nitisinone
Nitisinone is the only medication available to treat hereditary tyrosinemia type 1 (HT-1). It comes as a tablet, capsule, and a suspension form that you take by mouth, typically once or twice daily. Because this medication prevents you from breaking down tyrosine, you need to avoid foods high in tyrosine and phenylalanine, such as meat, fish, and eggs, while taking it.
What is Nitisinone?
What is Nitisinone used for?
Treatment of hereditary tyrosinemia type 1 (HT-1) in combination with a low tyrosine and phenylalanine diet
How Nitisinone works
Nitisinone is a 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor. HPPD is one of the enzymes in your body that help you break down tyrosine from the foods you eat.
If you have hereditary tyrosinemia type 1 (HT-1), you're missing another enzyme that's responsible for the final step of breaking down tyrosine. This means that tyrosine is only partially broken down. This partially broken down tyrosine is actually toxic to your body and can cause damage to your organs.
Nitisinone stops HPPD from working, which prevents tyrosine breakdown early on in the process, so that tyrosine doesn't turn into the toxins that can harm your body.
Drug Facts
What are the side effects of Nitisinone?
Common Side Effects
- High blood tyrosine levels (>10%)
Other Side Effects
- Low blood cell counts
- Pink eye
- Inflammation (redness, swelling, irritation) of cornea
- Changes in vision
- Sensitivity to light
Source: DailyMed
The following side effects have also been reported
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Less common
Black, tarry stools
bleeding gums
blindness
blood in the urine or stools
bloody nose
blurred vision
burning, dry, or itching eyes
change in color vision
chest pain or discomfort
chills
decreased vision
difficulty seeing at night
excessive eye tearing
eye redness, irritation, or pain
increased sensitivity of the eyes to sunlight
painful or difficult urination
pinpoint red spots on the skin
redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid
sores, ulcers, or white spots on the lips or in the mouth
swollen or painful glands
unusual bleeding or bruising
unusual tiredness or weakness
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Pros and cons of Nitisinone
Pros
Nitisinone is the only medication available for HT-1.
Available as tablets, capsules, and a suspension
Safe to use in babies as young as less than 1 years old
Cons
Can be expensive
It's preferred to store Orfadin in the refrigerator
Needs to be taken for entire lifetime
Pharmacist tips for Nitisinone
Make sure to tell your provider about all of the medications you're taking before starting nitisinone. Medications that interact with nitisinone include celecoxib (Celebrex), phenytoin (Dilantin), warfarin (Coumadin), and methotrexate. Don't start any new medications without talking to your provider or pharmacist first.
Although rare, nitisinone can lower your white blood cell and platelet counts, which might raise your risk for infection and bleeding. Contact your provider if you get signs of an infection (e.g., fever, tiredness, chills, cough, trouble breathing) or signs of bleeding (pale skin, fast heart rate, lightheadedness, blood in your urine or stool).
Tips for Orfadin (nitisinone capsules and suspension and generic nitisinone capsules only:
Take nitisinone capsules on an empty stomach at least 1 hour before or 2 hours after meals.
If you're having difficulty swallowing nitisinone capsules, you can open them and mix the contents in a small amount of water or applesauce right before you or your child are ready to take the dose. You can also mix the contents in baby formula.
Store Orfadin (nitisinone capsules in the refrigerator. However, the capsules can be stored at room temperature for up to 45 days.
Store Orfadin (nitisinone) suspension in the refrigerator before you use it. Once you open the bottle and start to use it, the suspension should be stored at room temperature. Once it has been brought to room temperature, the Orfadin suspension expires after 60 days.
Keep the generic nitisinone capsules in the container it comes in and store at room temperature away from light.
Tips for Nityr (nitisinone) tablets only:
You can take Nityr (nitisinone) tablets with or without food. If it hurts your stomach, take it with food to try and help.
If you or your child are having trouble swallowing Nityr (nitisinone) tablets, you can crush the tablets and mix with applesauce, but it needs to be taken within 2 hours. Don't mix Nityr (nitisinone) tablets with any other food.
You can mix 1-2 Nityr (nitisinone) tablets, depending on your dose, with room temperature water to make a suspension that you can drink. Once you make the suspension, it needs to be taken within 24 hours. Ask your pharmacist if you have any questions on how to make the suspension.
Keep the Nityr (nitisinone) tablets in the container it comes in and store at room temperature, away from light, to avoid damaging the medication.
Frequently asked questions about Nitisinone
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What are the risks and warnings for Nitisinone?
Nitisinone can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
High blood tyrosine levels
Since nitisinone blocks the enzyme that breaks down tyrosine to toxic chemicals, taking nitisinone can cause your blood tyrosine levels to get too high. Make sure to avoid foods high in tyrosine and in phenylalanine while taking nitisinone to avoid making your tyrosine levels too high. If your blood tyrosine levels get too high, you might get eye pain, damage to your eye, changes to your vision, sensitivity to light, changes in your mood or your ability to think, or thickened and bumpy skin on your soles and palms.
Low blood cell counts
Although rare, nitisinone can lead to low white blood cell and platelet counts. This can possibly raise your risk of serious infections, bleeding, and anemia, so your provider might check your blood cell counts while you're getting treated with this medication. If you develop any signs of infection (e.g., fever, tiredness, chills, cough, trouble breathing) or signs of bleeding (pale skin, fast heart rate, lightheadedness, blood in your urine or stool), contact your provider right away.
Side effects from glycerol (for Orfadin suspension only)
Risk factors: Taking 20 mL of Orfadin suspension or more per dose | Taking other medications containing glycerol together with nitisinone
Orfadin suspension contains glycerol, which is used as a sweetener to make the suspension taste better. Taking 20 mL or more of Orfadin suspension per dose can cause headache, upset stomach, and diarrhea because of the amount of glycerol each dose contains. If you experience any of these symptoms, contact your provider to see if you can be switched to Orfadin capsules.
Nitisinone dosage forms
Typical dosing for Nitisinone
Your dose of nitisinone depends on your weight.
The typical starting dose is 0.5 mg/kg by mouth twice a day.
Your provider might adjust your dose of nitisinone based on side effects and levels of certain chemicals in your blood.
Interactions between Nitisinone and other drugs
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Nitisinone images
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