Resolving DOAC interference on antithrombin activity testing on a FXa based method by the use of activated carbon

Area of Science:

• Clinical Chemistry
• Hematology
• Pharmacology

Background:

• Direct oral anticoagulants (DOACs) can interfere with antithrombin (AT) activity assays, leading to inaccurate results.
• Activated carbon (AC) has demonstrated efficacy in removing DOAC interference in other coagulation assays.
• The utility of AC in resolving DOAC interference specifically in AT assays requires investigation.

Purpose of the Study:

• To evaluate the effectiveness of activated carbon (AC) in removing direct oral anticoagulant (DOAC) interference in antithrombin (AT) activity measurements.
• To determine if AC can restore accurate AT activity readings in the presence of various DOACs.

Main Methods:

• Normal pooled plasma (NPP) was diluted to achieve AT activity levels of 25%, 50%, and 75%.
• Diluted NPP samples were spiked with different concentrations (100, 250, 500 ng/ml) of four DOACs (apixaban, edoxaban, dabigatran, rivaroxaban).
• AT activity was measured using a FXa-based assay before and after treatment with 20 mg/ml AC.

Main Results:

• All tested DOAC concentrations were below the limit of quantification after AC treatment.
• Activated carbon successfully removed DOAC interference, enabling accurate diagnosis of low AT levels across all dilutions.
• The degree of DOAC interference was directly proportional to the DOAC concentration, with anti-FXa DOACs showing the most significant impact on the assay.

Conclusions:

• Activated carbon is an effective method for eliminating interference from anti-FXa direct oral anticoagulants in FXa-based antithrombin activity assays.
• AC treatment allows for reliable assessment of antithrombin activity in patients treated with specific DOACs.