Solubility measurement, thermodynamic modeling and solubility parameters of Clarithromycin（form ӀӀ）in aqueous ethanolic solution

Abstract

ABSTRACT To develop and optimise the crystallisation process of clarithromycin, the solid–liquid equilibrium solubility and solvent effect of clarithromycin form ӀӀ in aqueous ethanol mixtures was experimentally determined at the temperature range from 273.15 K to 333.15 K under atmospheric pressure of 0.1 MPa. Experimental results confirmed that the crystal form did not change during the determination of solubility. The results indicated that the solubility of clarithromycin is dependent on the composition of the mixed solvent, and it reaches its maximum value when the mole fraction of ethanol in the mixture solvent is equal to 0.61. In addition, the solubility of clarithromycin was positively related to the temperature in the ethanol-water mixed solvent. Furthermore, solubility parameter was used to elucidate the relation between the solubility and the mixed solvent. The modified Apelblat equation, van’t Hoff equation, λh equation, CNIBS/R–K model and Jouyban–Acree model were employed to correlate the solubility data. The correlation results showed good agreement with the experimental data, the modified Apelblat equation provides the best correlation results. The NRTL equation was utilised to calculate the thermodynamic properties of the dissolution process of clarithromycin, and the dissolution process of clarithromycin was estimated to be endothermic and entropy-driven.