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Carsten Spanka - One of the best experts on this subject based on the ideXlab platform.

Edward C. Taylor - One of the best experts on this subject based on the ideXlab platform.

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Yoshifumi Maki - One of the best experts on this subject based on the ideXlab platform.

Wolfgang Kern - One of the best experts on this subject based on the ideXlab platform.

  • Impact of the simultaneous administration of the (+)- and (-)-forms of formyl-Tetrahydrofolic Acid on plasma and intracellular pharmacokinetics of (-)-Tetrahydrofolic Acid.
    Cancer Chemotherapy and Pharmacology, 2000
    Co-Authors: Eberhard Schleyer, Karl Lenhard Rudolph, Jan Braess, Michael Unterhalt, Gerhard Ehninger, Wolfgang Hiddemann, Wolfgang Kern
    Abstract:

    Purpose: To detect possible interactions between (−)-formyl-Tetrahydrofolic Acid (leucovorin, (−)-fTHF) and (+)-formyl-Tetrahydrofolic Acid ((+)-fTHF) on the plasma and intracellular pharmacokinetics following their simultaneous administration. Methods: Plasma levels of (−)-fTHF, (−)-methyl-THF, and (+)-fTHF were determined in samples from four volunteers following the administration of both (−)-fTHF and (±)-fTHF and in seven patients during a 5-fluorouracil (5-FU)/fTHF combination chemotherapy. In addition, the intracellular uptake of 14C-(−)-mTHF in the presence of (+)-mTHF at increasing concentrations was measured in vitro. Analyses were performed using a highly specific high-performance liquid chromatography procedure. Results: The pharmacokinetic parameters obtained for (−)-fTHF following the administration of (−)-fTHF only were: terminal half-life, 1.2 h; area under the curve, 10 μg · h/ml; maximum concentration, 12 μg/ml; clearance, 305 ml/min; volume of distribution, 19 l. The parameters did not differ significantly as compared with those obtained following the administration of (±)-fTHF to both volunteers and patients. There were no differences in the pharmacokinetics of (−)-mTHF or in the protein binding of both substances with the different forms of administration. The intracellular uptake of 14C-(−)-mTHF did not depend on the presence of (+)-mTHF at either concentration. Conclusions: These data suggest that (−)-fTHF is not therapeutically superior to (±)-fTHF and that the latter is appropriate during combination chemotherapy with 5-FU/fTHF in patients with colorectal cancers.

  • impact of the simultaneous administration of the and forms of formyl Tetrahydrofolic Acid on plasma and intracellular pharmacokinetics of Tetrahydrofolic Acid
    Cancer Chemotherapy and Pharmacology, 2000
    Co-Authors: Eberhard Schleyer, Karl Lenhard Rudolph, Jan Braess, Michael Unterhalt, Gerhard Ehninger, Wolfgang Hiddemann, Wolfgang Kern
    Abstract:

    Purpose: To detect possible interactions between (−)-formyl-Tetrahydrofolic Acid (leucovorin, (−)-fTHF) and (+)-formyl-Tetrahydrofolic Acid ((+)-fTHF) on the plasma and intracellular pharmacokinetics following their simultaneous administration. Methods: Plasma levels of (−)-fTHF, (−)-methyl-THF, and (+)-fTHF were determined in samples from four volunteers following the administration of both (−)-fTHF and (±)-fTHF and in seven patients during a 5-fluorouracil (5-FU)/fTHF combination chemotherapy. In addition, the intracellular uptake of 14C-(−)-mTHF in the presence of (+)-mTHF at increasing concentrations was measured in vitro. Analyses were performed using a highly specific high-performance liquid chromatography procedure. Results: The pharmacokinetic parameters obtained for (−)-fTHF following the administration of (−)-fTHF only were: terminal half-life, 1.2 h; area under the curve, 10 μg · h/ml; maximum concentration, 12 μg/ml; clearance, 305 ml/min; volume of distribution, 19 l. The parameters did not differ significantly as compared with those obtained following the administration of (±)-fTHF to both volunteers and patients. There were no differences in the pharmacokinetics of (−)-mTHF or in the protein binding of both substances with the different forms of administration. The intracellular uptake of 14C-(−)-mTHF did not depend on the presence of (+)-mTHF at either concentration. Conclusions: These data suggest that (−)-fTHF is not therapeutically superior to (±)-fTHF and that the latter is appropriate during combination chemotherapy with 5-FU/fTHF in patients with colorectal cancers.