Pharmacokinetics of ascorbic acid in man

Zetler, G.; Seidel, G.; Siegers, C.‐P.; Iven, H.

doi:10.1007/bf00558340

Cited by 29 publications

(11 citation statements)

References 21 publications

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“…For vitamin C, however, the information is unavailable, incomplete, or flawed (3)(4)(5)(6)(7)(8)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) Assays and Data Calculation. Samples for vitamin C were analyzed by HPLC with coulometric electrochemical detection as described (27,28).…”

mentioning

confidence: 99%

Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance.

Levine

Conry‐Cantilena

Wang

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

1,141

1,026

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Determinants of the recommended dietary allowance (RDA) for vitamin C include the relationship between vitamin C dose and steady-state plasma concentration, bioavailability, urinary excretion, cell concentration, and potential adverse effects. Because current data are inadequate, an in-hospital depletion-repletion study was conducted. Seven healthy volunteers were hospitalized for 4-6 months and consumed a diet containing <5 mg of vitamin C daily. Steady-state plasma and tissue concentrations were determined at seven daily doses of vitamin C from 30 to 2500 mg. Vitamin C steady-state plasma concentrations as a function of dose displayed sigmoid kinetics. The steep portion of the curve occurred between the 30-and 100-mg daily dose, the current RDA of 60 mg daily was on the lower third of the curve, the first dose beyond the sigmoid portion of the curve was 200 mg daily, and complete plasma saturation occurred at 1000 mg daily. Neutrophils, monocytes, and lymphocytes saturated at 100 mg daily and contained concentrations at least 14-fold higher than plasma. Bioavailability was complete for 200 mg of vitamin C as a single dose. No vitamin C was excreted in urine of six of seven volunteers until the 100-mg dose. At single doses of 500 mg and higher, bioavailability declined and the absorbed amount was excreted. Oxalate and urate excretion were elevated at 1000 mg of vitamin C daily compared to lower doses. Based on these data and Institute of Medicine criteria, the current RDA of 60 mg daily should be increased to 200 mg daily, which can be obtained from fruits and vegetables. Safe doses of vitamin C are less than 1000 mg daily, and vitamin C daily doses above 400 mg have no evident value.The recommended dietary allowance (RDA) for vitamin C is 60 mg daily, based on threshold urinary excretion of the vitamin and on preventing the vitamin C deficiency disease scurvy with a margin of safety (1, 2).. Ingestion of 60 mg daily was proposed to prevent scurvy for 30-45 days if vitamin C intake ceased (1-7). Threshold urinary excretion of vitamin C was reported at the 60-mg daily dose (3,4,7,8 tTo whom reprint requests should be addressed.

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mentioning

confidence: 99%

Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance.

Levine

Conry‐Cantilena

Wang

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

1,141

1,026

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“…In general, steady state concentrations of a drug are attained in about 4 to 5 half-lifes, following its continuous administration (Rowland & Tozer 1980). However upon the administration of larger doses ( 2 5 0 0 mg as an intravenous bolus), an elimination half-life in the range of 13 to 39 hr has been reported (Zetler et al 1976). However upon the administration of larger doses ( 2 5 0 0 mg as an intravenous bolus), an elimination half-life in the range of 13 to 39 hr has been reported (Zetler et al 1976).…”

Section: Discussionmentioning

confidence: 99%

“…In man, the elimination half-life of As-Ac ranges between 2 to 4 hr (Yung et al 1978). However upon the administration of larger doses ( 2 5 0 0 mg as an intravenous bolus), an elimination half-life in the range of 13 to 39 hr has been reported (Zetler et al 1976). Since this parameter for As-Ac has not been reported in rats, a study was conducted to investigate its pharmacokinetics in this animal.…”

Section: Discussionmentioning

confidence: 99%

Interaction of L‐Ascorbic Acid on the Disposition of Lead in Rats

Dalley

Gupta

Lam

et al. 1989

Pharmacology & Toxicology

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L-Ascorbic acid (As-Ac) has been investigated for its potential in the prophylaxis of lead poisoning. Using rats as the animal model, the pharmacokinetics of As-Ac was determined following a single intravenous dose (100 mg/kg) administered through a jugular vein. Plasma As-Ac levels were monitored using an enzyme assisted UV spectrophotometric method. The pharmacokinetic parameters of As-Ac obtained were used to establish a dosage regimen which could maintain its average plasma concentration of about 11 micrograms/ml at steady state in rats. The disposition of lead acetate (1 mg/kg) in rats was studied in the absence and presence of As-Ac at steady state. Lead concentrations were monitored in femur, kidney, liver and plasma over a 120 hr period using flameless atomic absorption spectrophotometry. In presence of As-Ac, femur, kidney and liver demonstrated 56, 22 and 41% respective reductions in their exposure towards lead. In addition, the half-life of lead in femur and plasma was found to be reduced by 27 and 51% respectively.

