Development of an Emulsion-Solvent Evaporation Technique for Microencapsulation of Drus-Resin complexes

Abstract Chlorpheniramine maleate was complexed with a carboxylic acid cation-exchange resin and the complexes were microencapsulated with polymethyl methacrylate using an emulsion-solvent evaporation technique. Microcapsules of larger mean diameters resulted from polymer solutions of increased viscosities. Addition of 3% finely divided solids to the encapsulation vehicle resulted in smaller microcapsules, whereas a 6% concentration had the opposite effect, an increased capsule mean diameter. Emulsion stabilizers, such as magnesium stearate, up to a 1% concentration reduced microcapsule size by as much as 50%. The process efficiency ranged from 73% to 99%, depending on the formulation and manufacturing conditions used. The rate of drug release from the microcapsules was directly related to the amount of polymer deposited and inversely proportional to the capsule size.