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