Chemotherapy Categories
Cell Cycle Nonspecific
- Exert a cytotoxic effect throughout the cell cycle.
- Effective against cells in resting phase.
- Commonly see a dose-response relationship.
- Concentration dependent – more effective when given in larger intermittent doses.
Alkylating Agents (and similar)
Work by DNA cross linking.
- Mustard gas derivatives: Mechlorethamine, Cyclophosphamide, Chlorambucil, Melphalan, and Ifosfamide.
- Ethylenimines: Thiotepa and Hexamethylmelamine.
- Alkylsulfonates: Busulfan.
- Hydrazines and Triazines: Altretamine, Procarbazine, Dacarbazine and Temozolomide.
- Nitrosureas: Nitrosureas are unique because, unlike most types of chemo treatments, they can cross the blood-brain barrier. They can be useful in treating brain tumors.
- Metal salts: Carboplatin, Cisplatin, and Oxaliplatin.
Anthracycline and Other Antibiotics
Bind with DNA to block RNA production.
- doxorubicin, daunorubicin, idarubicin, dactinomycin, mitomycin, mitoxantrone and bleomycin.
Cell Cycle Specific
- Drugs that inhibit or kill during a specific phase of the cell cycle.
- Schedule dependant – maintain a cytotoxic level of drug for a period of time to allow tumour to ‘cycle’ through.
- Generally produces the greatest cell kill if the amount of drug is divided and given in repeated fractions instead of single large dose.
- More effective against tumours with high growth fraction.
Antimetabolites
Inhibit specific enzymes involved in DNA/RNA replication (S phase).
Similar to normal substances within the cell. When the cells incorporate these substances into the cellular metabolism they are unable to divide.
- Folic acid antagonist: Methotrexate.
- Pyrimidine antagonist: 5-Fluorouracil, Foxuridine, Cytarabine, Capecitabine, and Gemcitabine.
- Purine antagonist: 6-Mercaptopurine and 6-Thioguanine.
- Adenosine deaminase inhibitor: Cladribine, Fludarabine, Nelarabine and Pentostatin.
Topoisomerase inhibitors
Interfere with the action of topoisomerase enzymes (topoisomerase I and II) which control the manipulation of DNA necessary for replication.
- Topoisomerase I inhibitors: Ironotecan, topotecan.
- Topoisomerase II inhibitors: Amsacrine, etoposide, etoposide phosphate, teniposide.
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