Evaluation of the pharmacokinetic interaction after multiple oral doses of linagliptin and digoxin in healthy volunteers

The aim of this study was to investigate whether multiple doses of the oral and highly selective dipeptidyl peptidase-4 inhibitor linagliptin affect the steady-state pharmacokinetics of the P-glycoprotein substrate digoxin. This single-center, open-label, two-period cross-over study involved healthy subjects (n = 20), randomized to treatment sequence AB or BA, where A comprised 0.25 mg digoxin qd for 5 days, then 0.25 mg digoxin qd plus 5 mg linagliptin qd for 6 days, and B comprised 0.25 mg digoxin qd for 11 days. A treatment-free period (>= 35 days for AB and 14 days for BA) separated each treatment in both sequences. There were no clinically significant changes in steady-state pharmacokinetic parameters of digoxin when it was co-administered with linagliptin. The ratio of the adjusted-by-treatment geometric mean ratios and associated 90% confidence intervals for the AUC(tau,ss), C-max,C-ss and renal clearance (CLR,0-24,ss) of digoxin were all within the bioequivalence range 80-125%, which is important as digoxin has a narrow therapeutic range. There was a low incidence of adverse events, which were randomly distributed between treatment groups. In conclusion, linagliptin did not alter the pharmacokinetics of digoxin in this study, indicating that linagliptin does not inhibit P-glycoprotein or other transporters relevant for digoxin pharmacokinetics. These results suggest that linagliptin and digoxin can be co-administered without dose adjustment. Administration of digoxin alone and with linagliptin was well tolerated.