Abstract
The objective of this study was to determine the mole fraction solubility of a poorly water soluble antipsychotic drug risperidone (RIS) in mono-solvents and various Transcutol + water co-solvent mixtures at 298.15 to 333.15 K. The experimental solubility of RIS was determined using shake flask method and resulting data were correlated with the modified Apelblat model at 298.15 to 333.15 K. Excellent correlation existed between the experimental data of RIS and the calculated one with absolute relative deviation in the range of 0.009-6.374%. The correlation coefficients were observed in the range of 0.996-0.999, indicating good fitting. The lowest mole fraction solubility of RIS was observed in pure water (1.100 x 10(-7) at 298.15 K) whereas the highest one was observed in pure Transcutol (5.163 x 10(-3) at 298.15 K). The enthalpies and entropies for RIS dissolution were observed in the range of 10.005-45.723 kJ mol(-1) and 33.558-137.246J mol(-1) K-1, respectively in all sample matrices, indicating that the dissolution of RIS is an endothermic and an entropy-driven process. Based on solubility data of this study, RIS was considered as practically insoluble in water and soluble in Transcutol and most of the co-solvent mixtures. Overall, these studies indicated that Transcutol could be used as a physiologically compatible co-solvent for solubility enhancement of RIS which could help in formulation development of RIS. (C) 2013 Elsevier B.V. All rights reserved.