Sodium Phenylacetate and Sodium Benzoate

Class: Ammonia Detoxicants
Chemical Name: Benzeneacetic acid, sodium salt
Molecular Formula: C₈H₇NaO₂C₇H₅NaO₂
CAS Number: 114-70-5

Medically reviewed by Drugs.com on Mar 22, 2022. Written by ASHP.

Introduction

Fixed combination of 2 ammonia detoxicants.

Uses for Sodium Phenylacetate and Sodium Benzoate

Acute Hyperammonemia

Adjunctive therapy for the treatment of acute hyperammonemia and associated encephalopathy in patients with urea cycle disorders (e.g., deficiency in carbamyl phosphate synthetase [CPS], ornithine transcarbamylase [OTC], argininosuccinate synthetase [ASS], or argininosuccinate lyase [ASL]); designated an orphan drug by FDA for this use.

Treat any episode of acute symptomatic hyperammonemia as a life-threatening emergency; prompt use of all necessary therapies (e.g., dialysis [preferably hemodialysis], caloric supplementation, protein restriction) to reduce ammonia concentrations is essential.

Hemodialysis is the preferred therapy for acute neonatal hyperammonemic coma, moderate to severe episodes of hyperammonemic encephalopathy, and episodes of hyperammonemia that fail to respond to an initial course of sodium phenylacetate and sodium benzoate therapy. In such patients, administration of sodium phenylacetate and sodium benzoate helps prevent reaccumulation of ammonia by increasing waste nitrogen excretion.

Concomitant therapy with IV arginine hydrochloride is required in patients with CPS, OTC, ASS, or ASL deficiency; however, IV arginine hydrochloride is contraindicated in patients with arginase deficiency. Pending specific diagnosis, also give IV arginine hydrochloride to hyperammonemic infants with suspected urea cycle disorders.

If a urea cycle disorder is suspected based on family history, document hyperammonemia before administering sodium phenylacetate and sodium benzoate.

Sodium Phenylacetate and Sodium Benzoate Dosage and Administration

General

• Initiate therapy immediately following the diagnosis of hyperammonemia.

• Prior to infusion, discontinue analogous oral agents (e.g., sodium phenylbutyrate).

• May administer an antiemetic during the infusion for management of possible nausea and vomiting.

• Start or resume oral therapy (e.g., sodium phenylbutyrate), dietary management, and protein restriction when ammonia concentrations reduced to the normal range.

• Dialysis is recommended for those patients who do not have a significant reduction in plasma ammonia levels within 4–8 hours after receiving sodium phenylacetate and sodium benzoate.

• Concomitant therapy with arginine hydrochloride may be required. Consult the prescribing information for arginine hydrochloride for complete dosing and other information.

Administration

IV Administration

For solution and drug compatibility information, see Compatibility under Stability.

Administer by IV infusion through a central venous line only; administration through a peripheral line may cau...