Sodium phenylbutyrate (Oral)
Medically reviewed on June 7, 2018
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
- Tablet, Enteric Coated
Therapeutic Class: Hyperammonemia Agent
Pharmacologic Class: Histone Deacetylase Inhibitor
Uses For This Medicine
Sodium phenylbutyrate is used together with a proper diet to help treat urea cycle disorders (including a specific liver enzyme deficiency) that help remove ammonia (nitrogen) from the body.
Ammonia is formed from the breakdown of protein in the body. If the ammonia cannot be removed by the body, then a buildup may cause serious unwanted effects. Sodium phenylbutyrate works by helping to reduce high levels of ammonia in the blood.
Sodium phenylbutyrate is available only with your doctor's prescription.
Before Using This Medicine
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For sodium phenylbutyrate, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to sodium phenylbutyrate or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Because of sodium phenylbutyrate's toxicity, use in children weighing less than 20 kilograms (44 pounds) is not recommended.
No information is available on the relationship of age to the effects of sodium phenylbutyrate in geriatric patients.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with Medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.
Interactions with Food/Tobacco/Alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other Medical Problems
The presence of other medical problems may affect the use of sodium phenylbutyrate. Make sure you tell your doctor if you have any other medical problems, especially:
- Edema (swelling from excess fluids in the body) or
- Heart disease or
- Heart failure or
- Kidney disease, severe—Increased retention of water may make these conditions worse.
- Kidney disease or
- Liver disease—Higher blood levels of sodium phenylbutyrate may result and increase the risk of side effects.
Proper Use of This Medicine
Take sodium phenylbutyrate exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. To do so may increase the chance of side effects.
Sodium phenylbutyrate comes with a patient insert. Read and follow the instructions in the insert carefully. Ask your doctor if you have any questions.
For patients taking the powder form of sodium phenylbutyrate:
- Sodium phenylbutyrate should be mixed with water or any food (solid or liquid). If the medicine is mixed with food, it should be taken right away. However, if it is mixed with water, the solution can be stored for up to one week at room temperature or in the refrigerator.
- Shake the mixed solution lightly before each use. Measure the dose with the level teaspoon or tablespoon that comes together with the package of sodium phenylbutyrate.
Take sodium phenylbutyrate with meals or feedings.
It is important that you follow any special instructions from your doctor, such as following a low-protein diet. Also, your doctor may recommend that you take amino acid supplements. If you have any questions about this, check with your doctor.
The dose of sodium phenylbutyrate will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of sodium phenylbutyrate. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For too much ammonia in the body:
- For oral dosage form (powder for solution):
- Adults, teenagers, and children weighing 20 kilograms (kg) (44 pounds) or more—The dose is based on body size and must be determined by your doctor. It is usually given four to six times a day with meals or feedings. The dose is usually not more than 20 grams a day.
- Children weighing up to 20 kg (44 pounds)—The dose is based on body weight and must be determined by your doctor. The usual dose is 450 to 600 milligrams (mg) per kilogram (kg) (205 to 273 mg per pound) of body weight per day. The dose is divided in equal amounts and given three to six times a day with meals or feedings. The dose is usually not more than 20 grams a day.
- For oral dosage form (tablets):
- Adults, teenagers, and children weighing 20 kg (44 pounds) or more—The dose is based on body size and must be determined by your doctor. It is usually given three times a day with meals or feedings. The dose is usually not more than 20 grams (40 tablets) a day.
- Children weighing up to 20 kg (44 pounds)—Use of the tablets is not recommended.
- For oral dosage form (powder for solution):
If you miss a dose of sodium phenylbutyrate, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
A strong, musty odor is normal for your medicine.
Precautions While Using This Medicine
It is very important that your doctor check your progress at regular visits to make sure that sodium phenylbutyrate is working properly. Blood tests may be needed to check for unwanted effects.
In case of emergency—There may be a time when you need emergency help for a problem caused by your urea cycle disorders. You need to be prepared for these emergencies. It is a good idea to wear a Medic Alert tag at all times. Also, carry an ID card in your wallet or purse that says you have this disease and a list of all of your medicines.
Check with your doctor right away if you have lightheadedness or sleepiness. These maybe symptoms of more serious problems.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.
This Medicine Side Effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
- Change in the frequency of breathing
- lack of or irregular menstruation
- lower back, side, or stomach pain
- mood or mental changes
- muscle pain or twitching
- nausea or vomiting
- nervousness or restlessness
- swelling of the feet or lower legs
- unpleasant taste
- unusual tiredness or weakness
- joint pain
- sore throat
- unusual bleeding or bruising
- Convulsions (seizures)
- dryness of the mouth
- fast, slow, or irregular heartbeat
- increased blood pressure
- increased thirst
- muscle cramps
- rectal bleeding
- swelling of the face
- unusual weight gain
- weak pulse
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- Changes in taste
- decreased appetite
- strong body odor
- Abdominal or stomach pain
- mental depression
- skin rash
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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More about sodium phenylbutyrate
- Sodium phenylbutyrate Side Effects
- During Pregnancy
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- Drug class: urea cycle disorder agents
Other brands: Buphenyl