ABSTRACTS 79 up, he or she may offer ways to explain the complex appeal and acceptance of fragranced products. SESSION C EMERGING TECHNOLOGIES FOR NEW PRODUCT DESIGN Liposomes: Potential application to the skin Norman. Weiner, University of Michigan College of Pharmacy, Ann Arbor, MI 48109 Liposomes recently have received much attention in the search for a more effective means of delivering intrinsically active drugs to their tissue targets. Li- posomes are microscopic vesicles consisting of one or more concentric lipid bilayers enclosing an equal number of aqueous compartments. The attractive- ness of liposomes as drug carriers lies in their abili- ties to encapsulate and physically protect drugs, to selectively concentrate drugs at various body sites, and even to facilitate the transport of some drugs across biological membranes. Liposomes are gener- ally nontoxic and readily metabolized, which adds measurably to their attraction. Recently, there have been a number of reports on the potential applica- bility of liposomes as drug carriers by the topical route. In a recent study, we have shown that lipo- somes themselves do not penetrate intact skin. They do, however, facilitate skin deposition of drugs which tend to associate with liposomal bilayers. The degree of facilitation is dependent on the na- ture of the drug and the lipid composition of the liposome. Liposomal encapsulation of hydrophilic drugs which are encapsulated in the liposome's aqueous compartments retards transport through the skin. Monolayer studies of drug-lipid interac- tions can be used to optimize the formulation with respect to transport properties. Of particular im- portance, we have demonstrated that liposomally encapsulated large polypeptides, but not free drugs, penetrate intact skin and maintain its biological ac- tivity. Liposomes: From theoretical membrane model to cosmetic tool George Strauss, Dept. of Chemistry, Rutgers Uni- versity, P.O. Box 789, Piscataway, NJ 08854 Liposomes have become an important model for studying reactions in biomembranes and simulta- neously have emerged as a vehicle for controlled de- livery of cosmetics, antibiotics, and drugs. Lipo- somes are closed vesicles consisting of one or more concentric lipid bilayer membranes. They are com- posed of polar lipids generally having two alkyl chains of 12 to 18 carbons. Examples include phos- pholipids, such as lecithin, and quaternized am- monium salts with two long-chain alkyls. Lipo- somes resemble biological membranes of cells and organelles: both have selective and limited perme- abilities to water and small molecules, have two-di- mensional fluidity, and can fuse with other mem- branes. Polar and non-polar substances can be in- corporated into the bilayer walls of liposomes or can be trapped in their inner aqueous compartments. Liposomes can be formed by several techniques. These include sonication, injection of alcoholic so- lutions into water, and change in pH. Solutes, such as fatty acids and their esters, steroids, and pro- teins, can be incorporated in the course of forming liposomes by the above techniques. Liposomes can be stabilized in the presence of certain saccharides. Administration of cosmetic or therapeutic sub- stances in liposome-encapsulated form rather than in the free state confers many advantages: un- wanted side reactions are eliminated delivery can, in some cases, be targeted for a specific type of cell or biological structure and a heavy one-time dosage is replaced by continuous delivery over an extended period. A practical approach to the development of mi- croemulsions Barbara H. Munk, Stepan, 22 Frontage Rd., Northfield, IL 60093 A practical and simple three-phase approach to the formulation of microemulsions has been developed. This approach was originally used to develop pesti- cide microemulsions but has been demonstrated to be useful in the formulation of products in other areas. In Phase I, the emulsification and solubility properties of the hydrophobic or "oil" phase with a variety of surfactants and solvents are defined. Promising surfactants and solvents are blended in Phase 2 to identify emulsifier systems which pro- vide the desired physical properties at fixed water and "oil" levels. These emulsifier systems are opti- mized in Phase 3 to produce the final formulation. Ternary phase diagrams are used in Phases 2 and 3 as a tool for quickly evaluating the ability of an emulsifier system to produce a microemulsion of a specified "oil phase." An example of the use of this approach to develop a cosmetic microemulsion will be discussed. Principles of cosmetic delivery systems Joel L. Zatz, Rutgers University College of Phar- macy, P.O. Box 789, Piscataway, NJ 08854 A cosmetic delivery system is a packaged group of ingredients intended for application to the skin. Though such system• may be structurally similar to dermal and transdermal devices used in drug de- livery, this need not be the case. They have several advantages: it is possible to utilize substances

80 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS lacking to some extent in esthetic elegance the rate of uptake of ingredients by skin may be limited or, if desired, enhanced and the system maintains con- tact with the skin for a desired time interval and fences the area. By virtue of its design, the system itself can be used to modify stratum corneum hy- dration. The degree of occlusion afforded by a thin film or laminate applied to the skin surface is thus an important characteristic. Skin transport kinetics depend on several factors. By virtue of high solu- bility within the matrix or slow diffusion through it, release to the skin surface may be rate-limiting. On the other hand, diffusion through a skin-con- tacting membrane within the system, or the skin itself, can be the controlling process. SESSION D REGULATORY CONCERNS AND NEW PRO- DUCT DEVELOPMENT Dial soap•Is it or isn't it (a drug)? Helen North-Root, The Dial Corporation, 15101 N. Scottsdale Road, Scottsdale, AZ 85254 The 40-year history of Dial soap emphasizing the procurement and maintenance of a new drug appli- cation (NDA), the subsequent marketing of Dial as an over-the-counter (OTC) drug product, and its present day marketing possibilities will be dis- cussed. The requirements for filing the initial ap- plication for an NDA (necessary forms, labels, studies, samples, and scientific rationale) will be outlined as will the requirements to maintain the NDA (post-market reporting of adverse drug expe- riences, annual reports, submission of advertise- ments and promotional labeling, and changes ne- cessitating filing a supplement). Shifts in regulatory policy enabling Dial soap to be sold as an OTC drug or as a cosmetic will be described.