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 patients, 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 in some patients with PKU. This helps to lower the amount of Phe in the blood in these patients.
The low-Phe diet is challenging, and so is consistently keeping your 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.
KUVAN does not work for everyone. However, studies have found that some people with mild, moderate, and severe PKU have responded to treatment with KUVAN. It is not possible to know whether KUVAN will work until you start taking it. Your doctor will determine whether or not KUVAN is working by checking to see if your blood Phe drops while the low-Phe diet is held constant.
Yes. In clinical trials, the benefit of KUVAN continued throughout the length of the study. KUVAN has been studied for periods from 1 to 136 weeks.
If you do not initially respond to KUVAN, your doctor 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.
In studies, side effects in patients taking KUVAN generally occurred at a similar rate as they did in patients who received placebo (a pill without any medicine in it).
The most common side effects reported when taking KUVAN included:
- Headache
- Diarrhea
- Abdominal pain
- Upper respiratory tract infection (like a cold)
- Throat pain
- Vomiting
- Nausea
The side effects listed are not all the side effects seen with KUVAN. You should talk to your doctor or pharmacist if you have concerns about these or other side effects.
You should also inform your doctor if you have any side effects when taking KUVAN.
Please see the KUVAN Patient Package Insert for more information.
Before taking KUVAN, tell your doctor if you:
- Have a fever
- Are pregnant or planning to become pregnant
- Are breast feeding
- Have or had liver or kidney problems
- Are allergic to KUVAN or any other medications
- Have poor nutrition or are anorexic
- Are taking levodopa
- Are taking medications that inhibit folate metabolism like methotrexate, because these medications could affect how KUVAN works in your body
- Are taking medicines for erectile dysfunction like Viagra (sildenafil), Levitra (vardenafil), or Cialis (tadalafil)
You should also tell your doctor about any other medicines you are taking, including prescription and nonprescription medicines, vitamins, and herbal supplements. KUVAN and many other medicines may interact with each other. Your doctor needs to know what medicines you take so he or she can decide if KUVAN is right for you.
- Store in a cool, dry place between 68°F and 77°F (20°C–25°C), with the cap closed tightly
- Do not leave KUVAN in hot or humid places (such as your car or bathroom cabinet)
- Protect from moisture. Do not remove the desiccant (the small packet included with your tablets). The desiccant absorbs moisture
- The color of the tablets may turn light yellow over time. This is normal, and you should take these tablets
- 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
- Remember to keep KUVAN and all other medications out of the reach of children
