46
Management
Table 13. OACs Pharmacokinetic Characteristics and Dosing
Class
Vitamin K
antagonist (VKA) Direct Thrombin Inhibitor
Name Warfarin Dabigatran
Metabolism S-isomer: CYP2C9
R-isomer: CYP1A2,
2C19, 3A4
Minimal
P-glycoprotein substrate CYP2C19, CYP3A4 Yes
Excretion 0% renal; very little
warfarin excreted
unchanged in urine
80% renal
Half-life 20–60 h 12–17 h
Renal dosing adjustment
based on actual body weight
N/A Creatinine
clearance
(CrCl) >30
mL/min
150 mg
twice daily
CrCl 15–30
mL/min
75 mg
twice daily
Drug interaction
management based on
concomitant therapy of
CYP3A4 inhibitors/p-
glycoprotein inhibitors
Adjust dose based on
INR trends
CrCl 30–50 mL/ min
with concomitant use of
dronedarone or systemic
ketoconazole: 75 mg twice
daily
CrCl < 30 mL/min: avoid
dabigatran use concomitantly
with dronedarone or systemic
ketoconazole
