Light liquid paraffin

Gel base was prepared by dispersing carbopol 934 (Hi-media, India) in distilled water with constant stirring at moderate speed for overnight. Oil phase of the emulsion was made with cetomacrogol 1000, cetostearyl alcohol, white soft paraffin, propylene glycol in light liquid paraffin (Hi-media, India). Aqueous phase was prepared by dissolving peptides (0.5% w/v) in distilled water. The oily and aqueous phases were separately incubated in a water bath at 60°C. Upon obtaining uniformity, oily phase was added to the aqueous phase with continuous stirring. Pre-heated gel base dispersion of carbopol 934 and vitamin ETPGS (Sigma, United States) were added to the emulsion steadily with continuous stirring to obtain homogenized gel. The temperature of the formulation was lowered to 40°C and isopropyl alcohol was added with continuous stirring. The pH was maintained at 6.8 ± 0.2 using saturated solution of citric acid. In vitro emulgel was characterized for its visual appearance under the microscope for the presence of any particle or grittiness. The pH of emulgel was determined by digital pH meter (Contech, India) by dissolving gel in distilled water. Gel extrudability or oozing out from the collapsible tube was determined by physical squeezing from a tube. Gel viscosity was measured using viscometer (Brookfield DV-l Prime, United States).