Aim: Oral anticoagulants are the most common used substance for treatment and prophylaxis of warfarin venous and arterial thromboembolic disorders in the world. Therapeutic index of warfarin is narrow. CYP2C9 is a hepatic microsomal enzyme and has a primary role in metabolism of warfarin and genetic variations of CYP2C9 may cause a serious effect on the response to warfarin in patients. The aim of this study was to determine the efficiency of CYP2C9 gene polymorphisms on drug metabolism in patients who had upper gastrointestinal system bleeding while using warfarin.
Methods: There was a total of 67 patients in this study, 37 of whom had upper gastrointestinal system bleeding when INR was above 3 while using warfarin (group 1), 30 of whom had no bleeding and INR was stable under 3 (group 2).
Results: There was no difference in terms of warfarin dose used among the groups (p>0.05). Mutant genotype, INR and aspirin usage were found significantly different in the group with bleeding (p less 0.05). When analyzed in terms of drug interaction, there was no difference between the two groups (p>0.05). Logistic regression analysis was made in order to determine the risk factors that may cause bleeding. Aspirin usage (p= 0.016) and genetic polymorphism (p= 0.024) were related to the increased risk of bleeding.
Conclusion: CYP2C9*2 and CYP2C9*3 polymorphisms were related to the increase of excessive anticoagulation and bleeding risk in the patients who used warfarin.