Effects of warfarin at beginning doses on patients with valve replacement.

Warfarin administered to patients with valve replacement at a dose of 0.1 mg/kg for 2 days after surgery, and blood levels of warfarin, TT, PT, HPT, total vitamin K and vitamin K1-epoxide were determined at various time intervals after the administration of the drug. The measurements were obtained from 15 patients: 8 patients with AVR, 6 patients with MVR, and 1 patient with DVR. The blood levels of warfarin reached a peak of 462 +/- 160 ng/ml 6 hours after the administration, TT, PT and HPT were 40% of the initial values 24 hours after the administration, and vitamin K1-epoxide was 1.28 +/- 0.30 ng/ml 24 hours after the administration. It is clear from the results that warfarin exhibits sufficient anticoagulant effects at a beginning dose of 0.1 mg/kg after surgery to prevent a sudden decrease in blood coagulation.