Prescription medicine
Glycerol phenylbutyrate Brand names: Ravicti
Glycerol phenylbutyrate (Ravicti) is a prescription medicine with an FDA approval on record since 2013. FDA's NDC Directory lists it from 7 generic labelers.
- Generic listed
- A presentation discontinued
Check it at the source: the glycerol phenylbutyrate FDA label on DailyMed (effective October 29, 2025, Horizon Therapeutics USA, Inc.); the NDA 203284 record on Drugs@FDA; every glycerol phenylbutyrate label on DailyMed.
Highlights of the record
FDA label of October 29, 2025; NDC Directory, Drugs@FDA and Orange Book, October 8, 2026
Used for
From the label: indications and usageRAVICTI is indicated for use as a nitrogen-binding agent for chronic management of patients with urea cycle disorders (UCDs) who cannot be managed by dietary protein restriction and/or amino acid supplementation alone.
Forms and strengths
- 1.1 g/ml
Liquid.
On the market
- Earliest approval on file
- February 1, 2013 Ravicti, Horizon Therap Us; Drugs@FDA’s file, where older or withdrawn approvals can be missing
- Generic approvals
- 7 first December 2, 2021; 7 with a marketed status in Drugs@FDA
- Labelers listed (NDC)
- 9 of which 7 under generic applications, 2 under brand applications, repackagers included
- Last listed patent
- September 22, 2030 Ravicti liquid; not a generic launch date
Supply and safety
- Pharmacy cost (NADAC)
- Not in the survey
- Shortage (FDA)
- None current 2 past records
- Recalls by its makers (FDA)
- No recall recorded
- FAERS reports
- 1,358 through July 30, 2026
What is glycerol phenylbutyrate used for?
From the label: indications and usageRAVICTI is indicated for use as a nitrogen-binding agent for chronic management of patients with urea cycle disorders (UCDs) who cannot be managed by dietary protein restriction and/or amino acid supplementation alone. RAVICTI must be used with dietary protein restriction and, in some cases, dietary supplements (e.g., essential amino acids, arginine, citrulline, protein-free calorie supplements). Limitations of Use: RAVICTI is not indicated for the treatment of acute hyperammonemia in patients with UCDs because more rapidly acting interventions are essential to reduce plasma ammonia levels. […]
FDA pharmacologic class: Nitrogen Binding Agent.
Source: FDA drug label (Ravicti), Horizon Therapeutics USA, Inc., effective October 29, 2025 (SPL set 900e7dc0-9afe-4f50-80de-90567bb78519), via openFDA; the full label on DailyMed
What does the patient leaflet for glycerol phenylbutyrate say first?
The FDA-approved Medication Guide or Patient Information that comes with the medicine, in its own words.
From the patient leaflet: What is the most important information I should know about RAVICTI?RAVICTI may cause serious side effects, including: Nervous system problems (Neurotoxicity). Phenylacetate (PAA), a breakdown product of RAVICTI, may cause nervous system side effects. Call your doctor or get medical help right away if you get any of these symptoms while taking RAVICTI: sleepiness lightheadedness change in taste problems with hearing confusion problems with memory worsening of numbness, tingling, or burning in your hands or feet headache feeling very tired (fatigue) nausea vomiting Your doctor may do blood tests to measure the amount of PAA in your blood during your treatment with RAVICTI.
From the patient leaflet: How should I store RAVICTI?Store RAVICTI between 68°F to 77°F (20°C to 25°C). Keep RAVICTI and all medicines out of the reach of children.
Source: FDA drug label (Ravicti), Horizon Therapeutics USA, Inc., effective October 29, 2025 (SPL set 900e7dc0-9afe-4f50-80de-90567bb78519), via openFDA; the full label on DailyMed
Is there a generic for glycerol phenylbutyrate (Ravicti)?
The FDA approved the first generic glycerol phenylbutyrate on December 2, 2021. 7 generic applications are approved; 7 of them carry a current (not discontinued) marketing status in Drugs@FDA; that status is not evidence that the generic is on sale. Drugs@FDA also holds 2 tentative approvals: the FDA found the generic approvable, but patents or exclusivity keep it from final approval for now.
