5-Fluorouracil (5-FU) Ð Is a highly toxic drug with a narrow margin of safety. It is effective against carcinoma of the colon, rectum, breast, stomach and pancreas, slows or stops growth of cancer cells and their spread in the body. Fluorouracil is a fluorinated pyrimidine. The method of chemical synthesis of Fluorouracil was described in the US Patent Nos. 2,802,005 and 2,885,396, issued in 1957 and 1959. The Patents protection for Fluorouracil is expired. Fluorouracil interferes with the synthesis of DNA and inhibits the formation of RNA. Since DNA and RNA are essential for cell division and grows, the effect of Fluorouracil provokes unbalanced growth and death of the cell. The effect of DNA and RNA deprivation are most marked on those cells which grow more rapidly and which take up Fluorouracil at a more rapid rate, that is, cancer cells. Fluorouracil is manufactured by Roche Laboratories (a division of Hoffman-La Roche Inc.) for intravenous administration. Following the injection, Fluorouracil not only distributes into tumors, but also into intestinal mucosa, bone marrow, liver and other tissues throughout the body. It diffuses readily across the blood-brain barrier and distributes into cerebrospinal fluid and brain tissue. The drug shows an extreme toxicity: severe hematological toxicity, gastrointestinal hemorrhage and even death may result from the use of Fluorouracil, despite meticulous selection of patients and careful adjustment of dosage.
