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Although phenytoin dose adjustments are not routinely required, dose adjustment of phenytoin should be considered if clinically indicated, since Vigabatrin may cause a moderate reduction in total phenytoin plasma levels.
Vigabatrin may moderately increase the Cmax of clonazepam resulting in an increase of clonazepam-associated adverse reactions.
There are no clinically significant pharmacokinetic interactions between Vigabatrin and either phenobarbital or sodium valproate. Based on population pharmacokinetics, carbamazepine, clorazepate, primidone, and sodium valproate appear to have no effect on plasma concentrations of vigabatrin.
Vigabatrin is unlikely to affect the efficacy of steroid oral contraceptives.
Vigabatrin decreases alanine transaminase (ALT) and aspartate transaminase (AST) plasma activity in up to 90% of patients. In some patients, these enzymes become undetectable. The suppression of ALT and AST activity by Vigabatrin may preclude the use of these markers, especially ALT, to detect early hepatic injury.
Vigabatrin may increase the amount of amino acids in the urine, possibly leading to a false positive test for certain rare genetic metabolic diseases (e.g., alpha aminoadipic aciduria).
from FDA，2021.10
