Effect of Various Liquids on the Diffusion of Salicylic Acid from Ointment Bases

Water, alcohol, and dimethyl sulfoxide were each incorporated at 1, 2, and 5 percent concentrations into four ointment bases containing salicylic acid. The bases tested were white petrolatum, a hydrogenated cottonseed oil base, a water-in-oil emulsion base and an oil-in-water base. The diffusion of salicylic acid from five samples of each mixture was determined at 20-min. intervals for a period of 2hr. All three liquids enhanced diffusion from the white petrolatum base and the water-in-oil base but tended to inhibit diffusion from the cottonseed oil base and the oil-in-water formula. In some instances the concentration of liquid appears to have an effect. Statistical analyses of data point out significance of differences.