Research carried out by Procter&Gamble and London School of Pharmacy shows that Aqueous Cream prescribed by many GPs is bad for eczema and atopic dermatitis.
Aqueous cream BP contains sodium layrul sulphate, a known irritant, that should not to be used on damaged skin!
Aqueous Cream BP is frequently prescribed for patients with eczema and is known to induce sensitivity in certain patients and also to decrease the thickness of the stratum corneum (SC). The aim of the present study was to investigate changes in corneocyte size, corneocyte maturity, selected protease activities, protein content and transepidermal water loss (TEWL) in normal forearm skin after a 28-day twice daily application of Aqueous Cream BP.
- Results indicate that corneocyte maturity and size decreased with increasing number of tape strips, and were significantly lower in treated sites compared with untreated sites.
- Protease activity and TEWL values were higher (P < 0·05) for the treated sites compared with untreated sites.
- The amount of protein removed from deeper layers of treated sites was significantly lower than from untreated sites.
- Treatment with Aqueous Cream BP is associated with increased desquamatory and inflammatory protease activity.
- in corneocyte maturity and size are also indicative of accelerated skin turnover induced by chronic application of this emollient.
- These findings question firmly the routine prescription of this preparation as a moisturizer in patients with atopic dermatitis!
http://www.ncbi.nlm.nih.gov/pubmed/21443526
@ Skin Forum
Professor Hadgraft, an expert in transdermal absorption at the London School of Pharmacy, is getting increasingly frustrated with false statements in womens’ and life style magazines and web sites.
“The skin is the largest organ of the body and absorbs 70% of the topically applied products!”
These statements are often substantiated by references to experiments on rodent or rabbit skin which are totally inappropriate. Other discussion members add that:
- These articles are written in response to new product launches and become no more that an advertising opportunity.
- The journalists are bedazzled by the hype presented by marketing.
- If scientists were to contribute to the information packs then these false statements would never have seen the light of day.
The Facts Behind Skin Absorption
- The skin possesses an outer layer, stratum corneum, which is a very impressive barrier. It is about one sixth the thickness of a piece of paper but stops us losing excessive water because of its unique structure.
- The stratum corneum has a structure of a brick wall, the skin cells – keratinocytes – are the bricks. If the bricks are bigger, the path any active ingredient has to go through when penetrating into the skin is longer, if smaller, the path is shorter.
- The “mortar” layer is an organised structure of orderly hydrophilic and hydrophobic domains. Actives soluble in water, eg. vitamin C, cannot penetrate into the lipophylic layer and oil soluble actives eg. vitamin A and E, cannot penetrate into water soluble layers. Actives soluble both in oil and water perform best.
- Absorption is variable depending on: the skin site and its condition, the properties of the active applied, the product in which the active is applied. Absorption is usually higher in the face than on the body; it is related to the cell size. Cheek corneocytes are small and the protease activity is higher on the cheek than forearm, leading to more penetration.
- For most of ingredients the percent of dose absorbed is around 1-2%. For some it is less than 0.1% For some, very few, it is 10-20%.
- The barrier properties of the skin and the subsequent low absorption of actives into the skin are a major problem in the topical treatment of skin diseases! The majority of active ingredients that have potential to affect the biology of the skin are rarely delivered in amounts to allow them to realise that potential!
Source: Skin Forum on LinkedIN and Inaugural SCS Lecture October 2011
