Thermodynamics of inclusion between chlorpropamide and α-cyclodextrin

Abstract

Chlorpropamide is an antidiabetic agent belonging to the sulfonylurea family, used for the treatment of Type 2 Diabetes Mellitus this drug has low solubility, which leads to bioavailability problems. One way to solve this complication is by using cyclodextrins, cyclodextrins are oligosaccharides that have a semi-rigid toroidal shape with a hydrophobic cavity, which is capable of containing non-polar molecules inside, forming an inclusion complex. Isothermal titration calorimetry is a technique that allows knowing the thermodynamic profile of the inclusion reaction between chlorpropamide and α-cyclodextrin (logK= 1.95 ± 0.01 M^-1, ∆G⁰= −2.70 ± 0.005 kcal mol^-1, ∆H⁰= −3.47 ± 0.06 kcal mol^-1, −T∆S⁰= 0.763 ± 0.07 kcal mol^-1), in the same way it allows reactions to be carried out at different temperatures, with which it is possible to determine the calorific capacity of the inclusion (∆C_P⁰= −0.119 kcal mol^-1 K^-1). The results obtained show that the reaction is exothermic, spontaneous and that the interactions that predominate of hydrophobic nature.