Development and in vitro evaluation of a novel floating multiple unit dosage form obtained by melt pelletization

The feasibility of preparing floating pellets by melt pelletization was investigated. The pellets were prepared in a high shear mixer. Formulations were based on a mixture of Compritol and Precirol as lipidic binders and on sodium bicarbonate as a gas-generating agent. The floating ability of the pellets was evaluated in vitro. Good floating capabilities were obtained for formulations containing the gas-generating agent in both the inner matrix and the outer coating layer of the pellets. As an example, a placebo formulation containing 50% lactose 450 Me, 22% Compritol, 15% Precirol, 8% sodium bicarbonate and 5% Methocel K100 (w/w) in the inner matrix, and 66% Precirol and 34% sodium bicarbonate (w/w) as a coating effervescent layer, showed very good floating capabilities. The percentage of floating placebo pellets was around 80% after 1 h and still above 75% for 23 h. Floating pellet formulations with high drug content, based on the use of tetracycline hydrochloride and theophylline were also evaluated. They showed a comparable floating ability to placebo formulations, combined with sustained release properties thanks to the lipophilic character of the binders used.