Dosage Forms
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet, Oral:
Carbaglu: 200 mg [scored]
Pharmacology
Mechanism of Action
N-acetylglutamate synthase (NAGS) is a mitochondrial enzyme which produces N-acetylglutamate (NAG). NAG is a required allosteric activator of the hepatic mitochondrial enzyme, carbamoyl phosphate synthetase 1 (CPS 1), which converts ammonia into urea in the first step of the urea cycle. In NAGS-deficient patients, carglumic acid serves as a replacement for NAG.
Pharmacokinetics/Pharmacodynamics
Distribution
Vd: ~2657 L
Metabolism
Via intestinal flora to carbon dioxide
Excretion
Feces (≤60% as unchanged drug); urine (9% as unchanged drug)
Time to Peak
Median: 3 hours
Half-Life Elimination
Median: 5.6 hours (range: 4.3 to 9.5 hours)
Use: Labeled Indications
Hyperammonemia: Adjunctive treatment of acute hyperammonemia and maintenance therapy of chronic hyperammonemia due to the deficiency of the hepatic enzyme N-acetylglutamate synthase (NAGS) in adult and pediatric patients
Contraindications
There are no contraindications listed in the manufacturer’s labeling.
Canadian labeling: Additional contraindications (not in US labeling): Hypersensitivity to carglumic acid or any component of the formulation; breastfeeding
Dosage and Administration
Dosing: Adult
Acute hyperammonemia: Oral: 100 to 250 mg/kg/day given in 2 or 4 divided doses (rounded to the nearest 100 mg); titrate to age-appropriate plasma ammonia levels. Concomitant adjunctive ammonia-lowering therapy recommended.
Chronic hyperammonemia: Oral: Usual dose (based on limited data): <100 mg/kg/day given in 2 or 4 divided doses; titrate to age-appropriate normal plasma ammonia levels
Dosing: Pediatric
Acute hyperammonemia: Infants, Children, and Adolescents: Oral: 100 to 250 mg/kg/day in 2 or 4 divided doses; round to the nearest 100 mg (ie, one-half of a Carbaglu tablet); titrate to age-appropriate plasma ammonia concentrations and clinical condition considerations (including nutritional requirements, protein intake, growth parameters, etc); concomitant ammonia-lowering therapy recommended.
Chronic hyperammonemia: Infants, Children, and Adolescents: Oral: Usual dose: 10 to 100 mg/kg/day in 2 or 4 divided doses; titrate to age-appropriate plasma ammonia concentrations and clinical condition considerations (including nutritional requirements, protein intake, growth parameters, etc).
Reconstitution
Oral: Each 200 mg tablet should be dispersed in at least 2.5 mL of water (no other foods/liquids) and administered immediately.
Oral syringe: Disperse each 200 mg tablet in 2.5 mL of water to yield a concentration of 80 mg/mL (shake gently in container). Appropriate volume of dispersion should be drawn up in an oral syringe and administered immediately (discard unused dispersion).
Nasogastric tube: Disperse each 200 mg tablet in water (2.5 mL per tablet for pediatric patients; ≥2.5 mL per tablet for adults) and shake gently; administer immediately.
Administration
Administer immediately prior to meals or feedings. Disperse in water prior to administration; should not be mixed with any other foods or liquids other than water .
Oral: Tablets should not be crushed or swallowed whole. After dispersion in water, administer immediately. Tablets do not dissolve completely, and some particles may remain; rinse container with water and administer rinse immediately.
Oral syringe: After dispersion of tablets in water, draw up appropriate volume and administer immediately (discard unused dispersion). After initial administration, refill oral syringe with a minimum of 1 to 2 mL of water and administer immediately.
Nasogastric tube: After dispersion of tablets in water, immediately administer through a nasogastric tube (tablets do not dissolve completely; some particles may remain). Follow with a flush with additional water to clear the tube.
Storage
Before opening, store refrigerated at 2°C to 8°C (36°F to 46°F). After opening, do not refrigerate or store above 30°C (86°F). Protect from moisture. Discard 1 month after opening.
Drug Interactions
There are no known significant interactions.
Adverse Reactions
>10%:
Central nervous system: Headache (13%)
Gastrointestinal: Vomiting (26%), abdominal pain (17%), diarrhea (13%)
Hematologic & oncologic: Anemia (13%), decreased hemoglobin (13%)
Infection: Infection (13%)
Otic: Otic infection (13%)
Respiratory: Tonsillitis (17%), nasopharyngitis (13%)
Miscellaneous: Fever (17%)
1% to 10%:
Central nervous system: Drowsiness (9%)
Dermatologic: Hyperhidrosis (9%), skin rash (9%)
Endocrine & metabolic: Weight loss (9%)
Gastrointestinal: Anorexia (9%), dysgeusia (9%)
Infection: Influenza (9%)
Neuromuscular & skeletal: Weakness (9%)
Respiratory: Pneumonia (9%)
<1%, postmarketing, and/or case reports: Acidosis, acquired blood coagulation disorder, brain damage, brain disease, central nervous system dysfunction, cerebral edema, coma, decreased white blood cell count, developmental delay (motor development), eating disorder, eosinophilia, epilepsy, hyperammonemia, hyponatremia, increased intracranial pressure, increased liver enzymes, lactic acidosis, lethargy, low serum ferritin, otitis media, respiratory failure, seizure, sepsis, thrombocytopenia
Warnings/Precautions
Other warnings/precautions:
- Experienced physician: Acute symptomatic hyperammonemia is a life-threatening emergency; management of hyperammonemia due to N-acetylglutamate synthase (NAGS) deficiency should be done in coordination with those experienced in the management of metabolic disorders.
- Nutritional management: Since hyperammonemia is the result of protein catabolism, complete protein restriction is recommended to be maintained for 24-48 hours and caloric supplementation should be maximized to reverse catabolism and nitrogen turnover.
Monitoring Parameters
Plasma ammonia; monitor for physical signs/symptoms of hyperammonemia (eg, lethargy, ataxia, confusion, vomiting, seizures, and memory impairment).
Pregnancy
Pregnancy Risk Factor
C
Pregnancy Considerations
Adverse events have been observed in animal reproduction studies. There are no adequate and well-controlled studies in pregnant women. However, due to the potential for irreversible fetal neurologic damage for untreated NAGS deficiency, women with this condition must remain on treatment throughout pregnancy.
Patient Education
- Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
- Patient may experience headache, diarrhea, abdominal pain, change in taste, sore throat, stuffy nose, weight loss, lack of appetite, vomiting, or nausea. Have patient report immediately to prescriber signs of infection, fatigue, sweating a lot, ear pain, or severe loss of strength and energy (HCAHPS).
- Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.
Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.
