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Sapropterin

Generic name: sapropterin

Brand names: Javygtor, Kuvan

Used for phenylketonuria
Last updated November 3, 2026 0 views
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What is sapropterin?

Sapropterin is used to reduce blood levels of phenylalanine in adults and children who are at least one month old with a specific type of phenylketonuria (PKU).

Sapropterin may also be used for reasons not mentioned in this medication guide.

This section was rewritten for readability and reviewed for meaning.

How should I take sapropterin?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Sapropterin can cause phenylalanine levels to get too low in children younger than 7 years old who use this medicine.

Take the medicine with food at the same time each day.

You may swallow the tablet whole or dissolve it in 4 to 8 ounces of water or apple juice.

  • It will take a few minutes for the tablet to dissolve, and you may see small pieces in the liquid. These pieces are safe for you to swallow.
  • Stir the mixture and then drink all of it within 15 minutes after the tablet dissolves.
  • To get the entire dose, add a little more water to the same glass, swirl gently and drink right away.
  • You may also crush the tablet and mix it with a small amount of soft food such as pudding or applesauce.

The powder for oral solution must be dissolved in 4 to 8 ounces of water or apple juice.

  • If you are giving this medicine to a baby who weighs less than 22 pounds, you may dissolve the powder in as little as 1 teaspoon of water or apple juice. Then give the liquid to the baby using an oral dosing syringe. If you do not have a dosing syringe, ask your pharmacist for one.
  • Stir the mixture and then drink all of it within 30 minutes after the powder dissolves.
  • You may also mix the powder with a small amount of soft food such as pudding or applesauce.
  • Make sure the powder is completely dissolved before drinking or eating the mixture.

Doses are based on weight in children and teenagers. Your child's dose may change if the child gains or loses weight.

You may need to follow a special diet. Follow all instructions of your doctor or dietitian. Learn about the foods you should eat or avoid.

While using sapropterin, you may need frequent blood tests.

Store at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.

This section was rewritten for readability and reviewed for meaning.

Warnings

Use only as directed. Inform your doctor if you are taking other medicines or have other medical conditions or allergies.

This section was rewritten for readability and reviewed for meaning.

Before taking this medicine

You should not use sapropterin if you are allergic to it.

Tell your doctor if you have ever had:

  • a stomach ulcer or bleeding; or
  • loss of appetite, or if you are malnourished.

It is not known if sapropterin will harm an unborn baby. Tell your doctor if you are pregnant or planning to become pregnant.

If you are pregnant, your name may be added to a pregnancy registry to monitor the effects of sapropterin on the baby.

Ask a doctor if it is safe to breastfeed while using sapropterin.

This section was rewritten for readability and reviewed for meaning.

Sapropterin side effects

Get emergency medical help if you have signs of an allergic reaction: hives, rash, wheezing, cough, difficulty breathing, nausea, feeling light-headed, flushing (warmth, redness, or tingly feeling), swelling of your face, lips, tongue, or throat.

Sapropterin may cause serious side effects. Call your doctor right away if you have:

  • behavior changes, seizures, or problems with speech;
  • fever, loss of appetite, difficulty swallowing, throat pain, severe stomach discomfort or pain, nausea, vomiting;
  • bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds; or
  • hyperactive behavior, such as fidgeting or moving around often, or talking too much.

Common side effects of sapropterin may include:

  • headache;
  • diarrhea;
  • vomiting; or
  • runny or stuffy nose, sore throat, cough.

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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Sapropterin dosing information

Usual Adult Dose for Phenylketonuria:

Initial dose: 10 to 20 mg/kg orally once a day-Blood phenylalanine (Phe) levels should be measured after 1 week, and then periodically; dose should be increased to 20 mg/kg/day if blood Phe levels have not decreasedMaintenance dose: Once responsiveness has been established, dose should be adjusted within the range of 5 to 20 mg/kg/day according to biochemical response. Non-Responders: -Patients whose phenylalanine levels do not decrease with treatment at 20 mg/kg/day for 1 month should be considered non-responders and treatment should be discontinued. Comments:-This drug should be used in conjunction with a phenylalanine-restricted diet. -Existing dietary protein and Phe intake should not be modified during the evaluation period -Response to therapy is determined by change in blood phenylalanine levels. Use: To reduce blood phenylalanine levels in patients with hyperphenylalaninemia due to tetrahydrobiopterin- (BH4-) responsive phenylketonuria (PKU).

Usual Pediatric Dose for Phenylketonuria:

1 month to 6 years:-Initial dose: 10 mg/kg orally once a day7 years or older: -Initial dose: 10 to 20 mg/kg orally once a day-Measure blood phenylalanine levels after 1 week, and then periodically; dose should be increased to 20 mg/kg/day if blood phenylalanine levels have not decreasedMaintenance dose: Once responsiveness has been established, dose should be adjusted within the range of 5 to 20 mg/kg/day according to biochemical response. Non-Responders: -Patients whose phenylalanine levels do not decrease with treatment at 20 mg/kg/day for 1 month should be considered non-responders and treatment should be discontinued. Comments:-This drug should be used in conjunction with a phenylalanine-restricted diet. -Existing dietary protein and Phe intake should not be modified during the evaluation period -Response to therapy is determined by change in blood phenylalanine levels. Use: To reduce blood phenylalanine levels in patients with hyperphenylalaninemia due to tetrahydrobiopterin- (BH4-) responsive phenylketonuria (PKU).

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is nearly time for your next dose. Do not take two doses in one day.

This section was rewritten for readability and reviewed for meaning.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

This section was rewritten for readability and reviewed for meaning.

What other drugs will affect sapropterin?

Tell your doctor about all your other medicines, especially:

  • levodopa;
  • methotrexate, valproic acid, phenobarbital, trimethoprim; or
  • medicine to treat impotence or pulmonary arterial hypertension--sildenafil (Viagra, Revatio), avanafil (Stendra), tadalafil (Adcirca, Cialis), vardenafil (Levitra, Staxyn).

This list is not complete. Other drugs may affect sapropterin, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

This section was rewritten for readability and reviewed for meaning.

Related medicines

Before you take this medicine: the information on this page is general and may not cover your personal circumstances. Read the label supplied with your medicine and ask a pharmacist or doctor if you are unsure, especially if you are pregnant, breastfeeding, taking other medicines or managing a long-term condition.
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