Interaction of sulphinpyrazone with warfarin

J. O. Miners, T. Foenander, S. Wanwimolruk, A. S. Gallus, D. J. Birkett

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    14 Citations (Scopus)


    The effect of sulphinpyrazone administration on the anticoagulant response was investigated in five patients receiving long-term treatment with warfarin. Sulphinpyrazone caused a rapid increase in prothrombin (PT) ratio in all five patients and warfarin dose had to be reduced by a mean of 46% to maintain the PT ratio in the therapeutic range. PT ratio and daily warfarin requirement returned to previous levels when sulphinpyrazone was ceased. Warfarin protein binding was not altered during sulphinpyrazone administration and sulphinpyrazone added to plasma in vitro did not increase warfarin free fraction. The average racemic plasma warfarin concentration over a dosage interval when adjusted for warfarin dose was not altered by sulphinpyrazone administration. The most likely mechanism for this drug interaction is a stereoselective effect of sulphinpyrazone on the metabolism of the warfarin enantiomers.

    Original languageEnglish
    Pages (from-to)327-331
    Number of pages5
    JournalEuropean Journal of Clinical Pharmacology
    Publication statusPublished - Jul 1982


    • drug interaction
    • drug metabolism
    • protein binding
    • Sulphinpyrazone
    • warfarin


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