What is Hydroxypinacolone Retinoate and what is its purpose?

Developed in the early 2000s, hydroxypinacolone retinoate, also known as HPR, is a synthetic ester of all-trans retinoic acid (vitamin A), with the chemical formula C₂₆H₃₈O₃ and a molecular weight of 398.58 g/mol. This innovative molecule was developed in the cosmetic field to provide benefits similar to retinoic acid, a retinoid used exclusively in the medical sphere and available by prescription only.

Chemically, hydroxypinacolone retinoate is more stable than retinol, a well-known derivative of vitamin A, due to the presence of the ester group in its structure. This group acts as a protective barrier around the retinoid core, limiting oxidation reactions that often affect retinol. Hydroxypinacolone retinoate is thus less sensitive to air, light, and heat. Moreover, unlike retinol, which must undergo a double enzymatic conversion (into retinal, then into retinoic acid), HPR is active upon application.

Its direct affinity for RAR (Retinoic Acid Receptors) enables the activation of signalling pathways involved in cell renewal, collagen synthesis, and pigmentation regulation, while avoiding the inflammatory cascade that often accompanies free retinoic acid. Moreover, its esterified structure slightly slows its skin penetration, contributing to a gradual release and reducing the risk of irritation. This gentle action makes it a particularly interesting choice for sensitive, reactive or beginner retinoid users.

Hydroxypinacolone retinoate stands out due to its diverse effects on the skin, far beyond simple cell renewal regulation. Its action on irregular pigmentation is particularly noteworthy: according to some sources, it may help to normalise melanin distribution and improve barrier function impaired by dryness. Thus, hydroxypinacolone retinoate could contribute to a more even and luminous complexion. Another interesting fact: hydroxypinacolone retinoate is believed to be capable of limiting inflammation and reducing redness and blemishes. This effect would be enhanced when combined with retinol and papain glycospheres, which facilitate penetration while preserving barrier function.

Furthermore, several studies in vitro and clinical trials have evaluated the effectiveness of hydroxypinacolone retinoate. A human fibroblast cellular model (HFF-1) was specifically used to compare the effects of HPR and retinyl propionate (RP), another vitamin A ester. The study revealed that a 5:9 ratio (HPR:RP) was optimal for stimulating fibroblast proliferation, increasing collagen production, and improving the expression of genes related to retinoid receptors. By subjecting 33 volunteers to patch tests, researchers also demonstrated that this combination was better tolerated than retinol, as shown in the graph below.