290 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS bonding mechanism. This method has real world application for the cosmetic chemist since FTIR can be used to show the presence or absence of polymer build-up on hair and the effect of pH on the adher- ence of cationic polymers to human hair. New polymeric microsponges can deliver emol- lients to the skin both as a sustained release and on demand Martin Katz, Ph.D., Advanced Polymer Systems, Inc., 3696C Haven Avenue, Redwood City, CA 94063, and Sergio Nacht, Ph.D., Vicks Research Center, Shelton, CT 06484 A novel polymeric, spherical, microscopic sponge has been created which can entrap active and func- tional ingredients such as emollients within a struc- tural network of microspores. These emollients are available both for sustained and demand release by pressure or diffusion. The microscopic sponges pos- sess individual structural integrity, so that they are substantially non-collapsible upon removal of the active ingredient. A typical emollient agent--mineral oil--was en- trapped in these Microsponges and the in vitro re- lease was demonstrated by radiochemical methods. When these particles were then incorporated into an oil-in-water emulsion, the sustained and demand release of the emollient from these microscopic sponges was established by the prolonged and re- peated softening effect on human skin, as measured by the gas bearing electrodynamometer (GBE) tech- nique. The advantages over an equivalent lotion containing the emollient encapsulated in a standard urea-formaldehyde resin were demonstrated by the GBE as well as with consumer panels. Opportunistic states of water in cosmetic emul- sions and skin Harry R. Elden, Ph.D., Institute for Skin Re- search, Xienta, Inc., Bernville, PA 19506 Pure water has an extraordinary set of biophysical properties. Water exists in various phases and asso- ciates with numerous components in cosmetic emulsions and skin. Ubiquity of water suggests that its properties in emulsions might be projected across interfaces to skin. So called unique substances that impart desired attributes to skin via topical emulsions might be influencing biophysical at- tributes of water. It is proposed, therefore, that water is the actual unique substance of emulsions, poised opportunistically to transfer and impart unique features to skin. This proposal is substan- tiated by published data on evaporation, friction, and electrical impedance of aging skin and (o/w) emulsions. New experimental data show that water is retained uniquely by skin, keratinous tissues, and cosmetic emulsions. Strategies designed to discover new substances that project desired features to skin will be illustrated by new data. The effect of solvents on sunscreen agents Nadim A. Shaath, Ph.D., Felton International Inc., 599 Johnson Ave., Brooklyn, NY 11237, and Louise E. Agrapidis-Paloympis and Robert A. Nash, Ph.D., St. John's University, School of Pharmacy, Jamaica, NY 11439 The effect of a sunscreen agent can be measured by determining the h. max (wavelength at which max- imum absorption occurs) and the extinction coeffi- cient • (intensity at maximum absorption). How- ever, earlier reports by Groves, Riegelman, Cum- pelnick and Shaath have shown that the performance of a sunscreen agent is influenced by the nature of the solvent in which it is dissolved. We have studied 12 sunscreen agents selected from the approved published list by the OTC panel of the FDA in 1978 and over a dozen solvents that are commonly used in the cosmetic industry. The re- suits which are correlated with molecular orbital theory reveal vital information that all cosmetic chemists involved in formulating sunscreen products should be aware of. On the theory of ultraviolet absorption of sunscreen chemicals Nadim A. Shaath, Ph.D., Felton International Inc., 599 Johnson Ave., Brooklyn, NY 11237 In this presentation molecular orbital and ultravi- olet theory will be used to explain why and how sunscreen chemicals do absorb harmful ultraviolet radiation. With the proposed theory, several prin- ciples related to the effectiveness of a sunscreen chemical can be explained and predicted. Specifi- cally, this knowledge will aid the chemist in his design and synthesis of new sunscreen chemicals by selecting the appropriate chromophores that will af- ford absorption in either the UV-A or UV-B regions (or any h. max required) and also yield the intensity (k-value or extinction coefficient) desired for their application. The cosmetic chemist will, with the aid of this theory, be able to select the most appropriate sunscreen either from the ap- proved list or from other sunscreen chemicals avail- able in the market. More importantly, trends in SPF, intensity of sunscreens, wavelengths at which they are effective (UVA, UVB or UVC), the effect of using combination sunscreens on cosmetic for- mulations, the effect of solvents on the h. max and intensity of sunscreens, and the solubility charac- teristics of a sunscreen chemical can be safely pre- dicted and accounted for.

