Abstract Number: PB0622
Meeting: ISTH 2020 Congress
Background: DOACs show reproducible pharmacokinetics/dynamics. However, knowledge of between-patients and within-patient variability in trough concentration levels may be important for optimal management.
Aims: To evaluate the variability in trough concentrations (TC) of patients treated with dabigatran etexilate or apixaban.
Methods: Blood was drawn from 135 patients (61% men) affected by NVAF (53%) or VTE, on either dabigatran (44%) or apixaban treatment, 11-12 hours after last dosing. Patients on dabigatran (57% NVAF, 32% on low dose, 70±14 years) and on apixaban (49% NVAF, 59% on low dose, 74±12 years) had an average estimated creatinine clearance (ECrCl) of 87±28 ml/min and 65±25 ml/min, respectively. All patients had at least 3 blood samples (average 4.5) taken over a period of 1 year (overall 614). We measured Dabigatran and apixaban plasma levels with reagents from Stago (Asnieres sur Seine, France).
Results: Coefficients for between-patients variability were 43.0% for dabigatran (median TC=96 ng/ml) and 50.2% for apixaban (median TC=83 ng/ml). Gender, age, ECrCl and dose explained 35% of the between-patients variation in apixaban levels (r2=0.348). Median within-patient variability was 25% for both dabigatran and apixaban (IQR 18%-32% and 14%-42%, respectively). Gender, ECrCl, and lower trough concentrations explained about 38% of the within-patient variability in dabigatran levels (r2=0.376). Low-dose, indication (VTE), and the indication-dose interaction explained only about 13% of the within-patient variability in Apixaban levels (r2=0.128).
Conclusions: Despite dose-adjustment for patients with NVAF or VTE based on ECrCl and age, the between-patients variability in dabigatran TC is still high, unpredictable, and comparable to that of apixaban with inclusion of patients on low dose prophylaxis. Based on a follow up of at least 1 year, within-patient variability is lower and partially predicted by gender and ECrCl for patients on dabigatran.
To cite this abstract in AMA style:Della Valle P, Pozzi L, Pattarini E, Tomassini L, Fattorini A, Crippa L, D'Angelo A. Variability in Dabigatran and Apixaban trough Concentrations [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/variability-in-dabigatran-and-apixaban-trough-concentrations/. Accessed December 5, 2021.
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