Tegafur

Tegafur (INN, BAN, USAN) is a chemotherapeutic fluorouracil prodrug used in the treatment of cancers. It is a component of the combination drug tegafur/uracil. When metabolised, it becomes 5-fluorouracil.

Medical uses
As a prodrug to 5-FU it is used in the treatment of the following cancers:
 * Stomach (when combined with gimeracil and oteracil)
 * Breast (with uracil)
 * Gallbladder
 * Lung (specifically adenocarcinoma, typically with uracil)
 * Colorectal (usually when combined with gimeracil and oteracil)
 * Head and neck
 * Liver (with uracil)


 * Pancreatic

It is often given in combination with drugs that alter its bioavailability and toxicity such as gimeracil, oteracil or uracil. These agents achieve this by inhibiting the enzyme dihydropyrimidine dehydrogenase (uracil/gimeracil) or orotate phosphoribosyltransferase (oteracil).

Adverse effects
The major side effects of tegafur are similar to fluorouracil and include myelosuppression, central neurotoxicity and gastrointestinal toxicity (especially diarrhoea). Gastrointestinal toxicity is the dose-limiting side effect of tegafur. Central neurotoxicity is more common with tegafur than with fluorouracil.

Mechanism of action
It is a prodrug to fluorouracil which is a thymidylate synthase inhibitor.

Pharmacokinetics
It is metabolised into fluorouracil by CYP2A6.