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 inthe size range of 15-40 um loaded with norethisterone were prepared by multipleemulsion (o/w/o) method by the glutarldehyde cross-linking and thermaldenaturation technique. Microspheres were prepared by using differentdrug/polymer ratios. Egg albumin was used as a mucoadhesive polymer in theformulation to increase the residence time of the microspheres on the nasalmucosa. The albumin microspheres were characterized and evaluated withrespect to the particle size, production yield, encapsulation efficiency, shape andsurface properties, drug polymer interaction, mucoadhesive property andsuitability for nasal drug delivery. The in vitro diffusion of NE from the preparedmicrospheres exhibited the extent of drug release decreased from 95 –60%. Therelease of the drug has been controlled by swelling control release mechanism. Noinitial burst release has been recorded except for NE microspheres stabilized using25% w/v glutarldehyde as cross-linking agent. The drug release from NEmicrospheres obeys Higuchi diffusion controlled model.