5-fluorouracil (intravenous), capecitabine, tegafur: DPD testing recommended before initiation to identify patients at increased risk of severe and fatal toxicity
DPD activity is rate limiting in the catabolism of 5-fluorouracil, and patients with DPD deficiency are therefore at increased risk of fluoropyrimidines-related toxicity. All patients should undergo testing for DPD deficiency before starting these medicines.
Source:
Medicines and Healthcare products Regulatory Agency