Solubility determination and solution thermodynamics of olmesartan medoxomil in (PEG-400 + water) cosolvent mixtures.

The solubility and solution thermodynamic properties of a weakly water-soluble compound olmesartan medoxomil (OLM) in binary 'polyethylene glycol (PEG-400) + water' cosolvent compositions were determined. The 'mole fraction solubility ( )' of OLM in binary 'PEG-400 + water' cosolvent compositions and pure solvents (PEG-400 and water) was determined at ' = 295.15-330.15 K' and ' = 0.1 MPa'. The Hansen solubility parameter (HSP) of OLM, pure PEG-400, pure water, and binary 'PEG-400 + water' cosolvent compositions free of OLM were also predicted. The obtained values of OLM were correlated using 'van't Hoff, modified Apelblat, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-van't Hoff' computational models with the error values of <4.0%. The maximum and minimum value of OLM was predicted in neat PEG-400 (1.15 × 10 at  = 330.15 K) and neat water (1.90 × 10 at  = 295.15 K), respectively. The OLM HSP was predicted to be more close with that of neat PEG-400. The value of OLM was found increased significantly with increase in temperature and PEG-400 mass fraction in all 'PEG-400 + water' cosolvent compositions including neat PEG-400 and neat water. An 'apparent thermodynamic analysis' studies presented an 'endothermic and entropy-driven dissolution' of OLM in all 'PEG-400 + water' cosolvent compositions including pure PEG-400 and pure water.