Abstract
The current research work proposed the solubility data and solution thermodynamic properties of the cardiovascular agent 6-phenylpyridazin-3(2H)-one [PPD] in twelve pharmaceutical solvents at T = 298.2 K to 318.2 K and p = 0.1 MPa. The measured solubilities of PPD were regressed well with van't Hoff and Apelblat models. The solid phases of pure and equilibrated PPD were characterized using differential scanning calorimetry and powder X-ray differactometry, and the results suggested no transformation of PPD into solvates/hydrates/polymorphs after equilibrium. The solubilities of PPD in a mole fraction at T = 318.2 K were noted at a maximum in dimethyl sulfoxide (DMSO, 4.73 x 10(-1)), followed by polyethylene glycol-400 (PEG-400, 4.12 x 10(-1)), Transcutol((R)) (3.46 x 10(-1)), ethyl acetate (EA, 81 x 10(-2)), 2-butanol (2.18 x 10(-2)), 1-butanol (2.11 x 10(-2)), propylene glycol (PG, 1.50 x 10(-2)), isopropyl alcohol (IPA, 1.44 x 10(-2)), ethylene glycol (EG, 1.27 x 10(-2)), ethanol (8.22 x 10(-3)), methanol (5.18 x 10(-3)) and water (1.26 x 10(-5)). Similar tendencies were also noted at other studied temperatures. The results of the apparent thermodynamic analysis showed an endothermic and entropy-driven dissolution of PPD in all pharmaceutical solvents. The results of the activity coefficients suggested a maximum interaction at the molecular level in PPD-DMSO, PPD-PEG-400 and PPD-Transcutol, compared with other combination of the solute and solvents.