Vincristine
An ESUN Article
Vincristine is a "mitotic inhibitor." Mitosis is the process of cell division in which each new cell receives the same amount of DNA as the parent cell. Drugs that block this process are called "mitotic inhibitors" or "antimitotic drugs." Vincristine and other chemotherapeutic agents are given through a small piece of tubing inserted into the patient’s vein either in a peripheral vein (e.g., a temporary IV in the arm) or a central vein via a Hickman catheter, Broviac catheter, or a port-a-cath (also known as a "port"). A port is a device surgically inserted under the skin into a large vein in the chest for long-term use to administer drugs and nutrients and to take blood samples.
Vincristine is a clear solution (i.e., it looks like water) that is injected into the patient over 2 to 5 minutes. Because vincristine is a vesicant (meaning it can cause severe tissue damage if it leaks out of the vein) if given in a peripheral vein, it must be given carefully by trained nurses. Vincristine can be given by itself on an out-patient basis; however, some centers suggest hospital admission when it is given with cyclophosfamide and doxorubicin. The most common dose is 2mg/m2 up to a maximum dose of 2 mg. The specific amount given is usually based on a patient's height and weight.
Vincristine has no immediate toxicities but can cause jaw pain, constipation, foot or leg numbness, pain or weakness (i.e., neuropathy). The pain is treated with Tylenol or stronger pain medicine. The constipation is treated with stool softeners or laxatives. The extremity neuropathy sometimes requires holding or reducing doses of the drug. Rarer side effects are mild suppression of blood counts, hair loss or seizures. There is not a maximum number of times that vincristine can be given to an individual, but too many doses over a given interval (such as when given weekly for more than 6 to 8 weeks) is likely to cause the side effects mentioned above, requiring “time-off” the vincristine.
Vincristine is often used in combination with other chemotherapy agents and administered according to a specific "protocol." For example, here is a typical treatment plan for the first line chemotherapy combining vincristine, doxorubicin and cyclophosphamide alternated with courses of the drugs ifosfamide and etoposide. The chemo is given every other or every third week, alternating between two courses, over 3 months. The first course is administered over 3 consecutive days. A sample dosing is: vincristine (2 mg/m2), doxorubicin (25 mg/m2), and cyclophosphamide (1200 mg/m2). The second course is administered over 5 consecutive days. A sample dosing is: Ifosfamide (1800 mg/m2) and etoposide (100 mg/m2). A single day of vincristine may be administered on "off weeks" for the first 7 weeks. Some of the drugs might have to be stopped or the dosage reduced due to the toxicity limits.
The drug mesna is given to help protect the bladder during this protocol. Because chemotherapy drugs kill both the tumor and many of the normal blood cells, a drug called filgrastim is also given to help the blood cells recover from the chemotherapy.
Dr. Karen Albritton
V1N1 ESUN Copyright © 2004 Liddy Shriver Sarcoma Initiative.