Studies on microencapsulated granules: Effect of drug-binder solubilities and added diluents on core properties and microencapsulation characteristics

ABSTRACT

This work was designed to elucidate how drugs with various solubilities could behave when made into uniform core by granulation, microencapsulated and subjected to dissolution. Ascorbic acid and paracetamol [chosen as model drugs] were granulated with hydro- alcoholic solutions containing different amounts of water to allow for different degrees of drug solubilities. The porosities of the formed granules were measured and found to vary with drug solubilities in the granulating solutions. The granules were microencapsulated with ethylcellulose, then tested for their polymer contents which found to increase progressively with increasing core porosities. Corresponding decreases in drug release dc/dt and permeability constants P were also observed and their values depended on the presence of other insoluble or soluble diluents in the core materials. Although the release kinetics were apparently first order for the whole samples, yet the duration of the linear segments in the dissolution curves were more pronounced for the less porous cores regardless of the drug being used. An extended investigation on microencapsulated granules of fixed porosities prepared by dry granulation [slugging] has proved the above findings: