Design and development of oral mucoadhesive multiparticulate system containing atenolol: in vitro-in vivo characterization.

The aim of the present study was to prepare mucoadhesive multiparticulate system for oral drug delivery using ionic gelation technique. Microspheres of different mucoadhesive polymers including hydroxypropyl methylcellulose (HPMC) K15M and carbopol 971P were prepared. In this technique cross linking of sodium alginate with calcium chloride was done which retarded the release of drug from the mucoadhesive polymer. In the present work atenolol was used as model drug. Interaction studies performed using FT-IR spectroscopy revealed that there was no drug to polymer interactions. Multiparticulates so prepared were discrete, bulky, free flowing and showed an average encapsulation efficiency ranging from 23-74%. Particle size of the multiparticulates as determined by the scanning electron microscopic analysis (SEM) studies was found to be between 561-831 microm. The prepared formulations also exhibited a good mucoadhesive strength which was determined in in vitro conditions through falling film technique. The multiparticulate so prepared also exhibited a good swelling index which confirmed the strong mucoadhesive property of the formulation. Atenolol release from the multiparticulate system was regulated and extended until 12 h and exhibited a non-Fickian anomalous transport from the swellable microspheres, as evident from the release rate exponent values which varied between 0.569-0.622. The stability studies performed on the optimized batch at 40 degrees C/75% RH for 90 d indicated no significant change in the physicochemical properties. In vivo radioimaging studies in rabbits showed the residence of mucoadhesive microspheres for 6-8 h in upper part of gastrointestinal tract (GIT).