Carbaglu (carglumic acid) prior authorization
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Defines prior authorization requirements for Carbaglu (carglumic acid) soluble tablets for FDA‑approved indications, specifying initial and continued therapy criteria for NAGS deficiency, methylmalonic acidemia (MMA), and propionic acidemia (PA). Affects providers requesting coverage under Curative Health Plan.
No material clinical or coverage changes in this revision.
Coverage Criteria for Carbaglu (carglumic acid)
Initial Therapy — NAGS deficiency
Covered when ALL of the following are met
Approval Duration: 12 months
Initial Therapy — MMA or PA (adjunctive therapy)
Covered when ALL of the following are met
Approval Duration: 1 month
Continued Therapy — NAGS deficiency
Covered when ALL of the following are met
Approval Duration: 12 months
Continued Therapy — MMA or PA
Review requirement
Approval Duration: as per initial review (1 month)
Prior authorization is required for Carbaglu (carglumic acid) and will be approved only when the medication is being used for an FDA‑approved indication and all applicable coverage criteria are met. Initial therapy for N‑acetylglutamate synthase (NAGS) deficiency is covered when all of the following are documented: 1) hyperammonemia with age‑appropriate plasma ammonia elevation (neonate ≥150 µmol/L; older child/adult >100 µmol/L), 2) NAGS deficiency confirmed by enzyme analysis (liver biopsy) or genetic testing, 3) inability to maintain normal ammonia on a protein‑restricted diet with appropriate amino acid supplementation, and 4) prescriber is a specialist or has consulted a specialist. Approval duration for NAGS initial therapy is 12 months.
Initial therapy for methylmalonic acidemia (MMA) or propionic acidemia (PA) as adjunctive treatment of acute hyperammonemia is covered when all of the following are met: 1) the drug is used as adjunctive therapy to standard of care for acute hyperammonemia, 2) diagnosis of MMA or PA is confirmed by enzyme and/or molecular genetic analyses, 3) the patient was hospitalized with a plasma ammonia level ≥50 µmol/L, and 4) prescriber is a specialist or has consulted a specialist. Approval for MMA/PA initial therapy is typically granted for 1 month. Continued therapy for MMA/PA requires review under the initial therapy criteria for each instance.
Initial Therapy
Initial therapy
Covered when ALL of the following are met
Approval Duration: 12 months
Approval Duration: 1 month
Continuation / Continued Therapy
NAGS continued therapy
Continued therapy requirements for NAGS deficiency
Approval Duration: 12 months
MMA/PA continued therapy
Continued therapy for MMA/PA
Approval Duration: as per initial review (1 month)
Clinical Thresholds and Coding-related Values
Provider Actions and Documentation Requirements
Prior authorization required for Carbaglu
Prior authorization is required for Carbaglu (carglumic acid) soluble tablets; approval is granted only when the medication is being used for an FDA‑approved indication and all listed coverage criteria are met.
Specialist prescriber or documented specialist consultation required
Prescriber must be a specialist or have consulted a specialist (examples: nephrologist, metabolic disorders) for both initial and continued therapy requests.
- Applies to NAGS deficiency initial and continued therapy and to MMA/PA initial therapy (consultation acceptable)
- Specialist requirement appears in each criteria set and is required for approval
Required clinical documentation and lab results
Submit documentation confirming the diagnosis and relevant laboratory values: for NAGS deficiency, enzyme analysis (via liver biopsy) or genetic testing plus plasma ammonia level by age; for MMA/PA, enzyme and/or molecular genetic analyses and hospitalization record with plasma ammonia ≥50 µmol/L.
- NAGS: enzyme analysis (liver biopsy) or genetic testing and elevated ammonia (Neonate ≥150 µmol/L; Older child/adult >100 µmol/L)
- MMA/PA: enzyme and/or molecular genetic analyses and documentation of hospitalization with plasma ammonia ≥50 µmol/L
- For continued NAGS therapy, include evidence of clinical benefit (plasma ammonia within normal range) and prior approval or criteria met previously
Risk of denial for noncompliant requests
Requests that do not meet the specified initial or continued therapy criteria — including missing diagnostic confirmation, lacking required ammonia thresholds, absent specialist involvement, failure to document hospitalization for MMA/PA, or no evidence of prior approval/clinical benefit for continuation — may be denied.
- Noncompliance examples: no enzyme or genetic confirmation; ammonia levels below required thresholds; no hospitalization documentation for MMA/PA; missing specialist consult documentation; no evidence of prior approval for continuation requests
Background
Carglumic acid (Carbaglu) is indicated to treat hyperammonemia due to NAGS deficiency and may be used as adjunctive therapy for acute hyperammonemia in organic acidemias such as MMA and PA. Management decisions are guided by documented plasma ammonia levels and definitive diagnostic testing (enzyme analysis or genetic testing). Specialist involvement (or consultation) in the patient’s diagnosis and management is required for initiation and continuation of therapy. Continued therapy for NAGS deficiency is covered when the member was previously approved or meets initial criteria and has demonstrated clinical benefit as evidenced by a plasma ammonia level within the normal range; approval duration for continued NAGS therapy is 12 months.
Definitions
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