Flucytosine (Ancotil): new contraindication in patients with DPD deficiency
MHRA Drug Safety Update October 2020
Flucytosine is a prodrug of 5-fluorouracil used to treat systemic yeast and fungal infections and can cause life-threatening and severe toxicity in patients with complete and partial dihydropyrimidine dehydrogenase (DPD) deficiency. Although pre-testing of DPD status before flucytosine treatment is not required, a new contraindication for patients with complete DPD deficiency has been introduced.
Advice for healthcare professionals:
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flucytosine should not be used in patients with known complete dihydropyrimidine dehydrogenase (DPD) deficiency due to the risk of life-threatening toxicity
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patients with a partial DPD deficiency are also at increased risk of severe toxicity
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do not delay antimycotic therapy with flucytosine for pre-treatment testing of DPD deficiency; however, consider determination of DPD activity if drug toxicity is confirmed or suspected
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in cases of drug toxicity, consider stopping treatment with flucytosine
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report suspected adverse drug reactions associated with flucytosine on a Yellow Card
References
MHRA. Drug Safety update (October 2020) Flucytosine (Ancotil): new contraindication in patients with DPD deficiency. Accessed at https://www.gov.uk/drug-safety-update/aminoglycosides-gentamicin-amikacin-tobramycin-and-neomycin-increased-risk-of-deafness-in-patients-with-mitochondrial-mutations