provider image
Welcome! You’re in GoodRx for healthcare professionals. Now, you’ll enjoy a streamlined experience created specifically for healthcare professionals.
Skip to main content

sodium phenylbutyrate

Generic Buphenyl
Used for Inherited Metabolic Diseases, Urea Cycle Disorders
Used for Inherited Metabolic Diseases, Urea Cycle Disorders

Sodium phenylbutyrate is a medication that's used as part of a treatment plan for people with urea cycle disorders (UCDs). It helps prevent the buildup of ammonia in the blood. It comes in tablet and powder form, which are available as lower-cost generic medications. It also comes as oral pellet and oral suspension formulations that are only available as brand-name medications.

Last reviewed on January 2, 2023
basics-icon

What is Sodium phenylbutyrate?

What is Sodium phenylbutyrate used for?

  • Long-term treatment for certain types of urea cycle disorders (UCDs)

How Sodium phenylbutyrate works

Sodium phenylbutyrate is a urea cycle disorder agent. It works by helping the body break down ammonia in people with urea cycle disorders (UCDs). This helps prevent a dangerous buildup of ammonia in the blood.

Normally, proteins in the liver turn ammonia into a waste product known as urea. The kidneys then get rid of urea by passing it in your urine. But in people with UCDs, the proteins that turn ammonia into urea either don't work correctly or are missing. This means that excess ammonia builds up, and the body can't get rid of it. Too much ammonia in the blood is very toxic, especially to the brain.

UCDs are caused by a genetic defect, and the symptoms of the condition start at birth. The toxic effects of ammonia are very serious for anyone, but especially for newborns. If not treated quickly, it can lead to seizures, coma, intellectual disabilities, and problems with motor skills.

Are you looking for information on Ammonul (sodium phenylacetate / sodium benzoate) instead?

Drug Facts

Common BrandsBuphenyl, Pheburane, Olpruva
Drug ClassUrea cycle disorder agent
Controlled Substance ClassificationNot a controlled medication
Generic StatusLower-cost generic available
AvailabilityPrescription only
basics-icon

What are the side effects of Sodium phenylbutyrate?

The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.

Common Side Effects

  • Changes in menstrual cycle (23%)
  • Poor appetite (4%)
  • Body odor (3%)
  • Bad taste in the mouth (3%)

Other Side Effects

  • Stomach pain or upset
  • Nausea or vomiting
  • Headache
  • Fainting
  • Weight gain
  • Depression
  • Rash

Source: DailyMed

The following side effects have also been reported

Side effects that you should report to your care team as soon as possible:

Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):

  • Body odor
  • Change in taste
  • Irregular menstrual cycles or spotting
  • Loss of appetite
pros-and-cons

Pros and cons of Sodium phenylbutyrate

thumbs-up

Pros

Can help manage ammonia levels for people with UCDs

Comes in tablet, oral pellet, powder, and oral suspension form

Tablets and powder available as lower-cost generics

Powder can be given by mouth or through a feeding tube

Powder dissolved in water can be stored for up to 1 week

thumbs-down

Cons

Must take several times a day

Missing a dose can be very serious if not taken in the same day.

Typically lifelong treatment, unless you get a liver transplant (if eligible)

Contains sodium, which can be dangerous for people with certain health conditions

Oral pellets contain sucrose, which can affect blood sugar levels.

pharmacist-tips

Pharmacist tips for Sodium phenylbutyrate

pharmacist
  • While taking sodium phenylbutyrate, stick to a low-protein diet. When protein gets broken down by the body, it raises the amount of ammonia in the blood as a waste product. This can be dangerous if you have a UCD.

    • Depending on the type of UCD you have, you might need to take certain types of dietary supplements. You also might need to work with a nutrition expert to make sure you're getting the proper nutrition.

      • Your provider will do tests to check the level of sodium phenylbutyrate that's in your blood every so often. This is to make sure you're absorbing the right amount of the medication for your condition. Your provider will also do tests to make sure the ammonia and protein levels in your blood stay within the normal range.

        • It's recommended that you wear a Medic Alert tag (or some form of medical alert ID) if you have a UCD. This lets healthcare providers know you have this condition in case you need treatment in an emergency situation. An episode of high blood ammonia can cause you to pass out, which requires quick, emergency treatment.

          For the sodium phenylbutyrate (Buphenyl) powder

          • Be sure to use the dosing spoons that are included with the medication to measure your dose properly. Household spoons should never be used to measure medications because they might not be accurate, even if you're specifically using a teaspoon or tablespoon.

            • Shake the sodium phenylbutyrate powder gently before measuring it out. The powder can be mixed with food, but must be eaten right away. If the food mixture sits for too long, the medication might not work as well. You can also mix the powder with water; you can store this mixture for up to 1 week at room temperature or in the refrigerator after it dissolves in the water.

              For the Pheburane oral pellets

              • Use the included dosing spoon to measure Pheburane oral pellets to make sure you get an accurate dose. This dosing spoon measures out the dose in grams of sodium phenylbutyrate.

