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  • Acenocoumarol Vs. Warfarin
  • Switching

Switching - Warfarin to Acenocoumarol48

The relationship between maintenance dosages of three vitamin K antagonists: Acenocoumarol, warfarin and phenprocoumon
van Leeuwen Y et al., Thromb Res. 2008;123(2):225-30.

In clinical situations (e.g. warfarin resistance, coumarin sensitivity), needing a switchover of therapy from one coumarin derivative to another, it is often difficult to arrive at a precise dose of the drug.

To develop a transition algorithm for the maintenance dosages of three frequently used coumarins: warfarin, phenprocoumon and acenocoumarol.

Fifty-eight patients switched from warfarin to phenprocoumon, 39 from acenocoumarol to phenprocoumon and 44 from acenocoumarol to warfarin. Each treatment was administered for 6 months.

Transition factors of maintenance doses for switch-over of coumarins
Direction of switch Transition factor 95% CI
Warfarin - phenprocoumon 0.41 0.39-0.43
Phenprocoumon - warfarin 2.36 2.24-2.48
0.84 0.79-0.89
1.15 1.08-1.22
1.85 1.78-1.92
0.53 0.51-0.55

CI, confidence interval.

Dose conversion chart -Warfarin to Acenocoumarol48
Warfarin dosage (mg) Transition factor* Acenocoumarol dosage (mg)
2 0.5 1
4 0.5 2
5 0.5 2.5
6 0.5 3
*Transition factor-0.53 is taken as approx 0.5 for calculation of dosage