Summary
Ethnic differences in drug disposition may potentially influence therapeutic response
to dabigatran, a reversible direct thrombin inhibitor used for the prevention and/or
treatment of various thromboembolic disorders. This analysis of data from 18 clinical
studies in healthy volunteers and patients with non-valvular atrial fibrillation (AF)
or undergoing knee or hip arthroplasty investigated whether there were any clinically
relevant differences in the pharmacokinetics and pharmacodynamics of dabigatran, the
active form of dabigatran etexilate, between Japanese and Caucasian subjects. In pooled
data from 14 phase I trials, total exposure (i.e. area under the plasma concentration-time
curve [AUC]) after administration of dabigatran 150 mg once or twice-daily was on
average 20% higher in Japanese than Caucasian subjects (median [10th to 90th percentile] 1,110 [644–1,824] vs. 924 [420–1,654] ng·h/ml) although the difference
between the groups was not significant. Within-trial comparisons in subjects treated
with dabigatran 150 mg twice-daily showed that AUC and maximum plasma concentration
differed by less than 10% between the two groups. In patients with AF, trough concentrations
after administration of 150 mg twice-daily were similar in Japanese and Caucasian
subjects (80.1 [34.5–193.8] vs. 71.0 [34.0–190] ng/ml). Various factors, including
body weight and renal clearance, may explain these observed pharmacokinetic differences.
The relationship between plasma concentration and coagulation markers was similar
and indicative of no difference in the exposure-pharmacodynamic response between these
two groups. In conclusion, the results of this analysis show that the pharmacokinetics
and pharmacodynamics of dabigatran are similar in Japanese and Caucasian subjects
and suggest that there is no need for dose adjustment of dabigatran in Japanese subjects.
Keywords
Dabigatran - ethnic origin - Japanese - pharmacokinetics - pharmacodynamics