POLYMERIC MICROPARTICLES PREPARED BY SPRAY-DRYING A DRUG-CONTAINING, AQUEOUS COLLOIDAL ACRYLIC POLYMER DISPERSION, EUDRAGIT RS30D

Polymeric microparticles were prepared from a drug-containing aqueous colloidal acrylic polymer dispersion, Eudragit RS30D, by a spray-dryin g method. The drug was either dissolved (chlorpheniramine maleate) or suspended (ibuprofen, naproxen) in the aqueous phase of the polymeric dispersion. Under optimal spray-drying conditions, the colloidal polym er particles coalesced into microparticles within the atomized droplet s. The microparticles were characterized with respect to yield, drug r elease, particle size and morphology. Spherical microparticles with dr ug loadings between 10 and 50% were obtained with an average particle size in the range of 5 to 20 mu m. The yield decreased with increasing drug loading and plasticizer level because of sticking and agglomerat ion. Chlorpheniramine maleate and ibuprofen acted ns plasticizers for the polymer. Although ibuprofen was suspended in the polymer dispersio n, it was dissolved in the microparticles, as indicated by X-ray diffr action studies. The drug release from the microparticles was delayed a nd was a function of the solubility of the drug and drug loading. The microparticles were incorporated into pellets or rapidly disintegratin g tablets as final dosage forms. The tablets disintegrated rapidly int o the microparticles, and the drug release was not affected by the com pression. With pellets, the drug release was further retarded because the pellets containing microcrystalline cellulose did not disintegrate into the individual microparticles.