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“…Seit mehreren Jahrzehnten weiß man, dass nur Dosen von bis zu 70 mg Vitamin C nahezu vollstä ndig resorbiert werden, bei 500 mg sind es nur noch 63 %, bei Dosen grö ßer als 1000 mg weniger als 50 %. Durch Retardierung kann die Bioverfü gbarkeit von Ascorbinsä ure deutlich erhö ht werden, wie wir bereits in den 70er Jahren in zwei Arbeiten nachgewiesen haben [20,24].…”

Section: Vitamin Cunclassified

Nutzen und Risiko einer Megavitamintherapie

2003

Erfahrungsheilkunde (Heidelb)

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ZusammenfassungDer Nutzen einer ü ber eine Supplementierung hinausgehenden Verabreichung hoher Dosen von Vitamin A, C oder E besteht in den pharmakodynamischen Effekten dieser Vitamine, ihren antioxidativen Eigenschaften und ihrem Einfluss auf das Immunsystem. Bei Vitamin B 6 liegt der Nutzen vor allem in der Kombination mit B 12 und Folsä ure bei der Kontrolle der Hyperhomocysteinä mie als Risikofaktor kardiovasculä rer Erkrankungen. Risiken einer Ü berdosierung sind als Hypervitaminosen bekannt, so im Falle von Vitamin A mit den Symptomen Anorexie, Reizbarkeit, trockene Haut, Blutungen sowie Periostschwellungen. Teratogene Eigenschaften fü hren zu fetalen Missbildungen. Dies trifft auch fü r das Provitamin A (Carotin) zu, was durch den Ersatz mit Lycopin vermieden werden kann, da Lycopin kein Vorlä ufer des Vitamin A ist. Bei Vitamin B 6 (Pyridoxal) ist nach hohen Dosen, ü ber einen lä ngeren Zeitraum gegeben, mit der Entwicklung sensorischer Neuropathien zu rechnen, Wechselwirkungen mit anderen Arzneimitteln (z.B. L-Dopa) sind ebenfalls bekannt. Fü r die Ü berdosierung von Vitamin C mü ssen mehrere kritische Anmerkungen gemacht werden. So kann nur mit einer dosisproportionalen Resorption (Bioverfü gbarkeit) von Vitamin C bis zu einer Tagesdosis von 70 mg gerechnet werden, dies wird teilweise durch Retardprä parate umgangen. Nach neueren Untersuchungen sollen hohe Vitamin C Dosen nicht nur antioxidativ, sondern auch prooxidativ wirken, dadurch werden die mutagenen Wirkungen an menschlichen Lymphozyten mit DNA-Schä digung erklä rt. Das wichtigste fettlö sliche Antioxidans ist Vitamin E. Dosen grö ßer als 1000 IU/Tag kö nnen Gerinnungsstö rungen hervorrufen und Interaktionen bei einer Antikoagulantientherapie. Im Rahmen der Krebstherapie werden hohe Dosen von diesen Vitaminen (E, A, C, B 6 ) in Kombination gegeben, z.B. bei Blasentumoren. Schlü sselwö rterMegavitamintherapie, Ü berdosierung, Vitaminsupplementierung, Vitamine A, C, E, Folsä ure, Vitamin B 6 , B 12 . AbstractThe benefit of an administration of high doses of vitamin A, C or E exceeding a supplementation consists of the pharmacodynamic effects of these vitamins, the antioxidative properties, and the influence of these vitamins on the immune system. In the case of vitamin B 6 , the advantage consists of the combination with B 12 and folic acid in the control of hyper-homocystinemia as a risk factor of cardiovascular diseases. Risks of an overdosage are known as hyper-vitaminoses, as it is the case with vitamin A with the symptoms anorexia, irritability, dry skin, bleedings as well as periosteal swellings. Teratogenic characteristics lead to fetal malformations. This is also true for the provitamin A (carotin), which can be avoided by using lycopene instead, because lycopene is not a precursor of vitamin A. In the case of vitamin B 6 (pyridoxal), the development of sensorial neuropathies must be expected, if high doses are administered over a longer period of time. Interactions with other drugs (e.g. L-dopa) are also known. Several critical notes must ...

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Pharmacokinetics of ascorbic acid in man

Cited by 29 publications

References 21 publications

Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance.

Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance.

Interaction of L‐Ascorbic Acid on the Disposition of Lead in Rats

Nutzen und Risiko einer Megavitamintherapie

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