Indication and Usage
ORFADIN is a synthetic reversible inhibitor of 4-hydroxyphenylpyruvate dioxygenase indicated for use as an adjunct to dietary restriction of tyrosine and phenylalanine in the treatment of hereditary tyrosinemia type 1 (HT-1).
Important Safety Information
- Inadequate restriction of tyrosine and phenylalanine intake can result in elevations in plasma tyrosine.
- Do not adjust Orfadin dosage in order to lower the plasma tyrosine concentration.
- Leucopenia and thrombocytopenia have been observed with treatment with Orfadin. Monitor platelet and white blood cell counts regularly during Orfadin therapy.
- Most common adverse reactions (incidence >2%) are hepatic neoplasm, liver failure, thrombocytopenia, leucopenia, visual system complaints including conjunctivitis, corneal opacity, keratitis, and photophobia.
- Use caution when administering ORFADIN with drugs that are metabolized by CYP2C9 because of a potential for increased systemic exposure of these drugs.
- ORFADIN should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Based on animal data, ORFADIN may cause fetal harm.
- Exercise caution when administering to a nursing woman. Because of the potential for serious adverse reactions in nursing infants from ORFADIN, a decision should be made to discontinue nursing or to discontinue the drug taking into account the importance of the drug to the mother.
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