Mai Khanfar

Inulin and poly(acrylic acid) grafted inulin for dissolution enhancement and preliminary controlled release of poorly water-soluble Irbesartan drug

In this article, inulin and poly(acrylic acid) grafted inulin copolymer were used to enhance the dissolution of poorly water-soluble Irbesartan drug and to control its drug release rate, respectively. Topological structure of inulin showed sleazy separable flower-like platelets and granules accumulated above each other, which adapt it to physically bind Irbesartan drug and enhance its dissolution. Consequently, the increase of inulin content in the polymeric matrix was found to increase the drug dissolution gradually until it reaches its maximum (∼90%) within the first 60 min. The release rate had followed zero-order transport mechanism. On the other hand, the poly(acrylic acid) grafted inulin copolymer, characterized using (1)H NMR, FTIR, TGA, and SEM techniques, was found to form highly consistent amorphous systems of two-dimensional surfaces with some voids topology. Such features adapted it to control Irbesartan drug dissolution (∼33%) and show Fickian diffusion mechanism.

Formulation factors affecting the release of ezetimibe from different liquisolid compacts

Context: Liquisolid technique is one of the methods used to improve the dissolution rate of the poorly water soluble drugs utilizing non volatile liquids.Objectives: Enhancement of the release of ezetimibe from different liquisolid formulations.Materials and Methods: Four liquid vehicles were used to prepare the liquid medications with different drug concentrations. The interaction between the drug and the excipients in liquisolid powders were characterized by DSC, X-ray, FTIR and SEM. Furthermore, the powder characteristics were evaluated by Carr’s Index and powder wetting time determinations, respectively. All prepared formulations were compressed at different pressures to end with the same constant porosity and the tablets were evaluated by different tests and compared with conventional formula. Results and Discussion: No interaction had been detected in all liquisolid formulations as shown in the results of XRD, FTIR, DSC and SEM. In addition to that, all liquisolid compacts had expressed faster dissolution profiles compared with that of conventional formula. Conclusion: The dissolution rate was affected by the drug concentration, solubility of the drug in the liquid vehicle and type of carrier. In addition, the presence of the liquid vehicle has been found to affect the mechanical properties of the liquisolid formulations.

Determination of the mechanism of uptake of organic vapors by chitoasn.

It was of interest to investigate the possible interactions that might occur between chitosan and various compounds of different polarities using solvent vapor sorption and Fourier Transform Infrared Spectroscopy (FTIR). The sorption system was composed of a gas inlet, a 2 meter gas cell and a gas outlet. The experimental set up allowed quantification of the free vapor and therefore the amount of the sorbed vapor by chitosan powder. The BET equation was applied to the experimental data to obtain the apparent monolayer sorption capacity (Sm) and the parameter C, which is related to the heat of interaction. Results demonstrated that the surface areas obtained for chitosan from the BET analyses for heptane, 1,4-dioxane and methanol were 421, 379 and 58 m2/g, respectively. These values were extremely higher than the value obtained from nitrogen vapor adsorption isotherm (4.56 m2/g). The difference is attributed to the partitioning of these compounds into the chitosan particles. The large difference in the Sm values between the nonpolar (heptane and 1,4-dioxane) and the semipolar compounds (methanol) also suggested that the polarity of the solvent might have a significant effect on the partitioning of the these compounds into the chitosan particles. The results obtained from this study also confirmed what was previously described regarding the ability of chitosan to act as a ‘fat magnet’ or a ‘fat sponge’.

Preparation of sustained-release dosage form of Venlafaxine HCl using liquisolid technique

Abstract Context: The aim of this study is to control the dissolution rate of Venlafaxine HCl. Objective: To prepare sustained release tablets of Venlafaxine HCl. Material and methods: Different liquisolid formulations, liquid vehicles, drug concentration in the liquid medication and different ratios of carrier to coating material (R) were prepared. The prepared powders were characterized for possible interactions between drug and excipients using differential scanning calorimetry, X-ray, Fourier transform infrared analysis and scanning electron microscopy. Powder flowability was also evaluated, then they are compressed at different compression forces, and the compressed tablets were evaluated for their mechanical properties and dissolution profile. Results: Release results show that sustained release behavior can be obtained from liquisolid formulation containing Tween 80 as liquid vehicle. Discussion: Many factors affect the retardation effect of Venlafaxine HCl such as the type of liquid vehicle, drug concentration in the liquid medication and R. The mechanism of the in vitro release profiles was found to be mainly controlled by diffusion and polymer relaxation. Conclusion: Sustained release formulation of Venlafaxine HCl was attained using the liquisolid technique.

Release behaviour of diclofenac sodium dispersed in Gelucire® and encapsulated with alginate beads

Sustained release polymeric particles containing diclofenac sodium dispersed in Gelucire® matrix and encapsulated in calcium alginate shell were prepared with different drug-to-polymer ratios and also with different concentrations of sodium alginate for a fixed drug-to-polymer ratio in an aqueous environment. Spherical particles were formed by dropping an emulsion of diclofenac sodium in Gelucire® matrix, emulsified with sodium alginate, into calcium chloride solution. The gelled beads formed by ionotropic gelation of alginate with calcium ions showed sustained release of the water soluble drug in in-vitro release study. Drug release was a function of square-root of time, suggesting a matrix diffusion release pattern. The rate of release was significantly suppressed with increasing proportions of Gelucire® in the mixture. Sustained and complete release was achieved with Gelucire® of low melting point and low HLB value. No significant drug release occurred in a dissolution medium of pH 1.5, whereas complete release was observed at pH 6.8, consistent with considerable swelling of the alginate gel at this pH.