Pharmacokinetics of the new antiepileptic drugs.

A physician's choice of an antiepileptic drug (AED) usually depends upon the patient's seizure type. But the pharmacokinetic characteristics of AEDs can further help determine the best drug for a particular patient. These characteristics, including absorption, elimination pathway, and potential for drug interactions, are of critical importance for patients who take other medication for comorbid conditions and for patients with impaired renal or hepatic function. The ideal AED would have a rapid, linear, consistent absorption rate with complete clearance, low plasma protein binding, and rapid central nervous system penetration. It would be eliminated predominantly by the kidneys. The new AEDs do not prompt the same concerns about interactions because they have much better pharmacokinetic profiles than the older drugs and as a result require less monitoring for potential interactions.