Drug interactions
Phenindione + Sulphasalazine
Severity: Moderate
Phenindione and Sulphasalazine: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Sulfasalazine has been associated with an enhanced anticoagulant effect of vitamin K antagonists, and phenindione is such an agent. This may raise the INR and the risk of bleeding.
What this interaction means in plain words
Phenindione and Sulphasalazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Possible displacement from protein binding and altered vitamin K handling; the mechanism is not firmly established.
What to do
Check INR more frequently when starting or stopping sulfasalazine. Adjust the phenindione dose to maintain the target INR.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Sulphasalazine
- Deferiprone + Sulphasalazine Major
- Pexidartinib + Sulphasalazine Major
- Sepiapterin + Sulphasalazine Major
- Acalabrutinib + Sulphasalazine Moderate
- Aceclofenac + Sulphasalazine Moderate
- Acetazolamide + Sulphasalazine Moderate
Frequently asked questions
Can I take Phenindione with Sulphasalazine?
MediHelp rates the interaction as moderate. Phenindione and Sulphasalazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Sulfasalazine has been associated with an enhanced anticoagulant effect of vitamin K antagonists, and phenindione is such an agent. This may raise the INR and the risk of bleeding.
How serious is the interaction between Phenindione and Sulphasalazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check INR more frequently when starting or stopping sulfasalazine. Adjust the phenindione dose to maintain the target INR.
What other medicines interact with Sulphasalazine?
MediHelp also lists interactions of Sulphasalazine with, for example, Deferiprone, Pexidartinib, Sepiapterin. The full list is on the Sulphasalazine page.
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