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

Tyrosinemia, or HT-1, is an inheritable genetic disorder.

Tyrosinemia type 1 is a genetic disorder caused by a mutation in the gene for the FAH enzyme, which is needed to break down tyrosine. It is inherited in a recessive manner. Recessive means that parents of a child with this disorder each carry one copy of the mutated gene but show no signs or symptoms of the condition themselves.

Boys and girls are affected in equal numbers.

For a child to be affected, both parents have to pass on one copy of the defective gene to the child. The risk of their child having hereditary tyrosinemia type 1 is 25%.

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

    • Tyrosine levels can increase in the blood if you do not restrict tyrosine and phenylalanine in your diet while taking Orfadin. Too much tyrosine in the blood can cause serious eye problems or other complications.
    • Do not adjust your Orfadin dosage in order to lower the tyrosine levels in the blood.
    • A reduction in the number of white cells and platelets in the blood have been observed during treatment with Orfadin. Your platelet and white blood cell counts should be monitored regularly during Orfadin treatment.
    • The most common adverse reactions to taking Orfadin are liver cancer, liver failure, low platelets or white cells in the blood, and complaints related to the eyes, including conjunctivitis, corneal opacity, inflammation of the cornea, and extreme sensitivity to light.
    • Tell your physician promptly if you have unexplained eye symptoms, rash, jaundice (yellowing of the skin or whites of the eyes) or excessive bleeding.
    • Use Orfadin during pregnancy only if the potential benefit justifies the potential risk to the fetus.
    • Nursing women should discontinue either Orfadin or breast-feeding based on the recommendation of your healthcare professional.
      Please see full Prescribing Information