Studies on phase diagram, thermodynamic stability and interfacial structure of solid dispersions of phenothiazine-adipic acid drug system

Abstract

In the present communication phase diagram, thermodynamic quantities, stability and interface structure of phenothiazine (PT)-adipic acid (AA) binary system have been reported. Eutectics (E1, E2) at 0.631 and 0.868 mole fraction of PT and addition compounds (A 1:1, A 4:1) are formed in the system. Partial and integral thermodynamic quantities such as excess Gibbs energy (gE), excess enthalpy (hE) and excess entropy (sE) of eutectic and non-eutectic mixtures were also calculated using activity coefficient data. The positive value of excess Gibbs free energy indicates deviation from ideal behavior which refers stronger association between like molecules during formation of binary mix. The positive value of Gibbs free energy of mixing (ΔGM) suggests the mixing for eutectic and non-eutectic is non-spontaneous. The size of critical nucleus at different undercoolings has been found in nanoscale, which may lead a big challenge in pharmaceutical world.