Capryloyl salicylic acid, also known as lipohydroxy acid, is a derivative of salicylic acid that was first developed by L'Oreal in the 1980s (R).
Capryloyl salicylic acid has an additional fatty chain compared to salicylic acid, which gives it a higher molecular weight and greater lipophilicity. As a result, it is able to penetrate the stratum corneum, but is slow to penetrate past it into the deeper layers of the skin. An in vitro experiment showed that only about 6% of capryloyl salicylic acid penetrated deeper than the stratum corneum after 16 hours, a fraction of the 58% for salicylic acid (R).
In an in vivo study, 17% of capryloyl salicylic acid was found to be retained in the stratum corneum after 4 days of applications, a higher rate of storage than the 10% for salicylic acid, indicating a greater reservoir effect (R, R).
| Outcome | Grade | Effect | Studies | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Skin Thickness | 
        B
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| Skin Barrier Function | 
        C
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| Skin Smoothness | 
        C
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| Skin Brightness | 
        C
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| Skin Firmness | 
        C
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| Outcome | Grade | Effect | Studies | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Keratinocyte Proliferation | 
        B
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| Melanin | 
        C
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| Inflammation | 
        C
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| Transglutaminase | 
        D
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| Filaggrin | 
        D
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