[Clinical implications of pharmacology and pharmacokinetics of tiagabine]

Tiagabine is a new antiepileptic drug which acts by blocking neuronal and glial GABA uptake and it is indicated in the treatment of partial epilepsies. Its pharmacokinetics is lineal, being extensively metabolized in the liver by means of CYP3A4 isoenzyme. Plasma elimination half life ranges between 5-8 hours in healthy volunteers, being markedly reduced when the drug is administered concomitantly with enzyme-inducing antinconvulsants. Tiagabine does not induce nor inhibit hepatic enzymes and, consequently, it does not modify the kinetics of simultaneously prescribed antiepileptic drugs. No relevant kinetic differences have been observed between adults and elderly subjects. Renal impairment does not alter the pharmacokinetic profile of tiagabine; hepatic disease, however, significantly reduces tiagabine elimination and lower daily doses of the drug are necessary in these patients. Although tiagabine elimination half life is short, it has been ascertained that therapeutic efficacy is similar when administered in 2 or 4 divided doses. Tiagabine is usually well tolerated; its most frequent side effects include dizziness, asthenia, nervousness, tremor, diarrhea and depressed mood.