What is glycerol phenylbutyrate?

Glycerol phenylbutyrate oral liquid is a clear, colorless to pale yellow oral liquid. It is insoluble in water and most organic solvents, and it is soluble in dimethylsulfoxide (DMSO) and greater than 65% acetonitrile. Glycerol phenylbutyrate is a nitrogen-binding agent. It is a triglyceride containing 3 molecules of PBA linked to a glycerol backbone, the chemical name of which is benzenebutanoic acid, 1', 1' ' –(1,2,3-propanetriyl) ester with a molecular weight of 530.65. It has a molecular formula of C 33 H 38 O 6 . The structural formula is: structure

What kind of drug is glycerol phenylbutyrate?

The FDA classifies glycerol phenylbutyrate as a nitrogen binding agent. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.

Can you take glycerol phenylbutyrate with other medicines?

It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run glycerol phenylbutyrate against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.

What brand names is glycerol phenylbutyrate sold under?

We track 2 glycerol phenylbutyrate-containing products in the U.S.: Glycerol Phenylbutyrate and Ravicti. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.

What forms does glycerol phenylbutyrate come in?

Across the brands we track, glycerol phenylbutyrate is currently marketed as liquid, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.

Is there a generic glycerol phenylbutyrate?

Yes. Our catalog lists 1 generic glycerol phenylbutyrate product alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.

Glycerol Phenylbutyrate: uses, dosing, side effects & brands

Glycerol Phenylbutyrate is a nitrogen binding agent sold in the U.S. under 2 brand and generic names. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.

By the pharmaranks editorial teamReviewed against the FDA (openFDA label, NDC Directory & Enforcement) sourcesHow we research

Key facts

Drug class: Nitrogen Binding Agent
Available as: Liquid
Sold as: 2 products — Glycerol Phenylbutyrate and Ravicti
Prescription?: Prescription only
Generic available?: Yes

How glycerol phenylbutyrate is dosed

From the FDA label for Glycerol Phenylbutyrate (application ANDA218738). Other glycerol phenylbutyrate products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.

Glycerol phenylbutyrate oral liquid should be prescribed by a physician experienced in management of UCDs. For administration and preparation, see full prescribing information. ( 2.1 , 2.6 ) Switching From Sodium Phenylbutyrate Tablets or Powder to Glycerol Phenylbutyrate Oral Liquid: Patients should receive the dosage of glycerol phenylbutyrate oral liquid that contains the same amount of phenylbutyric acid, see full prescribing information for conversion. ( 2.2 ) Initial Dosage in Phenylbutyrate-Naïve Patie nts ( 2.3 ): Recommended dosage range is 4.5 to 11.2 mL/m 2 /day (5 to 12.4 g/m 2 /day). For patients with some residual enzyme activity not adequately controlled with dietary restriction, the recommended starting dose is 4.5 mL/m 2 /day. Take into account patient's estimated urea synthetic capacity, dietary protein intake, and diet adherence. Dosage Adjustment and Monitoring: Follow plasma ammonia levels to determine the need for dosage titration. ( 2.4 ) Dosage Modifications in Patients with Hepatic Impairment: Start dosage at lower end of range. ( 2.5 , 8.7 ) 2.1 Important Administration Instructions Glycerol phenylbutyrate oral liquid should be prescribed by a physician experienced in the management of UCDs. Instruct patients to take glycerol phenylbutyrate oral liquid with food or formula and to administer directly into the mouth via oral syringe. Instruct patients…

Glycerol Phenylbutyrate side effects

The following clinically significant adverse reactions are described elsewhere in the labeling: Neurotoxicity [see Warnings and Precautions ( 5.1 )] Pancreatic insufficiency or Intestinal Malabsorption [see Warnings and Precautions ( 5.2 )] Most common adverse reactions (≥10%) in adults are: diarrhea, flatulence, and headache. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Teva at 1-888-838-2872 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. Assessment of adverse reactions was based on exposure of 45 adult patients (31 female and 14 male) with UCD subtype deficiencies of ornithine transcarbamylase (OTC, n=40), carbamoyl phosphate synthetase (CPS, n=2), and argininosuccinate synthetase (ASS, n=1) in a randomized, double-blind, active-controlled (glycerol phenylbutyrate oral liquid vs sodium phenylbutyrate), crossover, 4-week study (Study 1) that enrolled patients 18 years of age and older [see Clinical Studies ( 14.1 )] . One of the 45 patients received only sodium phenylbutyrate prior to withdrawing on day 1 of the study due to an adverse reaction. The most common…

Every glycerol phenylbutyrate product we track (2)

Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.

Glycerol Phenylbutyrate products
#	Drug	Rating	Type	Form	Generic?	Typical price
1	Glycerol Phenylbutyrate	46/100	Prescription	Liquid	—	—	View →
2	Ravicti	Not yet rated	Prescription	Liquid	—	—	View →

Frequently asked questions

What is glycerol phenylbutyrate?: Glycerol phenylbutyrate oral liquid is a clear, colorless to pale yellow oral liquid. It is insoluble in water and most organic solvents, and it is soluble in dimethylsulfoxide (DMSO) and greater than 65% acetonitrile. Glycerol phenylbutyrate is a nitrogen-binding agent. It is a triglyceride containing 3 molecules of PBA linked to a glycerol backbone, the chemical name of which is benzenebutanoic acid, 1', 1' ' –(1,2,3-propanetriyl) ester with a molecular weight of 530.65. It has a molecular formula of C 33 H 38 O 6 . The structural formula is: structure
What kind of drug is glycerol phenylbutyrate?: The FDA classifies glycerol phenylbutyrate as a nitrogen binding agent. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take glycerol phenylbutyrate with other medicines?: It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run glycerol phenylbutyrate against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is glycerol phenylbutyrate sold under?: We track 2 glycerol phenylbutyrate-containing products in the U.S.: Glycerol Phenylbutyrate and Ravicti. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does glycerol phenylbutyrate come in?: Across the brands we track, glycerol phenylbutyrate is currently marketed as liquid, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.

Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.

Glycerol Phenylbutyrate drug interactions

Corticosteroids, valproic acid, or haloperidol : May increase plasma ammonia level; monitor ammonia levels closely. ( 7.1 ) Probenecid : May affect renal excretion of metabolites of glycerol phenylbutyrate oral liquid, including phenylacetylglutamine (PAGN) and PAA. ( 7.2 ) CYP3A4 Substrates with narrow therapeutic index (e.g., alfentanil, quinidine, cyclosporine) : Glycerol phenylbutyrate oral liquid may decrease exposure; monitor for decreased efficacy of the narrow therapeutic index drug. ( 7.3 ) Midazolam : Decreased exposure; monitor for suboptimal effect of midazolam. ( 7.3 ) 7.1 Potential for Other Drugs to Affect Ammonia Corticosteroids Use of corticosteroids may cause the breakdown of body protein and increase plasma ammonia levels. Monitor ammonia levels closely when corticosteroids and glycerol phenylbutyrate oral liquid are used concomitantly. Valproic Acid and Haloperidol Hyperammonemia may be induced by haloperidol and by valproic acid. Monitor ammonia levels closely when use of valproic acid or haloperidol is necessary in patients with UCDs. 7.2 Potential for Other Drugs to Affect Glycerol Phenylbutyrate Oral Liquid Probenecid Probenecid may inhibit the renal excretion of metabolites of glycerol phenylbutyrate oral liquid including PAGN and PAA. 7.3 Potential for Glycerol Phenylbutyrate Oral Liquid to Affect Other Drugs Drugs with narrow therapeutic index that…