RESUMO
Albumin microspheres [AMS] have found many applications in the diagnosis and treatment in recent years and more than 100 diagnostic agents and drugs have been incorporated into AMS. In the present study Bovine Serum Albumin [BSA] based microspheres bearing propranolol hydrochloride were prepared by an emulsion-internal phase stabilization technique. The prepared microspheres were studied for particle size distribution, drug loading, release characteristics, bioadhesion and in-vitro controlled diffusion across the rat intestine. The microspheres had mean diameters between 1-25 mm of which more than 50% were below 5 mm. The encapsulated drug was found to be about 9% w/w of that initially added to microspheres and the superficial drug was 25% of the total amount of the encapsulated drug. Also AMS were noted to possess good bioadhesion in such a way that about 70% of microspheres remained adherent on the surface mucosa of rat jejunum.The drug release from albumin microspheres was mainly controlled by diffusion and showed a biphasic pattern with a high initial release [burst effect], followed by a more gradual terminal release. The total amount of drug released from microspheres after 12h was 70%. In vitro experiments on the rat intestinal segments revealed that the microspheres could effectively pass their content through intestinal membrane