Table 1.

Warfarin initiation algorithm

DAYINR VALUEWARFARIN DOSE AT 6:00pm
1Do not measure4 mg
2Do not measure4 mg
3Do not measure4 mg
4< 1.35 mg
1.3 or 1.44 mg
1.5 or 1.63 mg
1.7 or 1.82 mg
1.9 to 2.41 mg
≥ 2.5Repeat INR measurement daily. Hold warfarin until INR < 2.5, then administer 1 mg
  • INR—international normalized ratio.

  • Data from Siguret et al.9