Creative Biolabs is an internationally operating testing laboratory that provides a series of toxicology test services for cosmetic products. Our comprehensive safety testing capabilities meet the international regulatory requirements for cosmetic products. Now we provide multiple methods for skin irritation/corrosion testing.

The Introduction of Skin Penetration Test

A skin penetration test, also known as dermal penetration or percutaneous penetration, is the process to measure substances entering the skin through the skin barrier. Skin penetration studies can determine the amount of chemicals that penetrate the skin to further determine whether it is likely to be absorbed into the systemic circulation.

Figure 1. Structure of the epidermis and the intercellular lipid matrix. (Zsikó, 2019)

Factors Affecting Skin Penetration

• Physicochemical properties of the test sample, including lipophilicity, molecular weight, charge, and concentration.
• Area and duration of exposure.
• The qualities and integrity of the stratum corneum.
• Thickness of the epidermis.
• Temperature and local blood flow.

Figure 2. Routes of penetration. A: Intercellular penetration pathway, B: Follicular penetration pathway, C: Transcellular penetration pathway. (Zsikó, 2019)

Methods for Skin Penetration Determination

There are both in vitro and in vivo methods for skin penetration determination. According to the preference of the national regulatory agency and the correlation of the test results with human skin contact, the most suitable method can be selected. Since various countries and regions have successively not allowed skin absorption testing of new cosmetic ingredients in live animals, it has become a mainstream trend to use donated human skin or in vitro skin models for testing.

• The Animal Test (OECD 427)

Following OECD 427, the rat has been served as the most commonly used species for in vivo skin penetration testing. Using active substances in the form of radiolabels, it is possible to observe signs of toxicity in animals and obtain the skin absorption rate, amount, or percentage of the test material. Although the morphological characteristics of rat and human skin are very different, the generation of system dynamics and metabolic information may be related to humans and provide certain value.

• The Non-animal Test (OECD 428)

Skin absorption is mainly a passive process. Appropriate in vitro experimental studies have produced a large amount of chemical data and proved the effectiveness of this method. Using our customized Franz-type cells, in vitro skin permeation of actives can be measured. We can also conduct in vitro skin permeation studies based on radioactive and non-radioactive labels.

Advantages of our Non-animal Test

• No uses animals to avoid ethical and legal issues.
• Human skin can better simulate the real environment.
• The early stage of absorption can be determined.
• The exposure conditions can be easily changed.
• Easily evaluate a wider range of physical forms of test substances, such as solids, granules, and powders.
• Customized services to meet various needs.

Equipped with world-leading technology platforms and professional scientific staff, we are pleased to offer the most qualified services and products for our customers all over the world. If you are interested in our products or services, please do not hesitate to contact us for more detailed information.

Reference

1. Zsikó, S.; et al. Methods to evaluate skin penetration in vitro. Scientia Pharmaceutica. 2019, 87(3): 19.

• Cytotoxicity Test
• Skin Irritation/Corrosion Test
• Eye Irritation/Corrosion Test
• Skin Sensitization Test
• Genetic Toxicity Test
• Phototoxicity Test
• Endocrine Disruptor Activity Test
• Reproductive Toxicity Test
• Carcinogenicity Test