Once prepared, formulations were stored in tightly closed containers to further reduce the chances of evaporation of ethanol. Optimization of formulations was done by varying the two process parameters i.e. amount of SPC and alcohol. Amount of SPC was varied from 1% to 3% whereas alcohol concentration was varied from

20% to 40%. Different formulations with varying concentrations of SPC and alcohol were characterized for appropriate physicochemical attributes. It is seen from TEM photomicrograph that ethosomal vesicles are unilamellar in nature with near spherical shape (Fig. 2 inset). In contrast to the liposome vesicles that exhibit spherical shapes, ethosomal vesicles are showing some deviation in find more terms of shape, which could be due to absence of cholesterol and presence of ethanol that imparts some level of fluidity to the bilayer membrane. Vesicle size plays an important role in the overall performance of transdermal drug delivery system. Size analysis of the formulations showed that minimum vesicle size was observed to be 120.3±6.1 nm whereas maximum was 410.2±21.8 nm depending on the concentration of SPC and ethanol (Fig. 2). A surface plot was prepared to check the effect of both ethanol concentration and SPC concentration together on vesicle size. A zone of lowest vesicle size having a size range from 100–143 nm is clearly seen in Fig. 3. This particular zone is formed with

formulations having 1–2% of SPC and 35–40% Venetoclax of alcohol. However the lowest size is obtained with 1% of SPC and 40% of alcohol. A zone with the highest size range of 362.5–406.3 nm is formed with 2.5–3% of SPC and 20–25% of alcohol. ON-01910 molecular weight The size of the vesicles

was found to be increased with increasing concentrations of SPC from 1–3% whereas concentration of alcohol affected the vesicle size in the opposite way i.e. higher concentrations of alcohol produced lower vesicle size. It has been reported that high concentration of ethanol confers a surface negative net charge to the vesicular systems by manipulating some surface characteristics, which causes the size of vesicles to decrease [13]. When the amount of SPC was kept at 1% and the concentration of ethanol was increased from 20% to 40%, the size of the vesicles decreased from 212.4±8.3 to 120.3±6.1 nm (Fig. 2). Similarly when the amount of SPC was kept at 2% and 3% and the ethanol concentration was increased in the same manner the vesicle size was decreased from 295.1±14.2 to 147.8±8.3 nm and 410.2±21.8 to 201.2±11.2 nm, respectively (Fig. 2). Encapsulation efficiency is the fraction of total drug entrapped in the ethosomal system. It is an important parameter to evaluate as it determines drug holding capacity and ultimately the delivery potential of dosage form. Zones of different entrapment efficiencies with reference to the concentrations of SPC and ethanol can be identified from the three dimensional surface plot (Fig. 4).