Influence of neutron irradiation on Eudragit coated tablets: validation of neutron activation II

Pectin-based oral drug delivery to the colon

This review presents an overview of studies concerning oral formulations intended for site-specific drug delivery to the colon with pectin as the main excipient. The biological aspects covered include gastrointestinal transit and the enzymatic degradation of pectin. Scintigraphic methods demonstrating the functionality of pectin formulations are discussed. The main focus is on the various formulations reported, including matrix tablets, multiparticulate formulations as pellets and hydrogel beads, and pectin-based coatings. Also included is an evaluation of common excipients employed to improve colon specificity by crosslinking or increasing the hydrophobicity. Finally, properties of the pectin molecules that are important for successful formulations are examined. The conclusion is that the studies found in the literature provide an excellent platform for the development of pectin-based colon delivery systems.

Influence of the coating thickness and type of oral delivery system (tablets, pellets) on the stability towards degradation by neutron irradiation. Validation of neutron activation III

Enteric coated dexchlorpheniramine maleate (DCPA) tablets and pellets with varying coating thickness were subjected to several in vitro tests after irradiation by thermal neutrons in a flux of 1. 1 x 10(13) n cm-2 s-1 for 2, 4 or 15 min. The appearance of the tablet formulation changed extensively after exposure of the tablets to pile radiation. The irradiation caused the film to loosen from the surface of the core, indicating the generation of gases during the irradiation process. Already after irradiating the tablets for 2 min the disintegration and dissolution behaviour were significantly changed. The extent of tablet damage increased with increasing time of exposure and increasing thickness of the coating. Compared with the tablet formulation, the cores could resist a larger amount of irradiation since dissolution behaviour of the cores was only affected after 15 min of irradiation. This indicates that the irradiation procedure initially affects the coating of the formulation. Although the dissolution behaviour of the pellet formulations changed significantly after the irradiation procedure, the changes were too small to be attributed exclusively to radiation damage.