Anticonvulsant drugs alter plasma tryptophan concentrations in epileptic patients: implications for antiepileptic action and mental function.

In epileptic patients carbamazepine and diphenylhydantoin have opposite effects on whole and free plasma tryptophan concentrations, the former elevating and the latter depressing them. It is unlikely that these observations relate to the similar anti-epileptic properties of these two drugs but they may relate to their different effects on mental function and mood.