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On the stability of ascorbic acid in emulsified systems for topical and cosmetic use.

Authors
  • Gallarate, M
  • Carlotti, M E
  • Trotta, M
  • Bovo, S
Type
Published Article
Journal
International Journal of Pharmaceutics
Publisher
Elsevier
Publication Date
Oct 25, 1999
Volume
188
Issue
2
Pages
233–241
Identifiers
PMID: 10518678
Source
Medline
License
Unknown

Abstract

Several O/W microemulsions, O/W and W/O emulsions and a W/O/W multiple emulsion were prepared using non-ionic, non-ethoxylated, skin compatible emulsifiers. Ascorbic acid (vitamin C) was added to the emulsified systems and its stability against oxidation was studied at 45.0 degrees C in aerobic conditions and compared with that in aqueous solutions at different pH values. All emulsified systems provided protection to ascorbic acid, as its degradation rate, which increased with increasing pH, was slower in emulsified systems than in aqueous solutions. The highest protection of ascorbic acid was when it was dissolved in the inner aqueous phase of the W/O/W multiple emulsion, both at 45 and at 20 degrees C for long storage. A pseudo first-order mechanism was hypothesised for ascorbic acid degradation in the experimental conditions for as long as abundant dissolved oxygen was present.

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