Skip to Content
Get facts about myelofibrosis treatment options here

sodium phenylbutyrate

Generic Name: sodium phenylbutyrate (SOE dee um FEN il BUE ti rate)
Brand Name: Buphenyl

What is sodium phenylbutyrate?

Sodium phenylbutyrate is converted to a substance in the body that helps the kidneys eliminate waste substances from the body. These waste substances can produce ammonia, which is toxic if it builds up in your blood.

Sodium phenylbutyrate is used to treat urea cycle disorders in people who lack certain liver enzymes needed to properly eliminate waste substances from the body. This medicine helps prevent a build-up of ammonia in the blood.

Sodium phenylbutyrate may also be used for other purposes not listed in this medication guide.

What is the most important information I should know about sodium phenylbutyrate?

Seek emergency medical attention if you notice any signs of ammonia build-up, including mood or behavior changes, memory loss, thinking problems, muscle twitching, back and forth movement of the eyes, vomiting, increasing weakness, slurred speech, seizure (convulsions), and fainting.

Sodium phenylbutyrate will not treat immediate symptoms of an ammonia build-up.

What should I discuss with my health care provider before taking sodium phenylbutyrate?

You should not use sodium phenylbutyrate if you are allergic to it. This medicine will not treat immediate symptoms of an ammonia build-up.

To make sure sodium phenylbutyrate is safe for you, tell your doctor if you have:

  • congestive heart failure;

  • high blood pressure;

  • severe kidney disease;

  • swelling or fluid retention; or

  • epilepsy or other seizure disorder.

FDA pregnancy category C. It is not known whether sodium phenylbutyrate will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medicine.

It is not known whether sodium phenylbutyrate passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Do not give this medicine to a child who weighs less than 44 pounds unless your doctor tells you to.

How should I take sodium phenylbutyrate?

Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Take this medicine with each meal. Divide your total daily dose among all of your meals for the day.

Sodium phenylbutyrate powder should be mixed with food before consuming.

Shake the powder lightly before mixing it with food.

Use sodium phenylbutyrate regularly to get the most benefit. Get your prescription refilled before you run out of medicine completely. You may need to take this medicine for the rest of your life.

Call your doctor right away if you have any signs of infection such as fever, chills, redness, swelling, body aches, or weakness. An infection may cause your condition to go out of control even while you are taking sodium phenylbutyrate.

While using sodium phenylbutyrate, you may need frequent blood tests.

Sodium phenylbutyrate is only part of a treatment program that may also include diet, dialysis, and other medications. Follow your doctor's instructions very closely.

Keep using this medicine even if you feel well. Your condition may have no symptoms. If the urea cycle disorder is not under control, you may have a build-up of ammonia, which can cause life-threatening side effects.

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

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

Be sure to take this medicine with food.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking sodium phenylbutyrate?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Sodium phenylbutyrate side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Even with treatment, urea cycle disorders can cause a build-up of ammonia in the blood which can result in life-threatening side effects. Seek emergency medical attention if you notice any signs of ammonia build-up, including mood or behavior changes, memory loss, thinking problems, muscle twitching, back and forth movement of the eyes, vomiting, increasing weakness, slurred speech, seizure (convulsions), and fainting.

Call your doctor at once if you have:

  • severe drowsiness, confusion;

  • swelling, rapid weight gain;

  • a light-headed feeling, like you might pass out; or

  • pale skin, feeling short of breath, rapid heart rate.

Common side effects may include:

  • missed menstrual periods, changes in your regular cycle;

  • loss of appetite;

  • headache; or

  • unusual or unpleasant taste in your mouth.

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.

See also: Side effects (in more detail)

Sodium phenylbutyrate dosing information

Usual Adult Dose for Urea Cycle Disorders:

Patients weighing less than 20 kg: 450 to 600 mg/kg/day
Patients larger than 20 kg: 9.9 to 13 g/m2/day

Maximum dose: The safety or efficacy of doses in excess of 20 g (40 tablets) per day has not been established.

Comments:
-The tablets and powder are to be taken in equally divided amounts with each meal or feeding.
-Treatment must be combined with dietary protein restriction and, in some cases, essential amino acid supplementation.

