Solubility and thermodynamics of 6-phenyl-4,5-dihydropyridazin-3(2H)-one in various neat solvents at different temperatures.

Pyridazinone derivatives have been investigated either pre-clinically or clinically in the treatment of various cardiovascular diseases. The main problems associated with these drugs are the poor aqueous solubility and toxicity. Therefore, in the current study, the solubility of pyridazinone derivative i.e. 6-phenyl-4,5-dihydropyridazin-3(2H)-one [coded as PDP-6] was determined in eleven different neat solvents at temperatures “ T = 293.2 K to 313.2 K” and “atmospheric pressure p = 0.1 MPa”. Experimental mole fraction solubilities of PDP-6 were correlated well with van't Hoff and Apelblat models with mean percent deviation of < 6.0%. The mole fraction solubilities of PDP-6 at “ T = 313.2 K” were recorded highest in dimethyl sulfoxide [DMSO] (6.77 × 10 − 1 ) followed by 2-(2-ethoxyethoxy) ethanol (Transcutol®) (5.24 × 10 − 1 ), polyethylene glycol-400 [PEG-400] (8.47 × 10 − 2 ), ethyl acetate [EA] (1.45 × 10 − 2 ), ethylene glycol [EG] (1.09 × 10 − 2 ), propylene glycol [PG] (1.03 × 10 − 2 ), 2-butanol (7.78 × 10 − 3 ), 1-butanol (7.68 × 10 − 3 ), ethanol (6.96 × 10 − 3 ), isopropyl alcohol [IPA] (6.51 × 10 − 3 ) and water (1.61 × 10 − 6 ) and similar trend was also recorded at all five different temperatures investigated. “Apparent thermodynamic analysis” on mole fraction solubilities of PDP-6 indicated an endothermic dissolution of PDP-6 in all neat solvents studied. Based on these data, PDP-6 has been proposed as practically insoluble in water, sparingly soluble in ethanol, IPA, EG, PG, EA, 1-butanol and 2-butanol, soluble in PEG-400 and very soluble in DMSO and Transcutol®. [ABSTRACT FROM AUTHOR]