Tiagabine, a novel antiepileptic agent: lack of pharmacokinetic interaction with digoxin

Objective: To assess the possibility of any clinically relevant pharmacokinetic interactions between tiagabine, a novel antiepileptic drug, and digoxin. Methods: Potential pharmacokinetic interactions between tiagabine and digoxin were investigated in an open-label, two-period cross-over study in healthy male volunteers. Thirteen volunteers, aged between 18 and 43 years, were randomised to receive digoxin (0.5 mg twice a day for 1 day, then 0.25 mg once a day for 8 days) either alone or 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 concentration, area under the serum concentration-time curve from zero to 24 h and steady state serum concentration were calculated for digoxin and compared between treatment groups. Results: No statistically significant differences between treatment groups were observed for any of the 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 generally mild in nature; no serious adverse events were reported. Conclusions: At the doses administered, there is 30 evidence of a pharmacokinetic interaction between digoxin and tiagabine in healthy male volunteers.