Microtubule inhibitors

Question 1

Vincristine, Vinblastine

Answer 1

Mechanism: Alkaloids that bind to tubulin in M phase and block polymerization of microtubules so that mitotic spindle cannot form.
“Microtubules are the vines of your cells”.

Clinical use: Solid tumors, leukemias and lymphomas.

Toxicity: Vincristine-neurotoxicity (areflexia, peripheral neuritis), paralytic ileus.
Vinblastine blasts bone marrow (suppression).

Question 2

Paclitaxel, other taxols

Answer 2

Mechanism: Hyperstabilize polymerized microtubules in M phase so that mitotic spindle cannot break down (anaphase cannot occur).
“It is taxing to stay polymerized”.

Clinical use: Ovarian and breast carcinomas.

Toxicity: Myelosuppression and hypersensitivity.