Preparation and Evaluation of Nano-vesicles of Brimonidine Tartrate as an Ocular Drug Delivery System

The objective of the present investigation was to design a vesicular formulation of brimonidine tartrate and evaluate its ability to reduce the dosing frequency and improve the therapeutic efficacy of the drug. Nano-vesicles of brimonidine tartrate were prepared by film hydration method. The prepared vesicles were evaluated for photomicroscopic characteristics, entrapment efficiency, in vitro, and ex-in vitro drug release and in vivo intraocular pressure (IOP) lowering activity. The methods employed for preparation of vesicles produced nano vesicles of acceptable shape and size. The in vitro, and ex-in vitro drug release studies showed that there was slow and prolonged release of the drug, which followed zero-order kinetics. The IOP-lowering activity of nano vesicles was determined and compared with that of pure drug solution and showed that the IOP-lowering action of nano-vesicles sustained for a longer period of time. Stability studies revealed that the vesicle formulations were stable at the temperature range of 2-8°C, with no change in shape and drug content. The results of the study indicate that it is possible to develop a safe and physiologically effective topical formulation that is also convenient for patients

Viscosity studies of aqueous mixed electrolyte solutions

950-953Relative viscosity studies of ternary aqueous mixed electrolyte solutions for the systems KBr-NaBr, KBr-Bu4NBr, NaCI-NaBr and NaCI-Bu4NBr at various constant ionic strengths with varying electrolyte mole fractions (y) at 25°C are reported. The data are used to calculate viscosity B-coefficients of the total electrolyte as a function of solute mole fraction. The excess viscosity B-coefficients (BEx) have been calculated and found to be distinctly positive for all the systems studied. The variation of BEx with y and the magnitudes have been explained in terms cation-cation, anion-anion interactions and the specific structural interactions with solvent water

Application of Kirkwood-Buff theory of liquid mixtures to binary aqueous solutions of alcohols

1069-1074The various integrals over the pair correlation functions, GAA, Gww and GAW (A=alcohol, W= water) have been calculated for aqueous solutions of methanol, ethanol, 1-propanol and tertbutanol at 25°C by utilizing the thermodynamic properties like the isothermal compressibility, partial molar volumes and vapour pressure and by the application of an inverse procedure for KirkwoodBuff theory of solutions as suggested by Ben-Nairn. It is observed that as a function of concentration, GAA, GAW and Gww have extremas in the studied concentration range. The results are compared with similar systems reported earlier and are interpreted on the basis of solvent structural effects and hydrophobic interaction amongst the solute molecules. The behaviour of GAA in dilute concentration indicates that the strength of hydrophobic interaction decreases initially in all the studied water-alcohol systems. The mean square concentration fluctuation parameter N x)2 > as a function of concentration has been estimated using Gij values. These results are in agreement with the available scattering data, suggesting further that the main effect of alcohol is to interfere destructively with low density domains in water in dilute concentration of alcohols in water

Cellular alterations and modulation of protein expression in bitumen-challenged human osteoblast cells

Purpose There are many arguments on the carcinogenic potential of bitumen extract. The mechanism of bitumen-induced damage is not well understood at the molecular level. Therefore, in the present study, cell-transforming and tumor-inducing potential of bitumen extract was studied using in vitro [human osteosarcoma (HOS) cells] and in vivo [nude and severe combined immunodeficiency (SCID) mice] models. Methods Gas chromatography/mass spectrometry (GC/MS) analysis was carried out to find out the existence of carcinogenic compounds in the bitumen extract. Cell transformation test, anchorage independence assay, karyotyping assay, tumorigenicity assay, and 2-DE analysis were used to find out the effect of bitumen using the in vitro and in vivo models. Results GC/MS analysis showed the existence of carcinogenic compounds in the bitumen extract. HOS cells were treated with different concentrations (25, 50, and 100 μl/ml) of bitumen extract. Compared to the parental HOS cells, bitumen transformants (HOS T1 and HOS T2) showed the characteristics of anchorage independency, chromosomal anomaly, and cellular transformation. Interestingly, bitumen transformants were not able to form tumor in nude/SCID mice. Proteomic analysis revealed the existence of 19 differentially expressed proteins involved in progression of cancer, angiogenesis, cell adhesion, etc. Conclusions Exposure of bitumen extract to HOS cells results in the cellular transformation similar to cancer cells and can modulate proteins involved in the progression of cancer. We state that the non-tumorogenic potential of bitumen transformant in nude/SCID mice can be attributed to the downregulation of galectin-1, chromodomain helicase DNA-binding protein 1-like gene, and membrane-associated guanylate kinase 2 protein