194 JOURNAL OF COSMETIC SCIENCE served in involved skin (40,42). These patients also are more prone to develop an irritant contact dermatitis (43). Furthermore, they show a less pronounced so-called "hardening effect," i.e., with repeated skin barrier disruption, the barrier deterioration stopped after a certain time, suggesting that the stratum corneum adapts to the repeated barrier insults ( 44). The content of barrier lipids is reduced most prominently that of ceramide 1 and ceramide 3 is reduced in the stratum corneum of atopic dermatitis patients (42,45). This reduction of ceramide levels may result from the increased activity of the enzyme sphingomyelin deacylase (46,47). However, sebaceous gland activity is also reduced in these patients, the role of which remains unknown (48). Moreover, in the stratum corneum of atopic dermatitis patients the membrane-coating granules or la­ mellar bodies are incompletely extruded and organized. This, along with the altered stratum corneum lipid content, may partly explain the impaired barrier function in these patients (49). Finally, patients with atopic dermatitis show an increase in Staphylococcus aureus coloni­ zation (50,51). A reduction of S. aureus colonization resulted in a significant clinical improvement (5 2). Clinical observation indicates that treating atopic skin with an effective moisturizer leads to a clinical improvement in some cases without the use of antibiotics. Thus, ideal cosmetic vehicles for patients with atopic dermatitis should: • Improve barrier function • Have protective properties • Improve stratum corneum hydration • Have an antibacterial active compound (e.g., reduce colonization of S. aureus) These demands can be met by cosmetic vehicles: • Showing w/o emulsion properties with a high water content (27) • Containing a moisturizer (e.g., glycerol, urea) (53,54) • Having a physiological lipid mixture (5 5-57) • Containing an antiseptically active compound (e.g., triclosan) (30,58-59) In this regard, urea-containing cosmetic vehicles were able to improve skin barrier function and to reduce skin susceptibility to irritants in patients suffering from atopic dermatitis (54). Evening primrose oil (20%) in a w/o emulsion also improved barrier function and stratum corneum hydration in atopic patients (60). Some examples of useful simple formulations for water-rich (with low water activity) w/o vehicles for patients with atopic dermatitis are given below (1). W/0 EMULSION I Urea Glycerol 85% Triclosan Eucerinum w/o vehicle 1 1 Beiersdorf, Hamburg, Germany. 5.0 10.0 3.0 ad 100.0

W/O EMULSION II Urea Glycerol 85% Triclosan ROLES OF VEHICLES FOR SKIN TREATMENT Pionier KWH Pharm2 Citric acid anhydr. Magnesium sulfate heptahydrate Purified water W/O EMULSION III Glycerol 85% Triclosan Excipial U Lipolotio3 195 5.0 10.0 3.0 30.0 0.07 0.5 ad 100.0 10.0 2.0 to 100.0 These cosmetic vehicles have shown good stability for more than three months (1) and can be used for compounding with active ingredients like evening primrose oil or pale sulfonated shale oil (in w/o emulsion II) or glucocorticosteroids. As a note of caution, formulations intended for facial use should avoid urea due to its potential irritative potency (61). For patients showing allergic reactions to constituents of dermatological or cosmetic vehicles (e.g., patients with a long history of leg ulcers (62)), most fragrances, lanolin, and parabens should be avoided if possible. Propylene glycol can potentially induce irritant and allergic contact dermatitis (63). In such instances, the following vehicle can be recommended (1). COLD CREAM Cetylwaxester Beeswax Paraffin oil Purified water Preservatives q .s. ROLE OF WOOL WAX (LANOLIN) IN COSMETIC VEHICLES 11.75 13.5 63.25 ad 100.00 Lanolin, or wool wax, is the secretion product of the sebaceous glands of sheep, and serves to impregnate and protect their wool fibers. Commercially available lanolin is commonly a mixture of wool wax (65-75%), water (20-30%), and paraffin (up to 15%). Wool wax contains mainly sterol esters, ester waxes, hydroxy esters, and lanolin alcohols (6-12%), 2 Hansen & Rosenthal, Germany: mineral oil 77.9%, polygyceryl-3-isostearate 10.0%, isopropyle palmitate 8.0%, polyethylene 4.1 %. 3 Spirig AG, Egerkingen, Switzerland: containing 4% urea.