Thermal Stability of Some Anti-Inflammatory Pharmaceutical Drugs and Determination Of Purity Using (DSC)

Abstract

The thermal behavior of some anti-inflammatory drugs: diflunisal, tenoxicam and celecoxib are studied extensively by thermo gravimetric and differential thermal analyses (TGA/DTA) techniques. The thermo gravimetric data allowed determination of the kinetic and thermodynamic parameters: activation energy (Ea), frequency factor (Z) activation entropy (AS#) and reaction order (n) which calculated from TG-curves at different heating rates using different kinetic models: The relative thermal stabilities of the anti-inflammatory drugs have been evaluated on the basis of the kinetic and thermodynamic parameters. Also, the purities of these drugs are determined by differential scanning calorimetric (DSC) technique and compared with specialized pharmacopoeia methods. Analysis of the DSC data indicated that the degrees of purity of diflunisal, tenoxicam and celecoxib were similar to those found by pharmacopoeia methods (BP and USP). The simplicity, speed and low operational costs of thermal analysis justify its application in quality control of pharmaceutical drugs.