THE EFFECTIVENESS OF AN ORAL VITAMIN K_1 IN CONTROLLING EXCESSIVE HYPOPROTHROMBINEMIA DURING ANTICOAGULANT THERAPY

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Abstract
Vitamin K1 tablets for oral administration in doses of 2.5 to 20 mg were given to 75 patients in whom excessively elevated prothrombin time values were produced by prothrombinopenic anticoagulant therapy. In 85% of the patients studied the prothrombin time returned to a safe range (35 seconds or less) within 12 hours after the oral vitamin K1 in this dosage, and in 98% of the patients withing 24 hours. Prothrombin time fell below the lower therapeutic level of adequate anticoagulation in 15% of the patients at 12 hours following vitamin K1. Under such circumstances the administration of heparin ensured a continuing antithrombotic effect, until subsequent doses of coumarin or indandione agent again achieved an adequate hypoprothrombinemia. Since most hemorrhages during anti-coagulation occur in association with prothrombin time values above 35 seconds, vitamin K1 tablets for oral use provide an additional safeguard in coumarin and indandione therapy.