Effect of vitamin C on plasma total antioxidant status(TAS) in patients with paraquat intoxication

Abstract

Background : This study was undertaken to evaluate the effect of plasma concentration of vitamin C is on the plasma total antioxidant status(TAS) in patients with paraquat intoxication. Methods : As a preliminary research for this study, we measured plasma vitamin C levels, uric acid, TAS, and bilirubin from 100 healthy Koreans aged between 25-55 years. Various concentrations of vitamin C were constructed in vitro with normal pooled plasma between 1mg/dl and 100 mg/dL and TAS was measured. Both vitamin C concentrations and TAS were measured from the blood samples, taken at 0.5, 1, 2, 3, 5, 7, 9 hours after a bolus injection of vitamin C(50 mg/kg) from 7 volunteers who had been recruited from medical students at our hospital. Various amounts of vitamin C were given to 10 patients with paraquat intoxication for 5 consecutive days in the morning : first day ; 100 mg single dose, second day; 500 mg single dose, third day ; 1,000 mg single dose, fourth day : 3,000 mg single dose, and fifth day ; 3,000 mg three times every 8 hours. Results : The mean value of TAS and vitamin C measured in 100 healthy Korean adults was 2.22 ±0.16 mmol/L and 0.48±0.10 mg/dL. Age and sex do not influence these levels(p>0.05, data are not presented). A direct correlation was observed between TAS and vitamin C concentrations of 1 mg/dL and 100 mg/dL both in vivo and vitro. As the vitamin C concentration was increased gradually 5 consecutive days, the TAS values increased in the same way as follows : first day(vitamin C 100 mg) 2.26±0.98 mmol/L, second day(vitamin C 500 mg) 2.76±0.78 mmol/L, third day(vitamin C 1.000 mg) 2.81±0.68 mmol/L, fourth day(vitamin C 3.000 mg) 3.18 mmol/L. On the fifth day when 3.000 mg of vitamin C was given by bolus intravenous injection 3 times(every 8 hours for a day), the TAS values measured one hour after the injection was 3.58±0.37 mmol/L. Conclusion : When vitamin C is used as a free radical scavenger, the loading dose and maintenance dose should be around 2278 mg intravenous bolus and 146 mg/hour. High doses of vitamin C are effective and safe for patients with acute paraquat intoxication.