B. Sa et al., EFFECT OF MICROCAPSULE SIZE AND POLYISOBUTYLENE CONCENTRATION ON THE RELEASE OF THEOPHYLLINE FROM ETHYLCELLULOSE MICROCAPSULES, Journal of microencapsulation, 13(2), 1996, pp. 207-218
Citations number
13
Categorie Soggetti
Pharmacology & Pharmacy","Chemistry Applied","Engineering, Chemical
Ethylcellulose microcapsules containing theophylline were prepared by
the phase-separation coacervation process induced by non-solvent addit
ion in the presence of variable amounts of polyisobutylene. No statist
ical difference was evident between the different sized microcapsules
with respect to their drug content, wall thickness and in-vitro drug d
issolution profiles. Poly-isobutylene was, however, found to influence
the release profiles of drug to a great extent. An increase in polyis
obutylene concentration retarded the release of theophylline from the
microcapsules due to the formation of smaller and spheroidal coacervat
e droplets in larger volumes, which resulted in the formation of more
evenly coated microcapsules. Although the release of theophylline from
the microcapsules was found to fit both the first order and diffusion
controlled release processes, differential rate treatment indicated t
hat the overall release, in fact, was governed by diffusion controlled
process.