INVITRO EVALUATION OF SPRAY-DRIED MUCOADHESIVE MICROSPHERES FOR NASAL ADMINISTRATION

Microspheres of disodium cromoglycate (DSCG) were prepared with either polyacrylic acid (Carbopol 934) or sodium carboxymethylcellulose (NaCMC) by the spray-drying technique. The arithmetic mean diameter of the spray-dried particles ranged from 3.2 to 5.7 microns. The plain DSCG particles and the microspheres containing NaCMC were spherical and had a smooth surface, whereas the microspheres containing Carbopol 934 were more irregular and partly shrunken. The dissolution rate of the plain DSCG was prolonged when the drug was incorporated with the polymers. The more polymer the microspheres contained the slower the drug release rate. The in vitro mucoadhesion test showed that the plain DSCG was nearly as mucoadhesive as the the plain polymers. The microspheres of DSCG with either of the polymers were, however, clearly more mucoadhesive than the plain starting materials. The adsorption isotherms showed the hygroscopic nature of the polymers and DSCG. The hydration of the microspheres increased as a function of the drug content.