Oxonic Acid

Absorption

After administration of a single dose of 50 mg Teysuno (expressed as tegafur content), median Tmax for Teysuno components tegafur, gimeracil, and oteracil was 0.5, 1.0, and 2.0 hours, respectively .

Indications

Oteracil is used as an adjunct to antineoplastic therapy. When used within the product Teysuno, oteracil is indicated for the treatment of adults with advanced gastric (stomach) cancer when given in combination with cisplatin.

Definition

ChEBI: 5-azaorotic acid is a member of 1,3,5-triazines and a monocarboxylic acid.

Background

Oteracil is an adjunct to antineoplastic therapy, used to reduce the toxic side effects associated with chemotherapy. Approved by the European Medicines Agency (EMA) in March 2011, Oteracil is available in combination with Gimeracil and Tegafur within the commercially available product "Teysuno". The main active ingredient in Teysuno is Tegafur, a pro-drug of Fluorouracil (5-FU), which is a cytotoxic anti-metabolite drug that acts on rapidly dividing cancer cells. By mimicking a class of compounds called "pyrimidines" that are essential components of RNA and DNA, 5-FU is able to insert itself into strands of DNA and RNA, thereby halting the replication process necessary for continued cancer growth.
Oteracil's main role within Teysuno is to reduce the activity of 5-FU within normal gastrointestinal mucosa, and therefore reduce's gastrointestinal toxicity . It functions by blocking the enzyme orotate phosphoribosyltransferase (OPRT), which is involved in the production of 5-FU.

Metabolism

Based on the results of in vitro studies, a part of oteracil is non-enzymatically degraded to 5-azauracil (5-AZU) by gastric fluid, and is then converted to cyanuric acid (CA) in the digestive tract. Only a small amount of oteracil is metabolised in the liver because of its low permeability .