title: Main approaches for delivering antioxidant vitamins through the skin to prevent skin ageing.
abstract: BACKGROUND
  One of the major contributions to skin photoageing and diseases is oxidative stress, caused by UV radiation inducing reactive oxygen and nitrogen species. Successful prophylaxis and therapy would necessitate control of the oxidant/antioxidant balance at the affected site, which can be achieved through the external supply of endogenous antioxidants.
  
  
  METHODS
  This review discusses possible strategies for dermal delivery of the antioxidant vitamins E and C, as oral supplementation has proved insufficient. These antioxidants have low skin bioavailability, owing to their poor solubility, inefficient skin permeability, or instability during storage. These drawbacks can be overcome by various approaches, such as chemical modification of the vitamins and the use of new colloidal drug delivery systems. New knowledge is included about the importance of: enhancing the endogenous skin antioxidant defense through external supply; the balance between various skin antioxidants; factors that can improve the skin bioavailability of antioxidants; and new delivery systems, such as microemulsions, used to deliver vitamins C and E into the skin simultaneously.
  
  
  CONCLUSIONS
  A promising strategy for enhancing skin protection from oxidative stress is to support the endogenous antioxidant system, with antioxidants containing products that are normally present in the skin.
authors: University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, 1000 Ljubljana, Slovenia. mirjana.gasperlin@ffa.uni-lj.si
authors: Mirjana
authors: M
authors: Gašperlin
authors: Mirjam
authors: M
authors: Gosenca