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Plant Alkaloids

  • Vinblastine -- (Velban)

    • Mechanism of action: microtubule depolymerization

      • Mitotic arrest at metaphase; interferes with chromosome segregation

    • Clinical Use::

      • Systemic treatment of Hodgkin's disease

      • Lymphomas

    •  Adverse Effects:

      • Nausea

      • Vomiting

      • Alopecia

      • Bone marrow suppression

  • Vincristine -- (Oncovin)

    • Mechanism of action: microtubule depolymerization

      • Mitotic arrest at metaphase; interferes with chromosome segregation

    • Clinical Use::

      • In combination with prednisone: induction of remission in children with acute leukemia

      • Useful in treating some other rapidly proliferating neoplasms

    •  Adverse Effects:

      • Significant frequency of neurotoxic reactions

      • Occasional: bone marrow depression

  • Podophyllotoxins (etoposide {VP- 16}and teniposide {VM-26})

    • Etoposide and teniposide: structurally similar

    • Mechanism of action: Block cell cycle: in late S-G2 phase

      • Inhibition of topoisomerase II -- DNA damage

    • IV administration

    • Urinary excretion; some in bile

    • Clinical Use:

      •  Etoposide  (VP-16,VePe-sid):

        • Monocytic leukemia

        • Testicular cancer

        • Small cell lung carcinoma

      •  Teniposide (Vumon): lymphomas

    •  Adverse Effects:

      • Nausea

      • Vomiting

      • Alopecia

      • Significant hematopoietic toxicity and lymphoid toxicity

  •  Camptothecins (topotecan and irinotecan )

    • Mechanism of action: interfere with activity of topoisomerase I (cuts and religates single stranded DNA. DNA is damaged

    • Clinical Uses:

      • Topotecan: metastatic ovarian cancer -- including cisplatin-resistant forms (as effective as paclitaxel)

      •  Adverse Effects: Topotecan --

        • Primary

          • Neutropenia

          • Thrombocytopenia

          • Anemia

        • Other

          • Nausea

          • Alopecia

      • Irinotecan:  prodrug-metabolized active topoisomerase I inhibitor

        • Used in management of colon and rectal cancer, including tumors not responding to 5-FU

        • Adverse Effects: Irinotecan --

          • Most common: diarrhea

          • Also common: nausea, vomiting

          • Dose limiting adverse effect: myelosuppression

  • Taxanes (Paclitaxel (Taxol) and Docetaxel (Taxotere))

    • Paclitaxel (Taxol): derivative of the Western Yew

    • Mitotic spindle inhibitor: enhances tubulin polymerization

    • Clinical Uses:

      • Ovarian

      • Advanced breast cancer

    •  Dose-limiting Adverse Effects:

      • Neutropenia

      • Thrombocytopenia

      • Peripheral neuropathy

    • Docetaxel (Taxotere):Used in advanced breast cancer

      • Adverse Effects:bone marrow suppression

Salmon, S. E. and Sartorelli, A. C. Cancer Chemotherapy, in Basic and Clinical Pharmacology, (Katzung, B. G., ed) Appleton-Lange, 1998, p. 881-911.

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