[Relationship between maintenance dosages of fluindione (Préviscan) and warfarin (Coumadin) for patients 70 years and older]

Abstract

Introduction: Switching from fluindione, an indanedione vitamin K antagonist derivative, to warfarin, a coumarin one, or vice versa, requires to know the relationships between dosages of these two molecules.

Methods: We conducted a prospective study in 288 consecutive patients aged 70 years and over, converted from fluindione to warfarin. Patients who were retained for the analysis were those for whom maintenance dosages were obtained for both vitamin K antagonists.

Results: Eighty-two patients, mean aged 83 ± 6 years, were analysed. The average daily maintenance dosages were 13.8 ± 6.7 mg (range 5-35) and 3.7 ± 1.7 mg (range 1-8) for fluindione and warfarin, respectively. Using a linear regression model, we built a transition algorithm for the maintenance dosages of warfarin and fluindione.

Conclusion: This is the first study to propose a conversion algorithm to help prescribers to estimate the maintenance dosage when it is necessary for a patient to switch from fluindione to warfarin or conversely.

Keywords: Antivitamine K; Dosage; Fluindione; Posologie; Vitamin K antagonist; Warfarin; Warfarine.