What are the effects of using Carbimazole (antithyroid medication) and Apixaban (Factor Xa inhibitor) together?

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Last updated: May 16, 2025View editorial policy

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From the Guidelines

Carbimazole and apixaban can be used together, but careful monitoring is required due to the potential effects of carbimazole on thyroid function and subsequent coagulation status, rather than a direct drug interaction between the two medications. When considering the use of carbimazole and apixaban together, it's essential to understand that carbimazole, as an antithyroid medication, does not directly interact with apixaban, a direct oral anticoagulant, in terms of CYP3A4 or P-gp inhibition or induction, as discussed in the context of other medications 1. However, the primary concern with using these medications together lies in the indirect effects of carbimazole on the patient's coagulation status through the normalization of thyroid function. Thyroid disorders can influence coagulation, and as carbimazole treats hyperthyroidism, it may alter the anticoagulant effect of apixaban. Key considerations for managing patients on both carbimazole and apixaban include:

  • Regular monitoring of thyroid function tests to assess the impact of carbimazole on thyroid hormone levels.
  • Close monitoring of coagulation parameters, such as INR (if applicable) or other relevant tests for apixaban, to adjust the anticoagulant dose as necessary.
  • Watching for signs of unusual bleeding or bruising, as both medications can affect blood clotting.
  • Periodic complete blood counts to monitor for rare blood disorders that can be side effects of either medication. Patients should be advised to inform all healthcare providers about their combination therapy and not to adjust or stop either medication without medical supervision. Any new symptoms or concerns should be promptly reported to a healthcare provider for evaluation. Given the lack of direct interaction between carbimazole and apixaban regarding CYP3A4 or P-gp, as detailed in studies like 1, the focus should be on the clinical management of the patient's thyroid condition and anticoagulation status.

From the Research

Carbimazole and Apixaban Use Together

  • There are no direct studies on the use of Carbimazole and Apixaban together, however, studies on similar medications can provide some insight.
  • Methimazole, a medication similar to Carbimazole, has been shown to interact with warfarin, a medication similar to Apixaban, in patients with hyperthyroidism 2, 3.
  • The interaction between methimazole and warfarin can lead to alterations in thyroid hormone concentrations, which can in turn affect the intensity of anticoagulation 2, 3.
  • Clinicians should be aware of the need for close anticoagulation monitoring and dosage adjustment in patients receiving concomitant warfarin and methimazole 3.
  • It is possible that similar interactions could occur between Carbimazole and Apixaban, although more research is needed to confirm this.
  • Patients with hyperthyroidism being treated with antithyroid medications, such as Carbimazole, and anticoagulants, such as Apixaban, should be closely monitored for any potential interactions 2, 4, 5, 3.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Effect of methimazole on warfarin anticoagulation in a case of Graves' disease.

Blood coagulation & fibrinolysis : an international journal in haemostasis and thrombosis, 2008

Research

Hyperthyroidism: Diagnosis and Treatment.

American family physician, 2016

Research

Hyperthyroidism: A Review.

JAMA, 2023

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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