Excretion of antiepileptic drugs in sweat

In eight epileptic patients receiving chronic antiepileptic treatment, a study of the excretion in sweat of phenytoin, phenobarbitone and carbamazepine was performed. All three drugs were found to be present in sweat. Phenytoin sweat concentration was found to correspond to the free fraction in plasma and to be independent of sweat flow. Phenobarbitone sweat concentration was found to increase with increasing sweat flow. Regarding drug level monitoring it is proposed that under changing climatic conditions the phenomenon may be of clinical significance.