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Does size matter?
In my limited understanding of chemistry, smaller molecules are better able to travel deeper into the skin than larger molecules.
Does the molecular size of an ingredient influence your decision to used it in a formulation such as a moisturiser or serum? Does “encapsulation” make much of a difference to penetration and effectiveness when using an ingredient with a larger molecular structure?
Is there any regulation, that anyone knows of, regarding this?
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9 Replies
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Yes indeed size matters. A lot of macromolecules are not able to penetrate deep epidermis or dermis so lots of companies gave up collagens elastins and started using their fragments aka peptide molecules. If you are dealing with macromolecules maybe you can try penetration enhancers like propylene glycol, oleic acid, limonene etc. They will enhance performance of your product but it will be lower than smaller molecules anyway. What’s more important is this question: how deep you want to have this molecule?
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In the US, anything that affects the “structure or function” of the human body is classified as a drug by the FDA. That most definitely INCLUDES the skin.
In other words, penetrating the skin and then actually doing something automatically makes your product a pharmaceutical, a doctors-prescription-required drug. Selling or attempting to sell your product by saying that it does anything but temporarily affect the appearance of the skin without first filing a NDA is illegal. No one that I know of has gone to jail for this, but companies have been forcibly shut down over it.Deliberately trying to penetrate the skin is a bad idea, unless you have the resources to conduct extensive safety testing. -
Thanks for those answers. The reason I was asking was more intellectual than practical. I have to admit, I’m a little confused when it comes to the FDA regulations (what little I know of them). How deep is too deep? What classifies as ‘affecting the structure or function’? For example, the Joyce Blok anti-aging range (created in Australia) has an ingredient called Matrixyl 3000 (palmitoyl oligopeptide, tetrapeptide-1, glycerine, butylene glycol, and carbomer) which, according to them, stimulates collagen by tricking the skin into believing there are broken collagen strands that need to be fixed/replaced. Does that not affect the structure and function of the skin? Would this ingredient be allowed in an US cosmetic, or would it be considered a drug?
I’m from New Zealand and I know our regulations are a little different than the US or even the EU (I’m still doing research on this) but it’s good to have other viewpoints.
Sorry if this is a basic question, I haven’t done a lot of chemistry and I’m just trying to get my head around all of this!
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You can not legally make the claim that a material “stimulates collagen production” in cosmetics sold in the US.
You can read their position here.The ingredient would be allowed in the US. You just couldn’t say that it is stimulating collagen. It’s highly dependent on the claims. -
The FDA is in a peculiar position, due to the wording of some of the laws governing it.
The FDA has established a definition for what it considers a drug: a product “intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease,” or “intended to affect the structure or any function of the body.”BUT…there is a loophole, and an “anti-loophole”.The loophole says that in order for there to be a violation of FDA regulations, the company making the product must “claim” (communicate in some way to the user) that its products perform one or more of the functions that would make it a drug. That means that if you use a raw material like Matrixyl, you are OK unless/until you claim it does anything that the FDA considers a drug function (stimulates collagen, for example.)The “anti-loophole” says that there are some ingredients that are so widely recognized as being drugs that even the mere mention of them on your ingredient label is enough for the FDA to say that you are making a drug claim. Penicillin, for example. A skin cream containing Penicillin would be a drug no matter what you said (or didn’t say) about it. -
Do you thunk tranexamic acid (it’s a traditional drug to control hemorrhage when orally administered) could be a problem in cosmetics sold in the US?
Tranexamic acid is trending in cosmetics due some studies showing its topical use could prevent dark spots, improve skin’s barrier function and relief dryness.Here an example of cosmetic with TA: -
If it’s not a problem now, I bet it will be a problem in the future.
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Thanks heaps for that link Perry, and thanks Bobzchemist for you information also. I think it will prove really helpful. It’ll be interesting to see what the views on that are here in NZ.
Even after reading that link it all seems like a sticky tangled web with a very fine line to tread. Does it all come down to marketing and the wording used for the description of the claims of a product? It sounds like it would be a question of whether the company minds if it treads on the FDA’s toes or not, or how skilled their marketing department is.
It looks like I have more research to do!
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Ok, I think I just answered my own question. I didn’t realise something could be classified as both a cosmetic and drug. It all makes a bit more sense now!
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