Aim, Materials and Methods – Evaluation of the moisturizing effect (long term) and lenitive (short term)- IN&OUT DETOX®
The study was conducted to evaluate the soothing and moisturizing efficacy of a cosmetic active ingredient.
In the present research, subjective and objective techniques were used to evaluate the moisturizing and soothing effects.
The tested product is an active named IN & OUT DETOX® with the following INCI: Polyglycerin-6, Propanediol, Solanum Melongena (Eggplant) Fruit Extract, Bioflavonoids (Nobiletin), Brassica Oleracea Italica Fruit Extract. In this experimentation the active was added to 2% in an emulsion with the following INCI formula: Aqua, Caprylic / Capric Triglycerides, Ethyl Hexyl Stearate, Glyceryl Stearate, Cetearyl Alcohol, Glycerin, Cetyl Alcohol, Ceteareth-20, Phenoxyethanol, Dimethicone , Citric Acid, Sodium Dehydroacetate, Benzoic Acid, Lecithin, Ethylhexylglycerin, Tocopherol, Ascorbyl Palmitate.
SELECTION OF VOLUNTEERS
For this study a standard female sample was selected with the following inclusion criteria: age between 20-50 years, with normal or dry skin, good state of health, absence of skin diseases, absence of topical pharmacological treatments or systems in place, a negative history of atopy and DAC. The exclusion criteria were: pregnant and lactating women, minors. All subjects were informed about the study procedures and signed an informed consent.
The effectiveness of the product has been evaluated:
A) instrumentally measuring the degree of hydration, TEWL and erythema through the sensors of a Multiprobe Adapter System MPA5 of Courage & Khazaka Electronic GmbH (Cologne, Germany);
B) subjectively through dermatological clinical examination.
Evaluation of the skin hydration index
Measurement of skin hydration was assessed using the internationally recognized Corneometer method. The measurement is based on the evaluation of the dielectric constant of water. The measuring probe shows changes in the water content of the sample to be measured. A diffuse electric field, generated by the probe head, penetrates the first layers of the skin and determines the dielectricity.
In particular, the CORNEOMETER® CM825 (Courage + Khazaka, electronic GmbH) has been used for the instrumental evaluation of the moisturizing activity of the products. It allows the measurement of skin hydration by means of capacitance measurements between the stratum corneum and the probe probe. By pressing the front surface of the sensor on the skin, a number appears on the computer monitor: this number is related to the level of hydration on the skin surface. The measurement was performed on a cutaneous area, as flat as possible, taking care of
exert a constant pressure for a time set by the instrument itself. The sensor has been kept clean from time to time. A healthy skin in conditions of about 20 ° C of temperature and about 40-60% of environmental humidity should, in the monitored region, have a hydration index> 45.
The effect on redness reduction was assessed using the Mexameter MX 18 probe (Courage + Khazaka Electronic GmbH). This probe has a hole of about 4 mm in diameter. Four measurements were taken, at the corners of an area bounded with tape, for each volunteer expressed in units of hemoglobin (parameter E) where the minimum value corresponds to 500. The principle of measurement of skin reddening is based on a source of light, with three specific wavelengths, whose radiation is absorbed by the skin and diffusely reflected. A sensor analyzes the reflection diffused by the skin. If the skin is well vascularized, the hemoglobin value is also increased. As a result, stimulation of microcirculation can be assessed before and after topical application with hemoglobin measurement. The probe itself is used in addition to quantify the reddening of the skin (erythema) also to determine the degree of tanning of the skin (melanin).
The index of water evaporation from the epidermis (TEWL) of the skin area treated was measured using the TEWAMETER® TM300. The skin constantly loses water in the form of steam and TEWL is the most important parameter to evaluate the efficiency of the water barrier function of the skin. The measurement of water evaporation is based on the principle of diffusion in an open chamber and the physical basis of measurement is the law of diffusion discovered by Adolf Fick in 1855. The tool allows to evaluate the flow of water vapor through a specific unit of surface by changes in water concentration and temperature in the atmosphere near the stratum corneum. The measuring probe is a shallow cylinder (diameter 10 mm and 20 mm length) in order to minimize the influences due to air turbulence inside the probe. It consists of two pairs of sensors that measure humidity and temperature gradients in two different distances. After detecting the resulting humidity and temperature gradients, the TEWL is automatically calculated and displayed on the computer monitor.
The study was performed in single blind with 2 different modes: without control to evaluate the moisturizing activity and with control during the soothing evaluation. Moisturizing efficacy was evaluated in a Long Term Test lasting 7 days.
The area used for the test was, randomly, one of the two sides of the forearm 2 cm below the bend of the elbow. The clinical-instrumental evaluations were carried out at time t0 (baseline value) and after 7 days (t7d) in the Long Term Test. The product during the Long Term Test was applied according to its characteristics of use: application on the forearms or on the body 2 times a day. Before the measurements the subjects remained for 30 minutes in the medical clinic, to acclimatize the skin to the temperature and humidity of the air-conditioned room in which the tests were carried out. After the basal values were detected, the product was delivered with the instructions for use. At each study time a dermatological examination was performed to evaluate any side effects. The hydration index was obtained through 4 measurements carried out around a delimited point with a dermographic pen that was reapplied during the Long Term Test measurements. In each study time, if, after the acclimatization phase, at least 2 very different hydration values (greater than ± 5 corneometric units) we expected more time before proceeding with the evaluation. The lenitive efficacy was carried out with the aim of evaluating the short-term effects of the use of the active on human skin irritated by sodium lauryl sulphate (SLS). SLS, a surfactant often used in the induction of experimental irritant dermatitis in animals and humans, has the ability, when applied to the skin under occlusion, to create a dose- dependent increase in the erythema (EI) and TEWL (Savica 2004, Engel 2008). In this study the lenitive action was evaluated in the 24-hour Short Term Test. The seat used was the fly surface of both forearms about 4 cm above the wrist crease. After performing the basal measurements (t0) of colorimetry and TEWL, a patch containing 20% SDS for 4 hours was applied on both forearms. Once the Finn chambers had been removed, a further basal measurement (t0 SDS) of colorimetry was performed and TEWL. Subsequently, the detergent product was applied only on the right forearm using the sn side as a control. After 2 hours and 4 hours (t4h SDS) the other measurements were carried out.
For the evaluation of tolerability were recorded all the undesirable local events, immediate or delayed, occurred during the study, evaluating the severity, the time of onset, duration and possible relationship with the treatment.
All results were compared, with the baseline measurement at each time, using the Student t test for paired data or a non parametric test (Wilcoxon signed rank test) when the difference in averages did not present the characters of normality verified using the Shapiro-Wilk test. The results were considered significant if p <0.05 (95% Confidence Level) and were calculated using a Microsoft® Excel spreadsheet. All data were presented as mean ± standard deviation and in addition to the measured value they were also reported as differences vs basal (difference and percentage value).