Cytotoxic/antineoplastic drugs

Cytotoxic/antineoplastic drugs

These aim to inhibit reproduction of neoplastic cells  adverse affects occur when they inhibit normal cells.

Alkylating agents:
Most widely used agents. Highly reactive compounds.
Mechanism of action is by adding an alkyl group to DNA  cell death.
eg Nitrogen mustards (cyclophosphamide, mechlorethamine, ifosfamide); nitrosoureas (carmustine, lomustine); cisplatin

Antimetabolites:
Compete for binding sites on enzymes or incorporated into DNA or RNA

Methotrexate (folic acid analog):
• inhibits dihydrofolate reductase (enzyme that converts dihydrofolic acid into tetrahydrofolic acid – this is a necessary step in the activation of folic acid needed for synthesis of DNA, RNA and proteins)
• used in conjunction with leucovorin for some cancers to protect normal cells

Pyrimidine analogues:
• inhibit biosynthesis of pyrimidine, DNA and RNA
• eg cytarabine (becomes incorporated into DNA, suppressing further DNA synthesis); Fluorouracil (inhibits thymidylate synthetase)

Purine analogues:
• eg Mercaptopurine (disrupts purine synthesis)

See:
Chemotherapy and Pseudoscience