A thermodynamic study of sublimation, dissolution and distribution processes of anti-inflammatory drug Clonixin

Abstract

The saturated vapor pressure of Clonixin has been measured by the transpiration method in the temperature range of 419.15–443.15 К, and the thermodynamic functions of sublimation have been calculated. It has been found that the energy of the compound crystal lattice is equal to 108.4 kJ·mol−1. The drug solubility in solvents imitating biological media of the body (buffer pH 2.0 and 7.4, 1-octanol, hexane) and the distribution coefficients in the systems 1-octanol/buffer (pH 2.0 and 7.4) have been determined by the shake-flask method in the temperature range of 293.15–313.15 К. The compound solubility values in these solvents lie within the interval from 1.78·10−4 to 8.01·10−2 mol/l. The coefficients of the drug distribution from buffer pH 2.0 in 1-octanol are one order of magnitude higher than from buffer pH 7.4. Based on the experimental data, the thermodynamic functions of the drug dissolution, transfer and solvation have been calculated in the chosen solvents.