BUPHENYL^® is the only FDA-approved oral medication for the chronic adjunctive management of hyperammonemia in patients with urea cycle disorders (UCDs) involving deficiencies of carbamyl phosphate synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase (ASS). Patients with a UCD lack or are deficient in one of the key enzymes that comprise the urea cycle, the body’s primary vehicle for removing ammonia, a potent neurotoxin, from the bloodstream. Left untreated, UCDs can cause dangerously heightened levels of ammonia in the bloodstream (hyperammonemia), resulting in brain damage, coma, or death.

In patients with a UCD, BUPHENYL decreases elevated plasma ammonia glutamine levels by increasing waste nitrogen excretion in the form of phenylacetylglutamine.

BUPHENYL is not approved for use in acute hyperammonemia, a life-threatening event that requires prompt treatment. Information on AMMONUL^® (sodium phenylacetate and sodium benzoate) Injection 10%/10%, the only FDA-approved adjunctive therapy for the treatment of acute hyperammonemia in patients with UCD, can be found at: www.Ammonul.com.

Indication and Usage

BUPHENYL^® is indicated as adjunctive therapy in the chronic management of patients
with urea cycle disorders involving deficiencies of carbamyl phosphate synthetase
(CPS), ornithine transcarbamylase (OTC), and argininosuccinic acid synthetase (ASS).
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.

Any episode of acute hyperammonemia should be treated as a life-threatening emergency.

BUPHENYL must be combined with dietary protein restriction and, in some cases, essential amino acid supplementation.

Key Safety Information

BUPHENYL^® should not be administered to patients with known hypersensitivity to sodium phenylbutyrate or any component of this preparation. The most common adverse reactions associated with BUPHENYL were amenorrhea dysfunction, decreased appetite, body odor (probably caused by its metabolite phenylacetate), and bad taste or taste aversion. Patients with urea cycle disorders should not take valproic acid, haloperidol, or steroids as these drugs have been reported to increase blood ammonia levels, and probenecid may affect the kidneys’ excretion. Use with great care, if at all, in patients with congestive heart failure or severe renal insufficiency, and in clinical states where there is sodium retention with edema. Use caution when administering to patients with hepatic or renal insufficiency or inborn errors of beta oxidation. The safety or efficacy of doses in excess of 20 grams (40 tablets) per day has not been established.

Click here for important safety information

Click here for Full Prescribing Information