Nitisinone is used to treat certain inherited disorders (alkaptonuria or hereditary tyrosinemia type 1, also known as HT-1). Both conditions are caused by a shortage of certain natural substances that are needed to break down a nutrient (tyrosine) found in food. This effect causes a build-up of too much tyrosine and related substances in the body. Nitisinone works by helping to prevent the formation and build-up of several toxic substances that cause damage to the liver, kidneys, joints, and nervous system. For the treatment of HT-1, this medication must be used along with a diet low in protein, tyrosine, and phenylalanine.

Different brands of this medication have different uses. Do not change brands of this medication unless directed by your doctor.

Read the Patient Information Leaflet if available from your pharmacist before you start taking nitisinone and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth as directed by your doctor, usually once or twice daily.

If you are taking the capsules, take them on an empty stomach at least 1 hour before or 2 hours after a meal. If you are unable to swallow the capsules, you may open the capsules and mix the contents in a small amount of water, formula, or apple sauce. Take the mixture right away.

If you are taking the suspension, you may take the suspension with or without food. Shake the bottle well before each dose. Carefully measure the dose using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose. When using an unopened bottle of suspension for the first time, remove it from the refrigerator and let it warm to room temperature for 30 to 60 minutes before use.

If you are taking the tablets, you may take the tablets with or without food. If you have trouble swallowing the tablets whole, ask your pharmacist if your brand may be crushed and mixed in water or applesauce. Follow your pharmacist's instructions carefully.

The dosage is based on your medical condition, weight, and response to treatment. Your doctor may adjust your dose and schedule based on your response to treatment. Carefully follow your doctor's directions for taking this medication.

Take this medication regularly to get the most benefit from it. To help you remember, take it at the same time(s) each day.

It is very important that people taking this medication for HT-1 follow a special diet low in protein, tyrosine, and phenylalanine. Consult your doctor, pharmacist, or dietician for more details. (See also Drug Interactions and Precautions sections.)

The suspension may cause headache, upset stomach, or diarrhea. If any of these effects occur, tell your doctor or pharmacist promptly and discuss switching to other forms of nitisinone.

Remember that this medication has been prescribed because the doctor has judged that the benefit is greater than the risk of side effects. Many people using this medication do not have serious side effects.

This medication may rarely cause a low number of blood cells such as white cells and platelets. This effect can decrease your body's ability to fight an infection or cause easy bruising/bleeding. Tell your doctor right away if you develop any of the following symptoms:

• signs of infection (such as sore throat that doesn't go away, fever, chills)
• easy bruising/bleeding

This medication may cause high levels of tyrosine in the blood. It is very important to follow the low protein/low tyrosine diet recommended by your doctor. See also Precautions section. Too much tyrosine may cause skin, eye, or brain problems. Tell the doctor right away if any of these symptoms occur:

• eye redness/itching/discharge
• vision changes
• eye pain
• eye sensitivity (especially to light)
• dry/itchy skin
• sores on palms of hands/soles of feet
• developmental delays (such as holding head up, rolling over, crawling)

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact the doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before taking nitisinone, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• eye problems (such as cataracts, corneal ulcers)

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

People taking this medication are at risk for developing high levels of tyrosine in the blood, possibly leading to eye, skin, and nervous system problems. (See Side effects section.) To decrease the risk of high tyrosine levels, people with HT-1 should follow a diet low in tyrosine and phenylalanine. Avoid foods and beverages that contain aspartame or are high in tyrosine or phenylalanine. Foods high in tyrosine include soy products, turkey, fish, avocados, bananas, yogurt, and lima beans. Foods high in phenylalanine include milk, chicken, eggs, cheese, peanut butter. (See also Drug Interactions section.)

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

It is unknown if this drug passes into breast milk. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

This medication can slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include deuruxolitinib, ketorolac, sodium phenylbutyrate/taurursodiol, among others.

Many foods, drugs, or supplements may contain aspartame, tyrosine, or phenylalanine, which must be limited in people with HT-1. Check the labels on all products (especially artificially sweetened products) for aspartame, tyrosine, and phenylalanine content. Consult your doctor, pharmacist, or dietician for more details.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669.

Do not share this medication with others.

Lab and/or medical tests (such as eye exams, compete blood count, liver function, blood and urine tests for tyrosine and related substances) should be done before you start taking this medication and while you are taking it. Keep all medical and lab appointments. Consult your doctor for more details.

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store the tablets at room temperature away from light and moisture. Do not store the tablets in the bathroom. Store the suspension in the refrigerator before the first use. Do not freeze. After the first use, store the bottle of suspension at room temperature. Once opened, the suspension expires after 60 days. Different brands of the capsule form of this medication have different storage needs. Check the product package for instructions on how to store your brand, or ask your pharmacist. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.