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November 1983

Warfarin-Miconazole Interaction

Arch Intern Med. 1983;143(11):2214-2215. doi:10.1001/archinte.1983.00350110208047

To the Editor.  —The editorial by Hochman et al, published in the August 1982 Archives (142:1440-1442), was an excellent review of the relationship of antibiotics to the adverse effect of bleeding caused by the drugs and drug interactions with warfarin sodium. The antifungal agent, miconazole, should be added to the list of anti-infective agents known to potentiate the effect of warfarin sodium.Watson et al1 described two patients who were therapeutically and safely anticoagulated on warfarin for several months following the insertion of prosthetic mitral valves. A marked increase in prothrombin time with blood blisters and hematomas on the limbs occurred 11 to 12 days after administering miconazole, 250-mg tablets four times daily, for suspected fungal infections. The prothrombin time returned to the premiconazole level after therapy with the antifungal drug was discontinued.Oral miconazole is unavailable in the United States. However, according to the drug package insert for