@article {Pinnell:February 2001:1076-0512:137,
	author = "Pinnell, Sheldon R.",
	author = "Yang, Huanshu",
	author = "Omar, Mostafa",
	author = "Riviere, Nancy Monteiro",
	author = "DeBuys, Holly V.",
	author = "Walker, Linda C.",
	author = "Wang, Yaohui",
	author = "Levine, Mark",
	title = "Topical L-Ascorbic Acid: Percutaneous Absorption Studies",
	journal = "Dermatologic Surgery",
	volume = "27",
	year = "February 2001",
	abstract = "Background. <P></P>Reactive oxygen species generated by ultraviolet light result in photocarcinogenic and photoaging changes in the skin. Antioxidants protect skin from these insults. Objective. <P></P>This study defines formulation characteristics for delivering L-ascorbic acid into the skin to supplement the skin's natural antioxidant reservoir. Methods. <P></P>L-ascorbic acid or its derivatives were applied to pig skin. Skin levels of L-ascorbic acid were measured to determine percutaneous delivery. Results. <P></P>L-ascorbic acid must be formulated at pH levels less than 3.5 to enter the skin. Maximal concentration for optimal percutaneous absorption was 20&#37;. Tissue levels were saturated after three daily applications; the half-life of tissue disappearance was about 4 days. Derivatives of ascorbic acid including magnesium ascorbyl phosphate, ascorbyl-6-palmitate, and dehydroascorbic acid did not increase skin levels of L-ascorbic acid. Conclusions. <P></P>Delivery of topical L-ascorbic acid into the skin is critically dependent on formulation characteristics.",
	pages = "137-142(6)",
	url = "http://www.ingentaconnect.com/content/bsc/dsu/2001/00000027/00000002/art00008"
}