The main objective of the present study was to determine the feasibility of obtaining aqueous polymer-coated pellet formulations using EudragitR NE 30 D dispersion and chlorpheniramine maleate as the model drug. Many factors influence the rate of drug release from coated beads including, the substrate, the coating formulation and the coating process. A drug release profile that was comparable to that of the reference standard, DykatussR Capsules was obtained with a formulation employing 8.3% EudragitR NE 30 D, 0.5% talc and 1% polyethylene glycol. In vitro dissolution tests on this formulation showed drug release to be predictable, reproducible and independent of the dissolution methods or media. Short term storage confirmed the stability at room temperature (20°C) and low temperature (5C). Scanning electron micrographs of pellets stored at elevated temperatures i.e. 37°C with 80% relative humidity and 40°C illustrated the phenomenon of 'further gradual coalescence' which corresponded to the decrease in release of drug from the pellets.

Thesis (M.Sc.)-University of Natal, Durban, Westville, 1991.