September 1982

Phenylbutazone and Sulfinpyrazone Interaction With Oral Anticoagulant Phenprocoumon

Author Affiliations

From the Departments of Medicine, Santa Clara Valley Medical Center and the Institute for Medical Research, San Jose, Calif; the University of California, San Francisco; and Stanford University School of Medicine, Palo Alto, Calif.

Arch Intern Med. 1982;142(9):1634-1637. doi:10.1001/archinte.1982.00340220048010

• To compare the marked hypoprothrombinemic augmentation in man of racemic warfarin sodium by the pyrazolons phenylbutazone and sulfinpyrazone with that of the coumarin anticoagulant phenprocoumon, these interactions were studied prospectively in six normal subjects. Large single doses of racemic phenprocoumon, 0.6 mg/kg orally, were administered with and without daily phenylbutazone, 300 mg, or sulfinpyrazone, 400 mg, beginning three days before phenprocoumon and continuing for 14 days. Daily blood samples were drawn for phenprocoumon content and one-stage prothrombin time. Phenylbutazone markedly increased both the phenprocoumon concentrations and prothrombin times, whereas sulfinpyrazone did not.

(Arch Intern Med 1982;142:1634-1637)