Prescribing Information | Important Safety Information
Prescribing Information | Important Safety Information

What is Tyrosinemia Type 1?

Tyrosinemia type 1 (HT-1) is a very rare hereditary disorder. People with HT-1 lack the proper enzymes needed to break down tyrosine, an amino acid. This deficiency leads to a toxic buildup of tyrosine in the body which can damage tissue and organs.

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How is HT-1 Treated?

Two important factors are diet and medication.

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Get Help & Support

Discover resources for managing HT-1.

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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.

  • Please see full Prescribing Information