Pharmacokinetic profile of levetiracetam: toward ideal characteristics

Levetiracetam is a novel orally active antiepileptic drug with a unique preclinical profile. It has a high therapeutic index and potential antiepileptogenic effects. Results of clinical trials indicate activity in partial-onset and generalized seizures. The pharmacokinetic profile of levetiracetam closely approximates the ideal characteristics expected of an antiepileptic drug, with good bioavailability, rapid achievement of steady-state concentrations, linear and time-invariant kinetics, minimal protein binding, and minimal metabolism. The major metabolic pathway of levetiracetam is not dependent on the hepatic cytochrome P450 system, and levetiracetam does not inhibit or induce hepatic enzymes to produce clinically relevant interactions. Sixty-six percent of an administered levetiracetam dose is eliminated unchanged in urine; 24% is metabolized to an inactive metabolite that is detectable in blood and is also excreted in urine. Total body clearance of levetiracetam is decreased in patients with renal impairment, and doses should be modified according to creatinine clearance values. Levetiracetam is not appreciably protein-bound, nor does it affect the protein binding of other drugs. Thus, because of its minimal protein binding and lack of hepatic metabolism, the risk of drug interactions is very low. Levetiracetam has a wide margin of safety and patient-friendly pharmacokinetics that distinguish it from other currently available antiepileptic drugs. This profile may facilitate the clinical management of patients with epilepsy by providing a safer and less-complicated therapeutic strategy.