A derivative of the most potent form of vitamin A, retinoic acid. The ingredient can be sold under name Granactive Retinoid. Note that if a skincare brand discloses the concentration of Granactive Retinoid in a product, the concentration refers to a diluted form of Hydroxypinacolone Retinoate: 1% of Granactive Retinoid corresponds to 0.1% of Hydroxypinacolone Retinoate. Hydroxypinacolone Retinoate (HPR) is a unique derivative of retinoic acid because it can directly work in the skin and does not require additional conversion steps. According to studies done by the manufacturer on models of human skin (not real people), this derivative is more effective than other cosmetic versions of retinoids (such as retinol, retinaldehyde, and retinyl palmitate), and, at the same time, causes less irritation. It has been also demonstrated to be more stable than retinol which makes formulating with easier and increases the chances that a product with it will maintain its effectiveness after opening. The packaging should still ideally be air-tight. HPR is available over the counter in the EU, UK, Asia, Australia and New Zealand, but is only with a prescription in Canada.