Plasma and Urinary Levels of Vitamin C after Oral Administration of Calcium Ascorbate Preparation

Abstract

We have examined the plasma and urinary levels of vitamin C after oral administration of calcium ascorbate preparation in six healthy males(20〜27 years). They were given a preparation A or B in a two-period crossover trial. A contains 363 mg of calcium ascorbate and 700 mg of ascorbic acid, and B contains 1000 mg of ascorbic acid. The mean plasma concentration of vitamin C at 1 and 2 h was lower (p < 0.05), but was higher (p < 0.05) at 6 and 9 h in A than that in B. Truax was 3 h for both preparations. The mean Cmax (mg/100 ml, above the initial value) was 1.11 for A and 1.09 for B. The mean AUC_<0-24>(mg・h/100 ml)was 10.57 for A and 10.13 for B. The MRT_<0-24> (h) for A was 8.20 compared to 7.82 for B (p<0.05>). The MRT_<0-∞>(h) was 15.21 and 14.68 for A and B, respectively. The mean amount of vitamin C (mg, above the initial value) excreted in urine during the 0-3 h was 38 for A and 53 for B (p<0.05). During 3-6 h it was 133 and 122 (p<0.05) for A and B, respectively. The percentage of the dose excreted during the 0-24 h was essentially the same: 27.0 % for A and 26.7 % for B. The mean urinary excretion of oxalic acid (mg/24 h) following vitamin C administration was 33.7 for A and 34.8 for B, but the increase of oxalic acid was minor. In conclusion, we found that although minor differences were observed in absoption rate and residence time between A and B, calcium ascorbate and ascorbic acid show similar pharmacokinetics after oral administration.