Antimitotics

Antimitotics

Vinca-alkaloids block cells in mitosis by disturbing microtubule synthesis via binding to tubulin and inactivating it. They prevent the assembly of microtubules and thus the formation of the spindles, which leads the DNA to division over two daughter cells, resulting in a cell cycle arrest in the M phase.

Vinblastine is a drug used to treat lymphomas, germ cell tumors, and bladder carcinomas. Vincristine is indicated for lymphomas, leukemias and pediatric tumors. Vinorelbinecan be applied in case of metastised breast carcinoma, when other therapies fail.

Besides normal adverse effects such as vomiting, nausea and myelosuppression, vinca-alkaloids

can display neurotoxicity. Vincristine displays the most prominent neurotoxicity, but less myelosuppression, while vinorelbine causes less neurotoxicity, but more leucopenia and thrombocytopenia.

Taxanes also bind to microtubules, but causing an opposite effect compared to vinca-alkaloids: they enhance all aspects of tubulin polymerisation irreversibly. They stabilize the microtubules by inhibiting their depolymerisation. The microtubules become rigid and non-functional, resulting in an inhibition of the normal dynamic reorganisation of the microtubule network and an induction of cell shape changes.

Taxanes like paclitaxel and docetaxel are used to treat breast, ovary, endometrium and head and neck carcinomas. Their main toxicities are peripheral oedema, alopecia, bone marrow suppression, hypersensitivity reactions, and cardiac disturbances.

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Which of the following statements is NOT true?