FDA's NDC Directory lists glycerol phenylbutyrate from 7 labelers under a generic (ANDA) application and from 2 brand labelers. A listing means the company has registered the product for sale; it does not show that every pharmacy stocks it.
The Orange Book lists 14 patents for Ravicti liquid, the last expiring on September 22, 2030. A patent or exclusivity date is not the date a generic goes on sale: court cases and settlements move it either way.
- 2013 earliest approval on file
- 2021 first generic approved
- 2030 last listed patent
Source: Drugs@FDA, FDA NDC Directory and the Orange Book (openFDA bulk files, October 8, 2026)
Is glycerol phenylbutyrate in shortage?
No glycerol phenylbutyrate presentation is listed as in shortage in the FDA Drug Shortage Database (read October 8, 2026); its 2 records are all marked to be discontinued, the latest updated September 1, 2026. ASHP keeps a separate shortage list, which can differ.
| Presentation | Company | Status | Updated |
|---|---|---|---|
| RAVICTI, Oral Liquid, 1.1 g/1 mL (NDC 75987-050-06) | Amgen Inc. | To Be Discontinued | September 1, 2026 |
| RAVICTI, Oral Liquid, 1.1 g/1 mL (NDC 75987-050-07) | Amgen Inc. | To Be Discontinued | September 1, 2026 |
Every glycerol phenylbutyrate presentation in the FDA shortage database
Source: FDA Drug Shortage Database via openFDA, updated October 8, 2026
What does the glycerol phenylbutyrate label say about other medicines?
The glycerol phenylbutyrate label names 8 other medicines in its interaction, contraindication or warning sections. The sentences are the labels' own; a label lists what its studies and reports found, not every interaction.
| Medicine named | Section | What the label says |
|---|---|---|
| Cyclosporine | drug interactions | May affect renal excretion of metabolites of RAVICTI, including phenylacetylglutamine (PAGN) and PAA. ( 7.2 ) CYP3A4 Substrates with narrow therapeutic index (e.g., alfentanil, quinidine, cyclosporine): |
| Divalproex | drug interactions | DRUG INTERACTIONS Corticosteroids, valproic acid, or haloperidol: May increase plasma ammonia level; monitor ammonia levels closely. |
| Haloperidol | drug interactions | DRUG INTERACTIONS Corticosteroids, valproic acid, or haloperidol: May increase plasma ammonia level; monitor ammonia levels closely. |
| Midazolam | drug interactions | Decreased exposure; monitor for suboptimal effect of midazolam. |
| Probenecid | drug interactions | Drugs to Affect RAVICTI Probenecid Probenecid may inhibit the renal excretion of metabolites of RAVICTI including PAGN and PAA. |
| Quinidine | drug interactions | May affect renal excretion of metabolites of RAVICTI, including phenylacetylglutamine (PAGN) and PAA. ( 7.2 ) CYP3A4 Substrates with narrow therapeutic index (e.g., alfentanil, quinidine, cyclosporine): |
| Sodium phenylbutyrate | warnings and precautions | In clinical trials in patients with UCDs who had been on sodium phenylbutyrate prior to administration of RAVICTI, adverse reactions of headache, fatigue, symptoms of peripheral neuropathy, seizures, tremor and/or dizziness were reported. |
| Valproic acid | drug interactions | DRUG INTERACTIONS Corticosteroids, valproic acid, or haloperidol: May increase plasma ammonia level; monitor ammonia levels closely. |
Source: FDA drug label (Ravicti), Horizon Therapeutics USA, Inc., effective October 29, 2025 (SPL set 900e7dc0-9afe-4f50-80de-90567bb78519), via openFDA; the full label on DailyMed
What do FAERS reports show for glycerol phenylbutyrate?
The FDA Adverse Event Reporting System holds 1,358 reports that list glycerol phenylbutyrate among the medicines taken, through July 30, 2026, each a report of something that happened, not proof the medicine caused it; 65 are coded as a death and 601 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is.
Reports received each year
The most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026
What next?
- Other nitrogen binding agents
- the pharmacologic class, with prices and generics
- Glycerol phenylbutyrate side effects
- the label's list beside FAERS reports
- Glycerol phenylbutyrate shortage record
- every presentation, company and date
- Check an interaction
- what two or more labels say about each other