                • Swallow the oral pellets with a drink (e.g., water, fruit juices, protein-free infant formulas). You can also sprinkle the oral pellets onto a spoonful of applesauce or carrot puree, and then swallow the dose right away. Sprinkling it on other foods isn't recommended since it hasn't been studied.

                  • Don't chew the oral pellets or mix them into liquids because this can damage the coating on the pellets. Also swallow the oral pellets right after drinking or sprinkling on top of applesauce or carrot puree so the coating doesn't dissolve. Damage to the coating might cause the medication to not work as well.

                    For the Olpruva oral suspension

                    • When you get the medication, you'll get two different packets called Olpruva and Mix-Aid packets. The Olpruva packets contain sodium phenylbutyrate (the medication), and the Mix-Aid packets contain a substance that helps the medication become a mixture that you can drink when all added to water.

                      • Pour all of the contents of the Mix-Aid packet into a cup with about 4 ounces (one-half cup) of water, and stir. Then, empty the entire Olpruva packet(s) needed for your dose into the cup, and stir to make a mixture.

                        • Drink all of the mixture within 5 minutes of stirring. If you haven't consumed the mixture after 30 minutes, throw it away.

                          • Add another 4 ounces (one-half cup) of water into the same cup. Then, drink the water to make sure you've taken all of the medication in the cup.

                            faqs

                            Frequently asked questions about Sodium phenylbutyrate

                            How do I take sodium phenylbutyrate?
                            Sodium phenylbutyrate comes in many formulations (tablets, powder, oral pellets, and oral suspension), and they each have specific directions. In general, your daily dose of sodium phenylbutyrate should be divided up evenly throughout the day with each meal or feeding. Your or your child's provider will tell you how much medication to take at each meal or feeding. The powder can be given by mouth or through a feeding tube, while the tablets, oral pellets, and oral suspension can only be taken by mouth. Please refer to the Pharmacist Tips for more information on how to take each formulation of sodium phenylbutyrate, or ask your provider or pharmacist if you have any questions.
                            What should I do if I miss a dose of sodium phenylbutyrate?
                            If you forget to take a dose of sodium phenylbutyrate, take or give it as soon as possible that same day. If you remember the next day that you missed a dose the day before, contact your or your child's provider right away. They might want to check the blood for ammonia, protein, or medication levels. This is because there can be very serious side effects if a dose is missed. So, it's very important for you or your child to take the full amount of medication prescribed for a 24-hour period.
                            Who shouldn't take sodium phenylbutyrate?
                            Sodium phenylbutyrate should only be used by people with UCDs. If you or your child has heart, kidney, or liver problems, this medication might not be safe to take. Taking sodium phenylbutyrate can cause sodium to build up in your blood. If you have these conditions, this can lead to worsening heart problems, high blood pressure, or swelling. Ask your provider if sodium phenylbutyrate is right for you or your child.
                            Does sodium phenylbutyrate interact with any medications?
                            Yes. You shouldn't take sodium phenylbutyrate with valproic acid or haloperidol. These two medications can cause higher levels of ammonia in your blood, which is dangerous for people with UCDs. Steroids can break down protein in the body, which can also lead to higher ammonia levels. In addition, a gout medication known as probenecid might affect the way your body gets rid of sodium phenylbutyrate. This might put you at risk for more side effects from sodium phenylbutyrate. Ask your provider before taking any of these medications if you're being treated with sodium phenylbutyrate.
                            How common are UCDs?
                            UCDs overall affect 1 in 35,000 births. Most UCDs are diagnosed shortly after birth. Keep in mind that there are different kinds of UCDs. The type that you or your child is diagnosed with depends on which specific proteins don't work correctly or are missing.
                            GoodRxEducationalIcon

                            How to save using GoodRx

                            Compare Prices
                            1. Compare PricesSpecify your dosage and quantity to find out exactly how much you can save.
                            Select your free coupon
                            2. Select your free couponYou can use the displayed coupon, or compare prices at other pharmacies near you.
                            Show coupon to your pharmacist
                            3. Show coupon to your pharmacistPresent your printed or electronic coupon when you pick up your prescription.
                            Get free couponLearn more
                            warings-icon

                            What are the risks and warnings for Sodium phenylbutyrate?

                            Sodium phenylbutyrate can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.

                            risk-warning

                            High sodium levels

                            • Risk factors: Serious heart, liver, or kidney problems

                              The tablet, powder, oral pellets, and oral suspension forms of sodium phenylbutyrate all contain sodium. This can be dangerous for people who have serious kidney, liver, or heart problems. Too much sodium can build up in your blood, cause your body to hold onto water, and lead to swelling. This can cause high blood pressure and worsening medical problems. Talk to your provider before you take sodium phenylbutyrate if you have these conditions.

