Effect of Different Moisturizers on Skin Hydration

The Effect of Different Humectants in Hydroalcoholic Hand Gels on Skin Moisture

Abstract

According to the World Health Organization (WHO), alcohol-based hand disinfectants are the most effective formulations for killing microorganisms. The use of hydroalcoholic hand gels, which are alcohol-based disinfectants, has increased significantly with the emergence of coronavirus. With changing needs, hand gels with moisturizing properties have been developed. In this study, three different humectants (glycerin, isopropyl myristate, monopropylene glycol) were added to different hydroalcoholic hand gels and moisture values were measured.

Introduction

Hydroalcoholic gels are polymer structures containing high alcohol content for the purpose of disinfection.[1] This high alcohol content can cause skin dryness due to use.[2] A good hydroalcoholic gel to protect hands should contain protective substances such as glycerin or aloe vera.[3] The use of hydroalcoholic gels in biocidal and hygienic applications has shown an increase over the years, but accelerated further during the COVID-19 pandemic. In situations where access to water and soap is limited, alcohol-based hand disinfectants containing at least 60% alcohol are recommended to reduce the spread of microorganisms.[4] Due to their alcohol-based nature, hand disinfectants are slightly flammable and in some cases can cause skin toxicity. Today, it is observed that daily frequent use of hand gel causes dryness on our hands, and for this reason active substances with moisturizing effects are used in the structure of hydroalcoholic hand gels. Glycerin is a widely used humectant in cosmetic applications and has a trihydric alcohol structure. Glycerin does not exhibit toxic properties and is environmentally friendly. Due to the degree of hydroxyl groups in glycerin and its high hygroscopic properties, it is a versatile chemical and a good humectant. It also has antimicrobial effects. For this reason, it has a wide range of applications.[5] Isopropyl myristate (IPM) substitutes for natural oils due to its excellent spreading properties and is easily absorbed by the skin. IPM is also used as an auxiliary solvent. Monopropylene glycol is a humectant, that is, a component added to cosmetics to increase moisture retention on skin and hair. Monopropylene glycol is well tolerated by the skin and does not cause redness or irritation. Monopropylene glycol (MPG) is transparent, odorless, viscous and soluble in water like glycerin. Due to the bitter taste of MPG, its use in oral care products and lip gloss is limited.[6]

Materials and Methods

Hydroalcoholic hand gel formulations contained ethyl alcohol, polymer, water and glycerin, isopropyl myristate and monopropylene glycol as humectants. Moisturizing effects were evaluated using a corneometer. The MPA 5 device (Khazaka, Germany) was used for these studies. Tests were conducted in a conditioned environment at 20 degrees. Skin moisture can be directly calculated numerically using a corneometer. The basic principle of the method is the strength of the difference between the dielectric constant of water (81) and other substances by measuring the capacitance of a dielectric medium. Skin moisture values are expressed in a range of 0-130 AU.[6] [caption id="attachment_131488" align="aligncenter"] Figure 1. Khazaka MPA 5 Device[/caption] [caption id="attachment_131490" align="aligncenter"] Table 1. Skin Type Classification by AU Values.[7][/caption]Corneometer measurements were performed directly on the forearm before and after application of the hand gel formulation.

Results

The measured moisture values are shown in Table 2. [caption id="attachment_131491" align="aligncenter"] Table 2. Moisture values measured with corneometer over 60 minutes.[/caption] The corneometer values measured before application were quite similar for all four formulations. When evaluated after application, the highest moisturization was observed in glycerin and IPM. In the hand gel without humectant, although the moisture value increased after application, at the end of 60 minutes the moisture value was quite close to the initial value. In the formulations containing MPG, glycerin and IPM, the corneometer value at the end of 60 minutes was considerably higher than the baseline. As a result of the studies and measurements conducted, the most successful formulations in terms of moisturizing performance were observed to be hand gels containing glycerin and isopropyl myristate.

Esra Duygu Aracıer Balıkçı Research and Development Engineer EVYAP

Dr. Aslı Özge Avcı Tuna Research and Development Category Manager EVYAP

Enis Tek Long-term Intern EVYAP

Nazlı Karaca Summer Intern EVYAP

  References: 1. https://www.pharmaexcipients.com/new/hydroalcoholic-gel/ Last Accessed: 25.10.2021 2. Leslie, R. A., Zhou, S. S., & Macinga, D. R. (2020). Inactivation of SARS-CoV-2 by Commercially Available Alcohol-Based Hand Sanitizers. American Journal of Infection Control. 3. https://www.bestmedicaldiet.com/2020/05/21/hydroalcoholic-gel/?lang=en Last Accessed: 25.10.2021 4. http://www.tuba.gov.tr/files/images/2020/kovidraporu/Covid-19%20Raporu-Final%2B.pdf Last Accessed: 25.10.2021 5. Fluhr J.W., Bornkessel A. and Berardesca E. (2005). Glycerol- Just a Moisturizer? Biological and Biophysical Effects, in: Loden M and Maibach (Eds.), Dry Skin and Moisturizers: Chemistry and Function, CRC Press, Boca Raton (FL). 6. Yılmazer, M., Kafadar, B., Saka, B. (2019). Hümektan (Nemlendirici) Özellik Gösteren Gliserin, Propilen Glikol ve Sorbitolun Cilt Üzerindeki Etkileri ve Farkları. Journal of Turkchem. 7. Zuang, V., Rona, C., Distante, F., Berardesca, E. (1997). The Use of a Capacitance Device to Evaluate The Hydration of Human Skin. Journal of Applied Cosmetology, 15: 95-102.