Warfarin and Acitrom (acenocoumarol) are oral anticoagulants belonging to the vitamin K antagonist (VKA) class. Both are used to prevent or treat thromboembolic conditions, including deep vein thrombosis (DVT), pulmonary embolism (PE), and selected cases of atrial fibrillation and mechanical heart valve replacement. Although they act through the same biological pathway, their pharmacological properties and dosing characteristics differ.

Warfarin and acenocoumarol inhibit vitamin K epoxide reductase, an enzyme encoded by the VKORC1 gene. Inhibition of this enzyme reduces the regeneration of active vitamin K, thereby decreasing the production of functional vitamin K-dependent clotting factors II, VII, IX, and X. This reduces the blood’s ability to form clots.

Genetic variations in VKORC1 and CYP2C9 can influence responses to both medications. The VKORC1 gene affects sensitivity to vitamin K antagonists, while CYP2C9 encodes an enzyme involved in their metabolism. Reduced-function CYP2C9 variants can slow the clearance of these drugs and increase the risk of excessive anticoagulation. However, the magnitude of these effects can differ between warfarin and acenocoumarol because their pharmacokinetic properties are not identical.

Pharmacogenetic testing may therefore provide useful information when estimating an initial acenocoumarol dose, particularly in patients with relevant genetic variants. Studies in different populations, including Indian populations, have investigated associations between these variants and acenocoumarol dose requirements. Nevertheless, the strength of the evidence and the clinical usefulness of specific dosing algorithms vary across populations and treatment settings.

An important distinction is that international pharmacogenetic dosing recommendations and algorithms are more extensively established for warfarin. They should not automatically be applied to acenocoumarol without considering drug-specific evidence, local guidance, and the patient’s clinical characteristics.

As with warfarin, acenocoumarol dosing is influenced by age, liver function, dietary vitamin K intake, interacting medications, illness, and adherence. Regular INR monitoring is essential to assess anticoagulant response and guide dose adjustments.

In conclusion, CYP2C9 and VKORC1 testing may help explain individual differences in both warfarin and Acitrom dosing. However, genetic results should be interpreted using medication-specific evidence rather than assuming that identical dosing recommendations apply to both drugs. For either medication, genetic testing supports dose selection but does not replace INR-guided clinical management.