by 50–60%. Loss of antidepressant and analgesic effect is possible.
Symptoms
Return of depressive symptoms or neuropathic pain. In depression: relapse risk.
Management
During carbamazepine therapy, double amitriptyline with clinical efficacy monitoring. Alternative anticonvulsants without induction: levetiracetam, lamotrigine (no CYP3A4 induction).