Drug Interaction Between Valproic Acid and Meropenem: A Case Report

To report a probable interaction between meropenem and antiepileptic drugs that resulted in poor control of epileptic seizures. A previously healthy 21 years old woman admitted to emergency department with fever and stiff neck. Her Glasgow Coma Scale score was E3M5V4. Physical examination revealed conscious to tend to fall asleep, closed eyes and normal-sized and reactive pupils. Meropenem and vancomycin were initiated for the suspicion of menengitis. On the 3rd day of the antibiotic therapy generalized tonic clonic seizures were observed. Phenytoin and intravenous (IV) thiopental were initiated. The patient was intubated and mechanically ventilated. EEG revealed generalized epileptiform activity. In the following days, seizure activity continued. Levetirasetam, carbamazepine and VPA were added for treatment respectively, but seizures were continued. On the 20th day of meropenem therapy, interaction of carbapenems and anti-epileptic agents was suspected. Antibiotherapy was discontinued. Serum concentrations of VPA increased over the next days and achieved therapeutic levels. On day 21 she was extubated, no seizures occurred over the following 48 hours. She was discharged from the ICU, with blood anti epileptic concentrations within the therapeutic range. Carbapenems have a potential effect of inducing seizures and may also lower serum levels of antiepileptic drugs. Clinicians should be aware of this potential interaction that may be associated with serious adverse effects. Status epilepticus is one of the most important neurologic emergencies, and therapeutic control becomes more difficult as its duration becomes longer. Patients receiving antiepileptics and carbapenem group antibiotics concominantly should be closely monitored due to possible drug interaction between these agents.