Topical activity of ascorbic acid: from in vitro optimization to in vivo efficacy.
We present here a new cosmetic formula system containing 3% ascorbic acid based on an optimized oil-in-water (O/W) emulsion. This formulation demonstrated a good long-term stability of the active ingredient and also of the emulsion itself. It could be deduced from in vitro release studies that this O/W emulsion enabled a better release of the hydrophilic active agent than an alternative W/O emulsion. By measuring the ultraweak photon emission, which is a well-established parameter for the oxidative stress in the skin, the high in vivo antioxidant capacity of 3% ascorbic acid was demonstrated after 1 week of product application. This placebo-controlled study also proved that ascorbic acid in an O/W cream reduced oxidative stress in human skin significantly better than the derivative sodium ascorbyl-2-phosphate, a more stable vitamin C replacement commonly used in cosmetic formulations. With increasing age, the number of papillae in the epidermal-dermal junction zone in human skin are reduced. This implies a possible consequence of reduced mechanical resistance of the skin and impaired supply of the epidermis with nutrients. In a 1-month placebo-controlled study on 25 human volunteers, a significant increase in the number of dermal papillae after application of the 3% ascorbic acid cream was demonstrated, using a confocal laser scanning microscope. Fine lines and wrinkles are a characteristic sign of aged and especially photo-aged skin. Application of 3% ascorbic acid in a 12-week placebo-controlled usage study indicated a significant reduction of facial wrinkles. Altogether, 3% ascorbic acid in a cosmetic O/W emulsion has been shown to be appropriately stable and to enable a good release of the active agent in vitro as a precondition for a high efficacy in vivo. Application in vivo resulted in a significant reduction of oxidative stress in the skin, an improvement of the epidermal-dermal microstructure and a reduction of fine lines and wrinkles in aged skin. These results were received within a relatively short period of time of product application.
Raschke
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T
Beiersdorf AG, Research & Development Cosmed, Hamburg, Germany. Thomas.Raschke@Beiersdorf.com
Koop
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Düsing
H-J
HJ
Filbry
A
A
Sauermann
K
K
Jaspers
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S
Wenck
H
H
Wittern
K-P
KP
D000279:Administration, Cutaneous; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D018849:Controlled Clinical Trials as Topic; D003358:Cosmetics / Q000737:chemistry / Q000494:pharmacology*; D004058:Diffusion; D004339:Drug Compounding / Q000379:methods; D004355:Drug Stability; D004655:Emulsions; D005079:Excipients / Q000008:administration & dosage; D005260:Female; D006801:Humans; D018613:Microscopy, Confocal / Q000295:instrumentation; D008875:Middle Aged; D018384:Oxidative Stress / Q000187:drug effects; D015203:Reproducibility of Results; D015595:Skin Aging / Q000187:drug effects* / Q000473:pathology; D016896:Treatment Outcome; D014466:Ultraviolet Rays / Q000009:adverse effects
D000975:Antioxidants; D003358:Cosmetics; D004655:Emulsions; D005079:Excipients; D001205:Ascorbic Acid