Moderate
Established
Descripción
Carbamazepine and phenytoin have complex bidirectional interactions that can alter plasma levels of either drug in unpredictable ways.
Mecanismo
Both are CYP3A4 and CYP2C inducers; carbamazepine may increase phenytoin levels (via 10,11-epoxide pathway competition), while phenytoin induces carbamazepine metabolism, resulting in variable net effects.
Relevancia clínica
Plasma level monitoring is essential; either drug level may rise or fall, affecting seizure control and toxicity risk.
Manejo clínico
Monitor plasma levels of both drugs closely when co-prescribing; adjust doses based on levels and clinical response.