Development and characterization of fast-dissolving tablet formulations of glyburide based on solid self-microemulsifying systems

The aim of this work was to develop effective fast-dissolving tablet formulations of glyburide, endowed with improved dissolution and technological properties, investigating the actual effectiveness of the Solid-Self MicroEmulsifying Drug Delivery System (S-SMEDDS) approach. An initial screening aimed to determine the solubility of the drug in different oils, Surfactants and CoSurfactants allowed the selection of the most suitable components for liquid SMEDDS, whose relative amounts were defined by the con- struction of pseudo-ternary phase diagrams. The selected liquid SMEDDS formulations (Capyol 90 as oil, Tween 20 as Surfactant and Glycofurol or Transcutol as CoSurfactant) were converted into Solid- SMEDDS, by adsorbing them onto Neusilin (1:1 and 1:0.8 w/w S-SMEDDS:carrier), and fully characterized in terms of solid state (DSC and X-ray powder diffraction), morphological (ESEM) and dissolution prop- erties, particle size and reconstitution ability. Finally, the 1:1 S-SMEDDS containing Glycofurol as CoSurfactant, showing the best performance, was selected to prepare two final tablet formulations. The ratio test (t10 min ratio and DE60 ratio) and pair-wise procedures (difference (f1) and similarity (f2) factors) highlighted the similarity of the new developed tablets and the marked difference between their drug dissolution profiles and those of formulations based on the micronized drug. The S-SMEDDS approach allowed to develop fast-dissolving tablets of glyburide, endowed with good technological prop- erties and able to achieve the complete drug dissolution in a time ranging from 10 to 15 min, depending on the formulation composition.