Chitosan fortified repaglinide gastro-retentive mucoadhesive microsphere with improved anti-diabetic attribute

Repaglinide (RPG) has a high rate of absorption from the gastrointestinal system after oral administration due to low log P value. Hence, in this study the inotropic gelation process was used to fabricate mucoadhesive microspheres of RPG using biodegradable polymers such as guar gum, chitosan, and fenugreek seed mucilage. The mucoadhesive microspheres were characterized and tested in vitro followed with oral glucose tolerance test on animals. Scanning electron microscopy images demonstrated that the fabricated microspheres were smooth and spherical with lack of pores. The particle size and polydispersity index (PDI) of microsphere was observed as 300 ​μm and 0.349, respectively with high positive zeta potential of 38.4 ​mV. The results of percentage yield and swelling index analysis demonstrated 87.04 % and 90.65 %, respectively for optimized formulation with an in vitro release capability of 95.20 % in 10 ​h. In addition, the results suggested that the mucoadhesive microspheres successfully entrapped 94.86 ​± ​4.25 % of the RPG. These results clearly indicated that the optimized formulation of RPG fortified mucoadhesive microspheres reduced the blood glucose level (hyperglycemia due to glucose load 2 ​g/kg) significantly, compared to marketed RPG formulation (0.25 ​mg/kg) after 2 ​h of oral administration. Additionally, RPG incorporated microspheres enable the regulated blood glucose level over a 10 ​h. Hence, the formulation demonstrated overall improvement in anti-diabetic efficacy.