Anti-neoplastic agents, also called anticancer or chemotherapy drugs, are medicines used to treat different types of cancers. Cancer cells divide rapidly and uncontrollably, forming tumors and spreading to other parts of the body. Anti-cancer drugs work by slowing or stopping the growth of these abnormal cells.
What Is Cancer?
Cancer occurs when normal cells undergo genetic changes and begin to multiply beyond control. They invade nearby tissues and may spread (metastasize) to distant organs. Because cancer cells divide faster than most normal cells, chemotherapy targets these rapidly growing cells.
General Mechanisms of Anti-Cancer Drugs
Anti-neoplastic drugs act through different mechanisms:
- Damaging cancer cell DNA
- Blocking DNA or RNA synthesis
- Preventing cell division (mitosis)
- Inhibiting enzymes needed for cancer growth
- Triggering cancer cell death (apoptosis)
Classification of Anti-Neoplastic Agents
1. Alkylating Agents
These drugs add alkyl groups to DNA, making it impossible for cancer cells to replicate.
Examples: Cyclophosphamide, Chlorambucil, Melphalan, Busulfan.
Uses: Leukemia, lymphomas, breast cancer.
2. Antimetabolites
Antimetabolites resemble natural molecules needed for DNA synthesis but block cell division when incorporated into DNA/RNA.
Examples:
- Methotrexate – folate antagonist
- 5-Fluorouracil (5-FU) – pyrimidine analog
- Cytarabine – used in leukemia
3. Antibiotic Anti-Cancer Agents
These are not typical antibiotics used for infections; instead, they inhibit DNA replication in cancer cells.
Examples: Doxorubicin, Bleomycin, Mitomycin.
Uses: Solid tumors and blood cancers.
4. Plant Alkaloids
Derived from plants, these agents interfere with mitotic spindle formation and block cell division.
Examples:
- Vincristine and Vinblastine – act on microtubules
- Paclitaxel (Taxol) – stabilizes microtubules
5. Hormones and Hormonal Antagonists
Some tumors depend on hormones to grow; these drugs block hormone production or action.
- Anti-estrogens: Tamoxifen
- Aromatase inhibitors: Anastrozole
- Anti-androgens: Flutamide
- Corticosteroids: Prednisolone
6. Enzyme Inhibitors
These drugs block enzymes critical for cancer growth.
- Topoisomerase inhibitors: Etoposide, Topotecan
- Tyrosine kinase inhibitors: Imatinib
7. Miscellaneous Agents
Drugs with unique mechanisms.
- Hydroxyurea – inhibits DNA synthesis
- Procarbazine – disrupts DNA function
Drug Profiles
Cyclophosphamide
Class: Alkylating agent.
Mechanism: Forms cross-links in DNA, preventing cell division.
Uses: Breast cancer, lymphomas, autoimmune diseases.
Methotrexate
Class: Antimetabolite (folate antagonist).
Mechanism: Inhibits dihydrofolate reductase, blocking DNA synthesis.
Uses: Leukemia, breast cancer, choriocarcinoma.
5-Fluorouracil (5-FU)
Mechanism: Inhibits thymidylate synthase, preventing DNA formation.
Uses: Colon cancer, breast cancer.
Doxorubicin
Class: Anti-cancer antibiotic.
Mechanism: Intercalates DNA and produces free radicals.
Uses: Many solid tumors and leukemias.
Vincristine
Class: Plant alkaloid.
Mechanism: Prevents spindle formation in mitosis.
Uses: Leukemia, lymphoma.
Paclitaxel
Mechanism: Stabilizes microtubules, blocking cell division.
Uses: Breast and ovarian cancer.
General Adverse Effects of Anti-Cancer Drugs
Because chemotherapy targets rapidly dividing cells, it also affects fast-growing normal tissues.
- Hair loss (alopecia)
- Bone marrow suppression
- Nausea and vomiting
- Mouth ulcers
- Infections due to low immunity
Drug-Specific Side Effects
- Doxorubicin: Heart toxicity
- Bleomycin: Lung fibrosis
- Vincristine: Nerve toxicity
Detailed Notes:
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