Epilepsan Drug Interactions

Alcohol: Valproic Acid can increase CNS depressant activity from alcohol.
Aspirin, Carbamazepine, and Dicumarol: Valproic Acid use with drugs that have strong protein bonds (such as Aspirin, Carbamazepine, and Dicumarol) can cause changes in the concentration of the drug in serum.
Phenobarbital: There is evidence to suggest that Valproic Acid can cause an increase in Phenobarbital serum through non-renal clearance. This condition can cause severe CNS depression, a combination of Valproic Acid and Phenobarbital has also been reported to cause CNS depression without a significant increase in serum barbiturate or valproate concentrations. All patients receiving barbiturate therapy must be monitored closely for neurological toxicity. If possible, serum barbiturate concentrations should be known and if necessary, barbiturate doses can be reduced.
Pirimidone: Pirimidone is metabolized into barbiturates. Therefore, Pirimidone can also be involved in the same or similar interactions.
Phenytoin: Seizures have been reported to occur when Valproic Acid is combined with Phenytoin. In most reports, there has been a decrease in the total concentration of Phenytoin in plasma. However, an increase in the total concentration of phenytoin in serum has also been reported.
A decrease in total Phenytoin concentrations at the beginning of therapy followed by an increase in Phenytoin concentrations has also been reported. In addition, decreased total serum Phenytoin concentrations accompanied by increased levels of free (non-protein bound) Phenytoin have been reported. The dose of Phenytoin must be adjusted according to the clinical situation.
Clonazepam, Ethosuximide: Use of Valproic Acid and Clonazepam can negate the effects of drugs with each other. There is evidence of the effect of Valproate on serum Ethosuximide concentrations. Patients receiving valproate and Ethosuximide, especially along with other anticonvulsants, should be monitored for changes in serum concentrations of both drugs.
Aspirin and Warfarin: Be careful if Valproic Acid is given along with drugs that affect blood coagulation such as Aspirin and Warfarin.