THERMODYNAMICS OF PARACETAMOL SOLUBILITY IN SUGAR-WATER COSOLVENT SYSTEMS

The solubility of paracetamol in different concentrations of sorbitol, glucose and sucrose solutions was studied at 20 and 37°C. There was an appreciable decrease in solubility of the drug at both temperatures, the effect generally being more apparent at the lower temperature as reflected by the solubility ratios. Sorbitol exhibited the greatest effect followed by glucose then sucrose. Thermodynamic parameters were calculated and showed the nonspontaneity of the solubility process (positive free energy values). Entropy changes were positive or of small negative values, while enthalpy changes were positive and of relatively small values. Such results are compatible with the occurrence of hydrophobic interactions that led to a reduction in the solubility of the antipyretic agent. However, the effect of sugar concentration on the thermodynamic parameters was not the same with the three sugars tested, suggesting differences in their solvency characteristics. © 1990.