PRESS-COATED TABLETS FOR TIME-PROGRAMMED RELEASE OF DRUGS

A new dry-coated device for the release of drug after a programmable p eriod of time is proposed. It is intended to be used mainly in the the rapy of those diseases which depend on circadian rhythms. Some core fo rmulations, characterized by different release rates and mechanisms (c ontaining diltiazem hydrochloride or sodium diclofenac as model drugs) , were coated by compression with different polymeric barrier layers ( press-coated systems). The shell formulations tested contained either gellable or erodible polymers. The dissolution profiles of uncoated co res and press-coated devices were compared. The gellable and/or erodib le characteristics (properties) of the barrier formulations were also examined by means of a penetrometer. The coatings prevent drug release from the core until the polymeric shell is completely eroded or swoll en. This delay in release start is not influenced by the core composit ion and depends only on the shell formulation. Except for the time-lag , the release kinetics of the drug contained in the core are not signi ficantly influenced by the presence of the erodible barrier, but can b e widely modulated using a swellable polymeric shell.