Vincristine (brand name, Oncovin), formally known as leurocristine, sometimes abbreviated VCR, is a vinca alkaloid. It is a mitotic inhibitor, and is used in cancer chemotherapy. Vincristine is created by the coupling of indole alkaloids vindoline and catharanthine in the vinca plant. Mechanism Vincristine binds to tubulin dimers, inhibiting assembly of microtubule structures and arresting mitosis in metaphase. Because vincristines mechanism of action targets all rapidly dividing cell types, it not only inhibits cancerous cells but can also affect the intestinal epithelium and bone marrow. Uses Vincristine is delivered via intravenous infusion for use in various types of chemotherapy regimens. Its main uses are in non-Hodgkins lymphoma as part of the chemotherapy regimen CHOP, Hodgkins lymphoma as part of MOPP, COPP, BEACOPP, or the less popular Stanford V chemotherapy regimen in acute lymphoblastic leukemia (ALL), and in treatment for nephroblastoma. It is also used to induce remission in ALL with dexamethasone and L-Asparaginase, and in combination with prednisone to treat childhood leukemia. Vincristine is occasionally used as an immunosuppressant, for example, in treating thrombotic thrombocytopenic purpura (TTP) or chronic idiopathic thrombocytopenic purpura (ITP). Side-effects The main side-effects of vincristine are chemotherapy-induced peripheral neuropathy, hyponatremia, constipation, and hair loss. Chemotherapy-induced peripheral neuropathy, a progressive, enduring, often irreversible tingling numbness, intense pain, and hypersensitivity to cold, beginning in the hands and feet and sometimes involving the arms and legs, can be severe, and hence a reason to avoid, reduce, or stop the use of vincristine. One of the first symptoms of peripheral neuropathy is foot drop: A person with a family history of foot drop and/or Charcot-Marie-Tooth disease (CMT) should avoid the taking of vincristine. Accidental injection of vinca alkaloids into the spinal canal (intrathecal administration) is highly dangerous, with a mortality rate approaching 100 percent. The medical literature documents cases of ascending paralysis due to massive encephalopathy and spinal nerve demyelination, accompanied by intractable pain, almost uniformly leading to death. Several patients have survived after aggressive and immediate intervention. Rescue treatments consist of washout of the cerebrospinal fluid and administration of protective medications. Children may do better following this injury. One child, who was aggressively treated at the time of the injection, recovered almost completely with only mild neurological deficits.
Posted on: Thu, 20 Mar 2014 16:16:52 +0000