Evaluation of phenomena occurring during the preparation of matrix granules by the hot melt technique

The aim of this study was to evaluate the applicability of hot melt granulation for the formulation of a pH-sensitive intelligent tablet containing heat- and moisture-sensitive components. An appropriate combination of magnesium trisilicate, aluminium hydroxide, sodium bicarbonate, and basic butylated methacrylate copolymer (Eudragit E PO) exhibited a good disintegration profile, but poor processibility. Hot melt granulation was applied with the aid of polyethylene glycol 2000 to increase the tablettability. The effects of the composition and the process on the properties of the granules and tablets formed were assessed with thermoanalytical and conventional testing methods. The heating of mixtures containing basic butylated methacrylate copolymer (Eudragit E PO) below its glass transition caused a relevant change in the wettability of the granules. This was induced by an alteration in the microstructure of the agglomerates. Tablets prepared from the granules containing an appropriate ratio of polymers exhibited an appropriate mechanical and disintegration profile. The thermal behaviour of the mixture of polymers cannot be predicted from the properties of the starting materials. Their interaction, demonstrated by DSC, can cause significant structure-forming problems in the matrices. The parameters of the granules and tablets varied with the quantity of the polymer applied. With an appropriate combination of polymers, hot melt granulation can be a suitable method for the preparation of intermediates for the formulation of controlled-release antacid tablets. Thermal analysis can promote an understanding of the process and determination of its operational parameters.