Glycerol Phenylbutyrate (Oral)


Glycerol phenylbutyrate is used alongside a proper diet to treat urea cycle disorders. This medication is used in patients who cannot be treated with amino acid supplements or a low-protein diet.

Ammonia is formed due to the breakdown of protein in the body. If the body can't remove this ammonia, then a buildup can cause serious unwanted effects. This medication works by helping to remove ammonia from the body to reduce higher levels of ammonia in the blood.

This medication is only available with a prescription from your doctor. It is available in the form of a solution.

Conditions treated

  • Inherited Deficiency of Arginosuccinate Lyase

Type of medication

  • Solution

Side effects

Along with the intended effects of this medication, the consumption of Glycerol Phenylbutyrate can cause some unwanted side effects. Not all of these side effects may be present, but if they do occur, you may need to seek medical attention.

Inform your doctor or healthcare professional right away if you suffer from any of the following side effects whilst taking Glycerol Phenylbutyrate:

More common side effects

  • Loss of appetite

Some side effects which occur usually don't require medical attention. You will find that these side effects begin to subside once your body begins adjusting to the medication. If they are bothersome, you can contact your local pharmacist or healthcare professional for advice on ways to prevent or reduce the severity of these side effects. Seek advice from a medical professional if any of the side effects listed below become bothersome or persist.

More common side effects

  • A rash

Less common side effects

  • Belching

You may suffer from other side effects that are not listed below. If you notice anything unusual, you should seek advice from your local healthcare professional. Remember to report all side effects to the FDA on 1-800-FDA-1088.


The final dose received of any medication will depend on a number of factors including your age, weight and height, your reaction to the first dose, the strength of the medication and any other medications you are currently taking. It's important that you do not change or alter your dose without consultation with your doctor. If you take too much of a medication you may increase your risk of severe side effects, and if you take too little, then you reduce the effectiveness of the drug. Drug dosages are based on individuality.

For treatment of urea cycle disorders

For patients not on phenylbutyrate treatment:

Adults, teenagers, and children aged two and above: The dose is based on body size and will be determined by your doctor. The dose is 4.5 to 11.2 milliliters per square meter each day and divided into three equal doses. Your doctor will adjust your dose if necessary and as required. However, the dose is typically not more than 17.5 mL daily.

  • Children aged two months up to two years old: The dose and use must be determined by your doctor.
  • Children younger than two months old: This drug should not be used.
  • For patients switching from sodium phenylbutyrate to Ravictiâ„¢:
  • Adults, teenagers, and children two years of age and above: The final dose is the total daily dose of sodium phenylbutyrate that you have already been given multiplied by 0.8 and then split into three equal doses. The dose is typically not more than 17.5 milliliters daily.
  • Children two months up to two years old: As above
  • Children younger than two months old: As above

Missed dose If you miss a dose of this medication, you should take it as soon as you remember. However, if it's close to the time of your next scheduled dose, then skip the dose you have missed and revert back to your original dosing schedule. Under no circumstances should you double dose.


Interactions between drugs can cause serious reactions and side effects as well as reducing the effectiveness of either drug you are using. To help limit the possibility of interactions it's a good idea to give your doctor or healthcare professional a full list of all the current medications you are taking. This list should include all over the counter drugs, prescription and non-prescription medications, vitamins and any herbal products. You should also make your doctor or healthcare professional aware of any other medical conditions you currently suffer from as this too could increase your risk of interactions.

Inform your doctor if you are taking any of the drugs listed below. Your doctor may alter your dose or the frequency in which you use either medication.

  • Cyclobenzaprine

The presence of other medical conditions can affect the use of this medication. Ensure you let your healthcare professional or doctor know if you suffer from any other medical conditions, especially:

  • Nerve problems caution should be exercised as the use of this drug could make this condition worse.


Allergies You should let your doctor or healthcare professional know if you have ever suffered from an allergic reaction to this drug or similar drugs. You should also make them aware of any other allergies you suffer from including to dyes, animals, preservatives, and foods.

Pediatric population Appropriate studies that have been conducted to date have not indicated a pediatric-specific problem that could limit the effectiveness of glycerol phenylbutyrate in the pediatric population. However, efficacy and safety have not yet been established in children aged two months up to two years of age. The use of this drug is not indicated in children younger than two months old.

Geriatric population Studies conducted to date have not suggested there is a geriatric-specific problem that could reduce the usefulness of this medication in the older population. However, elderly patients are more likely to suffer from liver or kidney problems, which could require a degree of caution and an adjustment in the dose for those patients receiving this drug.

Use in pregnancy and breastfeeding

It is unknown whether this medication can harm an unborn child. You should inform your doctor if you are currently pregnant or intend on falling pregnant.

If you do become pregnant, your name could be listed on a pregnancy registry. This will be to monitor the outcome of the pregnancy and to study any effects of this drug on the infant.

It is unknown whether glycerol phenylbutyrate can pass into breast milk or if it could harm a baby receiving breastmilk. You should discuss this with your doctor, but you should avoid breastfeeding while using this medication.

Proper Use

This medication will come with a Medication Guide. You should follow and read all the instructions and ask your doctor or healthcare professional if you have any questions.

Use a dosing cup or oral syringe to measure your dose.

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

  • Use an oral syringe to measure your dose, then place it on the tip of the g-tube or nasogastric tube.

It's important that your doctor monitors your progress at regular checkup appointments to ensure this medication is working correctly. You can check for side effects with blood tests.

Check with your doctor immediately if you suffer from any of the following problems:

  • Change or loss of taste

These could be signs of more serious problems.


This medication should be stored in a closed container and kept at room temperature. It should be stored away from moisture, heat, and light. You should prevent this medication from freezing. Ensure this medication is kept out of the reach of children. Do not keep medication that has passed its expiry date or you no longer require. You should ask your local pharmacist for specific advice on the best way to dispose of any medication you no longer need.


When used correctly, Glycerol Phenylbutyrate is successful in the treatment of reducing the buildup of ammonia in the blood of those who suffer from urea cycle disorder when used alongside other methods of treatment such as a change in diet. This drug should not be used in children younger than two months old. The safety and efficacy of this medication have not been established in children. Due to a large number of interactions possible, it's important you give your doctor a complete list of all medications you are currently taking. You should let your doctor know if you are pregnant or plan on becoming pregnant whilst using this medication. You should also avoid breastfeeding whilst taking this medication. You should not alter your dose without consultation with your doctor as to do so could increase your risk of side effects and reduce the effects of this drug. If you require any further information about the practical use of this drug or if you have any questions, contact your doctor.