ABSTRACTS 325 uate changes induced by altered skin hydration under simulated winter atmospheric conditions, i.e., low relative humidity and temperature. The stage provides information on effects of cosmetic treatments so that the necessity for in vivo testing during initial phases of experimentation and product formulation is reduced. The VTS apparatus may also be used to investigate underlying molec- ular actions when combined with spectroscopic techniques. For example, VTS data on fully hy- drated skin show both reversible and irreversible thermal transitions in mechanical properties. These temperature-dependent changes in mechanical properties coincide with transitions detected also by differential scanning calorimetry, infrared, and nuclear magnetic resonance spectroscopy, sug- gesting that specific molecular events may be corre- lated with macroscopic mechanical properties with this apparatus. Percutaneous absorption kinetics of topically applied substances A. Athani, L. H. Block, C. C. Collins, and S. Ma- hashabde, Duquesne University School of Phar- macy, Pittsburgh, PA 15282 Topical drug and cosmetic formulations have been used for many years. However, it is only with the advent, in recent years, of transdermal drug de- livery systems--which provide a systemic drug ef- fect after topical application--that serious efforts have been made to evaluate the rate and extent of percutaneous or transdermal absorption of sub- stances from topical formulations. The characteriza- tion of the absorption of a substance should involve a consideration of transport kinetics including ab- sorption, metabolism, and binding of the substance in conjunction with its systemic disposition. An analog model is proposed which facilitates the use of kinetic parameters obtained from in vivo and in vitro experiments to estimate the amount absorbed over a period of time. This model facilitates the es- timation of regional and systemic uptake and po- tential risk from exposure to topically applied sub- stances. SESSION E ACTION AND EFFECTS OF COSMETIC IN- GREDIENTS Biological effects of some topical materiMs on sebaceous gland activity Ronald L. Rizer, Dermal Research Department, Johnson Wax, Racine, WI 53403-5011 The human sebaceous glands are specialized micro- organs which produce the oily material found on the surface of the skin. These glands are typically active at birth, but lie quiescent during childhood until adrenarche, when they become activated to produce sebum by the adrenal androgens, and continue to produce sebum through old age under the influence of adrenal and gonadal androgens. Until recently it was thought that only drugs or endocrine changes could affect sebaceous gland ac- tivity. It is now clear that certain exogenous agents and conditions can affect the glands. For example, certain cosmetic vehicles, some natural oils, and a variety of botanicals will either increase or decrease sebaceous gland activity. Whether these changes have clinical ramifications is unclear. Specific drugs which affect sebaceous activity will be compared to selected cosmetic "actives." The various cutaneous activities of retinoids Carl W. Ehmann and Joel Gordon, Johnson & Johnson Baby Products Company, Grandview Road, Skillman, NJ 08558 At physiological concentrations, retinoids can sub- stitute for many or all of the biological activities of vitamin A. At pharmacological doses, retinoids can have a pleomorphic effect on the skin. Depending upon the structure of the molecule, its concentra- tion, pharmacodynamics, the model systems em- ployed, and its affinity for specific retinoid re- ceptors, a variety of cutaneous activities (including paradoxical ones) can be demonstrated. Retinoids have been shown to affect genetic expression, pro- ducing specific functional and structural proteins in the dermis and epidermis. Their abilities to control cellular and tissue differentiation and proliferation are well known. Newer information indicates that retinoids significantly affect intercellular communi- cation, desquamation in immune modification, and possibly neovascularization. Depending upon a va- riety of factors including concentration, model systems, etc., retinoids may stimulate or inhibit these biological responses. These biological activi- ties can provide understanding of the known cuta- neous therapeutic effects provided by retinoids. They include the topical and systemic treatments of precancerous and cancerous lesions, and therapies for acne, psoriasis, ichthyosis, seborrhea, and many other common and rare dermatological conditions. They also appear to affect the process of photo- aging and perhaps cutaneous aging itself. However, because of the variety of pharmacological effects, retinoids can cause cutaneous toxicities and, with oral dosing, the potential for significant systemic ones. The challenge for the future is to understand the structural versus functional relationships for a tremendous number of potentially useful retinoids. This approach should lead to the designing and de- velopment of retinoids with a narrowly focused

