Thermodynamic analysis of atorvastatin calcium in solvent mixtures at several temperatures

Cosolvency is a widely used method employed to enhance drug solubility. There are limited data on the solubility of atorvastatin calcium (ATC). The aim of this work is to determine ATC solubility in glycerol + water and 2-propanol + water mixtures at several temperatures (293.15, 298.15, 303.15, 308.15 and 313.15 K). The apparent thermodynamic properties of the ATC dissolution process including Gibbs free energy (Delta G degrees(sol)), enthalpy (Delta H degrees(sol)) and entropy (Delta S degrees(sol)) were calculated. The ATC solubility in various concentrations of the anionic, cationic and non-ionic surfactant was explored. The drug is most efficiently dissolved in sodium lauryl sulphate (SLS). Tween 20 did not cause any increment in drug solubility. Benzalkonium chloride may form an insoluble salt with ATC anion resulting in a decrease in drug solubility. Cosolvency data were correlated by Jouyban-Acree and Jouyban-Acree-van't Hoff equation.

Automated summary

Cosolvency is a widely used method to improve drug solubility, and this study aimed to determine the solubility of atorvastatin calcium (ATC) in different solvent mixtures. The apparent thermodynamic properties of ATC dissolution process were calculated, and the solubility of ATC in various concentrations of different surfactants was explored. Sodium lauryl sulphate (SLS) was found to be the most effective in dissolving the drug, while Tween 20 did not show any improvement. Benzalkonium chloride may decrease the drug solubility due to the formation of insoluble salt with ATC anion. The cosolvency data were analyzed using Jouyban-Acree and Jouyban-Acree-van't Hoff equations.