Effect of pH on Apparent Oil/Water Partition Coefficient of Prodrugs of Indomethacin

OBJECTIVE To study the effect of pH on apparent oil/water partition coefficient of prodrugs of indomethacin. METHODS The apparent oil/water partition coefficient of prodrugs of indomethacin was measured by shaking flask method. The concentration of prodrugs of indomethacin was determined by UV. RESULTS When the temperature was 25 ℃, the prodrugs of indomethacin have the highest partition coefficients in n-octanol/pH 4 buffer solution system. CONCLUSION The apparent oil/water partition coefficients of prodrugs of indomethacin are correlated to pH of the medium and the polarity of group which is added.