Efficacy testing

Efficacy testing: moisturizing and hydration

Skin hydration

There are three layers of the skin - the epidermis, the dermis and the hypodermis (subcutaneous tissue). The epidermis is the outermost skin compartment, which has a thin hydro-lipid layer on top of it. This film consists of secretions of the sebaceous and sweat glands, and it helps maintain the skin’s firmness. It serves also as an additional barrier to prevent the excessive loss of transcutaneous water and the entry of harmful substances.

The epidermis itself is composed of 5 different layers. The top layer of the epidermis is the stratum corneum, which is made up of dead, keratinized cells that shed about every two weeks in a process known as desquamation.

Skin hydration is important for normal functioning of the skin and is primarily linked to the ability of the stratum corneum to retain water. While the amount of water in the inner layers of the skin is relatively constant, the water content of the corneum depends on different factors:

The rate at which the water in the dermis reaches the stratum corneum

The rate at which the water is eliminated by evaporation (transepidermal water loss - TEWL)

The ability of the stratum corneum to retain water

The last factor is linked to the presence of natural hygroscopic agents (collectively known as a natural moisturizing factor (NMF)) and the organization of the intercellular lipids, which form a barrier to water loss.

Signs of skin dehydration

Adequate water content of the stratum corneum (skin moisture) is essential for maintaining healthy skin. Increased water loss disrupts skin desquamation resulting in visible appearance of dry and flaky skin.

Claims related to hydration

Moisturizing

Hydrating

Measurement principles and instruments

Measurements are performed using Callegari 1930 Company - Soft Plus device, which is an instrument designed to assess a variety of skin parameters.

Measurements include:

Evaluation of skin hydration

Soft Plus measures the hydration of the stratum corneum through the scientifically acknowledged capacitive method, which measures the amount of electric current passing through a capacitor.

Efficacy testing protocol is prepared for each product individually with close cooperation with the sponsor. Based on the claims, usage regime and efficacy expectations, we prepare a protocol that is suitable for the type of product and can confirm product efficacy. The studies can be performed over a different time period (from a few days to several weeks or months) depending on the claim and type of measurement.