Trends in utilization of warfarin and direct oral anticoagulants in older adult patients with atrial fibrillation

PURPOSE

Results of a study to determine trends in oral anticoagulant (OAC) use and OAC switching in patients with atrial fibrillation (AF) or atrial flutter are presented.

METHODS

Warfarin has been the most prescribed anticoagulant in patients with AF for decades. Since 2010, several direct OACs (DOACs) have gained U.S. marketing approval for stroke prevention in AF or atrial flutter. A cross-sectional longitudinal analysis was conducted using healthcare and prescription claims databases to characterize OAC use and rates of OAC and DOAC switching during the period 2008-14 in cohorts of Medicare beneficiaries 65 years of age or older with AF or atrial flutter.

RESULTS

Overall, 66% of patients with AF or atrial flutter were receiving OACs during the study period. The prevalence of warfarin use decreased from 69.8% in 2008 to 42.2% in 2014. This decrease in warfarin use was paralleled by an increase in dabigatran use, which rose from 1.3% in 2010 to 12.1% in 2011 and then declined to 7.6% in 2014. The prevalence of rivaroxaban use increased from 0.13% in 2011 to 13.87% in 2014. Among anticoagulated patients, an average of 6% annually were switched from one OAC to another.

CONCLUSION

Overall OAC utilization in patients with AF or atrial flutter remained steady over the study period. Beginning in 2010, a gradual decrease in use of warfarin was paralleled by an increase in use of DOACs.

Pharmacology, pharmacokinetics, and pharmacodynamics of dabigatran etexilate, an oral direct thrombin inhibitor

Dabigatran etexilate is a novel, oral reversible direct thrombin inhibitor that is rapidly absorbed and converted to its active form, dabigatran. Dabigatran has been shown to be a potent, competitive, and reversible inhibitor of thrombin, inhibiting both thrombin activity and generation. Studies in healthy volunteers and in patients undergoing orthopedic surgery indicate that dabigatran has a predictable pharmacokinetic profile, allowing for a fixed-dose regimen without the need for coagulation monitoring. In healthy volunteers, peak plasma concentrations of dabigatran are reached approximately 2 hours after oral administration. The elimination half-life is 12 to 14 hours, with clearance predominantly occurring via renal excretion of unchanged drug. Dabigatran is not metabolized by cytochrome P450 isoenzymes, has no interactions with food, and also has a low potential for drug-drug interactions. The pharmacokinetic profile of dabigatran is consistent across a broad range of different patient populations and is unaffected by gender, body weight, ethnic origin, obesity, and mild-to-moderate hepatic impairment. Small differences in dabigatran pharmacokinetics associated with age are attributable to variation in renal function. Dabigatran etexilate produces a predictable pharmacodynamic effect and requires no coagulation monitoring. It has been approved in the European Union (EU) and Canada for prophylaxis of thromboembolism in patients undergoing total knee or hip arthroplasty. Ongoing clinical trials are investigating its use in the treatment of venous thromboembolism, prevention of stroke in patients with nonvalvular atrial fibrillation, and treatment of thromboembolic complications, following acute coronary syndromes.