BIOLOGICAL SIGNIFICANCE

Vincristine, also known as leurocristine, is a vinca alkaloid from the Madagascar periwinkle (Catharanthus roseus, formerly Vinca rosea and hence its name). It is a mitotic inhibitor, and is used in cancer chemotherapy.

CLINICAL USE

Vincristine, injected intravenously only, is used in various types of chemotherapy regimens

Its main uses are in non-Hodgkin's lymphoma as part of the chemotherapy regimen CHOP, Hodgkin's lymphoma as part of MOPP or COPP, or the less popular Stanford V chemotherapy regimen, and in acute lymphoblastic leukemia.

It is occasionally used as an immunosuppressant, e.g. in thrombotic thrombocytopenic purpura (TTP).

Vincristine is used to treat Kaposi's sarcoma (a type of cancer) and non-Hodgkin’s lymphoma. Kaposi's sarcoma has become the fourth most common AIDS-defining illness.

MODE OF ACTION

Tubulin is a structural protein which polymerises to form microtubules. The cell cytoskeleton and mitotic spindle, amongst other things, are made of microtubules. Vincristine binds to tubulin dimers, inhibiting assembly of microtubule structures. Disruption of the microtubules arrests mitosis in metaphase. The vinca alkaloids therefore affect all rapidly dividing cell types including cancer cells, but also intestinal epithelium and bone marrow.

STRUCTURE: