KUVAN (Tetrahydrobiopterin)

What is this medication?

Kuvan (sapropterin) is used along with a restricted diet to control blood phenylalanine levels in adults and children one month of age and older who have phenylketonuria (PKU; an inborn condition in which phenylalanine may build up in the blood and causes decreased intelligence and a decreased ability to focus, remember, and organize information).

Kuvan will only work for some people who have PKU, and the only way to tell if Kuvan will help a particular patient is to give the medication for a period of time and see whether his or her phenylalanine level decreases.

Kuvan belongs to a class of medications called cofactors. It works by helping the body to break down phenylalanine so it will not build up in the blood.

How should I use this medication?

Take Kuvan exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.

Kuvan 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 Kuvan 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 Kuvan 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 Kuvan, you may need frequent blood tests.

What if I miss a dose?

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

How should I store this medication?

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

What are the possible side effects of using this medication?

Get emergency medical help if you have signs of an allergic reaction to Kuvan:

• hives,
• rash,
• wheezing,
• cough,
• difficulty breathing,
• nausea,
• feeling light-headed,
• flushing (warmth, redness, or tingly feeling),
• swelling of your face, lips, tongue, or throat.

Kuvan may cause serious side effects. Call your doctor at once 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 Kuvan side effects 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.

What other drugs will affect Kuvan?

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 interact with sapropterin, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.