Formulation and evaluation of diclofenac controlled release matrix tablets made of HPMC and Poloxamer 188 polymer: an assessment on mechanism of drug release

In this study, hydrophilic hydroxypropyl methylcellulose matrices with various concentrations of Poloxamer 188 were used in the development of oral controlled release tablets containing diclofenac sodium. Four formulations of hydrophilic matrix tablets containing 16.7% w/w HPMC and 0, 6.7, 16.7 and 25.0% w/w Poloxamer 188, respectively, were developed. Tablets were prepared by direct compression and characterized for diameter, hardness, thickness, weight and uniformity of content. The influence of various blends of hydroxypropyl methylcellulose and Poloxamer 188 on the in vitro dissolution profile and mechanism of drug release of was investigated. In the four formulations, the rate of drug release decreased with increasing the concentration of Poloxamer 188 at the initial dissolution stages due to the increase in the apparent viscosity of the gel diffusion layer. However, in the late dissolution stages, the rate of drug release increased with increasing Poloxamer 188 concentration due to the increase in wettability and dissolution of the matrix. The kinetic of drug release from the tablets followed non-Fickian mechanism, as predicted by Korsmeyer-Peppas model, which involves diffusion through the gel layer and erosion of the matrix system

Cross-linked guar gum and sodium borate based microspheres as colon-targeted anticancer drug delivery systems for 5-fluorouracil

The aim was to prepare cross linked polymer of 5-fluorouracil loaded microspheres containing guar gum and sodium borate for colon-targeted drug delivery systems. Micro spheres were prepared using emulsification cross linking method. The influence of drug polymer ratio, cross linker agent concentrations and cross linking timing on in vitro drug release and characteristics in terms of drug loading, entrapment efficiency and yielding percentage were investigated. The optimum drug loading, entrapment efficiency and percent yield were obtained from formulations with the lowest content of cross linker agent over 2 h of cross linking timing but with the highest drug to polymer ratio 1:11. The optimum in vitro drug release was obvious upon decreasing drug to polymer ratio up to 1:09, resulting in 81.5% drug release over 24 h. In conclusion, micro spheres composed of gaur gum and sodium borate can delay and control the release of 5-fluorouracil over 24 h. Thus, further in vivo studies are suggested for final assessment