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Alerts & Contraindications

Important Treatment Information


  • Arginine HCl is given intravenously (IV) to UCD patients in the hospital setting. Arginine HCl is sometimes used by pharmacists to create a pediatric suspension (liquid) for oral use in UCD children. Arginine HCl can cause acidosis. Patients receiving arginine HCl may require additional monitoring for acidosis by their metabolic physician.
  • Arginine free base powder is the standard used for daily oral administration for chronic management of some urea cycle disorders. It does not cause acidosis.

Families should check to ensure the product they are receiving from their pharmacy for oral administration is arginine free base. If arginine HCl has been substituted by the pharmacy, the metabolic physician needs to be notified in case additional monitoring for acidosis is needed. Even healthcare professionals are not always aware of the difference in these two products.

With an increasing amount of unregulated dietary supplement products on the market, it is very important to stay vigilant and make sure which form of arginine you are receiving from the pharmacy. Some pharmacies have started distributing Arginine HCl powder instead of Arginine free base powder to patients without notifying the patient/family or treating physician of the substitution. Your metabolic physician will determine whether it is safe to continue on arginine HCl and whether additional monitoring is needed. If the physician wishes the patient to receive arginine free base only, the prescription must state explicitly "arginine free base."  

FDA Warning

FDA Drug Warning - Valproic Acid (trade name Depakote, anticonvulsant) strongly contraindicated in UCD patients.

Hyperammonemic encephalopathy, sometimes fatal, has been reported following initiation of valproate therapy in patients with urea cycle disorders, a group of uncommon genetic abnormalities, particularly ornithine transcarbamylase deficiency. Prior to the initiation of valproate therapy, evaluation for UCD should be considered in the following patients: 1) those with a history of unexplained encephalopathy or coma, encephalopathy associated with a protein load, pregnancy or postpartum encephalopathy unexplained mental retardation, or history of elevated plasma ammonia or glutamine; 2) those with cyclical vomiting and lethargy, episodic extreme irritability, ataxia, low BUN, or protein avoidance; 3) those with a family history of UCD or a family history of unexplained infant deaths (particularly males); 4) those with other signs and symptoms of UCD. Patients who develop symptoms of unexplained hyperammonemic encephalopathy while receiving valproate therapy should receive prompt treatment (including discontinuation of valproate therapy) and be evaluated for underlying urea cycle disorders. For more information, click here. 


Warning - Corticosteroid (prednisone, Solu-Medrol, etc.) & Haloperidol Contraindication: Use of these medications may cause breakdown of body protein and result in fatal increase in plasma ammonia levels.

Sodium Phenylbutyrate for treatment of Urea Cycle Disorders Medication usage precaution:  When administered as part of a drug treatment regimen for urea cycle disorders, sodium phenylbutyrate should not be exposed to heat, or mixed or taken with any acidic beverages such as orange juice, lemonade, etc.