Buphenyl

Manages urea cycle disorders involving deficiencies of carbamoyl phosphate synthetase…. NDA 20572, held by Horizon Therap US. Sodium Phenylbutyrate.

As of Nov 15, 2026, NDA 20572 (Buphenyl), held by Horizon Therap US, was first approved by FDA on May 13, 1996, with 6 approved supplements and 0 published complete response letters.

First approved: May 13, 1996
Review: Priority
Supplements approved: 6
Complete response letters: 0

What It's For

From the FDA-approved label (Indications and Usage)

INDICATIONS AND USAGE BUPHENYL is indicated as adjunctive therapy in the chronic management of patients with urea cycle disorders involving deficiencies of carbamoyl phosphate synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase (AS). It is indicated in all patients with neonatal-onset deficiency (complete enzymatic deficiency, presenting within the first 28 days of life). It is also indicated in patients with late-onset disease (partial enzymatic deficiency, presenting after the first month of life) who have a history of hyperammonemic encephalopathy. It is important that the diagnosis be made early and treatment initiated immediately to improve survival.

Full prescribing information on DailyMed ↗

Approvals and New Uses

The original application and every efficacy supplement, newest first; all 7 submissions below

Date	Submission	Status	Documents
May 13, 1996	Original applicationNew dosage form · Priority review	Approved	None posted

Products

1 strengths and forms

Product	Active ingredient	Marketing
Buphenyl500MG · tablet;oral	Sodium Phenylbutyrate	DiscontinuedReference drug

All 7 submissions, including labeling and manufacturing supplements


Jul 29, 2022	Supplement 25Labeling · Standard review	Approved	Label Letter
Oct 6, 2015	Supplement 21Manufacturing · Priority review	Approved	None posted
Aug 2, 2013	Supplement 20Manufacturing · Priority review	Approved	None posted
Mar 31, 2009	Supplement 16Labeling · Standard review	Approved	Label Letter
Oct 9, 1998	Supplement 2Labeling · Standard review	Approved	None posted
Nov 7, 1996	Supplement 1Manufacturing · Priority review	Approved	None posted
May 13, 1996	Original applicationNew dosage form · Priority review	Approved	None posted

Identifiers

Application: NDA 20572
Drugs@FDA: Overview at FDA
Company: Horizon Therap US

Approvals, supplements, products and documents come from FDA's Drugs@FDA data files, refreshed daily; Drugs@FDA lists approved applications only. Complete response letters are FDA's published letters. Drugs@FDA and FDA complete response letters