Cytostatic Therapy: Antimetabolites

Active ingredients Dosage (ung Special features
Methotrexate 40 mg/m² i. v. over 30 minutes For use, methotrexate may be administered perorally (p. o.), intravenously (i. v.), intraarterially (i. a.), subcutaneously (s. c.), intrathecally, intravitreally, and as an intramuscular injection (i. m.).
Cytarabine 100-200 mg/m² i. v. over 7 days Cytarabine is rapidly effective and is used primarily in induction therapy of AML*
Fluorouracil (FU or 5-fluorouracil/5-FU). 600 mg/m² i. v. over 30 minutes Note: genetic disorders in the metabolism of the cytostatic drug (see below).

* Acute Myeloid Leukemia (AML).

  • Mode of action: Antimetabolites are chemical compounds that, because of their structural similarity to natural metabolites, inhibit their metabolic pathways (inhibitors). This results in a disruption of physiological enzyme function in the biological process at hand.
  • Side effects: Liver damage, gastric ulceration, hemorrhagic enteritis (bloody bowel inflammation), leukopenia (white blood cell deficiency), thrombopenias (platelet deficiency), nausea (nausea), vomiting, sterility, sensitivity disorders, alopecia (hair loss), carcinogenicity (increased risk of secondary/secondary or subsequent tumors), nephrotoxic, lung damaging – depending on the drug.
  • Note: For prevention of mucositis (mucosal inflammation), MASCC (Multinational Association of Supportive Care in Cancer) recommends sucking ice cubes 30 min before starting 5-fluorouracil administration – (level of evidence II).
  • Genetic disorders in the metabolization of the cytostatic drug: fluorouracil is degraded in the body via the enzyme dihydropyrimidine dehydrogenase (DPD); DPD levels are decreased in up to 8% of the population, and the enzyme is completely absent in 0.5% of the population! The resulting increased toxicity may be manifested by neutropenia (reduction of neutrophil granulocytes in the blood), neurotoxicity, diarrhea (diarrhea), and stomatitis (inflammation of the oral mucosa). The following prodrugs are also affected: Capecitabine, Tegafur, and Flucytosine. Capecitabine and tegafur. Required in these cases is a dose reduction: in heterozygous carriers of the mutations “c.2846A>T” and “c.1236G>A” the dose should be reduced by 25% and in heterozygous carriers of the mutations “DPYD* 2A” and “c.1679T>G” by 50%.
  • Antidote for poisoning with 5-fluorouracil or capecitabine (precursor (prodrug) of 5-fluorouracil): Uridine triacetate

The effects, indications, side effects and substances listed above represent an overview and do not claim to be complete.