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 (x _e)' of OLM in binary 'PEG-400 + water' cosolvent compositions and pure solvents (PEG-400 and water) was determined at 'T = 295.15-330.15 K' and 'p = 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 x _e 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 x _e value of OLM was predicted in neat PEG-400 (1.15 × 10^-2 at T = 330.15 K) and neat water (1.90 × 10^-7 at T = 295.15 K), respectively. The OLM HSP was predicted to be more close with that of neat PEG-400. The x _e 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.