No significant CYP-metaboism. No capacity for CYP-induction or irreversible CYP-inhibition. Side effects such as nausea, vomiting and anorexia may be potentially porphyrinogenic through reduction in caloric intake.

Tegafur is considered to be an orally active prodrug of fluorouracil (Chemical name: 5-Fluoro-1-(tetrahydro-2-furyl)uracil).

The most common preparation of tegafur, UFT, contains of a mixture of tegafur and uracil in the optimal molar ratio of 1:4. It is used as the first line treatment of colorectal cancer complicated by metasatases. It is given as combination therapy with calciumfolinate. Common adverse reactions of tagafur that can be confused with an acute porphyric attack are nausea, vomiting, abdominal pain, diarrhoea or obstipation, myalgia dorsal pain and arthalgia. Side effects such as nausea, vomiting and anorexia may be potentially porphyrinogenic through reduction in caloric intake.

Conversion of tegafur to 5-fluorouracil takes place via microsomal C-5´oxidation partly mediated by CYP2A6, and via C-2 cytosolic hydrolysis catalyzed by unknown enzymes. The metabolism of 5-fluorouracil formed from tegafur follows the usual metabolic pathway for formation of the naturally occurring pyrimidine uracil. Neither tegafur, uracil nor fluorouracil inhibit cytochroms P450 CYP1A2, 2C9, 2C19, 2D6 or 3A4. See the monograph of fluorouracil for further details.

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