Granulated colloidal silicon dioxide-based self-microemulsifying tablets, as a versatile approach in enhancement of solubility and therapeutic potential of anti-diabetic agent: formulation design and in vitro/in vivo evaluation.

The current research work was executed with an aim to explore and promote the potential of self-microemusifying drug delivery systems (SMEDDS) in the form of tablets, in order to enhance solubility and oral bioavailability of poorly aqueous soluble drug Repaglinide (RPG). RPG-loaded liquid SMEDDS were developed consisting Labrafil M 1944CS, Kolliphor EL and Propylene glycol, which were then characterized on various parameters. After characterization and optimization, liquid SMEDDS were converted into solid form by adsorbing on Aeroperl® 300 pharma and polyplasdone(TM) XL. Further, selection of suitable excipients was done and mixed with prepared solidified SMEDDS powder followed by the preparation of self-microemulsifying tablets (SMET's) wet granulation-compression method. SMET's were subjected to differential scanning calorimetry (DSC) and particle X-ray diffraction (RXRD) studies, results of which indicated transformation of crystalline structure of RPG because of dispersion of RPG at molecular level in liquid SMEDDS. This was further assured by micrographs obtained from scanning electron microscope. SMET's shown more than 85% (30 min) of in vitro drug release in contrast to conventional marketed tablets (13.2%) and pure RPG drug (3.2%). Results of in vivo studies furnished that SMET's had shown marked decrease in the blood glucose level and prolonged duration of action (up to 8 h) in comparison with conventional marketed tablets and pure RPG drug. In conclusion, SMET's serves as a promising tool for successful oral delivery of poorly aqueous soluble drug(s) such as RPG.