Retinyl palmitate is an ester of Retinol and is the major form of vitamin A found in the epidermis. Retinyl palmitate has been widely used in pharmaceutical and cosmetic formulations.In Vitro: Retinyl palmitate has a high molecular weight and a stable formulation. To be active, Retinyl palmitate should be enzymatically converted in the skin to retinol by cleavage of the ester linkage and must then be converted to tretinoin via oxidative processes.In Vivo: The topical administration of Retinyl palmitate in rats results in increased protein and collagen and an epidermal thickening.