Evaluation of sustained release aqueous suspensions containing microencapsulated drug-resin complexes

Abstract

Cellulose Acetate Butyrate coated resinates released chlorpheniramine faster if the microcapsules were hydrated by suspension prior to release studies when compared to dry, unsuspended microcapsules. Contrasting a sulfonic acid resinate with a carboxylic acid resinate showed a reduced rate of release for chlorpheniramine from both coated and uncoated sulfonic acid resinates. Microcapsules of smaller diameter released chlorpheniramine faster than larger coated resinates of a similar batch. Microcapsules prepared under identical conditions released pseudoephedrine, diphenhydramine, and chlorpheniramine at different rates, with pseudoephedrine being released the fastest and chlorpheniramine the slowest. Aging of aqueous suspensions containing the coated resinates at room and elevated temperatures resulted in drug release profiles which were within experimental error.