Moderate
Established
Deskripsi
Carbamazepine reduces valproic acid levels through enzyme induction, while valproic acid inhibits epoxide hydrolase, increasing the toxic carbamazepine-10,11-epoxide metabolite.
Mekanisme
Carbamazepine induces CYP3A4, accelerating valproate metabolism; valproate inhibits epoxide hydrolase, causing accumulation of the carbamazepine 10,11-epoxide metabolite which causes neurotoxicity.
Signifikansi Klinis
Double-edged interaction: both subtherapeutic valproate and carbamazepine toxicity (diplopia, ataxia, nausea) are risks despite normal carbamazepine parent drug levels.
Penatalaksanaan
Monitor plasma levels of both drugs and the carbamazepine-10,11-epoxide metabolite; reduce carbamazepine dose if epoxide levels are high.