Аnti-Xa activity in patients with non-valvular atrial fibrillation treated with apixaban and rivaroxaban

Kochetkova E.K.: Department of Clinical Pharmacology and Propedeutics of Internal Diseases, Sechenov First Moscow State Medical University

Drozdov V.N.: Department of Clinical Pharmacology and Propedeutics of Internal Diseases, Sechenov First Moscow State Medical University

Shikh E.V.: Department of Clinical Pharmacology and Propaedeutics of Internal Diseases, Sechenov First Moscow State Medical University, Moscow

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Summary

Direct oral anticoagulants (DOAC) are widely used for prevention of stroke in patients with atrial fibrillation. The need for therapeutic drug monitoring of DOACs remains unclear. Measurement of anti-Xa activity that directly correlates with serum drug concentration seems to be a promising approach for monitoring of Xa inhibitors.

Aim

To determine minimum and maximum anti-Xa activity in patients with atrial fibrillation treated with rivaroxaban or apixaban at different doses.

Material and methods

102 patients with atrial fibrillation treated with rivaroxаban (n=56) or apixаban (n=46) were enrolled in our study. Anti-Xa activity was measured with photocolorimetric method before and within 2-4 hours after intake of DOAC.

Results

Individual anti-Xa levels were highly variable. In patients treated with apixaban 5 or 10 mg daily, median minimum anti-Xa activity was 19.3 and 81.0 ng/mL, respectively (p<0.05), whereas median maximum anti-Xa levels were 369.8 and 403.0 ng/mL. In patients treated with rivaroxaban 10, 15 or 20 mg daily, median minimum anti-Xa activity was 27.0, 55.1 and 108,0 ng/mL, respectively (р<0.05), whereas median maximum anti-Xa levels were 117.0, 238.0 and 266.7 ng/mL.

Conclusion

Individual anti-Xa levels were highly variable in patients treated with Xa inhibitors. Minimum anti-Xa activity depended on the dose of DOAC and was significanly lower than maximum anti-Xa level.

Key words

anti-Xa activity, atrial fibrillation, rivaroxaban, apixaban.