Solubility prediction of indomethacin in PEG 400+water mixtures at various temperatures

The objective of this study was to determine the equilibrium saturated solubility as well as mole fraction solubility of indomethacin in distilled water, polyethylene glycol 400 (PEG 400) and PEG 400 + water mixtures at the temperature range of 293.15 to 318.15 K. The equilibrium solubilities of indomethacin were determined by shake flask method and resulting data were analyzed by regression analysis. The experimental data were well correlated with the modified Apelblat model at various temperatures studied. The solubilities of indomethacin were found to be increased exponentially with increase in temperature in mono-solvents as well as in PEG 400 + water mixtures. The equilibrium saturated solubility as well as mole fraction solubility of indomethacin was found to be significantly higher in pure PEG 400 than distilled water and PEG 400 + water mixtures. The equilibrium and mole fraction solubility of indomethacin in pure PEG 400 at the temperature of 298.15 K were found to be 0.0831 g/g and 0.093, respectively. The relative absolute deviation (AD) between experimental and theoretical mole fraction solubility was found to be less than 1% in mono-solvents as compared to PEG 400 + water mixtures. Solubility data of present study indicate that PEG 400 could be successfully applied as a cosolvent in preformulation studies and formulation development of indomethacin as an alternate cosolvent of ethanol and propylene glycol.