Sodium Benzoate/Sodium Phenylacetate

Sodium benzoate/sodium phenylacetate is used as adjunctive therapy for the treatment of acute hyperammonemia and associated encephalopathy in patients with deficiencies in enzymes of the urea cycle.

Sodium benzoate/sodium phenylacetate is available under the following different brand names: Ammonul.

Dosages of Sodium Benzoate/Sodium Phenylacetate:

Dosage Forms and Strengths

Injectable Solution

• 10% / 10%

Dosage Considerations – Should be Given as Follows:

Urea Cycle Enzyme Deficiency

• Indicated as adjunctive therapy for the treatment of acute hyperammonemia and associated encephalopathy in patients with deficiencies in enzymes of the urea cycle

• Loading dose (greater than 20 kg): 5.5 g-5.5 g/m² intravenous (IV) infusion over 90-120 minutes  
  • Maintenance: 5.5 g-5.5 g/m² IV infusion over 24 hours

• Loading dose (less than 20 kg): 250 mg-250 mg/kg (2.5 mL/kg) IV infusion over 90-120 minutes
  • Maintenance: 250 mg-250 mg/kg (2.5 mL/kg) IV infusion over 24 hours

Monitor

• Serum ammonia, neurological tests, clinical response, electrolytes

Common side effects of sodium benzoate/sodium phenylacetate include:

• Vomiting
• Acidosis
• Agitation
• Anemia
• Brain swelling (edema)
• Coma
• Convulsions
• Diarrhea
• Disseminated intravascular coagulation (DIC)
• High blood ammonia (hyperammonemia)
• High blood sugar (hyperglycemia)
• Low blood calcium (hypocalcemia)
• Low blood pressure (hypotension)
• Injection site reactions
• Mental impairment
• Nausea
• Fever
• Respiratory distress
• Skin disorder
• Urinary tract infection (UTI)

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

• Sodium benzoate/sodium phenylacetate has no listed severe interactions with other drugs.
• Serious interactions of sodium benzoate/sodium phenylacetate include:
  • valproic acid
• Moderate interactions of sodium benzoate/sodium phenylacetate include:
  • amoxicillin
  • ampicillin
  • flucloxacillin
  • nafcillin
  • penicillin G aqueous
  • penicillin VK
  • pivmecillinam
  • probenecid
  • temocillin
  • ticarcillin
  • tobramycin inhaled
• Sodium benzoate/sodium phenylacetate has no listed mild interactions with other drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

Warnings

• This medication contains sodium benzoate/sodium phenylacetate. Do not take Ammonul if you are allergic to sodium benzoate/sodium phenylacetate or any ingredients contained in this drug.
• Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.

Contraindications

• Hypersensitivity

Effects of Drug Abuse

• No information available

Short-Term Effects

• See "What Are Side Effects Associated with Using Sodium Benzoate/Sodium Phenylacetate?”

Long-Term Effects

• See "What Are Side Effects Associated with Using Sodium Benzoate/Sodium Phenylacetate?”

Cautions

• Discontinue oral anti hyperammonemia drugs prior to administration
• Caution in hepatic/renal impairment, heart failure, sodium retention associated with edema
• Avoid repeat loading doses
• Nausea/vomiting may occur
• Contains 30.5 mg/mL of sodium in the undiluted product
• Phenylacetate has been associated with neurotoxicity risk
• Administration through peripheral line may cause burns

Pregnancy and Lactation

• Use sodium benzoate/sodium phenylacetate with caution during pregnancy if the benefits outweigh the risks. Animal studies show risk and human studies are not available or neither animal nor human studies were done.
• It is not known if sodium benzoate/sodium phenylacetate is distributed in breast milk. Use caution while breastfeeding.