Preparation and in vitro characterization of mucoadhesive Norethisterone - egg albumin microspheres for nasal administration

In this study suitable, smooth, spherical, cross-linked egg albumin microspheres in the size range of 15-40 um loaded with norethisterone were prepared by multiple emulsion (o/w/o) method by the glutarldehyde cross-linking and thermal denaturation technique. Microspheres were prepared by using different drug/polymer ratios. Egg albumin was used as a mucoadhesive polymer in the formulation to increase the residence time of the microspheres on the nasal mucosa. The albumin microspheres were characterized and evaluated with respect to the particle size, production yield, encapsulation efficiency, shape and surface properties, drug polymer interaction, mucoadhesive property and suitability for nasal drug delivery. The in vitro diffusion of NE from the prepared microspheres exhibited the extent of drug release decreased from 95 –60%. The release of the drug has been controlled by swelling control release mechanism. No initial burst release has been recorded except for NE microspheres stabilized using 25% w/v glutarldehyde as cross-linking agent. The drug release from NE microspheres obeys Higuchi diffusion controlled model.