KUVAN Frequently Asked Questions
Questions About KUVAN® (sapropterin dihydrochloride)?
Whether you’re considering including KUVAN Tablets or Powder for Oral Solution as part of your PKU management plan or have recently started taking it, you’re likely to have some questions.
KUVAN is a medication for PKU. KUVAN functions like BH4, a substance that naturally occurs in the body.
Normally, BH4 helps the enzyme known as PAH (short for phenylalanine hydroxylase) work. The PAH enzyme breaks down the amino acid Phe, found in many foods, into other needed chemicals in the body. In PKU, the PAH enzyme isn’t working, which allows too much Phe to build up in the blood. This can eventually affect the brain if left untreated.
In many people with PKU, KUVAN increases the activity of the PAH enzyme that isn’t working properly. In other words, the PAH enzyme that isn’t working “wakes up” and starts to process the Phe. This helps to lower the amount of Phe in the blood.
The low-Phe diet is challenging, and so is consistently keeping your blood Phe level low. A low-Phe diet still allows a certain amount of Phe to pass from the food you eat into your bloodstream. KUVAN, together with a low-Phe diet, helps you lower your blood Phe level and keep it low day after day. KUVAN addresses the problem from a different angle than diet does. KUVAN works by stimulating the PAH enzyme to break down the Phe in your body, thereby lowering your blood Phe levels.
If you are an adult with PKU with blood Phe levels above 600 micromol/L (10 mg/dL), learn about another treatment option here.
KUVAN does not work for everyone. However, studies have found that some people with mild, moderate, or severe PKU have responded to treatment with KUVAN. It is not possible to know whether KUVAN will work for you until you start taking it. Your clinic team will determine whether or not KUVAN is working by checking to see if your blood Phe level drops while you are on a low-Phe diet.
Yes. In clinical trials, the benefit of KUVAN continued throughout the length of the study. KUVAN has been studied for periods from 1 to 164 weeks.
If you do not initially respond to KUVAN, your clinic team may consider another trial of KUVAN if there is reason to believe that diet, change in use of medical food, or other factors affecting blood Phe level (such as fever or illness) may have affected your results.
KUVAN can cause serious side effects, including:
- Severe allergic reactions. Stop taking KUVAN and get medical help right away if you develop any of these symptoms of a severe allergic reaction:
- Wheezing or trouble breathing
- Lightheadedness or fainting
- Inflammation of the lining of the stomach (gastritis). Gastritis can happen with KUVAN and may be severe. Call your doctor right away if you have any:
- Severe upper stomach-area discomfort or pain
- Black, tarry stools
- Blood in your vomit or stool
- Nausea and vomiting
- Blood Phe levels that are too low. Some children under the age of 7 who take high doses of KUVAN each day may experience low blood Phe levels
- Too much or constant activity (hyperactivity) can happen with KUVAN. Tell your doctor if you have any signs of hyperactivity, including:
- Fidgeting or moving around too much
- Talking too much
The most common side effects of KUVAN are:
- Runny nose and nasal congestion
- Sore throat
Tell your doctor if you have any side effect that bothers you or that does not go away.
These are not all the possible side effects of KUVAN. For more information, ask your doctor or pharmacist. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Please see the KUVAN Patient Package Insert for more information.
Before you take KUVAN, tell your doctor if you:
- Have a fever
- Have liver or kidney problems
- Are allergic to sapropterin dihydrochloride or any of the ingredients in KUVAN
- Have poor nutrition or have loss of appetite
- Are pregnant or plan to become pregnant
Pregnancy Registry: There is a pregnancy registry for women who take KUVAN during pregnancy. The purpose of this registry is to collect information about the health of you and your baby. Talk to your doctor about how you can take part in this registry
- Are breastfeeding or plan to breastfeed. It is not known if KUVAN passes into your breast milk. Talk to your doctor about the best way to feed your baby if you take KUVAN
Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal and dietary supplements. KUVAN and other medicines may interact with each other.
Especially tell your doctor if you take:
- A medicine that contains levodopa
- An antifolate medicine
- Avanafil (Stendra®), sildenafil (Revatio®, Viagra®), tadalafil (Adcirca®, Cialis®), vardenafil (Staxyn®, Levitra®)
Tell your doctor if you are not sure if your medicine is one that is listed above.
Know the medicines you take. Keep a list of them to show your doctor and pharmacist when you get a new medicine.
KUVAN is taken one time each day. Take KUVAN exactly as your doctor tells you. Your doctor should tell you how much KUVAN to take and when to take it.
- Your doctor can change your dose depending on how you respond to treatment
- Take KUVAN once a day with food and preferably at the same time each day
- If you forget to take your dose of KUVAN, take it as soon as you remember that day. If you miss a day, do not double your dose the next day, just skip the missed dose
- If you take too much KUVAN, call your doctor for advice
KUVAN Tablets and Powder contain the same blood Phe-lowering medication. Both dosage forms are taken once a day (at the same time each day) with food—preferably your largest meal of the day.
KUVAN Tablets for Oral Use
- KUVAN Tablets should be taken whole, crushed and dissolved in 4 to 8 oz of water or apple juice, or crushed and mixed with a small amount of soft food, such as applesauce or pudding
- It may take a few minutes of stirring for the tablets to completely dissolve in liquid
- Don’t be concerned if you see small, undissolved pieces floating on top. This is normal and safe for you to swallow
KUVAN Powder for Oral Solution
- KUVAN Powder should be poured directly into 4 to 8 oz of water or apple juice or mixed with a small amount of soft food, such as applesauce or pudding
- The powder should dissolve completely within 15 seconds
- When dissolved, KUVAN Powder has lower acidity than KUVAN Tablets
- Store in a cool, dry place between 68°F and 77°F (20°C-25°C)
- Do not leave KUVAN in hot or humid places, such as your car or bathroom cabinet
- Keep KUVAN Tablets in the original bottle with the cap closed tightly
- Protect from moisture. Do not remove the desiccant (the small packet included with your tablets). The desiccant absorbs moisture
- The packet of KUVAN Powder for Oral Solution should not be opened until ready to use. After opening, use the entire packet
- The color of the KUVAN Tablets or Powder for Oral Solution will vary between off-white to yellow and may change over time. This is normal
- Liquids mixed with KUVAN Powder for Oral Solution may change color; this is normal and safe, and should be fully consumed within 30 minutes of preparation
- Do not keep KUVAN that is out of date, or that you no longer need. Be sure that if you throw any medicine away, it is out of the reach of children
- Keep KUVAN and all medicines out of the reach of children