Selected Anticoagulants (Vit K antagonists)/Barbiturates Interactions

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

The barbiturate medicine may cause your body to process the anti-clotting medicine (blood-thinner) more quickly.

What might happen:

When these two medicines are used together, your anticoagulant (anti-clotting medicine) may not work as well.On the other hand, if the doctor has stabilized you on this combination of medicines and then you stop taking the barbiturate, there may be an increased chance of bleeding. Signs of bleeding may include bleeding from your gums, nose bleeds, unusual bruising, or dark stools.

What you should do about this interaction:

Contact your healthcare professionals (e.g. doctor or pharmacist) as soon as possible about taking these two medicines together. Your doctor may want to check your laboratory tests (e.g. INR) more frequently and adjust your anticoagulant dose until you are stable on the combination.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

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  • 3.MacDonald MG, Robinson DS. Clinical observations of possible barbiturate interference with anticoagulation. JAMA 1968 Apr 8;204(2):97-100.
  • 4.This information is based on or an extract from the UW Metabolism and Transport Drug Interaction Database (DIDB) Platform, Copyright University of Washington 1999-2019..
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Selected from data included with permission and copyrighted by First Databank, Inc. This copyrighted material has been downloaded from a licensed data provider and is not for distribution, except as may be authorized by the applicable terms of use.

CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.