Ertapenem-induced reduction in valproate levels: case report and review of the literature.

The concomitant use of carbapenems and valproate is not recommended because carbapenems may decrease serum concentrations of valproate. Increasing the dose of valproate may not compensate for the reduction, which puts the patient at risk for recurrent seizures. Therefore, close monitoring of valproate levels is necessary when initiating a carbapenem antibiotic in patients whose condition has been stabilized with valproate therapy. Several case reports of significant reductions in serum valproate concentrations following initiation of carbapenem antibiotics have been published. To the authors’ knowledge, however, there has been no published systematic review of the carbapenem–valproate interaction. We report a case of ertapenem-induced reduction in valproate concentration and describe the extent, clinical relevance, potential mechanisms, and therapeutic options for management of the carbapenem– valproate interaction.