ABSTRACTS 291 Influence of solvents on paraben permeation through idealized skin model membranes John N. Twist, and Joel L. Zatz, Ph.D., Rutgers College of Pharmacy, P.O. Box 789, Pis- cataway, NJ 08854 The effect of various solvents on permeation of methylpropyl -- and butylparaben through polydi- methylsiloxane membranes, a model for skin, has been investigated. Flux from saturated solution should theoretically be the same, independent of solvent, in the absence of membrane-solvent inter- action. This was experimentally observed for water, various glycols and glycol-water mixtures, despite enormous differences in paraben solubility in these vehicles. However, there was significant increase in flux from solutions containing various aliphatic al- cohols. The nature of solvent-membrane interaction was investigated through studies of solvent uptake, paraben partitioning, and diffusivity within the membrane. The results indicated that an increase in partition coefficient was the major effect responsible for enhanced flux. Physical chemical properties af- fecting solvent activity influenced the results. The variables investigated here are also expected to de- termine solvent interaction with skin. SESSION F PRODUCT EFFICACY An in vivo system to evaluate efficacy of anti- aging products Peter P. Pugliese, M.D., and Kathleen Klinger, Xienta, Inc., Box 98, Bernville, PA 19506 The purpose of this study was to develop an in vivo model to determine the efficacy of anti-aging products designed to inhibit lipid peroxidation for- mulation by functioning as antioxidants. The system employs the hairless mouse model and utilizes ultraviolet radiation to induce lipid peroxi- dation. The test product is applied prior to irradia- tion and the animal sacrificed after a predetermined period. The epidermis is removed and assayed for malonyldialdehyde by the thiobarbituric acid method. Experience with tocopheryl acetate and betacarotene at various concentrations indicates that these substances are effective anti-aging ingre- dients. A dose-response curve of ultraviolet radia- tion and malonyldialdehyde production will be pre- sented. Pros and cons of the methodology will also be discussed. Single fiber studies of hair depilation R. R. Wickett, Ph.D.,* and Robert Mermel- stein,* S.C. Johnson & Son, 1525 Howe Street (M/S #136), Racine, WI 53403 A single-fiber method for investigating reduction kinetics in hair has been applied to the study of hair depilation. Time required to reduce the tensile stress supported by a hair was found to correlate to in vivo depilation times with commerical depila- tories. Reaction of hair with several reducing agents under depilating conditions was investigated by this method. Depilation rates were increased by in- creasing pH or adding guanidine salts. Rates were decreased by the addition of n-propanol, triacetin, glycerin, or propylene glycol. Emulsion state was also found to affect reduction kinetics. An experi- ment with a central composite design was used to produce a response surface for the effect of TGA concentration, pH, and guanidine hydrochloride concentration on depilation rate. A new procedure to characterize the surface topography of skin Harold Lipshitz, Ph.D., Dermametrics, Box 27, Carlisle, MA 01741 This paper describes an optical method that permits precise quantitative topographical mappings and the calculation of characteristic statistical param- eters of the skin's surface. The procedure utilizes instrumentation (patent pending) that allows mea- surements to be made on the skin or on replicas thereof. The instrumentation consists of a light re- flective optical system, a stage precisely position- able in the three orthogonal directions, and a data acquisition system. Using this system, a procedure was developed to measure the distances from an ar- bitrary reference plane to closely spaced points on the surface of the skin as a function of its x,y coor- dinates in the reference plane. Computerized three- dimensional plots of the data result in picturizations of the skin's surface, whose resolution is greater than that obtained with mechanical profilometry. The computerized image, so obtained, is in excel- lent agreement with scanning electron micrographs (SEMs) of replicas of the same surface. The depths of depressions on replicas of the skin's surface, as determined from stereoscopic SEM data, were within 2% of that measured by this procedure. Using this data, a number of statistical parameters characteristic of the skin's topography were calcu- lated. The methodology promises to be a valuable tool for evaluating the efficacy of emollients. Substantivity to keratins as measured by ESCA W. C. Harris and E. D. Goddard, Specialty Chem- icals Division, Union Carbide Corp., Old Saw Mill River Road, Tarrytown, NY 10591 It is well known that the composition of the outer- most layer of skin and hair is very important in re- lation to their perceived condition. Thus, to assess the effects of various topical treatments, it is desir-