Serum ascorbic acid concentrations in previously unsupplemented greyhounds after administration of a single dose of ascorbic acid intravenously or per os

Summary Plasma vitamin C concentrations (mean + SD) were measured after a large (1 g) dose of vitamin C was administered orally or intravenously to each of four trained greyhounds in a randomized cross-over design. Concentrations increased (p<0.05) for 2 h but returned to baseline by 6 h after supplementation. Peak concentrations were greater (p<0.01) after intravenous than oral administration (6.1±1.2 vs. 0.54±0.23 mg/dl). This suggests that vitamin C must be administered many times daily to maintain plasma concentrations above normal.