Oral bioavailability of dabigatran etexilate (Pradaxa(®) ) after co-medication with verapamil in healthy subjects

Abstract

Aim: To investigate the effect of the P-glycoprotein inhibitor verapamil on the pharmacokinetics and pharmacodynamics of dabigatran etexilate (DE).

Method: In this two part multiple crossover trial in 40 healthy subjects, DE 150 mg was given alone or with verapamil at different doses, duration of treatment (single vs. multiple dosing), formulations, and timings (before, concurrently or after DE). Primary pharmacokinetic endpoints were determined from concentrations of total dabigatran (unconjugated plus conjugated). Pharmacodynamic endpoints were determined from clotting time.

Results: The greatest effect was observed with single dose verapamil 120 mg immediate release given 1 h before single dose DE. Geometric mean area under the plasma concentration curve [AUC(0,∞)] and maximum analyte concentration in the plasma (Cmax ) were increased by 143% [90% confidence interval (CI) 91, 208] and 179% (90% CI 115, 262), respectively. The effect was reduced to a 71% and 91% increase in AUC and Cmax , respectively, when DE was administered with verapamil 240 mg extended release. After multiple verapamil dosing, DE AUC(0,∞) and Cmax increases were 54% and 63%, respectively. However, DE given 2 h before verapamil increased DE AUC(0,∞) and Cmax by <20%. With regard to clotting prolongation, the dabigatran plasma concentration-effect relationship was generally not affected by the co-administration of verapamil. Concomitant administration of DE and verapamil did not reveal any unexpected safety findings.

Conclusion: Verapamil increased DE bioavailability, likely due to inhibition of P-glycoprotein. Our results suggest that an interaction between verapamil and DE can be minimized if DE is administered 2 h prior to verapamil.

Figure 1

Overview of effects of verapamil on dabigatran exposure (study parts 1 and 2). AUC(0,∞), area under the concentration–time curve; CI, confidence interval; DE, dabigatran etexilate; ER, extended release; IR, immediate release; MD, multiple dose; SD, single dose; V, verapamil. The boundaries for bioequivalence (90% CI between 0.80 and 1.25) are shown as dashed lines. , Single dose study [AUC(0,∞) ratios]; , Multiple dose study [AUC(0,∞) ratios]

Figure 2

Geometric mean plasma concentration–time profiles of total dabigatran after single oral administration of 150 mg dabigatran etexilate alone or with co-administration of 120 mg verapamil immediate release twice daily or four times daily (study part 1). DE, dabigatran etexilate; IR, immediate release; V, verapamil. , Treatment A (150 mg DE alone); , Treatment C (DE 1 h after V IR 120 mg twice daily); , Treatment E (DE 1 h after V IR 120 mg four times daily); , Treatment D (DE 2 h before V IR 120 mg twice daily)