CurrentCignaPolicy IP0438

Carglumic acid (Carbaglu) coverage

Defines medical necessity, authorization, reauthorization, and exclusions for carglumic acid (Carbaglu) for members of Cigna-administered health benefit plans.

Policy Summary

PayerCigna

PolicyCarglumic acid (Carbaglu) coverage

Policy CodePolicy IP0438

Change TypeNo material change

Effective DateMay 1, 2025

Next Review Date

Key ActionObtain prior authorization documenting the specified medical necessity criteria for the requested indication.

SourceLink

POLICY UPDATE CHANGES

No material clinical or coverage changes in this revision.

2covered clinical indications

12 moNAGS initial approval

7 daysPA/MMA initial approval

>=50 µmol/Lammonia threshold

Coverage Criteria for Carglumic Acid (Carbaglu)

NAGS deficiency (Initial and Continuation Therapy)

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NAGS diagnosis: Documented diagnosis of NAGS deficiency with hyperammonemia confirmed by enzymatic, biochemical, or genetic analysis

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Dietary management: Medication is prescribed in conjunction with a protein-restricted diet

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Specialist involvement: Medication is prescribed by, or in consultation with, a metabolic disease specialist (or specialist who focuses on the treatment of metabolic diseases)

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Non-covered product rule: Non-Covered Product Criteria is met (refer to non-covered product/table criteria)

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Beneficial response for reauthorization: For continuation (reauthorization), documentation of beneficial response is required in addition to the above criteria

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Propionic acidemia or Methylmalonic acidemia with Hyperammonemia (Acute Treatment)

Covered when ALL of the following are met

PA/MMA diagnosis: Documented diagnosis of propionic acidemia or methylmalonic acidemia with hyperammonemia (acute treatment) confirmed by enzymatic, biochemical, or genetic analysis

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Ammonia level: Documentation of plasma ammonia level >= 50 micromol/L>= 50 micromol/L

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Concomitant therapies: Medication is prescribed in conjunction with other ammonia-lowering therapies

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Specialist involvement: Medication is prescribed by, or in consultation with, a metabolic disease specialist (or specialist who focuses on the treatment of metabolic diseases)

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Duration limit: Initial treatment limited to up to 7 days; continue until ammonia < 50 micromol/L<= 7 days or until ammonia < 50 micromol/L

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Non-covered product rule: Non-Covered Product Criteria is met (refer to non-covered product/table criteria)

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Provider Requirements, Prior Authorization, and Exclusions

Prior Authorization

Prior Authorization Required

Prior authorization is required for coverage of Carbaglu (carglumic acid). Initial authorization durations vary by indication: up to 12 months for NAGS deficiency with hyperammonemia; up to 7 days for acute treatment of propionic acidemia or methylmalonic acidemia with hyperammonemia. Reauthorization: up to 12 months for NAGS deficiency; continuation beyond the initial 7-day approval is not applicable for propionic acidemia or methylmalonic acidemia (acute treatment).

Prior authorization required prior to initiation of therapy
Initial approval: NAGS deficiency — up to 12 months; Propionic/Methylmalonic (acute) — up to 7 days
Reauthorization: NAGS deficiency — up to 12 months; Propionic/Methylmalonic (acute) — continuation beyond initial 7 days not applicable

Documentation Required

Non‑Covered Product / Branded vs Generic

When a branded Carbaglu product is requested but a bioequivalent generic oral suspension is available, document a trial of the generic formulation and a clinical reason why the generic cannot be used (e.g., formulation difference in inactive ingredient(s) that would cause a significant allergy or serious adverse reaction). Receipt of sample product does not meet documentation requirements.

Branded product requests require documentation of trial of the generic oral suspension
If generic trial not possible, document specific formulation-related allergy or serious adverse reaction risk
Samples do not satisfy trial/documentation requirements

Denial Risk

Excluded Uses / Denial Conditions

Uses that are excluded and will be denied include chronic or maintenance therapy for propionic acidemia or methylmalonic acidemia beyond the acute 7‑day approval period. Any other use not specified as medically necessary is considered experimental, investigational, or unproven and is not covered.

Chronic use of Carbaglu beyond 7 days for propionic or methylmalonic acidemia — not covered
Any use not meeting the medical necessity criteria in this policy is considered experimental/investigational and excluded

Background on Carglumic Acid

Carbaglu (carglumic acid) is a synthetic analog that activates carbamoyl phosphate synthetase 1 (CPS1) to support urea cycle function. It is used as adjunctive therapy in disorders associated with hyperammonemia, but its role varies by indication; notably, long‑term use in conditions such as propionic acidemia and methylmalonic acidemia lacks supporting clinical evidence and is not indicated beyond 7 days.

Definitions

inv-11: NAGS deficiency — define the disorder and mechanism relevant to coverage

DefinitionRare urea cycle disorder caused by deficiency of N-acetylglutamate synthase (NAGS), resulting in insufficient N‑acetylglutamate production and resultant hyperammonemia.

Mechanism relevant to therapyLack of NAGS leads to decreased activation of carbamoyl phosphate synthetase 1 (CPS1), impairing the urea cycle’s ability to convert ammonia to urea.

DiagnosisUsually requires genetic, enzymatic, or biochemical confirmation; therapeutic trial of Carbaglu may be initiated empirically in unexplained hyperammonemia due to testing delays.

inv-12: Propionic acidemia / Methylmalonic acidemia (PA/MMA) with hyperammonemia — define these conditions and relation to NAGS inhibition

DefinitionPropionic acidemia (PA) and methylmalonic acidemia (MMA) are inborn errors of metabolism causing accumulation of metabolites that can inhibit NAGS and lead to hyperammonemia.

PathophysiologyAccumulation of propionyl‑CoA (and related metabolites) acts as a competitive inhibitor of NAGS, reducing N‑acetylglutamate and impairing CPS1 activation.

Clinical relation to Carbaglu useCarbaglu (carglumic acid) is indicated as adjunctive therapy for acute hyperammonemia in PA/MMA; it should be continued until ammonia < 50 micromol/L and for a maximum of 7 days.

Policy Summary

PayerCigna

PolicyCarglumic acid (Carbaglu) coverage

Policy CodePolicy IP0438

Change TypeNo material change

Effective DateMay 1, 2025

Next Review Date

Key ActionObtain prior authorization documenting the specified medical necessity criteria for the requested indication.

SourceLink

On This Page

OpenPayer

Carglumic acid (Carbaglu) coverage

Coverage Criteria for Carglumic Acid (Carbaglu)

Coding and Clinical Thresholds

Provider Requirements, Prior Authorization, and Exclusions

Background on Carglumic Acid

Definitions