Drug interactions
Phenindione + Quinine
Severity: Moderate
Phenindione and Quinine: 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
Quinine may enhance the anticoagulant effect of vitamin K antagonists such as phenindione, and it can itself cause thrombocytopenia. Together this may raise the risk of bleeding.
What this interaction means in plain words
Phenindione and Quinine 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
The mechanism is not well established; possible additive hypoprothrombinemic effect and quinine-related thrombocytopenia.
What to do
Monitor INR or prothrombin time and platelet count closely when starting or stopping quinine, and adjust the phenindione dose accordingly.
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 Quinine
- Arsenic trioxide + Quinine Contraindicated
- Dofetilide + Quinine Contraindicated
- Dronedarone + Quinine Contraindicated
- Ibutilide + Quinine Contraindicated
- Mefloquine + Quinine Contraindicated
- Nilotinib + Quinine Contraindicated
Frequently asked questions
Can I take Phenindione with Quinine?
MediHelp rates the interaction as moderate. Phenindione and Quinine 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. Quinine may enhance the anticoagulant effect of vitamin K antagonists such as phenindione, and it can itself cause thrombocytopenia. Together this may raise the risk of bleeding.
How serious is the interaction between Phenindione and Quinine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor INR or prothrombin time and platelet count closely when starting or stopping quinine, and adjust the phenindione dose accordingly.
What other medicines interact with Quinine?
MediHelp also lists interactions of Quinine with, for example, Arsenic trioxide, Dofetilide, Dronedarone. The full list is on the Quinine page.
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