From the FDA Drug Label
When PCCs are used, monitoring for the anticoagulation effect of apixaban using a clotting test (PT, INR, or aPTT) or anti-factor Xa (FXa) activity is not useful and is not recommended. There is no experience with antifibrinolytic agents (tranexamic acid, aminocaproic acid) in individuals receiving apixaban There is no experience with systemic hemostatics (desmopressin and aprotinin) in individuals receiving apixaban and they are not expected to be effective as a reversal agent.
The use of thistle and its effects on haemostasis are not mentioned in the provided drug label for apixaban. Therefore, no conclusion can be drawn about the relationship between thistle and haemostasis in patients taking apixaban 1.
From the Research
Milk thistle (Silybum marianum) may potentially affect blood clotting and haemostasis, so caution is advised for individuals on anticoagulant medications or with bleeding disorders, as evidenced by the potential interactions with anticoagulants like warfarin, heparin, or direct oral anticoagulants 2. The active compound silymarin in milk thistle has been shown to have mild antiplatelet activity, which could theoretically increase bleeding risk when combined with blood thinners. Patients taking anticoagulants should consult their healthcare provider before using milk thistle supplements, as dosage adjustments of their medications may be necessary. Those with bleeding disorders should also exercise caution. Some key points to consider include:
- The interaction between milk thistle and anticoagulants may occur because silymarin may inhibit certain cytochrome P450 enzymes involved in drug metabolism, potentially increasing the blood levels and effects of anticoagulants 3.
- Milk thistle's mild antiplatelet effects could compound the anticoagulant effects of medications, increasing the risk of bleeding.
- While milk thistle is generally considered safe at recommended doses (typically 140-800 mg of silymarin daily), monitoring for unusual bleeding or bruising is important when using this supplement, especially in combination with anticoagulant therapy 4.
- A network meta-analysis found that warfarin had the highest risk of intracranial hemorrhage, followed by dabigatran, edoxaban, aspirin, apixaban, rivaroxaban, and placebo, highlighting the importance of careful consideration when using anticoagulants with milk thistle 2. In summary, patients taking anticoagulants or with bleeding disorders should exercise caution when using milk thistle supplements, and consult their healthcare provider to discuss potential interactions and necessary precautions 2.