j. Soc. Cosmet. Chem., 42, 159-166 (May/June 1991) Efficacy of a deodorant and its components: Triethylcitrate and perfume ANDREAS LUKACS, HANS CHRISTIAN KORTING, OTTO BRAUN-FALCO, and KLAUS STANZL, Department of Dermatology, Ludwig-Maximilians- Universitiit, Munich (A.L., H. C.K., O.B. -F. ), and Department of Research and Development, Sebapharma GmbH & Co., Boppard (K.S. ), Germany. Received June 18, 1990. Synopsis Both perfumes and acids are considered as potential active ingredients of deodorants. In a double-blind controlled trial, deodorant preparations containing perfume and triethylcitrate in a 60% ethanol base were compared to preparations lacking either perfume or triethylcitrate, and to a placebo preparation. The degree of offensive smell of the axillae of 30 healthy volunteers was assessed by sniffing. The skin surface pH and the bacterial flora were examined at the same time. The total preparation with both perfume and triethylcitrate was effective compared to the placebo with respect to the reduction of malodor. Moreover, the perfume component indicated efficacy in this respect. But triethylcitrate was not effective in the present formula. A marked influence on the skin surface pH could not be shown with any of the preparations. Thus, alterations of the bacterial flora if demonstrated at all could not be traced to a change in skin surface pH. INTRODUCTION The offensive smell of malodorous skin has become a major concern for many individuals (1). Over the last century a whole range of varying deodorants has been developed (2). Perspiration contributes a lot to the problem (1). In fact, antiperspirants have also been found effective to control body odor. Although antiperspirants form a frequent ingre- dient of commercial deodorants, they are not considered as deodorants in a stricter sense. So far, four major types of deodorants in this stricter sense of the term have been proposed: 1) antimicrobials, 2) perfumes, 3) odor absorbers, and 4) acidifiers. The rationale for the use of antimicrobials lies in the effect on the quantity of the bacterial skin surface flora. Various bacterial species on human skin are thought to produce substances from primarily nonodorous sweat, which then form the chemical substrate of offensive body odor (3-7). Nowadays antimicrobials are disfavored more and more in the given context. This applies to both topical antibiotics as well as to disin- fectants. Although the latter group of substances is still frequently used, there is 159

160 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS growing concern with respect to the ecological consequences. Triclosan (8), e.g., as a major representative of the whole class, has been suggested to contain dioxine derivatives (9). Perfumes are still widely considered as an adequate ingredient for deodorants. One should, however, not overlook the growing concern with the induction of allergic contact dermatitis (10). Therefore, there is a clear demand for alternative principles. Odor blotting (or extinguishing), as made possible by substances such as zinc ricino- leate, was proposed some years ago (11). They are, however, not yet widely accepted, perhaps because of their limited efficacy. Most recently, it has been proposed to use substances that liberate acidic components on human skin, such as triethylcitrate that forms citric acid after enzymatic ester cleavage on the skin surface. The rationale for this principle is to shift the skin surface pH to a more acidic side in order to prevent bacterial destruction of sweat components (12). It is well known that body odor is especially produced in certain regions such as the axilla, where the skin surface pH is less acidic than in other parts of uncovered skin (13). Moreover, a relationship between skin surface pH and bacterial microflora was demon- strated recently (14). A deodorant containing triethylcitate has so far only preliminarily been characterized (12). Therefore, it seemed useful to compare the efficacy of a recent commercial preparation containing triethylcitrate, perfume oil, and ethanol in a double- blind controlled study. Facing the expected mechanism of action of such a preparation apart from the body odor itself, the axilla skin pH and the quantity of the bacterial flora were analyzed. VOLUNTEERS AND METHODS SUBJECTS Fifteen healthy males and 15 healthy females with a minimum age of 18 years were enrolled. Written informed consent was obtained in every case. The age of the volun- teers ranged from 23 to 50 years more than 90% were 23 to 29 years of age. For general skin cleansing all persons were provided with Simple Soap TM (Albion Soap Company, Hampton, Middlesex, UK), a preparation said to contain no perfumes or antimicrobial additives (15). During the trial the panelists were not allowed to use any other cosmetic in the axillary region. Epilation habits had to be kept constant. TRIAL DESIGN The trial was based on a crossover design as proposed by Baxter and Reed (15). Four deodorant preparations differing in composition were applied in a double-blind fashion accoMing to a balanced random plan. The preparation used for each of the two axillae was always different in a given trial period. On the whole, there were three trial periods of three weeks each. The commercial deodorant preparation called "test product" con- tained 2% triethylcitrate in 60% ethanol and perfume (1% perfume oil, FAL 58306, International Flavours and Fragrances, Hamburg, FRG). The pH of this preparation was adjusted to 5.5 with small amounts of citric acid. The two additional preparations either contained no perfume or no triethylcitrate. The fourth preparation contained just dis-