Failure of Vitamin C to Affect the Pharmacokinetic Profile of Antipyrine in Man

A possible interaction of vitamin C with the metabolism of drugs which are oxidized (e.g., antipyrine and diphenylhydantion) is indicated from data in animals. The effect of megadoses of vitamin C (300 mg/day to 4800 mg/day) was therefore tested in human volunteers receiving antiprine (single oral dose) or diphenlhydantoin (chronic therapy). The half-life, volume of distribution, and plasma clearance of antipyrine were not affected by vitamin C treatment. Steady-state plasma levels of diphenylhydantoin in two epileptic patients were similar before and during vitamin C (1.2 Gm/day for 18 days) treatment. It is concluded that vitamin C, in commonly used megadoses, has no effect on the metabolism of antipyrine or diphenylhydantoin in men.