A patient who has been taking phenobarbital for epilepsy begins taking valproic acid (Depakote) as adjunct therapy. You note in this patient that he is very drowsy. What will you do?

A. While valproic acid can cause hepatotoxicity, the immediate concern in this scenario is excessive sedation, not liver injury. Liver function tests may be indicated later, but they do not address the acute adverse effect. B. Increasing the dose of valproic acid would likely worsen sedation rather than improve seizure control. The drowsiness suggests drug accumulation or interaction, so increasing the dose is unsafe. C. Phenobarbital and valproic acid are both central nervous system depressants, and valproic acid can increase phenobarbital levels by inhibiting its metabolism. The resulting excessive sedation indicates that the phenobarbital dose may need to be reduced. Notifying the prescriber allows for dose adjustment and safe management of drug interactions while maintaining seizure control. D. Tolerance to sedation may develop over time, but in the short term, the patient is experiencing significant drowsiness, which can increase the risk of falls, respiratory depression, and accidents. Immediate intervention is required rather than assuming tolerance will occur.