Comparative Study on Estimation of Acenocoumarol Levels in Blood in Patients with Extremes and Normal INR Values after Valve Replacement Surgery

Abstract

Introduction: Acenocoumarol is an oral-anticoagulant which is commonly used but with narrow therapeutic index and there is no relation between dose and adverse effects. The response of acenocoumarol varies according to individual. Adverse effect like bleeding occurs even when INR is in normal range. Therapeutic drug monitoring of acenocoumarol is essential to prevent life threatening complication. Aim: To study the association between plasma concentration of acenocoumarol at trough and Cmax levels with their corresponding Internalized Normalised Ratio (INR) values in patients who have undergone valve replacement. Materials and Methods: After Human Ethics Committee approval, 56 patients were enrolled for the study. Participants who were taking acenocoumarol 2 mg with low INR, normal INR and high INR was included. Blood samples taken for estimation of trough and Cmax concentrations of acenocoumarol were analysed by High Performance Liquid Chromatography (HPLC) method. Results: The was no statistically significant correlation between INR of all the three groups and respective plasma concentration of acenocoumarol taken at trough and Cmax by Pearson’s correlation (p-value=0.187). The plasma concentration of acenocoumarol taken at trough and Cmax of all the three groups of participants was not statistically different by ANOVA (p-value=0.164). Conclusion: The present study concludes that measuring INR alone will have limited value for dose adjustment of acenocoumarol as proved by other studies for warfarin. Hence, estimation of plasma concentration of acenocoumarol will be ideal and appropriate for the dose adjustment of acenocoumarol.

Keywords

• high-performance liquid chromatography
• international normalised ratio
• oral-anticoagulants
• therapeutic drug monitoring