Potentiation of anticoagulant effect of warfarin by phenylbutazone.

THE administration of the pyrazolone derivatives, phenylbutazone and oxyphenbutazone, to a patient already being treated with coumarin anticoagulant drugs can lead to serious hemorrhagic complications.1 2 3 4 5 6 The means whereby these drugs potentiate the prothrombinopenic effect of the coumarins is not clear. It is not caused by impaired liver function or defective vitamin K metabolism since these drugs do not alter blood coagulation when given alone.7 , 8 In 1956 Sigg et al.1 reported a decrease in the disappearance rate of ethylbiscoumacetate in 1 of their patients when phenylbutazone was given. They attributed this to delayed renal excretion of the coumarin drug. Weiner and . . .

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[3]  M. J. Eisen.  COMBINED EFFECT OF SODIUM WARFARIN AND PHENYLBUTAZONE. , 1964, JAMA.

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[6]  O'Reilly Ra,et al.  The pharmacological basis of oral anticoagulant therapy. , 1966, Thrombosis et diathesis haemorrhagica. Supplementum.

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[8]  A. Quick.  HEMORRHAGIC DISEASES. , 1958, California and western medicine.

[9]  B. Brodie,et al.  Observations on the antirheumatic and physiologic effects of phenylbutazone (butazolidin) and some comparisons with cortisone. , 1954, The American journal of medicine.

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[11]  M. Hoag,et al.  HEREDITARY TRANSMISSION OF EXCEPTIONAL RESISTANCE TO COUMARIN ANTICOAGULANT DRUGS. THE FIRST REPORTED KINDRED. , 1964, The New England journal of medicine.

[12]  A. Miller,et al.  Potentiation of anticoagulant therapy by oxyphenylbutazone. (A probable case). , 1965, Postgraduate medical journal.

[13]  A. Conney,et al.  Drug interactions in man , 1965, Clinical pharmacology and therapeutics.