Vincristine

Definition

Vincristine is a drug used to treat certain types of cancer. Vincristine is available under the trade names Oncovin, Vincasar, and Vincrex, and may also be referred to as vincristine sulfate, or VCR. The drug was previously known as leurocristine, or LCR.

Purpose

Vincristine is an antineoplastic agent used to treat leukemia, Hodgkin's disease, malignant lymphomas, neuroblastoma, rhabdomyosarcoma, Wilms' tumor, as well as other cancers.

Description

Vincristine was approved by the Food and Drug Administration (FDA) in 1984.

Vincristine is a naturally occurring compound that is extracted from periwinkle plants. It belongs to a group of chemicals called alkaloids. The chemical structure and biological action of vincristine is similar to vinblastine and vinorelbine.

Vincristine prevents the formation of microtubules in cells. One of the roles of microtubules is to aid in the replication of cells. By disrupting this function, vincristine inhibits cell replication, including the replication of the cancer cells.

Vincristine is used in combination with other drugs to treat leukemia. It is also used in combination with other drugs, such as mechlorethamine, procarbazine and prednisone, to treat Hodgkin's disease. It is also used in combination to treat non-Hodgkin's lymphomas, neuroblastoma, rhabdomyosarcoma, and Wilms' tumor. Vincristine is also used less frequently to treat other types of cancer.

Recommended dosage

Vincristine is administered by intravenous injection once per week. The initial dose of vincristine may be adjusted upward or downward depending on patient tolerance to the toxic side effects of treatment.

Precautions

Vincristine must only be administered by individuals experienced in the use of this cancer chemotherapeutic agent. Vincristine must only be administered intravenously, that is, directly into a vein. Accidental administration of vincristine into the spinal cord fluid is a medical emergency that may result in death. Vincristine has a low therapeutic index. It is unlikely there will be therapeutic benefit without toxic side effects. Certain complications can only be managed by a physician experienced in the use of cancer chemotherapeutic agents.

Because vincristine is administered intravenously and is extremely irritating, the site of infusion and surrounding tissue should be monitored for signs of inflammation.

Some experts recommend blood tests to ensure that the number of white blood cells is adequate for treatment to continue. Infections should also be controlled before vincristine treatment starts.

Vincristine is not recommended for use in patients with the demyelinating form of Charcot-Marie-Tooth syndrome.

Vincristine is not recommended for patients receiving radiation therapy though a port in the liver.

Vincristine may cause harm to a fetus when administered to pregnant women. Only in life-threatening situations, should this treatment be used during pregnancy. Women of childbearing age are advised not to become pregnant during treatment. Women should stop nursing before beginning treatment, due to the potential for serious adverse side effects in the nursing infants.

Side effects

The side effects of vincristine treatment are usually related to the dose of drug and are generally reversible. Toxic side effects may be more common in patients with poor liver function.

Toxicity of the nervous system is the principal adverse side effect associated with vincristine treatment. This toxicity may cause numbness, pain, especially of the jaw, tingling, and headaches. Lengthy treatment at high doses may cause even more severe toxicity. Constipation is a common side effect. Laxatives and enemas are typically used to prevent severe constipation. Shortness of breath is a potentially severe side effect that patients should report to their doctor. Additional side effects, including rash, an increase or decrease in blood pressure, dizziness, nausea and vomiting, hearing impairment, and hair loss (alopecia) may occur.

Interactions

Drugs that may alter the metabolism of vincristine, particularly itraconazole, should be used with caution due to the potential for interactions. Hearing impairment may be enhanced when vincristine is used with other drugs that affect the ear. These drugs include platinum-containing antineoplastic agents, such as cisplatin. Seizures have been reported in patients taking vincristine and phenytoin. The doses of vincristine and phenytoin may need to be adjusted to decrease the chance of this problem.

Marc Scanio

Alkaloid

—A nitrogen-containing compound occurring in plants.

Microtubles

—A tubular structure located in cells that help them to replicate.

Therapeutic index

—A ratio of the maximum tolerated dose of a drug divided by the dose used in treatment.