In vitro and in vivo Studies of Repaglinide Fast Dissolving Tablet Utilizing Solid Dispersion Techniques
Dalia Abdel-Rhman Attia *
Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, British University in Egypt (BUE), Cairo, Egypt and Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt.
*Author to whom correspondence should be addressed.
Abstract
Repaglinide according to the biopharmaceutics classification system is considered as class II drug, which suffers from low aqueous solubility and hence, low bioavailability. The current study concerned with improvement of the aqueous solubility and dissolution rate of repaglinide by using solid dispersion techniques with different polymers. Moreover, fast-dissolving tablets of repaglinide solid dispersion with superdisintegrant were formulated to enhance the repaglinide bioavailability. In the present study, solid dispersion formulae of repaglinide were prepared by utilizing different polymers namely polyethylene glycol 6000, mannitol and urea in various drug: polymer ratio (1:1, 1:3, 1:5, 1:10) by using melting and solvent evaporation methods. The solubility of repaglinide in different carriers was estimated, and solid dispersions were prepared and characterized. The drug release profile was carried out in phosphate buffer 6.8 using USP type I dissolution apparatus. From the above studies, it was found that the fusion method shows the better enhancement of dissolution in comparison to the solvent evaporation method. Among carriers used and based on the in vitro release study, the faster drug release appeared from solid dispersion prepared with urea in ratio 1:10. The increase in dissolution rate of repaglinide was confirmed by X-ray diffraction spectral studies of its solid dispersion which showed a significant decrease in drug crystallinity. The absence of interactions between drug and polymer was confirmed by differential scanning calorimetry and Fourier transform infrared spectroscopy studies. In addition, formula repaglinide solid dispersion FU10 was selected to develop a fast dissolving tablet that disintegrates rapidly and releases the maximum amount of repaglinide using Ac-Di-Sol as superdisintegrant. The prepared batches of tablets were tested for mechanical strength properties (hardness and friability), weight variation, disintegration, drug content and in vitro dissolution studies. Furthermore, pharmacokinetic studies with the selected fast dissolving tablet of repaglinide in solid dispersion were conducted on human volunteers. The fast dissolving tablet is a promising formulation for repaglinide that results in higher solubility, a rapid onset of action, and enhanced systemic bioavailability.
Keywords: Pharmacokinetics, fusion, in vitro drug release, phase solubility, repaglinide, solid dispersion.