Vitamin C, also known as ascorbic acid, has been widely employed in pharmaceutical and cosmetic preparations, including semisolid topical dosage forms, for the formulation protection against oxidation and to exert physiological/biological activities. The Vitamin C major biologic activity is related to the maintenance of the organism oxidation–reduction potential. Besides its antioxidant property, the ascorbic acid acts on the free-radical inactivation, enzymatic co-factor, inhibition of the nitrosamines formation, participation on the synthesis of collagen, carnitine, tyrosine and reactions dependent of the cytocrome P450, intervention on the iron and histamine metabolism, skin depigmentant, and immunological reactions [1–7].