Emtricitabine was discovered by Emory researchers Dr. Dennis C. Liotta, Dr. Raymond F. Schinazi and Dr. Woo-Baeg Choi and licensed to Triangle Pharmaceuticals by Emory University in 1996. Triangle was acquired by Gilead in 2003. Emtricitabine, marketed by Gilead as Emtriva, was first approved by the U.S. Food and Drug Administration in July 2003 for the treatment of HIV infection in combination with other antiretroviral agents. Emtricitabine, a synthetic nucleoside analog of cytidine, is phosphorylated by cellular enzymes to form emtricitabine 5'-triphosphate. Emtricitabine 5'-triphosphate inhibits the activity of the HIV-1 reverse transcriptase by competing with the natural substrate deoxycytidine 5'-triphosphate and by being incorporated into nascent viral DNA which results in chain termination.

Flucytosine (5-flucytosine, Ancobon) is an antifungal agent used for treatment of serious fungal infections caused by Candida or Cryptococcus. A fluorinated cytosine analog it was originally developed as an anti-tumor agent, but was found to be non-effective against tumors. Monotherapy with 5-FC is limited because of the frequent development of pathogens resistance. It is often used in in combination with amphotericin B. The severe side effects of 5-flucytosine include hepatotoxicity and bone-marrow depression. 5-fluorocytosine is a prodrug to the cytotoxic compound 5-fluorouracil. Although the exact mode of action is unknown, it has been proposed that flucytosine acts directly on fungal organisms by competitive inhibition of purine and pyrimidine uptake and indirectly by intracellular metabolism to 5-fluorouracil. Flucytosine is taken up by fungal organisms via the enzyme cytosine permease. Inside the fungal cell, flucytosine is rapidly converted to fluorouracil by the enzyme cytosine deaminase. Fluorouracil exerts its antifungal activity through the subsequent conversion into several active metabolites, which inhibit protein synthesis by being falsely incorporated into fungal RNA or interfere with the biosynthesis of fungal DNA through the inhibition of the enzyme thymidylate synthetase.

Floxuridine is a pyrimidine analog that acts as an inhibitor of the S-phase of cell division. This selectively kills rapidly dividing cells. Floxuridine is an anti-metabolite. Anti-metabolites masquerade as pyramidine-like molecules which prevents normal pyrimidines from being incorporated into DNA during the S phase of the cell cycle. Flurouracil (the end-product of catabolism of floxuridine) blocks an enzyme which converts cytosine nucleosides into the deoxy derivative. In addition, DNA synthesis is further inhibited because fluoruracil blocks the incorporation of the thymdine nucleotide into the DNA strand. Floxuridine is used for palliative management of gastrointestinal adenocarcinoma metastatic to the liver, when given by continuous regional intra-arterial infusion in carefully selected patients who are considered incurable by surgery or other means. Also for the palliative management of liver cancer (usually administered by hepatic intra-arterial infusion).Floxuridine first gained FDA approval in December 1970 under the brand name FUDR. The drug was initially marketed by Roche, which also did a lot of the initial work on 5-fluorouracil. The National Cancer Institute was an early developer of the drug. Roche sold its FUDR product line in 2001 to F H Faulding, which became Mayne Pharma.

Tegafur (INN, BAN, USAN) is a chemotherapeutic fluorouracil prodrug used in the treatment of cancers. It is a component of the combination drugs tegafur/uracil and tegafur/gimeracil/oteracil. UFT is an anticancer medication composed of a fixed molar ration (1:4) of tegafur and uracil. This drug is commonly used in the treatment of head and neck cancer, gastric cancer, colorectal cancer, hepatic cancer, gallbladder cancer, bile-duct cancer, pancreatic cancer, lung cancer, breast cancer, bladder cancer, prostatic cancer, or uterine cervical cancer. In the body, tegafur is converted into 5-fluorouracil (5-FU), the active antineoplastic metabolite. The mechanism of cytotoxicity of 5-FU is thought to be derived from the fact that 5-fluoro-deoxyuridine-monophosphate (FdUMP), the active metabolite of 5-FU, competes with deoxyuridine-monophosphate (dUMP), thereby inhibiting thymidylate synthase and subsequently DNA synthesis. Another active metabolite of 5-FU, 5-fluorouridine-triphosphate (FUTP) is integrated into cellular RNA, inhibiting RNA function. Uracil, when combined with tegafur, enhances the antitumor activity of 5-FU due to higher 5-FU concentrations in the tumor tissue versus normal surrounding tissue compared with tegafur alone. Uracil inhibits degradation of the released 5-FU. The combination of these two drugs enhances the antitumor activity of Tegafur.

Flosfluridine tidoxil, a thymidylate synthase inhibitor that was developed for the treatment of actinic keratosis and solid tumors, e.g. breast and colorectal cancers. These studies were suspended and information about the further development of this drug is not available.

There is no information in the literature related to the biological and/or pharmacological application of 2-Ethoxy-5-fluorouracil.