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

Adopting a specific diet and staying on medication is critical.

Children born with hereditary tyrosinemia type 1 lack the ability to break down the amino acid tyrosine. As a result, toxic substances build up in the blood, causing, among other things, liver failure, kidney dysfunction and neurological crisis. Therefore, the earlier a patient can start to manage the tyrosine levels in the blood, the greater their ability to reduce the risk of symptoms associated with tyrosinemia. Orfadin (previously known as NTBC) used in conjunction with dietary restriction of tyrosine and phenylalanine was approved by the FDA in 2002 for the treatment of patients with HT-1. It helps to prevent the buildup of specific metabolic compounds, and dramatically improves a patient's survival probability compared to treating with diet alone.

Clinical study results and efficacy of treatment.

Orfadin was studied in one open-label, uncontrolled study of 207 patients with HT-1. In patients presenting HT-1 symptoms younger than 2 months of age:  
2 yr survival probability 4 yr. survival probability
Orfadin plus dietary restrictions 88% 88%
Historical controls (dietary restriction alone) 29% 29%
In patients presenting HT-1 symptoms between 2 and 6 months of age:  
2 yr survival probability 4 yr. survival probability
Orfadin plus dietary restrictions 94% 94%
Historical controls (dietary restriction alone) 74% 60%
  • The starting dose of Orfadin was 0.6 to 1mg/kg/day and in some patients the dose was increased to 2 mg/kg/day
  • Median duration of treatment was 22 months
  • Efficacy was assessed by comparison of survival and incidence of liver transplant to historical controls
Learn more about Orfadin and proper diet for HT-1.

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