Inclusion complexes and self-assembled cyclodextrin aggregates for increasing the solubility of benzimidazoles

Albendazole and fenbendazole are imidazole derivatives that exhibit broad spectrum activity against parasites, but the low solubility of these drugs considerably reduces their effectiveness. Complexation of albendazole and fenbendazole with cyclodextrins (ß-cyclodextrin and hydroxypropyl-ß-cyclodextrin) in both water and an aqueous solution of polyvinylpyrrolidone (PVP-k30) was studied to determine if it could increase the solubility and dissolution rate of the drugs. In an aqueous solution, ß-cyclodextrin increased the solubility of albendazole from 0.4188 to ~93.47 µg mL-1 (223×), and of fenbendazole from 0.1054 to 45.56 µg mL-1 (432×); hydroxypropyl-ß-cyclodextrin, on the other hand, increased solubility to ~443.06 µg mL-1 (1058×) for albendazole and ~159.36 µg mL-1 (1512×) for fenbendazole. The combination of hydroxypropyl-ß-cyclodextrin and polyvinylpyrrolidone enabled a solubility increase of 1412× (~591.22 µg mL-1) for albendazole and 1373× (~144.66 µg mL-1) for fenbendazole. The dissolution rate of the drugs was significantly increased in binary and ternary systems, with hydroxypropyl-ß-cyclodextrin proving to be more effective. The presence of the water-soluble PVP-k30 increased the dissolution rate and amorphization of the complexes. Analysis of the changes in displacement and the profile of the cyclodextrin bands in the 1H NMR spectra revealed a molecular interaction and pointed to an effective complexation in the drug/cyclodextrin systems. Monomeric forms and nanoclusters of cyclodextrins were observed in the drug/cyclodextrin systems, suggesting that the increase in solubility of the drugs in the presence of cyclodextrins should not be attributed only to the formation of inclusion complexes, but also to the formation of cyclodextrin aggregates

Simultaneous determination of anti-diabetic drugs

A novel reverse phase, isocratic HPLC method is described to separate five anti-diabetic drugs i.e., glimepiride, metformin, sitagliptin, rosiglitazone and pioglitazone. Nucleosil C18 analytical column was used as stationary phase, while mobile phase consisted of acetonitrile:phosphate buffer: methanol (40/40/20, v/v) pH 2.0. Effluent was monitored at a flow rate 1 mL/min and detected at wavelength of 240 nm. This research produced excellent chromatography over a wide concentration range of 25-10000 ng/mL. Sepprated and well resolved quantifiable peaks were obtained and test results were linear in this range. Correlation coefficient of more than 0.9990 was witnessed as well as Low %RSD values i.e., maximum 2.0% documented excellent precision of the method. Good recoveries from pharmaecutical (99-101%), urine and plasma samples (>96%) in a range of concentrtion granted very good linearity, accuracy and precision. The projected method has satisfactory applications in quality control of these molecules as well as quantification of these molecules in urine and plasma samples.