326 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS pharmacological activity for selected biological ef- fects. Penetration and metabolism of active cosmetic ingredients Thomas S. Spencer, Ph.D., Cygnus Research Cor- poration, Redwood City, CA 94063 The stratum corneum, the outermost layer of skin, forms an effective barrier to protect the body from solvents, detergents, toxic chemicals, and toxins, while simultaneously allowing transport of water and carbon dioxide out of the body. The barrier property of skin is supplemented by enzymatic and hydrolyric processes that metabolize small amounts of compounds that do penetrate the skin. Among skin metabolic functions are estradiol metabolism to estrone by skin enzymes and hydrolysis of toxic chemicals. Panthenol, vitamin A derivatives, plant steroIs, and linoleic acid are cosmetic ingredients that penetrate skin and have desirable biological ac- tivity. Conversely, emulsifiers, detergents, and pre- servatives penetrate skin at low, but biologically significant, levels, sometimes causing skin irrita- tion. Among the more common components, mois- turizers and emollients like glycerin, petrolatum, and lactic acid are absorbed and moisturize the skin. Comparative rates of penetration and means of increasing penetration will be discussed in relation to pharmacological effects on skin. SESSION F RAW MATERIALS New developments with lipoaminoacids and their salts David B. Braun, R. T. Vanderbilt Co., Inc., 30 Winfield St., Norwalk, CT 06855 Although lipoaminoacids and their salts have been commercially available for several years, recent studies have uncovered new performance benefits from the use of these materials in skin and hair treatment products. Lipacide © lipoaminoacids, de- rived from hydrolyzed animal collagen and a fatty acid chloride, have been found to limit sebaceous excretion and provide bactericidal activity on the skin, suggesting efficacy in acne treatment products. They also relieve itching and pain asso- ciated with mild erythema or other skin trauma and are effective against the bacteria Pityrosporum ovale found in excess in the scalp of those suffering from dandruff and/or seborrhea. Data are also presented showing that salts of these lipoaminoacids are low- irritation surfactants with excellent lathering prop- erties that provide performance benefits in shampoo and soaps for frequent use on sensitive skin. Phys- ical and toxicological properties and prototype skin and hair treatment formulations are also presented. How to formulate superior microemulsions Joel Denis, Gattefosse Corporation, 3 Westchester Plaza, Elmsford, NY 10523 Microemulsions have long been of interest to cos- metic chemists, but serious limitations have pre- cluded their use in finished product formulations. They are formed spontaneously by the simple mix- ture of the constituents at room temperature--they can be described as transparent, low-viscosity iso- tropic liquids which are thermodynamically stable. To date, however, harsh detergents were required for their formation. With breakthroughs, it is now possible to produce quality non-irritating micro- emulsions using mild surfactants. The technology comprises a new system for cosmetic chemists, per- mitting mixture of hydrosoluble and liposoluble "actives" in a new vehicle with distinct benefits over classic emulsions. They can be used advanta- geously for skin care products (e.g., skin oils with hydrosoluble components) and sun care products (sun oils, after-sun items, etc.). In either case, the result is a crystal-clear cosmetically elegant liquid, with a superb skin feel and excellent stability. Stability with time delivery when applied water-in-oil-in-water multiple emulsions made practical Wil Hemker, BF Goodrich Technical Center, P.O. Box 122, Avon Lake, OH 44012 Liposomes and polymeric solid entrappeal liquids have captured the attention of cosmetic formulators for their advanced delivery function in skin care products. The alluring potential of multiple-phase emulsions as delivery systems has remained princi- pally a laboratory curiosity due to their limited sta- bility and the complexity of selecting emulsifiers to form these emulsions. A practical approach of pre- paring stable water-in-oil-in-water (w/o/w) mul- tiple emulsions has been achieved. A divergent technique, unburdened from the limitations of HLB emulsification, has resulted in long-term sta- bility and controlled ingredient delivery when in- corporating an amphiphatic polyelectrolyte emulsi- fier. Electro-steric emulsion stabilization of the w/o phase in the W 2 phase makes possible this liquid delivery system. Stability is demonstrated by the kinetic rate of water-soluble reagents moving from the W• to the W 2 phase. Prototypical aspects for the protected delivery of reactive skin and hair care ingredients will be presented and discussed. Cosmetic raw materials from renewable natural resources N. B. Desai, Grillo Werke AG, 4100 Duisburg 11, Federal Republic of Germany As renewable natural resources, carbohydrates such as sugar and glucose are gaining more and more