5-FU, or fluorouracil, was developed in 1957 by a man named Charles Heidelberger, though several others were involved in research surrounding the chemotherapy drug. Doctors often combine it with leucovorin, a water-soluble folate vitamin, because leucovorin increases the toxicity of 5-FU. 5-FU and leucovorin commonly treat colon, breast, ovarian, esophageal, head/neck, pancreatic, bladder and skin cancer.
Mechanism of Action
5-FU comes from a chemotherapy family called antimetabolites. Once taken into the body, 5-FU and leucovorin metabolize and change into chemicals called FdUMP and FUTP. These metabolites incorporate themselves into the cancer cell, where they inhibit the creation of DNA and RNA. The cancer cell needs DNA and RNA to replicate and grow; without them, the cell cannot divide.
Administration
5-FU is a clear fluid typically given through an intravenous infusion. It is also given in a cream form to treat cancer on the skin's surface. Administration of leucovorin typically occurs before that of 5-FU. The Chemotherapy Source Book reports that 5-FU is one of the few chemotherapy drugs that crosses into the brain. It is mainly metabolized by the liver.
Dosing and Schedule
Dosing of most chemotherapy drugs, including 5-FU and leucovorin, is based on the weight of the patient. Other factors can include patient age and overall health status, the type of cancer being treated, and kidney and liver function. 5-FU may be given once weekly or be infused slowly, over one to five days, once a month.
Side Effects
Common side effects include lowered blood-cell counts, diarrhea, mouth sores, numbness and tingling in hands and feet, watering eyes, taste changes and poor appetite. 5-FU also irritates the vein when administered and causes discoloration along the vein in some patients. The Chemotherapy Source Book states that damage to the nervous system and heart also can occur with the use of 5-FU.
Macmillan Cancer Support lists less common but possible side effects as hair loss, nail bed changes, rashes, sensitivity to sunlight and nausea and vomiting. Leucovorin is listed by The Chemotherapy Source Book as causing mild nausea and vomiting and allergic reaction consisting of rashes and itching.
Prevention/Solution
Tactics to reduce 5-FU's side effects include sucking on ice chips during the drug's administration to prevent mouth sores and irritation. Taking oral vitamin B6 can help prevent numbness and tingling in hands and feet, and anti-nausea medications and steroids may prevent other side effects.
References
- "The Chemotherapy Source Book"; Michael C. Perry, PhD.; 2007
- Chemocare.com: 5-FU
- Cancer Research: A History of Cancer Chemotherapy
