Pharmacokinetics of Intravenously and Orally Administered Memantine in Swine

A pharmacokinetic study of intravenously and orally administered memantine was run on 12 pigs. The blood samples were collected up to 12 hours after drug administration. The memantine plasma levels were determined using a validated method of liquid chromatography coupled with mass spectrometry detection. Six pharmacokinetic models were screened and the best one describing the absorption and disposition of memantine was chosen. The pharmacokinetics of memantine in pigs is best described by a monocompartmental pharmacokinetic model and 1 order kinetics for both absorption and elimination processes. The memantine has an absolute bioavailability of about 34% and is rapidly cleared from the body, with an elimination rate constant from the central compartment of 0.34±0.06 hr and a mean half-life of 2 hours. Rezumat A fost realizat un studiu al farmacocineticii memantinei după administrare intravenoasă şi orală la 12 porci. Au fost prelevate probe sangvine timp de 12 ore după administrare. Concentraţiile plasmatice ale memantinei au fost determinate utilizând o metodă validată de cromatografie de lichide cuplată cu spectrometria de masă. Au fost testate 6 modele farmacocinetice şi în final ales modelul farmacocinetic optim. Farmacocinetica memantinei la porci este descrisă optim de un model monocompartimental, cu procese de absorbţie şi eliminare de ordinul 1. Memantina are o biodisponibilitate absolută de aproximativ 34% şi este rapid epurată din organism, având o constantă a eliminării din compartimentul central de 0.34±0.06 ore şi un timp de înjumătăţire mediu de 2 ore.