Tretinoin

What is tretinoin?

Tretinoin, also known as all-trans retinoic acid, is a metabolite of vitamin A. It is produced in the body from other retinoids that are ingested, such as retinol, retinyl esters and carotenoids (R). It is also the main bioactive component of rosehip seed oil, in which its concentration has been found to be at least 0.357 ml/L (R).

Does tretinoin get absorbed?

Tretinoin penetrates poorly into the skin. When topically applied, approximately 80% of tretinoin remains on the skin surface, and its penetration through the stratum corneum depends on the vehicle (R).

While gel-based formulations of tretinoin tend to trap the molecule, keeping it on the surface of the skin, cream formulations increase penetration to a small extent (R). The initial diffusion into the stratum corneum takes place relatively rapidly within a few minutes, but further diffusion into the epidermis and dermis proceeds more slowly (R).

Nano-lipoidal carriers such as solid lipid nanoparticles and nanostructured lipidic carriers have been shown to enhance the photostability and skin delivery of tretinoin (R).