J. Cosmet. Sci., 64, 329–340 (September/October 2013) 329 Moisturizing effect of topical cosmetic products applied to dry skin JANA POLASKOVA, JANA PAVLACKOVA, PAVLINA VLTAVSKA, PAVEL MOKREJS, and RAHULA JANIS, Department of Fat, Tenside, and Cosmetics Technology ( J.P., J.P., P.V., R.J.), and Department of Polymer Engineering (P.M.), Tomas Bata University in Zlin, 762 72 Zlin, Czech Republic. Accepted for publication march 18, 2013 Synopsis One of the complications of “diabetes mellitus” is termed diabetic foot syndrome, the fi rst symptoms of which include changes in the skin’s condition and properties. The skin becomes dehydrated, dry, and prone to excessive formation of the horny layer, its barrier function becoming weakened. This function can be re- stored by applying suitable cosmetic excipients containing active substances. The aim of this study was to evaluate and compare the effects of commercially available cosmetic products (CPs) designed for the care of diabetic foot, through a group of selected volunteers using noninvasive bioengineering methods. Statistical surveys (p 0.05) evaluated these CPs as regards to their hydration effect and barrier properties. Special at- tention was devoted to CPs with the declared content of 10% urea, and that the infl uence of this preparation’s ability to hydrate and maintain epidermal water in the epidermis was confi rmed. INTRODUCTION Diabetes mellitus (DM) belongs to a group of heterogeneous diseases. The World Health Organization defi nes DM as a state of chronic hyperglycemia, which may be caused by a number of exogenous and endogenous factors acting simultaneously. The clinical course of each type of DM is highly variable, but a single common characteristic is the presence of hyperglycemia, which occurs on the basis of insuffi cient action of insulin in the tissues. Abnormalities, however, occur in the metabolism of fat and protein as well, in addition to those in electrolyte and water management of the body (1–3). DM, like other endo- crine disorders, may be the cause of changes in the function and properties of the skin. Skin complications occur in approximately 30% of patients and may also be the fi rst sign of DM. Hyperglycemia and reduced insulin are factors involved in deterioration of skin function, causing the skin of patients with DM to decrease hydration capacity, in addition to reducing the activity of the sebaceous glands (4,5). DM causes glycosylation products Address all correspondence to Jana Pavlackova at pavlackova@ft.utb.cz.

JOURNAL OF COSMETIC SCIENCE 330 in the collagen contained in the dermis to increase. Furthermore, the abnormal prolifera- tion and differentiation of keratinocytes in the epidermis can be assumed to have effects on the function of the stratum corneum (SC) in patients with DM. The response to me- chanical stresses is plantar SC hypertrophying such stresses potentially being a high-risk factor for ulcerations to develop in persons suffering from DM (6–15). A number of pub- lications dedicated to skin changes in DM exist (16–24). For patients with DM, the skin suffers from the lack of lipids supporting skin hydration, with injuries caused due to dry skin potentially leading to infections or even diabetic foot syndrome. Caring for dry skin on the foot is one of the basic recommendations of educa- tional activities conducted for people with diabetes. Feet should be inspected and bathed on a daily basis, carefully dried after a bath, especially between the toes, and oiled using a greasy ointment or moisturizer (5,20,21,25–28). The purpose of this basic foot care is to improve or preserve the skin’s elasticity. A rule of thumb for diabetic foot states that pre- venting defects is better than healing them subsequently. Ideal skin moisturizers not only soften the skin, but also create a protective fi lm on its surface and in terms of physiology, limit transepidermal water loss (TEWL). The extent of such an effect depends on the overall composition of the applied preparation (29,30). Substances possessing these properties may include, for instance, urea or glycerol. According to some authors (31–37), glycerol- containing creams dispose of similar clinical effect as urea-based creams. Glycerol and urea easily penetrate into SC and enhance its capacity of water uptake. These studies also suggest that suitable urea-containing formulations can favor more barrier properties. This study deals with monitoring the declared hydration effects of six commercial cos- metic products (CPs) designed for the care of diabetic foot, the same employing corneo- metric methods and determining TEWL. It has been declared by the producers of the moisturizers under test that the CPs were designed especially for people with diabetes to take daily care of dry and cracked skin of the foot, for skin regeneration and intense mois- turizing, softening, and restoring, or enhancing the skin’s barrier function. The humec- tants that all the preparations chiefl y utilize are glycerol and urea, in varying proportions. For Eucerin® (cream) and Allpresan® (foam), the producer declared a 10% urea content. The moisturizing effects of the tested products were compared with a prepared ointment base, lacking the active substances mentioned earlier. EX PERIMENTAL PART GROUP OF VOLUNTEERS The process of selecting volunteers and the testing procedure followed the principles enshrined in the International Ethical Guidelines for Biomedical Research Involving Hu- man Participants (38). The study included 22 women (N = 22) aged 45 ± 8 years. All the female volunteers met the criteria for inclusion in the study, completed a study participa- tion questionnaire and signed an informed consent form to participate in the study. None of the persons withdrew from the study before its completion. The female volunteers were instructed to avoid applying any CPs to any application area 12 h before and throughout the test only an evening shower with water was permitted. Measurements were taken in an air-conditioned room (temperature 24 ± 2 °C, relative humidity of 60 ± 4%) tem- perature of the skin of volunteers was 33.2 ± 0.7°C.