COMPATIBILITY STUDIES OF MULTICOMPONENT TABLET FORMULATIONS. DSC AND EXPERIMENTAL MIXTURE DESIGN

An experimental mixture design was applied to a Differential Scanning Calorimetry (DSC) study performed to evaluate naproxen compatibility in tablet formulations consisting of four classic excipients (sorbitol, sodium carboxymethylcellulose, polyethylene glycol 2000 and Veegum) each in adequate concentration ranges accounting for the relevant values actually used in pharmaceutical formulations. Twenty-seven different tablets were obtained from as many mixtures prepared according to the experimental design plan and analyzed in a random order by DSC. Statistical evaluation of experimental data enabled correlation of both enthalpy and onset temperature variations of drug melting endotherm (selected as responses indicative of the presence of drug-excipient interactions) with the mixture composition. Variance analysis (ANOVA) confirmed the reliability of the postulated polynomial model in providing adequate prediction of true system behaviour