j. Cosmet. Sci., 49, 175-181 (May/June 1998) The oreasiness of moisturizers: A methodological study GREGOR B. E. JEMEC and HANS CHRISTIAN WULF, Department of Dermatology D, Bispebjerg Hospital, University of Copenhagen, DK-2900 Hellerup, Denmark. Accepted for publication May 15, 1998. Synopsis The aim of this study was to investigate if simple blotting can be used to provide reproducible quantitative data on the amount of excess moisturizer. Simple blotting of excess moisturizer was studied, changing the volume applied, the time allowed for absorption (before blotting), the time allowed for blotting, the area studied, the region studied, the blotting pressure, and the type of blotting paper. The coefficient of variation was calculated for each parameter. A standardized procedure is described: application of 50 pl/25 cm 2 of moisturizer on volar forearm skin. After 20 minutes blotting was performed with a 25 cm 2 (5 by 5 cm) piece of ordinary filter paper with pores of medium size. Blotting was done for 120 seconds with firm pressure applied by a rubber-gloved hand. The method had a coefficient of variation of 23% and was significantly correlated to skin surface lipids as measured by the Sebumeter (p 0.0001). Different commonly used moisturizers, as well as a protective cream and a simple gel, were compared using the new method, and the results were found to be in accordance with the clinical impression of cream greasiness. It appears to be possible to quantify non-absorbed moisturizer on the skin surface with an accuracy similar to that of other biophysiological methods. This simple method offers an improved possibility to classify moisturizers ac- cording to cosmetic acceptability and to quantify absorption for a better assessment of relative moisturizer efficacy. INTRODUCTION Moisturizers contain varying amounts of water, which evaporate shortly after applica- tion, leaving a lipid residue (1). It is speculated that the cumulative effects of moistur- izers are due to the absorption of this lipid residue, while short-term effects are mostly due to simple hydradon by the water phase of the moisturizer. The effects of any moisturizer is, however, also determined by the actual pattern of use by the individual, i.e., how is it applied and in what context, e.g., before clothing, after bathing, etc. Little is known about this, but it is speculated that the most common practical use involves application immediately prior to dressing, i.e., that only a short time is available for absorption of the applied moisturizer. A considerable excess residue of moisturizer lipids are thus left to be absorbed by the clothes. This unabsorbed excess represents a measure of the greasiness of the moisturizer that may affect actual use and cosmetic acceptability. We therefore describe a simple method to study this problem. 175

176 JOURNAL OF COSMETIC SCIENCE In addition, a quantification of the unabsorbed excess is necessary to identify the ab- sorbed or active proportion of the moisturizer, which is necessary in any future estimates of the relative efficacy of different moisturizers, i.e., effect per milligram of absorbed cream. MATERIALS AND METHODS All testing was conducted on healthy volunteers following informed consent. Prelimi- nary methodological studies were carried out using one type of moisturizer only (Loco- base ©, Yamanouchi Pharma, Leidendorp, Netherlands), while different commonly used moisturizers, a protective cream, and a simple gel were used in the final study (see Ta- ble I). The basic hypothesis of the study was that a standardized collection of excess or residue following a single application is a reliable method for the study of moisturizer greasiness in vivo. The basic design involved application of a known volume of moisturizer to a standardized area of volar forearm skin, allowing time for evaporation of the water phase of the moisturizer, and finally absorption of excess moisturizer into a standard laboratory filter paper. The increased weight of this filter paper then reflects the amount of excess moisturizer (=blotted weight) according to the following simple equation: Blotted mg = applied mg - (evaporated water mg + residue after blotting mg + absorbed by skin mg) The following preliminary studies were carried out in healthy volunteers to assess the variability of this simple method. Table I Moisturizers Used and Their Declared Contents Brand and producer Constituents Residue % (mean 95% confidence interval) Vaseline ©, Johnson & Johnson, New Jersey Locobase ©, Yamanouchi Europe B.V., Leiderdorp, Netherlands Decubal creme ©, Dumex A.S., Denmark Clinique Moisture-On-Call © , Clinique Laboratories, New York Nivea Visage ©, Beiersdorf OY, St. Karins, Finland Kerodex ©, ArSiMa, Copenhagen, Denmark Gel Petrolatum Cetearyl alcohol, ceteth-20, mineral oil, petrolatum, citric acid, sod. citr. anhydr., ethylparaben, purified water Isopropyl myristate in glycerin, purified lanolin, dimeticomin cetolatum, polysorbate 60, sorbic acid, purified water N/A Liposome complex 10% Paraffin products, sodium phosphate, emulgators, iron oxides, methylparaben Cellulose gum, glycerin, water, benzalconium chloride, disodium EDTA 48.2 (43.4-52.9) 37.9 (34.6-41.2) 19.6 (17.8-21.4) 14.7 (13.3-16.0) 14.5 (13.0-16.0) 9.8 (7.9-11.7) 1.5 (0.6-2.3) N/A = no data available. Unabsorbed % is the percentage of the applied cream that could be blotted from the surface of the skin after 20 minutes, and can be seen as an expression of the greasiness of the cream.