Loading and maintenance dose algorithms for phenprocoumon and acenocoumarol using patient characteristics and pharmacogenetic data.

Aims: Polymorphisms in CYP2C9 and VKORC1 influence patients' phenprocoumon (PHE) and acenocoumarol (ACE) dose requirements. To provide physicians with tools to estimate the patient's individual dose, we aimed to develop algorithms for PHE and ACE.

Methods And Results: In two Dutch anticoagulation clinics, data on age, sex, height, weight, co-medication, coumarin derivative doses, and international normalized ratio values were obtained from 624 patients taking PHE and 471 taking ACE.

Vitamin K1 supplementation to improve the stability of anticoagulation therapy with vitamin K antagonists: a dose-finding study.

Background: Poor anticoagulant stability in patients using vitamin K antagonists is a risk factor for both bleeding and thrombosis. In previous studies supplementation with low dose vitamin K(1) was shown to improve the stability of anticoagulant control. We set up a study to confirm earlier reports and to determine the optimal daily dose of vitamin K(1) in preparation of a large study with clinical endpoints.

Effects of cytochrome P450 2C9 polymorphisms on phenprocoumon anticoagulation status.

Objective: Our objective was to assess whether there is an association between the presence of allelic variants of the gene for cytochrome P450 (CYP) 2C9 and anticoagulation problems during the initial phase of phenprocoumon treatment.

Methods: A prospective follow-up study was performed at 2 anticoagulation clinics in The Netherlands. Included subjects started phenprocoumon during the study period, had their first check of the international normalized ratio (INR) on the third or fourth day of therapy, and had an indication for the low therapeutic range (INR, 2.

Comparison of control and stability of oral anticoagulant therapy using acenocoumarol versus phenprocoumon.

Variability in the control of oral anticoagulant therapy has been associated with a heightened risk of complications. We compared control of anticoagulation between two commonly used coumarins, phenprocoumon and acenocoumarol, and among anticoagulation clinics. All qualifying patients were managed at six regional anticoagulation clinics in the Netherlands.

Lifestyle and diet as risk factors for overanticoagulation.

The risk of hemorrhage when using coumarin anticoagulants sharply increases when the International Normalized Ratio (INR) is > or =6.0. We performed a case-control study among outpatients of an anticoagulation clinic to identify sociodemographic-, lifestyle-, and dietary factors related to overanticoagulation.