Development and characterisation of metformin loaded spray dried Bora rice microspheres

Bora rice, a glutinous rice, is grown in Assam (a north eastern state of India) and is used traditionally for various purposes. The rationale of this study was to prepare and to assess Metformin loaded mucoadhesive spray dried microspheres using locally grown Bora rice powder. Metformin loaded microspheres were prepared using Bora rice and sodium alginate by spray drying method. For the study of the consequence of parameters of spray drier on the properties of microspheres, parameters such as aspirator flow rate, temperature, feed flow rate and concentration of the spray solution were changed. The in-vitro release properties were also studied. Almost spherical microspheres were obtained with significant swelling and mucoadhesivity. Dissolution study was carried out in phosphate buffer (pH 7.4) for 7 hrs. It was also noted to possess good mucoadhesive in such a way that about 90% of microspheres remained adherent on the surface of intestinal mucosa of pig skin. The total amount of drug released from microspheres after 7 hr. was 80%. The release of drug was not affected by the changes in parameters but was affected when sodium alginate concentration was changed. It was observed that microsphere properties changed as the parameters were changed. Smaller particles were obtained when the concentration of the spray solution, aspirator flow rate, the temperature difference between inlet and outlet and feed flow rate were lower.