Valproic acid and meropenam is commonly co-administrated in neurosurgical patients. Meropenem potentially
decreases the valproic acid level, which may cause perioperative seizure. There has been no previous report of drug
interaction between valproic acid and meropenem in Thailand. The authors report a patient who faced uncontrolled seizure
after co-administrated valproic acid and meropenem. The level of valproic acid was assessed in different times after the
administration of meropenem. Rapid decrease of valproic level was detected. However, due to the administration of other
antiepileptic agents, seizure did not develop. It is important for the physicians to recognize drug interaction between valproic
acid and meropenem. Avoiding co-administration of both agents, valproic acid level monitoring and additive of other
antiepileptic agents seem to be the appropriate solution.

Keywords: Drug interaction, Valproic acid, Meropenem