Health Guide
Drug Guide

Sodium phenylbutyrate (Oral route)


SOE-dee-um fen-il-BUE-ti-rate

Brand Names:

Dosage Forms:



Hyperammonemia Agent


Histone Deacetylase Inhibitor

Uses of 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. This medicine works by helping to reduce high levels of ammonia in the blood.

This medicine 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 this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine 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.

Older adults

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.

Other 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.

Other interactions

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 this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

Proper Use of This Medicine:

Take this medicine 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.

This medicine 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 this medicine:

Take this medicine 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 this medicine 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 this medicine. 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.

Missed dose

If you miss a dose of this medicine, 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 this medicine 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.

Side Effects of This Medicine:

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:

More common
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
Less common
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:

Less common
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.

Last Updated: 10/12/2016

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Thomson & A.D.A.M