THERMODYNAMIC ANALYSIS OF MOISTURE ADSORPTION ISOTHERM FOR MEFENAMIC ACID TABLETS.

The present study investigated the thermodynamic properties of Mefenamic acid tablets at three temperatures (25, 35, 45oC) based on the experimental sorption data studied earlier in a previous study. The net isosteric heat of adsorption and the differential entropy were found to decrease as the water activity increases. A 4th order polynomial equation described both of them. A linear enthalpy-entropy relationship is disclosed with 95.6 % correlation factor. The isokinetic temperature was differed significantly from the harmonic mean temperature implying the linear enthalpy-entropy compensation and enthalpy drawn adsorption process. The enthalpies associated to GAB's model (GAB: Guggenhein - Anderson and de Boer) were also investigated and discussed. [ABSTRACT FROM AUTHOR]