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Formulation and In Vitro Evaluation of Floating Tablets of Pioglitazone for Oral Sustained Release Employing Olibanum Gum and HPMC

G. Chinna Devi and K. P. R. Chowdary

The objective of the study is to formulate and evaluate floating tablets of pioglitazone employing olibanum gum, a natural gum resin in comparison to HPMC K15 M, a synthetic cellulose derivative. Floating tablets of pioglitazone were prepared employing olibanum gum and HPMC K15 M as matrix formers, sodium bicarbonate as gas generating agent and bees wax and ethyl cellulose as floating enhancers and the tablets were evaluated for In vitro buoyancy and drug release characteristics. The floating characteristics of the formulations which contained sodium bicarbonate (15%) alone were not satisfactory with both the two polymers and need to be improved. Increasing the strength of sodium bicarbonate from 15% to 20% has not much improved the floating characteristics. Addition of bees-wax (15%) and ethyl cellulose (5%) has significantly enhanced the buoyancy of the tablets formulated with both the two polymers. Pioglitazone release from the floating tablets prepared was slow and spread over 24 h and depended on the polymer used and composition of the tablets. Drug release was diffusion controlled and followed zero order kinetics. Non-Fickian diffusion was the drug release mechanism from all the tablets formulated. Pioglitazone release from the tablets containing beeswax and ethyl cellulose along with the matrix forming polymers was slow and spread over more than 24 h. The T90 values were in the range 19-24 h with these tablets. These tablets exhibited a floating time of 44 h after a floating lag time in the range 2-6 min. Olibanum is found suitable as matrix former for floating tablets and is comparable to HPMC K15M, a widely used polymer for floating tablets and for controlled release. Since olibanum gum is of natural origin, it is non-toxic, biocompatable and cheaper.