Dabigatran etexilate (Pradaxa) is a prodrug; it is metabolized to dabigatran, a direct thrombin inhibitor. It is recently FDA approved to reduce the risk of ischemic stroke or systemic embolism in atrial fibrillation patients. Patients with difficulty in maintaining stable states of therapeutic anticoagulation with warfarin, or with limited access to warfarin management, are considered populations where the clinical utility of dabigatran would be maximal.
The drug undergoes renal excretion with a half-life of 12-17 hours, dependent on baseline renal function. Compliance with this drug may be an issue, as it requires twice daily dosing. In patients with CrCl (creatinine clearance) of > 30 mL/min dose is 150mg twice daily; for patients with CrCl of 15-30 mL/min dose is 75mg twice daily; it should not be used in patients with stage V chronic kidney disease with a CrCl of < 15 mL/min.
There is no antidote or reversal agent for dabigatran. Its onset of effect is rapid, with full anticoagulation effect achieved in 1-2 hours after the initial dose. No ongoing laboratory monitoring can effectively establish the level of anticoagulant effect. Thrombin time (TT) provides a sensitive measure of circulating dabigatran. If the TT is normal, no dabigatran effect should be present; the degree of TT abnormality does not effectively measure the risk of hemorrhage. Only a normal TT is therefore valuable.
Periprocedural guidelines are in evolution. The Mayo Pharmaceutical Formulary Committee has recommended that for procedures with a risk of hemorrhage, in patients with a CrCl of > 50 mL/min, the drug should be discontinued for 5 days prior to the procedure. For patients with a CrCl of< 49 mL/min, dabigatran should be discontinued for 7 days. For elective procedures with a high risk of hemorrhage, a pre-operative Thrombin time could be considered.
Post- procedure, re-initiation of dabigatran should be delayed for at least 48 hrs after major surgery. Dabigatran should not be restarted within 24 hours of epidural catheter placement or neuraxial injection.
Out of an abundance of caution, we (Mayo Radiology and Mayo Pain Clinic) have chosen to stop Pradaxa for 7 days for elective epidural pain procedures.
Connolly SJ, et al. RELY Trial Investigators. Dabigatran versus Warfarin in Patients with Atrial Fibrillation. N Engl J Med. 2009;361:1139-51.
van Ryn J et al. Dabigatran etexilate - a novel, reversible, oral direct thrombin inhibitor: Interpretation of coagulation assays and reversal of anticoagulant activity. Thromb Haem. 2010; 103:1116-1127.