Ingredients that hamper penetration in formula

Hi everyone, 

Skin penetration enhancers ingredients or tecnologies that enhance penetration are well known, but is there any ingredient that can hamper the penetration in the skin?



  • AdamnfinemanAdamnfineman Member
    edited June 22
    From my experience I found that a high level of occlusive agents can hamper penetration by forming a layer between the skin and the active ingredients.

    I tried to make a cooling massage oil that was 84% mineral oil with 10% menthol and there was no cooling effect at all. I made a post about it here and the forum concluded that the mineral oil was inhibiting the menthol from coming in contact with skin.
    Lab Assistant to a Cosmetic Formulator at a contract manufacturing company. New to the field and willing to learn.
  • PharmaPharma Member, Pharmacist
    There is not one penetration enhancing ingredient which works for everything nor is there something which would reduce penetration of everything (except wrapping yourself in cling film before applying a product LoL). Regarding cling film and occlusive agents: they're maybe the best and oldest 'penetration technology'. They generally increase penetration of most everything if they don't result in for example a broken emulsion with the actives floating on top.
    I'm taking the other example of @Adamnfineman : Mineral oil does reduce menthol penetration by the same 'penetration mechanism' it enhances penetration of salicylic acid: Solubility (or insolubility, respectively). If an active ingredient is more soluble in the base than the skin, it reduces penetration (unless the base is readily penetrating skin such as DMSO) but if the active is a lot less soluble in the base than the skin it enhances penetration. A minimum solubility in the base and the skin are more or less required for either effect.
    And then there are the other penetration enhancing effects too... many of which are only poorly understood and more theory and guesswork than proven facts. I wouldn't go as far as saying that penetration enhancers are well known. Some are, true, but most are just abused by marketing and it would only be okay to call them penetration enhancers when the final product in question has actually been shown to do so. Anyway, if you know those effects, then you also know what might be done to revers/weaken them. As a rule of thumbs (guesswork quote > 90% :wink: ) I would say that formulating something (especially emulsions) wherein one doesn't explicitly plan for enhanced penetration of a given ingredient more likely ends up with a product which hampers its penetration than one which accidentally enhances it.
  • jeremienjeremien Member
    Thanks to both of you! especially @Pharma, it makes a lot of sense! The use of oil, which, depending on the solubility of the active ingredient, can enhance or hinder penetration.
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