[The effect of hyperlipidemia on pharmacokinetics of free phenytoin]

The problem of the effects of metabolic changes on drug pharmacokinetics is not yet sufficiently known. Phenytoin was used for the assessment of the effects of lipid profile disturbances on drug pharmacokinetics. Phenytoin is a lipophilic substance. It was shown that hyperlipidaemia changed phenytoin pharmacokinetics and the pattern of these changes depended on the type of hyperlipidaemia. In hypercholesterolaemia and in mixed hyperlipidaemia the level of free phenytoin was raised in the blood. It should be remembered that hypercholesterolaemia and mixed hyperlipidaemia are conditions increasing the risk of phenytoin overdosage and this should be considered in establishing drug dosage.