In vitro properties of film-coated diltiazem hydrochloride pellets compressed into tablets

Abstract

The mechanical properties of ethylcellulose films were determined to evaluate effects of polymer, plasticizer, and dispersed solid. The concentration of propylene glycol was shown to exhibit no significant effect on the tensile strength while that of diethyl phthalate did. Both plasticizers were also found to have significant effects on the film elongation. Theoretical calculations revealed that the release of diltiazem hydrochloride from ethylcellulose film-coated pellets could be described by the combination of constant and non-constant activity source diffusion-controlled model. A dramatic modification in drug release characteristics was observed after the film-coated pellets had been compressed into tablets. However, the increase in compression force within the working range (181.8, 272.7, and 363.6 kg) was distinctly found to slightly affect the release from pellets being compressed. These behaviors may not be caused by flaws or failures within the film, but instead by the appreciable alterations in some physical properties of the film itself under pressure. The electron photomicrographs confirmed such a hypothesis. © 1994.