TIAGABINE, A NOVEL ANTIEPILEPTIC AGENT - LACK OF PHARMACOKINETIC INTERACTION WITH DIGOXIN

Objective: To assess the possibility of any clinically relevant pharma cokinetic interactions between tiagabine, a novel antiepileptic drug, and digoxin. Methods: Potential pharmacokinetic interactions between t iagabine and digoxin were investigated in an open-label, two-period cr oss-over study in healthy male volunteers. Thirteen volunteers, aged b etween 18 and 43 years, were randomised to receive digoxin (0.5 mg twi ce a day for 1 day, then 0.25 mg once a day for 8 days) either alone o r co-administered with tiagabine (4 mg three times daily for 9 days). Following a 7-day washout period, volunteers crossed over to the other dosing regimen. Peak serum concentration, time to maximum serum conce ntration, area under the serum concentration-time curve from zero to 2 4 h and steady state serum concentration were calculated for digoxin a nd compared between treatment groups. Results: No statistically signif icant differences between treatment groups were observed for any of th e derived digoxin pharmacokinetic parameters. The most common adverse events reported during digoxin alone;Ind in combination with tiagabine were somnolence and headache; an overall greater frequency of adverse events was reported during combined treatment. Adverse events were ge nerally mild in nature; no serious adverse events were reported. Concl usions: At the doses administered, there is 30 evidence of a pharmacok inetic interaction between digoxin and tiagabine in healthy male volun teers.