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NITYR® (nitisinone) Tablets are a competitive inhibitor of 4-hydroxyphenyl-pyruvate dioxygenase indicated for the treatment of adult and pediatric patients with Hereditary Tyrosinemia Type 1 (HT-1) in combination with dietary restriction of tyrosine and phenylalanine.


Do not take NITYR if you are allergic to nitisinone or any other ingredients. Tell your healthcare provider about any health problems, and if you are pregnant or planning to become pregnant and/or breastfeeding, before starting treatment.


Eye Symptoms, Developmental Delay and Skin Changes Due To Elevated Plasma Tyrosine Levels:

Inadequate restriction of tyrosine and phenylalanine intake can result in elevations of plasma tyrosine. Plasma tyrosine levels above 500 micromol/L may lead to ocular signs and symptoms including corneal ulcers, corneal opacities, keratitis, conjunctivitis, eye pain, and photophobia; intellectual disability and developmental delay; or painful hyperkeratotic plaques (thickening of the skin) on the soles and palms.

  • Your healthcare provider should not adjust NITYR dosage in order to lower the levels of tyrosine in the blood.
  • Your healthcare provider will obtain a slit-lamp examination prior to initiating NITYR treatment, regularly during treatment and may reexamine you if you develop symptoms or if your tyrosine levels are above 500 micromol/L.

Changes in blood profile:

  • You may develop leukopenia (reduction in the number of white blood cells, which form part of the immune system) and severe thrombocytopenia (abnormally low levels of platelets, which help the blood to clot).
  • Your healthcare provider will monitor platelet and white blood cell counts and will adjust your medication accordingly.


The most common adverse reactions (≥1%) in patients with HT-1 taking nitisinone are elevated tyrosine levels, low platelets (thrombocytopenia) or white cells in the blood (leukopenia), and complaints related to the eyes, including conjunctivitis, corneal opacity, inflammation of the cornea, eye pain, blepharitis, cataracts, granulocytopenia and extreme sensitivity to light (photophobia), nosebleed (epistaxis), itching (pruritus), skin inflammation (exfoliative dermatitis), rash (maculopapular rash), dry skin and alopecia.

Adverse reactions reported in less than 1% of the patients, included death, seizure, brain tumor, brain disease, excessive restlessness, bluish skin, abdominal pain, diarrhea, rash on mucous membranes such as the mouth, gastrointestinal hemorrhage, black colored stools, elevated liver enzymes, liver enlargement, low blood sugar levels, sepsis, and bronchitis.


Nitisinone can interfere with the effect of other medicines. Tell your healthcare provider or pharmacist if you are taking, have recently taken or might take any other medicines.


Pregnancy: The safety of this medicine has not been studied in pregnancy. Tell your healthcare provider immediately if you become pregnant or planning to become pregnant.
Lactation: The safety of this medicine has not been studied in breastfeeding women. Tell your healthcare provider immediately if you plan to breastfeed.
Pediatric Use: The safety and effectiveness of nitisinone has been established in pediatric patients for the treatment of HT-1 in combination with dietary restriction of tyrosine and phenylalanine. Use of NITYR in pediatric patients is supported by evidence from one open-label, uncontrolled clinical study conducted with another oral formulation of nitisinone in 207 patients with HT-1 ages 0 to 22 years (median age 9 months).
Geriatric Use: Clinical studies of nitisinone did not include any subjects aged 65 and over. No clinical studies of nitisinone have been performed in geriatric patients. Your healthcare provider will adjust the dose based on your requirements.

For more detailed information, please refer to the full Prescribing Information at

If you get any side effects, talk to your healthcare provider. This includes possible side effects not listed on this website.

You may also report side effects directly by calling Cycle Pharmaceuticals Ltd at 1-855-831-5413, or the FDA at: 1-800-FDA-1088 or

This website is for education purposes only. It is not intended to be, and should not be used as, a substitute for medical advice.

Cycle Vita: 888-360-8482

Medical information team: 855-831-5413

©2024 Cycle Pharmaceuticals Ltd. All rights reserved.
NITYR is a registered trademark of Cycle Pharmaceuticals Limited in the United States.

US-NIT-2400014 | Date of Preparation: March 2024