Freeze etch of microencapsulated drugs

Abstract

Microcapsules are discrete drug-containing particles formed by dispersing drug crystals or molecules in a biodegradable polymeric matrix. Such microcapsules have been designed to be administered via injection. The advantages offered by this form of drug administration would be particularly valuable in the outpatient treatment of chronic schizophrenics who cannot be relied upon to give themselves proper dosages.In this study a model, long-acting neuroleptic was prepared by dispersing chloropromazine (CPZ) in a biodegradable polymer, poly (d, 1-lactide). Poly (d, 1-lactide) undergoes slow hydrolytic deesterification to lactic acid which is then metabolized to C02 and eliminated, thus avoiding the necessity of surgical removal of spent microcapsules. Four batches of microcapsules, differing in percentage CPZ to total capsule weight, were prepared and tested for drug release rate in an in vitro dissolution study (Fig. 1). Samples from each batch were mounted, coated and examined in a Cambridge Mark 2A SEM (Figs. 2, 3). Particle sizes ranged from 88um to 105um and were calculated from the micrographs.