                              risk-warning

                              Damage to nerves

                              Sodium phenylbutyrate is broken down into a substance called phenylacetate. Some people receiving injections of phenylacetate (e.g., Ammunol (sodium phenylacetate / sodium benzoate)) have reported nerve damage. Sodium phenylbutyrate isn't approved as an injection, and studies show that nerve damage isn't likely to happen when taking sodium phenylbutyrate by mouth or through a feeding tube. While this risk is low, make sure to let your provider know if you experience extreme tiredness, dizziness, lightheadedness, headache, confusion, memory problems, or nerve pain.

                              risk-warning

                              Low potassium levels

                              It's possible that sodium phenylbutyrate could cause your potassium levels to drop too low. While quite rare, it's important to be aware of this risk. If you experience nausea or vomiting, muscle weakness or spasms, or irregular heart beat, let your provider know right away.

                              risk-warning

                              Contains sucrose (Pheburane oral pellets only)

                              • Risk factors: History of diabetes | Genetic conditions affecting the ability to digest sugars

                                Pheburane oral pellets contain sucrose, which is a type of sugar. This can affect your blood sugar levels. If you have diabetes, talk to your provider before taking Pheburane to make sure it's safe for you. This medication should be avoided if you have certain conditions that affect your ability to digest sugars.

                                dosage

                                Sodium phenylbutyrate dosage forms

                                Typical dosing for Sodium phenylbutyrate

                                Your provider will determine the right total daily dose for you or your child. The total daily dose is split into equal doses throughout the day (3 to 6 times per day). Each dose is taken with each meal or feeding.

                                The powder can be taken by mouth or through a feeding tube. The tablets, oral pellets (Pheburane), and oral suspension (Olpruva) can only be taken by mouth.

                                • Adults and children weighing more than 44 lbs (all formulations): The dose is based on your body surface area (BSA), which takes into account both your height and weight. The typical dose is 9.9 grams/m2 to 13 grams/m2 of BSA per day.

                                • Children weighing less than 44 lbs (powder and oral pellets only): The dose is based on your child's body weight. The typical dose is 450 mg/kg to 600 mg/kg of body weight per day.

                                contraindications-icon

                                Sodium phenylbutyrate contraindications

                                Contraindications are specific health conditions or situations in which a person should not take a medication due to safety concerns. If you have any of the following conditions or if any of the following apply to you, let your healthcare provider know because Sodium phenylbutyrate will not be safe for you to take.
                                • Treating an emergency episode of high ammonia

                                alternatives

                                What are alternatives to Sodium phenylbutyrate?

                                There are a number of medications that your doctor can prescribe in place of Sodium phenylbutyrate. Compare a few possible alternatives below.
                                Sodium phenylbutyrate
                                Used for:
                                • Long-term treatment for certain types of urea cycle disorders (UCDs)

                                Used for:
                                • Long-term treatment of urea cycle disorders (UCDs)

                                Get savings updates for Sodium phenylbutyrate

                                Receive price alerts, news, and other messages from GoodRx about Sodium phenylbutyrate and other healthcare topics and relevant savings offers.

                                By providing your email, you consent to receive marketing communications from GoodRx, which may include content and/or data related to men’s health, women's health, reproductive care, or sexual health. You agree to the GoodRx Terms of Use and acknowledge the Privacy Policy. You can unsubscribe at any time.

                                References

                                Best studies we found

                                Acer Therapeutics Inc. (2022). Olpruva (sodium phenylbutyrate) for oral suspension [package insert].

                                American Chemical Society. (2021). Urea.

                                American Heart Association. (2022). Get the scoop on sodium and salt.

                                View All References (7)

                                Centers for Disease Control and Prevention. (2020). Spoons are for soup, milliliters are for medicine.

                                Flint, B., et al. (2023). Body surface area. StatPearls.

                                Horizon Therapeutics plc. (n.d.). Urea cycle disorders 101.

                                Horizon Therapeutics USA, Inc. (2023). Bupheyl- sodium phenylbutyrate tablet; sodium phenylbutyrate powder [package insert]. DailyMed.

                                Medunik USA. (2023). Pheburane- sodium phenylbutyrate pellet; sodium phenylbutyrate kit [package insert]. DailyMed.

                                Mokhtarani, M., et al. (2013). Elevated phenylacetic acid levels do not correlate with adverse events in patients with urea cycle disorders or hepatic encephalopathy and can be predicted based on the plasma PAA to PAGN ratio. Molecular Genetics and Metabolism.

                                Stone, W. L., et al. (2023). Urea cycle disorders. StatPearls.

                                GoodRx Health has strict sourcing policies and relies on primary sources such as medical organizations, governmental agencies, academic institutions, and peer-reviewed scientific journals. Learn more about how we ensure our content is accurate, thorough, and unbiased by reading our editorial guidelines.
                                Was this page helpful?

                                Browse medications

                                View All

                                Research prescriptions and over-the-counter medications from A to Z, compare drug prices, and start saving.