Sparfosate (PALA) is a stable transition state analogue for an aspartate transcarbamylase- cartalyzed reaction with antineoplastic activity. PALA is a potent inhibitor of aspartate transcarbamylase (Ki about 10(-8) M for ACTases of various origins), which in whole cells blocks the de novo synthesis of pyrimidines. Thus PALA inhibits de novo pyrimidine biosynthesis and increases the extent to which fluorouracil metabolites are incorporated into RNA. In vivo, low doses of PALA inhibit whole body pyrimidine synthesis. While this action is cytotoxic in vitro, extensive human testing demonstrates that PALA alone is devoid of selective antitumor activity. Interest in the therapeutic action of PALA derives from the demonstration that its action potentiates the cytotoxicity of several cytotoxic drugs, notably 5-fluorouracil (5-FU). Development of Sparfosate for cancer and Hepatitis B treatment is assumed to have been discontinued.

Mexoprofen was studied as an analgesic agent. This compound has never been marketed.

Emitefur or BOF-A2 is a fluorinated pyrimidine antimetabolite exerting antineoplastic properties. It is a compound composed of 5-fluorouracil (5-FU) and 3-cyano-2,6-dihydroxypyridine (CNDP), an inhibitor of 5-FU degradation by dihydrouracil dehydrogenase in order to prolong the blood 5-FU level as well as increase selective toxicity to a tumor. Emitefur demonstrated clinical activity in preliminary studies in Japan. Emitefur development for the treatment of solid tumors has been discontinued.

Turofexorate Isopropyl (XL335) is a potent, selective, and orally bioavailable FXR agonist. Binds to the ligand-binding domain (LBD) of human FXR. Turofexorate Isopropyl resides in a predominately hydrophobic pocket with only a few polar atoms making contact with WAY-362450. Turofexorate Isopropyl promotes transcription of the human BSEP, human SHP, and mouse IBABP genes utilizing reporter constructs with EC50 of 17, 230, and 33 nM, respectively in promoter assays. Turofexorate Isopropyl had been in phase I clinical trials for the treatment of hyperlipidemia. This compound was originally discovered by Exelixis Pharmaceuticals, then licensed to Wyeth (now a wholly-owned subsidiary of Pfizer). However, the studies were discontinued.

Tiafibrate is a dithiahexadecanediol derivative patented by Juste S. A. Quimico-Farmaceutica as a hypocholesteremic agent. In rats, Tiafibrate at 125 mg/kg day orally for 14 days gave a 38.8% decrease in blood lipids and a 33.7% decrease in blood cholesterol.

Fluorescein Lisicol (NRL972) is a fluorescent-labelled bile acid analog that is used as an investigational marker for liver function, specifically hepatic biliary transporter function. Fluorescein Lisicol has been used in trials investigating the pharmacokinetics of hepatic cirrhosis, viral hepatitis, non-alcoholic steatohepatitis and non-alcoholic fatty liver disease.

Fenaperone exerts tranquilizing and neuroleptic properties.

Furethidine, a pethidine analog was studied as an analgesic agent. This compound is not currently used in medicine and is listed in schedules of the single convention on narcotic drugs of 1961 as amended by the 1972 protocol.