AbstractThe influence of vitamin C on the pharmacokinetics of antipyrine was investigated in eleven elderly men aged 65–74. Antipyrine (15 mg kg−1) was administered intravenously on three separate occasions over a 7‐week period: (a) before dietary vitamin C restriction, (b) after approximately 5 weeks of dietary vitamin C restriction, and (c) after 2 weeks of vitamin C supplementation (500 mg orally twice daily). The mean plasma and leucocyte vitamin C levels (±S.D.) before vitamin C restriction were 1·26 ± 0·31 mg dl−1and 26·6 ± 6·7 μg 10−8leucocytes, respectively. These values decreased and then increased significantly following vitamin C restriction and supplementation, respectively. The mean plasma half‐life of antipyrine was 10·2h and the mean plasma clearance was 2·561h−11·73 m−2before vitamin C restriction. No significant changes in the clearance, volume of distribution, or half‐life of antipyrine occurred during the study, indicating that short‐term alterations in vitamin C intake do not affect the pharmacokinetics