Nutritional Management:
-To promote growth and development, plasma levels of ammonia, arginine, branched-chain amino acids, and serum protein should be maintained within normal limits while plasma glutamine is maintained at levels less than 1000 micromole/L.
-The allocation of dietary nitrogen into natural protein and essential amino acids is a function of age, residual urea-cycle enzyme activity, and the dose of sodium phenylbutyrate.
-Patients with argininosuccinic acid synthetase deficiency and those with late-onset disease (partial deficiencies, including females heterozygous for ornithine transcarbamylase), initially may receive a diet containing the age-determined minimal daily natural protein allowance. The protein intake may be increased as tolerated and determined by plasma glutamine and other amino acid levels.
-Citrulline supplementation is required and recommended for patients diagnosed with neonatal-onset deficiency of carbamylphosphate synthetase (CPS) or ornithine transcarbamylase (OTC); citrulline daily intake is recommended at 0.17 g/kg/day or 3.8 g/m2/day.
-The free-base form of arginine may be used instead of citrulline in patients with milder forms CPS and OTC deficiency (daily intake is recommended at 0.17 g/kg/day or 3.8 g/m2/day).
-Arginine supplementation is needed for patients diagnosed with deficiency of argininosuccinic acid synthetase; arginine (free base) daily intake is recommended at 0.4 to 0.7 g/kg/day or 8.8 to 15.4 g/m2/day.

Usual Pediatric Dose for Urea Cycle Disorders:

Patients weighing less than 20 kg: 450 to 600 mg/kg/day
Patients larger than 20 kg: 9.9 to 13 g/m2/day

Maximum dose: The safety or efficacy of doses in excess of 20 g (40 tablets) per day has not been established.

Comments:
-Tablets indicated for children weighing more than 20 kg and for adults
-The tablets and powder are to be taken in equally divided amounts with each meal or feeding.
-Treatment must be combined with dietary protein restriction and, in some cases, essential amino acid supplementation.

Nutritional Management:
-To promote growth and development, plasma levels of ammonia, arginine, branched-chain amino acids, and serum protein should be maintained within normal limits while plasma glutamine is maintained at levels less than 1,000 micromole/L.
-The allocation of dietary nitrogen into natural protein and essential amino acids is a function of age, residual urea-cycle enzyme activity, and the dose of sodium phenylbutyrate.
-At the recommended dose of sodium phenylbutyrate, infants with neonatal-onset carbamylphosphate synthetase (CPS) or ornithine transcarbamylase (OTC) deficiencies initially receive a daily dietary protein intake limited to approximately 1.6 g/kg/day for the first 4 months of life. If tolerated, the daily protein intake may be increased to 1.9 g/kg/day during this period.
-From 4 months to 1 year of age, it is recommended that the infant receive at least 1.4 g/kg/day, but 1.7 g/kg/day is advisable.
-From 1 to 3 years of age, the protein intake should not be less than 1.2 g/kg/day; 1.4 g/kg/day is advisable during this period.
-For neonatal-onset patients with CPS or OTC deficiency who are at least 6 months of age, it is recommended that the daily protein intake be equally divided between natural protein and supplemental essential amino acids.
-Citrulline supplementation is required and recommended for patients diagnosed with neonatal-onset deficiency of carbamylphosphate synthetase (CPS) or ornithine transcarbamylase (OTC); citrulline daily intake is recommended at 0.17 g/kg/day or 3.8 g/m2/day.
-The free-base form of arginine may be used instead of citrulline in patients with milder forms CPS and OTC deficiency (daily intake is recommended at 0.17 g/kg/day or 3.8 g/m2/day).
-Arginine supplementation is needed for patients diagnosed with deficiency of argininosuccinic acid synthetase; arginine (free base) daily intake is recommended at 0.4 to 0.7 g/kg/day or 8.8 to 15.4 g/m2/day.

What other drugs will affect sodium phenylbutyrate?

Tell your doctor about all medicines you use, and those you start or stop using during your treatment with sodium phenylbutyrate, especially:

  • divalproex (Depakote);

  • haloperidol (Haldol); or

  • valproic acid (Depakene, Stavzor).

This list is not complete. Other drugs may interact with sodium phenylbutyrate, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Where can I get more information?

  • Your pharmacist can provide more information about sodium phenylbutyrate.
  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
  • Disclaimer: Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2012 Cerner Multum, Inc. Version: 3.01. Revision Date: 2014-07-16, 12:00:50 PM.

Hide