There are some other things you can do with an ingredient to enhance how well it absorbs into skin. What are you putting it on with? How are you applying it?
#Does your skin absorb water skin
Getting through the skin doesn’t necessarily mean that the substance ends up in the blood, since not all locations have the same blood flow, and the blood vessels are at different depths, so the actual amounts of these substances that get to the blood are much lower. Note that this table only shows percutaneous absorption – in other words, absorption through the skin. You can see that the different substances have different permeabilities, and you can see some areas are better at absorbing things (armpit (axilla), jaw angle, ear canal and, uh, scrotum… I’m assuming the additional 101.6% for parathion is experimental error), while others are pretty impermeable (foot, palm, forearm). Your skin doesn’t have the same permeability all over, so skin absorption depends on the location of application.įor example, here’s a table (from this book) showing the permeabilities of hydrocortisone and two pesticides through skin in different locations. It has to have the right balance of hydrophilic and lipophilic (the right polarity) to get into the skin, then leave the skin and enter the blood.Īs you’d expect, drugs that can be delivered transdermally tick these boxes – but most drugs don’t, and it’s the same for other substances that encounter your skin. Your skin is also both watery and oily at the same time, and things that dissolve in water tend not to dissolve in oil. The smaller the molecule, the more easily it squeezes in between all the substances already in your skin, sort of like how you try to make yourself as small as possible to get through a crowd. How well a substance gets through your skin into the blood depends on the structure of the substance itself.įirstly, molecular size is important. Well, how much of a substance absorbs into skin depends on a ton of things (which is why the blanket statement of 60% rings alarm bells for us pharma nerds).
So why do some things get through skin into the bloodstream? If skin is such a good barrier, does that mean skincare doesn’t work? Absorption depends on a lot of different things Take transdermal patches, like nicotine patches – as well as lots of penetration enhancers that help the nicotine get through skin, they also need a liner to protect the ingredients from rubbing off.Įven with all this intentional effort and design, there’s still 10-95% of the drug remaining on the surface of the skin with the transdermal drug products currently on the market. Compared to the total number of medications on the market, the number of transdermal medications are extremely limited, and lots of formulating tricks are used to get them through the skin. They’re also easier to administer to uncooperative patients.īut while transdermal medications sound great, it actually takes a lot of effort to get drugs through your skin and into your bloodstream. Transdermal products can be designed to release the drug more slowly and consistently than other methods. Alternatively, you can avoid the digestive system altogether with IV drips, injections, suppositories etc. To compensate for this, you have to take a lot more of the medication so that enough of it makes it to your bloodstream to have an effect. One of the biggest headaches in designing medications is first pass metabolism, which is when your digestive system metabolises and gets rid of oral medications before they get absorbed into your bloodstream. Transdermal medications have a few advantages. (They smile smugly as I take a sip of water. If skin’s such a great barrier, they say, why do medicated creams and patches work?
You can see this in everyday life as well:
So by default, the amount of substances absorbed is going to be closer to 0% than 100%. If things were so easily absorbed into skin, humans would’ve died a long time ago (probably from exploding after absorbing a tree or something).
One of your skin’s main functions is to act as a barrier – that is, it blocks substances from getting into the deeper living layers of your body. The video is here on YouTube, keep scrolling for the written version… Skin is not a sponge Let’s break down how human skin works, and why this myth is just plain wrong. It also tends to be cited by the sorts of people who push “non-toxic” products, which is very much a BS marketing tactic. It’s so far from the truth, and it’s cited with such an air of authority that it really ticks me off. The myth that “60% of what’s applied to your skin is absorbed into your bloodstream” is one of my pet peeves.
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