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glycerol phenylbutyrate (Oral route)

GLI-ser-ol fen-il-BUE-ti-rate

Commonly used brand name(s)

In the U.S.

  • Ravicti

Available Dosage Forms:

  • Solution

Therapeutic Class: Hyperammonemia Agent

Uses For glycerol phenylbutyrate

Glycerol phenylbutyrate is used together with a proper diet to treat urea cycle disorders. glycerol phenylbutyrate is used in patients who cannot be treated with a low-protein diet and amino acid supplements.

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. glycerol phenylbutyrate works by helping to remove ammonia (nitrogen) from the body reduce high high levels of ammonia in the blood.

glycerol phenylbutyrate is available only with your doctor's prescription.

Before Using glycerol phenylbutyrate

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 glycerol phenylbutyrate, the following should be considered:


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


Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of glycerol phenylbutyrate in children. However, safety and efficacy have not been established in children 2 months up to 2 years of age. Use of glycerol phenylbutyrate is not indicated in children younger than 2 months of age.


Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of glycerol phenylbutyrate in the elderly. However, elderly patients are more likely to have kidney or liver problems, which may require caution and an adjustment in the dose for patients receiving glycerol phenylbutyrate.

Breast Feeding

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

  • Intestinal malabsorption (trouble absorbing food in the intestines) or
  • Pancreatic insufficiency (trouble digesting food properly caused by lack of enzymes made by the pancreas)—May not work properly in patients with these conditions.
  • Kidney disease or
  • Liver disease, moderate to severe—Higher blood levels of glycerol phenylbutyrate may result and increase the risk of side effects.
  • Nerve problems—Use with caution. May make this condition worse.

Proper Use of glycerol phenylbutyrate

Take glycerol 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.

glycerol phenylbutyrate comes with a Medication Guide. Read and follow the instructions carefully. Ask your doctor if you have any questions.

It is important that you or your child follow any special diet instructions from your doctor, such as using a low-protein diet. If you have any questions about this, check with your doctor.

Use an oral syringe or dosing cup to measure your dose. You may also give glycerol phenylbutyrate with a nasogastric tube or gastrostomy tube (g-tube).

To use the oral liquid with a nasogastric tube or g-tube:

  • Use an oral syringe to measure your dose and place it on the tip of the nasogastric tube or g-tube.
  • Inject the medicine into the tube.
  • Flush the tube with 30 mL of water to rinse all of the medicine into the stomach.
  • Rinse the tube again with additional 30 mL of water to clear the tube.


The dose of glycerol 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 glycerol 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 oral dosage form (liquid):
    • For treatment of urea cycle disorders:
      • For patients not on phenylbutyrate treatment:
        • Adults, teenagers, and children 2 years of age and older—Dose is based on body size and must be determined by your doctor. The dose is 4.5 to 11.2 milliliters (mL) per square meter (m[2]) per day and divided into 3 equal doses. Your doctor may adjust your dose as needed. However, the dose is usually not more than 17.5 mL per day.
        • Children 2 months up to 2 years of age—Use and dose must be determined by your doctor.
        • Children younger than 2 months of age—Use is not indicated.
      • For patients switching from sodium phenylbutyrate to Ravicti™:
        • Adults, teenagers, and children 2 years of age and older—The dose is the total daily dose of sodium phenylbutyrate that you are already taking multiplied by 0.8 and divided into 3 equal doses. Your doctor may adjust your dose as needed. However, the dose is usually not more than 17.5 milliliters (mL) per day.
        • Children 2 months up to 2 years of age—Use and dose must be determined by your doctor.
        • Children younger than 2 months of age—Use is not indicated.

Missed Dose

If you miss a dose of glycerol 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.

Precautions While Using glycerol phenylbutyrate

It is very important that your doctor check the progress of you or your child at regular visits to make sure that glycerol phenylbutyrate is working properly. Blood tests may be needed to check for unwanted effects.

Check with your doctor right away if you have burning, tingling, numbness or pain in the hands, arms, feet, or legs, headache, lightheadedness, confusion, memory problems, sleepiness or unusual drowsiness, change or loss of taste, hearing loss, or unusual tiredness or weakness. 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.

glycerol phenylbutyrate 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:

More common
  • Continuing nausea or vomiting
  • increase in the frequency of seizures
  • loss of appetite
  • swelling of the face
  • tiredness and weakness

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:

More common
  • Bloated or full feeling
  • diarrhea
  • excess air or gas in the stomach or intestines
  • headache
  • nausea
  • passing gas
  • rash
  • upper abdominal or stomach pain
  • vomiting
Less common
  • Acid or sour stomach
  • belching
  • heartburn
  • indigestion
  • stomach discomfort or upset

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)

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