Nityr Side Effects Center

Last updated on RxList: 9/11/2020
Nityr Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Nityr ?

Nityr (nitisinone) tablets are a hydroxyphenyl-pyruvate dioxygenase inhibitor indicated for the treatment of hereditary tyrosinemia type 1 (HT-1) in combination with dietary restriction of tyrosine and phenylalanine.

What Are Side Effects of Nityr ?

Common side effects of Nityr include:

Dosage for Nityr ?

The recommended initial dosage of Nityr is 0.5 mg/kg orally twice daily. The maximum dosage of Nityr is 1 mg/kg orally twice daily.

What Drugs, Substances, or Supplements Interact with Nityr ?

Nityr may interact with CYP2C9 substrates such as nonsteroidal anti-inflammatory drugs (NSAIDs), phenytoin, fluvastatin, antidiabetics, angiotensin receptor blockers (ARBs), warfarin, erectile dysfunction drugs, antifungals, antidepressants, diuretics, ketamine, tamoxifen, THC, limonene, tapentadol, montelukast, and others. Tell your doctor all medications and supplements you use.

Nityr During Pregnancy and Breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant before using Nityr; it is unknown how it may affect a fetus. It is unknown if Nityr passes into breast milk. Consult your doctor before breastfeeding.

Additional Information

Our Nityr (nitisinone) Tablets Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Nityr Consumer Information

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Some side effects may result from not properly following your diet plan and consuming restricted foods or beverages.

Call your doctor at once if you have:

  • a sudden change in behavior, ability, or development (sitting up, crawling, walking, talking, etc);
  • easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;
  • nausea, diarrhea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
  • vision problems;
  • eye pain, redness or swelling, burning, white or yellow patches on your eyes; or
  • calluses, peeling, or hardened skin on the palms of your hands or the soles of your feet.

Common side effects may include:

  • vision changes, your eyes may be more sensitive to light;
  • eye pain, red or puffy eyes;
  • nosebleeds;
  • increased sensitivity of your eyes to light;
  • rash or itching;
  • dry or peeling skin; or
  • thinning hair.

The liquid form of nitisinone may contain glycerol and can cause headache, upset stomach, or diarrhea.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Nityr (Nitisinone Tablets)


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Nityr Professional Information


Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The safety of NITYR has been established based on studies of another oral formulation of nitisinone in patients with HT-1 [see Clinical Studies]. Below is a display of the adverse reactions of nitisinone in these studies.

Nitisinone was studied in one open-label, uncontrolled study of 207 patients with HT-1, ages 0 to 22 years at enrollment (median age 9 months), who were diagnosed with HT-1 by the presence of succinylacetone in the urine or plasma. The starting dose of nitisinone was 0.3 to 0.5 mg/kg twice daily, and the dose was increased in some patients to 1 mg/kg twice daily based on weight, biochemical, and enzyme markers. The recommended starting dosage of NITYR is 0.5 mg/kg twice daily [see DOSAGE AND ADMINISTRATION]. Median duration of treatment was 22 months (range 0.1 to 80 months).

The most serious adverse reactions reported during nitisinone treatment were thrombocytopenia, leukopenia, porphyria, and ocular/visual complaints associated with elevated tyrosine levels [see WARNINGS AND PRECAUTIONS]. Fourteen patients experienced ocular/visual events. The duration of the symptoms varied from 5 days to 2 years. Six patients had thrombocytopenia, three of which had platelet counts 30,000/microL or lower. In 4 patients with thrombocytopenia, platelet counts gradually returned to normal (duration up to 47 days) without change in the nitisinone dose. No patients developed infections or bleeding as a result of the episodes of leukopenia and thrombocytopenia.

Patients with HT-1 are at increased risk of developing porphyric crises, hepatic neoplasms, and liver failure requiring liver transplantation. These complications of HT-1 were observed in patients treated with nitisinone for a median of 22 months during the clinical trial (liver transplantation 13%, liver failure 7%, malignant hepatic neoplasms 5%, benign hepatic neoplasms 3%, porphyria 1%).

The most common adverse reactions reported in the clinical trial are summarized in Table 1.


Most Common Adverse Reactions* in Patients with HT-1 Treated with Nitisinone**
Elevated tyrosine levels>10%
Corneal Opacity2%
Eye Pain1%
Exfoliative Dermatitis1%
Dry Skin1%
Maculopapular Rash1%
*reported in at least 1% of patients;
** another oral formulation of nitisinone

Adverse reactions reported in less than 1% of the patients, included death, seizure, brain tumor, encephalopathy, hyperkinesia, cyanosis, abdominal pain, diarrhea, enanthema, gastrointestinal hemorrhage, melena, elevated hepatic enzymes, liver enlargement, hypoglycemia, septicemia, and bronchitis.

Read the entire FDA prescribing information for Nityr (Nitisinone Tablets)

© Nityr Patient Information is supplied by Cerner Multum, Inc. and Nityr Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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