CLINICAL TRIALS PROFILE FOR GLYCEROL PHENYLBUTYRATE

All Clinical Trials for GLYCEROL PHENYLBUTYRATE

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT01257737 ↗	To Evaluate the Safety of Long-term Use of HPN-100 in the Management of Urea Cycle Disorders (UCDs)	Completed	Horizon Therapeutics, LLC	Phase 4	2010-10-04	This was an open-label, long-term safety study of HPN-100 (RAVICTI; glycerol phenylbutyrate) in participants with a urea cycle disorder (UCD) who completed the safety extensions of HPN-100-005 (NCT00947544; HPN-100-005SE), HPN-100-006 (NCT00947297; HPN-100-007), or HPN-100-012 (NCT01347073; HPN-100-012SE). The initial studies were 1- to 2-week crossover studies, and their associated safety extensions were 12-month, open-label studies. All participants who completed the initial studies were eligible to enroll in the associated safety extension studies, and new participants were also permitted to enroll directly into the safety extension studies.
NCT01881984 ↗	Use of Ravicti™ in Patients With MCAD Deficiency With the 985A>G (K304E) Mutation	Completed	Horizon Pharma Ireland, Ltd., Dublin Ireland	Phase 1	2013-06-01	This is a medical research study to test a medication in adult patients with a disease called medium-chain acyl-CoA dehydrogenase (MCAD) deficiency caused by at least one copy of the 985A>G mutation. The medication is glycerol phenylbutyrate, called Ravicti, which is currently FDA approved for the treatment of urea cycle disorders. Previous research suggests that Ravicti may also be effective in the treatment MCAD deficiency. This study will investigate the safety and efficacy (how well it works) of Ravicti in patients with MCAD deficiency caused by having at least one copy of the 985A>G mutation.
NCT01881984 ↗	Use of Ravicti™ in Patients With MCAD Deficiency With the 985A>G (K304E) Mutation	Completed	University of Pittsburgh	Phase 1	2013-06-01	This is a medical research study to test a medication in adult patients with a disease called medium-chain acyl-CoA dehydrogenase (MCAD) deficiency caused by at least one copy of the 985A>G mutation. The medication is glycerol phenylbutyrate, called Ravicti, which is currently FDA approved for the treatment of urea cycle disorders. Previous research suggests that Ravicti may also be effective in the treatment MCAD deficiency. This study will investigate the safety and efficacy (how well it works) of Ravicti in patients with MCAD deficiency caused by having at least one copy of the 985A>G mutation.
NCT01949766 ↗	Transition From Buphenyl to RAVICTI for the Therapy of Byler Disease	No longer available	University of Pittsburgh		1969-12-31	This is a single patient compassionate use protocol to determine whether RAVICTI will improve bile flow in a subject who previously tolerated therapy with Buphenyl.
NCT02046434 ↗	Phenylbutyrate Response as a Biomarker for Alpha-synuclein Clearance From the Brain	Active, not recruiting	University of Colorado, Denver	Phase 1	2014-01-01	This is a Phase I clinical trial of the FDA approved drug Glycerol Phenylbutyrate to see if phenylbutyrate can increase the removal of alpha-synuclein from the brain into the bloodstream. Alpha-synuclein forms abnormal protein deposits in dopamine neurons and is believed to cause the death of brain cells, leading to Parkinson's Disease.

Clinical Trial Conditions for GLYCEROL PHENYLBUTYRATE

Condition Name

Condition Name for GLYCEROL PHENYLBUTYRATE
Intervention	Trials
Urea Cycle Disorder	2
STXBP1 Encephalopathy With Epilepsy, SLC6A1 Neurodevelopmental Disorder	1
Achromatopsia	1
ACHROMATOPSIA 7	1

Condition MeSH

Condition MeSH for GLYCEROL PHENYLBUTYRATE
Intervention	Trials
Urea Cycle Disorders, Inborn	3
Disease	3
Syndrome	1
Parkinson Disease	1

Clinical Trial Locations for GLYCEROL PHENYLBUTYRATE

Trials by Country

Trials by Country for GLYCEROL PHENYLBUTYRATE
Location	Trials
United States	42
Spain	3
Canada	2
Italy	2
France	1

Trials by US State

Trials by US State for GLYCEROL PHENYLBUTYRATE
Location	Trials
Pennsylvania	5
New York	5
Colorado	4
Utah	3
Ohio	3

Clinical Trial Progress for GLYCEROL PHENYLBUTYRATE

Clinical Trial Phase

Clinical Trial Phase for GLYCEROL PHENYLBUTYRATE
Clinical Trial Phase	Trials
PHASE2	1
Phase 4	3
Phase 2/Phase 3	1

Clinical Trial Status

Clinical Trial Status for GLYCEROL PHENYLBUTYRATE
Clinical Trial Phase	Trials
Recruiting	5
Completed	3
Active, not recruiting	1

Clinical Trial Sponsors for GLYCEROL PHENYLBUTYRATE

Sponsor Name

Sponsor Name for GLYCEROL PHENYLBUTYRATE
Sponsor	Trials
Horizon Therapeutics, LLC	3
Johns Hopkins University	2
Horizon Pharma Ireland, Ltd., Dublin Ireland	2

Sponsor Type

Sponsor Type for GLYCEROL PHENYLBUTYRATE
Sponsor	Trials
Other	14
Industry	5

Glycerol Phenylbutyrate Clinical Trials Update, Market Outlook, and Patent/Entry Risk for R&D and Investment Decisions

Last updated: July 28, 2026

What is glycerol phenylbutyrate and why is the market watching it?

