EVALUATION OF BILIRUBIN DISPLACING EFFECT OF INDOMETHACIN BY DETERMINATION OF ERYTHROCYTE-BOUND BILIRUBIN

The effect of indomethacin on bilirubin binding to human erythrocytes at different bilirubin/albumin molar ratios varying from 0.5 -3.0 was studied. Progressive addition of indomethacin produced a linear increa se in erythrocyte-bound bilirubin. This increase was more pronounced u p to 280 mu M drug concentration at all molar ratios,being maximum at higher bilirubin/albumin molar ratio. On the other hand, percent incre ase in erythrocyte-bound bilirubin produced by the drug was found to b e maximum at lowest bilirubin/albumin molar ratio and decreased on inc reasing bilirubin/albumin molar ratio. From these results we conclude that indomethacin induces displacement of bilirubin from albumin, thus increases bilirubin binding to human erythrocytes to a significant de gree even at lower concentrations.