Sonication Lab Report

Method of preparation: - The preparation method for lecithin organogel is quite simple and easy. Weighed amount of lecithin (350mM) is to be dissolved in non-polar solvent like isopropyl palmitate (IPP) or isopropyl myristate (IPM) with the help of vortexing and bath sonication. Triamcinolone acetonide (0.5%) was dissolved in previously formed micellar dispersion of Lecithin-IPP. Most critical and important step in gel formation is addition of polar solvent. As the above solution becomes clear and transparent, polar solvent is to be added, mostly water to it in very much less quantity. The gel formation occurs at very narrow range of water concentration. Brief sonication is needed for the removal of air bubbles.

Formulation

Lecithin being a key gelating ingredient in the formulation should get optimised for its concentration required for gelation. Trial batches for selection of appropriate non-polar solvent and polar solvent are performed along with their concentrations aiming at formation of stable gel. Various non-polar solvents were used for trials like isopropyl palmitate, isopropyl myristate, ethyl oleate, Transcutol etc. Polar solvents only having the structuring capacity for LOs and can form stable gel. Hence, polar solvents with higher values of surface tension and dielectric constant along with H-bond forming ability can be used for lecithin organogel. Water, glycerol, propylene glycols were tried for optimization.

Construction of Pseudo ternary phase diagram: - Lecithin organogel is basically the formulation system consisting of mainly three components i.e. Lecithin, Isopropyl palmitate (non-polar solvent) and water (polar solvent). Though the concentration of third component is very less, there occurs a need for construction of pseudo ternary phase diagram. The diagram is consisting of above mentioned components and is constructed with the help of PROSIM software in order to determine the gel forming region.

Rheological studies:

The optimized formulation of 0.5% Triamcinolone acetonide lecithin organogel and blank LO without drug were applied over the dialysis membrane (mol.wt.12000-14000) weighing approximately 100mg with 28ml diffusion media as 1% SLS in water. The temperature was maintained at 37±0.2 oC with magnetic stirring at 250 rpm. The samples of 1ml were withdrawn from each diffusion cells at different time intervals up to 8 hr and equal amount of diffusion media was replaced allowing to maintain sink conditions. Then samples were analysed on HPLC and dilutions were done if needed. Calculations were done and graph was plotted as Time in hr against % Cumulative drug