Abstract
Many preparations containing ascorbic acid are commercially available as over-the-counter (OTC) drugs and dietary supplements. In this study, we compared the properties of various OTC preparations and prescriptions for the medical use of ascorbic acid, and investigated their antioxidative potencies. In each preparation, the total vitamin C content corresponding to the indicated amount was confirmed. Ascorbic acid release from the preparations was not influenced by the pH of the release media. Based on the results of the drug release examination, the dosage form and additives were assumed to control the drug release from the preparations. The ratio of the amount of dehydroascorbic acid to that of total vitamin C at 120 min after the start of the release test was about 4-7 and 6-12% in the first and second fluids respectively (pH 1.2 and 6.8), respectively, and the oxidation of ascorbic acid increased over time. The total antioxidant capacity in the tested medium of the drug release experiment corresponded to the concentration of ascorbic acid. Based on these results, it is considered that the total amount of ascorbic acid absorbed into the bloodstream is an important influence on the antioxidative potency in vivo when preparations containing ascorbic acid are orally ingested.