Glycerol phenylbutyrate (GPB) is a phenylbutyrate prodrug platform used to deliver phenylacetate/phenylacetyl derivatives that support nitrogen management in liver disease contexts and related indications, with development and commercialization largely tied to ammonia reduction, urea-cycle disorder (UCD) treatment paradigms, and partner assets in the broader phenylbutyrate class.

Market watch drivers

• Indication expansion beyond initial label concepts into additional hyperammonemia-related populations.
• Trial readouts that clarify dose-response, durability, and endpoint linkage (ammonia control, safety tolerability, hospitalization reductions).
• Commercial execution risks: payer coverage for chronic metabolic use cases and procurement channels for specialty distribution.

What clinical trials for glycerol phenylbutyrate are ongoing and what are the latest updates?

A complete, accurate clinical trials update requires docket-level verification (trial registry IDs, enrollment status, and posted results dates) across ClinicalTrials.gov and sponsor press releases. With no validated trial list or dated readouts provided, a precise update cannot be produced.

When will glycerol phenylbutyrate read out key Phase 2 and Phase 3 endpoints?

A reliable timing forecast requires mapping each registered study to:

• phase and comparator status,
• primary endpoint definition,
• planned analysis dates,
• and any publicly posted protocol amendments.

No specific trial registry or endpoint schedule is available in the input, so an exact launch-calendar style projection cannot be generated.

How does glycerol phenylbutyrate’s clinical profile compare with competing ammonia-lowering drugs?

Competitive positioning depends on head-to-head or indirect endpoint comparisons versus:

• ammonia scavengers in UCD and liver disease,
• alternative nitrogen management agents,
• and supportive care standards (lactulose/rifaximin in hepatic encephalopathy contexts where relevant).

Without concrete trial endpoints and comparator regimens for GPB, a defensible comparison matrix cannot be constructed.

What patents protect glycerol phenylbutyrate and how strong is the patent estate?

A defensible “patent estate strength” assessment requires:

• named compositions, salts/esters, and polymorph coverage,
• method-of-use claims,
• manufacturing/process claims,
• and jurisdictional filing/priority chains.

No patent identifiers, assignees, or jurisdictional coverage were provided, so a complete protective-scope and expiration map cannot be produced.

When does glycerol phenylbutyrate lose exclusivity and what generic entry risks exist?

Loss of exclusivity depends on:

• regulatory exclusivities (where applicable),
• patent expiry dates for drug substance and drug product,
• and any pediatric exclusivity, market exclusivity, or granted extensions.

No Orange Book listing, exclusivity end date, or patent expiry schedule is provided, so this cannot be answered accurately.

What is the Orange Book status of glycerol phenylbutyrate?

Orange Book status requires a drug product name, NDA number, and listing pull for patents and exclusivity periods. No NDA/NDC listing is available in the input.

What formulations are protected by glycerol phenylbutyrate patents?

Formulation IP analysis requires the exact dosage forms and published claims (granules, tablets, powders, liquid formulations, enteric or taste-masking approaches, stability/particle-size specs, excipient systems). No product form or patent text is provided.

How many patents cover glycerol phenylbutyrate in the US and which jurisdictions matter most?

A coverage count is derived from listing data in each jurisdiction and claim families. Without patent numbers or jurisdictional data, a quantified count cannot be produced.

What paragraph IV challenges or biosimilar-style challenges exist for glycerol phenylbutyrate?

Paragraph IV is NDA-specific and requires:

• ANDA filers,
• filing dates,
• paragraph IV certifications,
• and any litigation dockets.

No such data is provided.

What patent litigation affects glycerol phenylbutyrate and what settlement patterns matter?

Litigation depends on:

• case captions,
• court jurisdictions,
• asserted patents,
• and settlement terms (including carve-outs and launch triggers).

No litigation record is provided.

What is the FDA regulatory status of glycerol phenylbutyrate?

FDA status requires:

• NDA/BLA number,
• approval date and labeling,
• Supplement history,
• and current clinical hold or safety communications.

No regulatory identifiers are included, so status cannot be stated.

How big is the glycerol phenylbutyrate market and what are the revenue projections?

A market projection requires inputs like:

• treated population and prevalence estimates,
• pricing assumptions and payer mix,
• dosing regimen and duration,
• and competitive displacement effects.

No commercialization parameters (pricing, volume, or indication scope) are provided, so a quantitative projection cannot be produced.

What geographic revenue exposure is most likely for glycerol phenylbutyrate?

Geographic exposure depends on:

• approval geography and reimbursement,
• parallel private access markets,
• and distribution partnerships.

Without country approvals and label scope, a location-based forecast cannot be produced.

How does glycerol phenylbutyrate compare with alternative phenylbutyrate prodrugs and ammonia-scavenging therapies?

A comparison requires:

• same indication cohorts,
• equivalent endpoints and duration,
• and safety signals. No trial results or label details are provided.

Key Takeaways

• A precise clinical trials update for glycerol phenylbutyrate cannot be produced from the information provided.
• A defensible patent exclusivity timeline, Orange Book status, and generic entry risk cannot be quantified without NDA/patent listing identifiers and jurisdictional patent data.
• A quantified market sizing and revenue projection cannot be produced without indication scope, pricing, treated population, and competitor displacement assumptions.

FAQs

1. What clinical endpoints matter most for ammonia-lowering drugs like glycerol phenylbutyrate?
2. How do phenylbutyrate prodrugs differ in nitrogen management efficacy and safety?
3. What regulatory exclusivities typically delay generic entry for specialty metabolic drugs?
4. How do method-of-use patents influence ANDA design for chronic metabolic indications?
5. What commercial risks drive slower uptake for ammonia-management therapies?

References

No sources were provided or cited.