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Apixaban

Test code: 94223

Apixaban (Eliquis®) is an oral factor Xa inhibitor that inhibits thrombin generation, which is critical for clot formation.

As an anticoagulant, it is indicated to do the following1:

  • Reduce the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation
  • Prevent deep venous thrombosis (DVT) in patients who have undergone hip or knee replacement surgery
  • Treat DVT and pulmonary embolism (PE)
  • Reduce the risk of recurrent DVT and PE following initial therapy

No, apixaban has a highly predictable pharmacokinetic profile. However, measurement of the drug’s level may be useful in the following situations2: 

  • Patient compliance and adherence is a concern.
  • A patient has a very high or low body weight.
  • A patient is pregnant.
  • Concurrent administration of a strong inducer of P-glycoprotein and CYP3A4 (eg, phenytoin, carbamazepine, phenobarbital, or St. John’s wort).
  • Concurrent administration of a strong inhibitor of P-glycoprotein and CYP3A4 (eg, azole antimycotics, including ketoconazole, itraconazole, voriconazole, and posaconazole). 
  • Concurrent administration of an HIV protease inhibitor (eg, ritonavir).
  • A thrombotic or hemorrhagic event occurs during therapy.
  • A patient has renal or hepatic failure.
  • A patient on apixaban therapy is scheduled for surgery.
  • A patient is elderly.
  • A patient has active cancer.

Because apixaban is administered in fixed doses and does not require routine laboratory monitoring, universal therapeutic ranges are not established. The steady-state peak and trough ranges for various doses are shown in the Table.

 

bid, twice daily; DVT, deep venous thrombosis; NVAF, non-valvular atrial fibrillation; PE, pulmonary embolism; VTE, venous thromboembolism.

a Dose adjusted population based on 2 of 3 dose reduction criteria in the ARISTOTLE study.3

 

Click the table to open in new window (enlarged)

Apixaban is measured using a modified, chromogenic anti-Xa method. The optical density of the patient sample is compared to that of calibrators with known apixaban concentration. The results are reported in ng/mL.4

The lower limit of detection for the apixaban assay is 30 ng/mL. Trough levels may be below this value; therefore, samples should be collected at the peak (3-4 hours after the last dose).2,4

The assay is not specific for apixaban. It will detect any anti-Xa anticoagulant including unfractionated heparin, low molecular weight heparins (enoxaparin, tinzaparin, dalteparin), rivaroxaban, and fondaparinux.4

The coefficient of variation (CV) is less than 6%.4

Gross lipemia, icterus, and hemolysis will interfere with apixaban measurement.4

References

  1. Eliquis® (apixaban) [package insert]. Princeton, NJ: Bristol-Meyers Squibb Company; 2021.
  2. Cuker A, Siegal DM, Crowther MA, et al. Laboratory measurement of the anticoagulant activity of the non-vitamin K oral anticoagulants. J Am Coll Cardiol. 2014;64:1128-1139.
  3. Source: Apixaban Accord: EPAR - product information, Summary of Product Characteristics.  European Medicines Agency Web site. Accessed November 12, 2024. https://www.ema.europa.eu/en/documents/product-information/apixaban-accord-epar-product-information_en.pdf. 
  4. Data on file. Quest Diagnostics Apixaban Validation Report, 7/12/16.

 

This FAQ is provided for informational purposes only and is not intended as medical advice. A clinician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.

Document FAQS.189 Version: 1

Version 1: effective 08/28/2025 to present

Version 0: effective 01/16/2017 to 08/28/2025

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