BLOOD LEVEL INCREASED 2-4 TIMES BY ASPIRIN & FELBAMATE AND REDUCED BY CARBAMAZEPINE, PHENOBARBITONE, PHENYTOIN AND PRIMIDONE BECAUSE OF INCREASED METABOLISM. POTENTIATE CNS DEPRESSANTS INCLUDING ALCOHOL.CAUTION SHOULD BE TAKEN WHEN GIVEN IN COMBINATION WITH OTHER ANTIEPILEPTICS AS COMPLEX AND UNPREDICTABLE SIDE EFFECTS MAY TAKE PLACE.
RIFAMPICIN INCREASED CLEARANCE OF VALPROATE BY 40%
CIMETIDINE, RANITIDINE, CHLORPROMAZINE, HALOPERIDOL, CLONAZEPAM, LORAZEPAM, ACETAMINOPHEN, LITHIUM, ORAL CONTRACEPTIVES & ANTACIDS HAD NO SIGNIFICANT EFFECTS ON VALPROIC ACID METABOLISM OR CONCENTRATION.
VALPROATE DECREASED SERUN CLEARANCE OF AMITRIPTYLINE , NORTRIPTYLINE & CARBAMAZEPINE.
CO-ADMINISTRATION OF VALPROATE INCREASED THE FREE FRACTION OF DIAZEPAM BY 90% IN HEALTHY VOLUNTEERS.
ETHOSUXIMIDE--VALPROATE INHIBITS THE METABOLISM OF ETHOSUXIMIDE.
THE DOSE OF LAMOTRIGINE SHOULD BE REDUCED WHEN CO-ADMINISTERED WITH VALPROATE.
VALPROATE WAS FOUND TO INHIBIT THE METABOLISM OF PHENOBARBITAL.
VALPROATE DISPLACES PHENYTOIN FROM ITS PLASMA ALBUMIN BINDING SITES AND INHIBITS ITS HEPATIC METABOLISM. CO-ADMINISTRATION OF VALPROATE WITH PHENYTOIN IN NORMAL VOLUNTEERS WAS ASSOCIATED WITH A 60% INCREASE IN THE FREE FRACTION OF PHENYTOIN.
ZIDOVUDINE-- THE CLEARANCE OF ZIDOVUDINE (100 MG Q8H) WAS DECREASED BY 38% AFTER ADMINISTRATION OF VALPROATE