This week, we’re looking at the research surrounding Surfactants on Atopic Dermatitis. First a recap of eczema skin and its ‘compromised’ characteristics that warrant special care during skin cleansing.
The defective skin barrier in atopic dermatitis makes it:
– Increased skin permeability
– Increased transepidermal water loss
– Increased bacterial colonization
– Reduced antimicrobial peptides (AMP) expression, possibly resulting in higher incidences of infection
– Elevated skin pH
The above makes eczema skin more prone to irritants and more vulnerable to the ‘harsh’ effects of surfactants, discussed last week:
- Alkalization – Elevated skin pH has the impact of (i) reducing skin lipids (ii) allows for growth of harmful bacteria like staph bacteria and (iii) increases transepidermal water loss (TEWL)
- Damage to Skin Lipids
- Damage to Skin Cells
- Toxic to Skin Cells
- Irritation to Skin
Research on Surfactant Impacts on Eczema Skin
Much of the research focuses on certain surfactant ingredients, as below:
A defective skin barrier requires careful selection of cleansing product
(I) Chlorhexidine Gluconate is the antiseptic for use on eczema skin as it causes the least atopic dermatitis skin lesions.
This is from a study examining the Effect of Hand Antiseptic Agents Benzalkonium Chloride, Povidone-Iodine, Ethanol, and Chlorhexidine Gluconate on Atopic Dermatitis in NC/Nga Mice. The four common antiseptic agents in hand sanitizers are:
Benzalkonium Chloride (BZK): A Cationic detergent with strong antiseptic activity, more gentle than that of ethanol-based BUT with reported contact dermatitis cases
Povidone-iodine (PVP-I) – Commonly use in mouthwash and in disinfection before surgery, low toxicity in humans BUT with reported contact dermatitis cases
Ethanol (Et-OH) – Broad antibacterial and antiviral spectrum BUT result in rough hands because of its strong defatting effect on the skin
Chlorhexidine gluconate (CHG) – Broad antibacterial spectrum AND with low incidences of contact dermatitis
(II) Reduce the use of Sodium Lauryl Sulphate (SLS)
In a study involving twenty volunteers with atopic dermatitis, it was found that repeated exposure to sodium lauryl sulphate and sodium hydroxide lead to a more pronounced impairment of the skin barrier function and significant transepidermal water loss.
SLS is a known skin irritant that damages the lipid barrier, causing inflammation and detachment of the skin layers (denaturation discussed last week).
(III) Reduce Cocamidopropyl Betaine (CAPB)
In another study involving 1674 patients, atopic dermatitis was associated with contact hypersensitivity to cocamidopropyl betaine (CAPB), but not to cocamide diethanolamide DEA or amidoamine. CAPB is an amphoteric surfactant, that is considered milder than SLS and a very common surfactant in many products. However, CAPB is cytotoxic, i.e. toxic to skin cells.
(IV) The Use of Hydrophobically modified polymers (HMPs)
The recent studies on surfactants are in agreement that for patients with skin conditions, a gentle liquid cleanser containing HMPs are more appropriate. Addition of cationic polymers to skin cleansers can further protect the skin and improve moisturization. To further improve cleanser mildness, adding hydrophobically modified polymers (HMPs) to cleansers make it less irritating to the skin. This is due to the formation of larger micelle of the surfactant, i.e. the larger the less likely to penetrate and remove skin lipids.
Above is similar to the care to note when cleansing baby skin, as well as what to use/ avoid to limit the harmful effects of surfactants on skin discussed in the previous two weeks. For all the posts in this Surfactant Skincare Series, see:
- Surfactants and Functions
- Cleansing Baby Skin
- Impact on Skin