Objective : This study is to determination retinol penetration into the skin from various topical retinol products with different concentrations and formulation compositions.
Methods: Twelve topical retinol products of different concentrations and formulations were purchased from Amazon. Three retinol in isopropyl myristate (0.1, 0.5, and 1%) solutions were also prepared. 10 ul of retinol product or retinol solution was applied on human cadaver skin placed on a heating pad. After six hours, residue retinol product on the skin was clean with alcohol wipes, and then tape striped 24 times with scorch tap. Retinol content in the tape and rest of the skin was extracted with methanol and then determined with a HPLC method.
Results: Less than 10% of retinol from applied topical retinol products or self-prepared retinol solutions was penetrated into the skin. Most of the retinol penetrated into the skin was presented in the stratum corneum. There is a linear relationship between the amount of retinol penetrated into the skin and the retinol concentration in the product.
Conclusions: The amount of retinol penetration into the skin was depended on the retinol content in the topical retinol product, while the composition of various topical retinol products showed little impact in the amount of retinol penetration into the skin.
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