Capecitabine is a recently developed drug. It is a type of medicine called an antimetabolite because it interferes with the metabolism and growth of cells. Capecitabine is an unusual anti-cancer drug in that it is most active in cancer cells; normal cells are exposed to far lower concentrations of the drug. Cancer cells convert capecitabine into another anti-cancer drug called 5-fluorouracil (fluorouracil). This substance prevents cells from growing and reproducing by interfering with the production of DNA and RNA. Eventually the cells die.
Capecitabine has been approved by the U.S. Food and Drug Administration for the treatment of metasta-sized breast cancer that is resistant to standard chemotherapy. Capecitabine may be used in combination with the drug docetaxel (Taxotere). A study completed in 2000 found that 56% of women receiving this combination therapy survived at least one year, with an average survival time of 14 months.
A study completed in 2001 found that capecitabine is as effective as 5-fluorouracil for treating metastasized colorectal cancer, and has fewer and less severe side effects. However, it does not increase the average survival time of approximately 13 months.
Recommended dosage
The dosage of capecitabine depends on a number of factors including body size. The average dosage is 2500 mg per square meter of body surface area per day. Capecitabine is a pill that is taken with water within 30 minutes after a meal. It may be taken every 12 or 24 hours. For colorectal cancer, capecitabine may be administered for two weeks, followed by one week off, for a total of 30 weeks.
Precautions
Capecitabine can temporarily reduce the number of white blood cells, thus reducing the body's ability to
fight infection. Thus, it is very important to avoid exposure to infections and to receive prompt medical treatment. Immunizations (vaccinations) should be avoided during or after treatment with capecitabine. It also is important to avoid contact with individuals who have recently taken an oral polio vaccine.
Capecitabine may temporarily reduce the number of blood platelets that are necessary for blood clotting. The risk of bleeding may be reduced by:
Capecitabine can cause birth defects and fetal death in animals. Therefore this drug should not be taken by pregnant women or by either the man or the woman at the time of conception. Because capecitabine may cause serious side effects, women usually are advised against breast-feeding while taking this drug.
Some individuals may have an allergic reaction to capecitabine. Allergies to foods, preservatives, or dyes, or to the drug 5-fluorouracil must be considered before this drug is prescribed.
Side effects
Common side effects of capecitabine may include:
loss of appetite (anorexia)
diarrhea
nausea and vomiting
stomach or abdominal pain
swelling, peeling, redness, or blistering of hands and feet
numbness, pain, itching, or tingling in hands and feet
pain, swelling, or sores in the mouth or on the lips
Side effects of capecitabine may include symptoms of infection, such as fever, chills, sore throat, or swollen glands, or symptoms of liver malfunction. Side effects also may include unusual bleeding or bruising due to the reduction in blood platelets.
Other diseases or medical conditions may increase the side effects associated with capecitabine. Chicken pox or shingles (Herpes zoster) may become very severe and spread to other parts of the body. If heart, kidney, or liver disease is present, the side effects related to these organs may be more severe. In addition, in the presence of liver disease, the amount of capecitabine in the body may be higher. Individuals over the age of 80 often experience more severe side effects with capecitabine.
Interactions
Other drugs that may interact with capecitabine include:
Coumarin-type anticoagulants that are used to thin the blood and medicines containing aspirin can increase the chances of bleeding. Folic acid, alone or in a multi-vitamin, may increase the side effects of capecitabine. Finally, capecitabine can increase the effects on the blood of other cancer medicines or radiation therapy.
