What laboratory test can detect apixaban (Eliquis) use?

From the Guidelines

To detect apixaban (Eliquis) use, an anti-Factor Xa activity assay specifically calibrated for apixaban is the most appropriate laboratory test. This test is necessary because apixaban directly inhibits Factor Xa in the coagulation cascade, and standard coagulation tests like PT, aPTT, or regular INR are not reliable for detecting its use 1. The anti-Factor Xa activity assay measures the anticoagulant effect of Eliquis in the blood, with results typically reported in ng/mL or μg/L, and therapeutic ranges varying based on the indication for treatment.

Key Considerations

• The timing of the blood draw is crucial, with levels being highest 3-4 hours after a dose and lowest just before the next dose.
• This test should be ordered by a healthcare provider, as it requires proper interpretation in the clinical context and is not routinely available at all laboratories.
• If apixaban use is suspected without prior knowledge, discussion with a healthcare provider is necessary to determine if testing is appropriate and necessary 1.

Test Characteristics

• The anti-Factor Xa activity assay is a specialized blood test that measures the anticoagulant effect of apixaban.
• The test results are typically reported in ng/mL or μg/L.
• Therapeutic ranges vary based on the indication for treatment.

Clinical Context

• Apixaban is a direct Factor Xa inhibitor, and its use requires monitoring with a specific assay.
• Standard coagulation tests are not reliable for detecting apixaban use.
• The anti-Factor Xa activity assay is the most appropriate test for detecting apixaban use, as recommended by recent guidelines 1.

From the FDA Drug Label

As a result of FXa inhibition, apixaban prolongs clotting tests such as prothrombin time (PT), INR, and activated partial thromboplastin time (aPTT). The Rotachrom Heparin chromogenic assay was used to measure the effect of apixaban on FXa activity in humans during the apixaban development program.

The laboratory test that can detect apixaban (Eliquis) use is the Rotachrom Heparin chromogenic assay, which measures the effect of apixaban on FXa activity. Additionally, apixaban use can also be detected by its effect on clotting tests such as prothrombin time (PT), INR, and activated partial thromboplastin time (aPTT) 2.

From the Research

Laboratory Tests for Detecting Apixaban Use

• The following laboratory tests can be used to detect apixaban use:
  • Chromogenic anti-FXa assays 3, 4, 5, 6, 7
  • Anti-Xa LMWH assay 7
  • HPLC-UV method 6
• These tests can measure the concentration of apixaban in plasma, with chromogenic anti-FXa assays being the most commonly recommended method 3, 4, 5, 6
• The anti-Xa LMWH assay can be used as an alternative when drug-specific calibrators are not available, but it may not be as accurate as drug-specific anti-Xa assays 7
• The HPLC-UV method is a reliable quantitative technique, but it may not be as readily available as chromogenic anti-FXa assays 6

Characteristics of Laboratory Tests

• Chromogenic anti-FXa assays:
  • Show linear dose-response curves with apixaban 3, 4
  • Can measure apixaban concentrations in the range of 0-1000 μg/L 3
  • Have good precision and accuracy 5, 6
• Anti-Xa LMWH assay:
  • Can be used to detect clinically significant apixaban or rivaroxaban levels 7
  • Has a good correlation with drug-specific anti-Xa assays 7
• HPLC-UV method:
  • Is a reliable quantitative technique 6
  • Can measure apixaban concentrations in the range of 8-39 ng/mL 6

Limitations of Laboratory Tests

• APTT and PT assays are not recommended for measuring apixaban concentration due to their limited sensitivity and variability 3, 5
• Anti-Xa LMWH assay may not be as accurate as drug-specific anti-Xa assays 7
• HPLC-UV method may not be as readily available as chromogenic anti-FXa assays 6