Otsuka Pharmaceutical was developing URACIL C-13, 2- ([2-13C]uracil) breath test for diagnosis of cancer and gastric emptying disorders. Dihydropyrimidine dehydrogenase (DPD) deficiency is critical in the predisposition to 5-fluorouracil dose-related toxicity. The phenotypic [2-(13)C]uracil breath test (UraBT) demonstrated 96% specificity and 100% sensitivity for identification of DPD deficiency. Phase II development of the breath test was ongoing. As phase II clinical study didn't exploit performance as diagnostic medicines, the development of [2-13C]uracil was discontinued.

Uramustine (INN) or uracil mustard is a chemotherapy drug which belongs to the class of alkylating agents. It is used in lymphatic malignancies such as non-Hodgkin's lymphoma. Uracil Mustard selectively inhibits the synthesis of deoxyribonucleic acid (DNA). The guanine and cytosine content correlates with the degree of Uracil Mustard-induced cross-linking. At high concentrations of the drug, cellular RNA and protein synthesis are also suppressed. After activation, it binds preferentially to the guanine and cytosine moieties of DNA, leading to cross-linking of DNA, thus inhibiting DNA synthesis and function. The DNA damage leads to apoptosis of the affected cells. Chemically it is a derivative of nitrogen mustard and uracil.

Uracil is a common and naturally occurring pyrimidine derivative, one of the four nucleobases in the nucleic acid of RNA In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by it’s methylated form -- thymine. Originally discovered in 1900 by Alberto Ascoli, it was isolated by hydrolysis of yeast nuclein;[4] it was also found in bovine thymus and spleen, herring sperm, and wheat germ. It is a planar, unsaturated compound that has the ability to absorb light. Uracil readily undergoes regular reactions including oxidation, nitration, and alkylation. While in the presence of phenol (PhOH) and sodium hypochlorite (NaOCl), uracil can be visualized in ultraviolet light. Uracil also has the capability to react with elemental halogens because of the presence of more than one strongly electron donating group. Uracil readily undergoes addition to ribose sugars and phosphates to partake in synthesis and further reactions in the body. Uracil becomes uridine, uridine monophosphate (UMP), uridine diphosphate (UDP), uridine triphosphate (UTP), and uridine diphosphate glucose (UDP-glucose). Each one of these molecules is synthesized in the body and has specific functions. Uracil's use in the body is to help carry out the synthesis of many enzymes necessary for cell function through bonding with riboses and phosphates. Uracil serves as allosteric regulator and coenzyme for reactions in the human body and in plants. Uracil can be used for drug delivery and as a pharmaceutical. When elemental fluorine is reacted with uracil, 5-fluorouracil is produced. 5-Fluorouracil is an anticancer drug (antimetabolite) used to masquerade as uracil during the nucleic acid replication process. In combination with Tegafur, uracil used as a chemotherapy drug (called UFT or UFUR) used in the treatment of cancer, primarily bowel cancer. UFT is an anticancer medication composed of a fixed molar ratio (1:4) of tegafur and uracil to be administered with calcium folinate.