CurrentCignaPolicy N/A

Metabolic Disorders - Phenylbutyrate Products Prior Authorization Policy

This Cigna prior authorization policy governs coverage criteria and authorization requirements for prescription phenylbutyrate products used in the chronic management of urea cycle disorders for affected members and providers.

Policy Summary

PayerCigna

PolicyMetabolic Disorders - Phenylbutyrate Products Prior Authorization Policy

Policy CodePolicy N/A

Change TypeClarified diagnostic confirmationcosmetic wordingadjusted conditions

Effective DateN/A

Next Review DateN/A

Key ActionObtain prior authorization and document genetic or enzymatic confirmation of a urea cycle disorder (or elevated ammonia) and that therapy is prescribed with a protein‑restricted diet.

SourceLink

POLICY UPDATE CHANGES

Modified option of approval regarding genetic testing confirmation to state genetic or enzymatic testing confirming a urea cycle disorder.

The note with examples of phenylbutyrate products was updated to use Ravicti's generic name, glycerol phenylbutyrate.

Removed 'Concomitant therapy with another phenylbutyrate product' from Conditions Not Covered.

4phenylbutyrate products named

1 yrapproval duration (confirmed UCD)

3 moapproval duration (ammonia only)

03/12/2025

Policy Summary

PayerCigna

PolicyMetabolic Disorders - Phenylbutyrate Products Prior Authorization Policy

Policy CodePolicy N/A

Change TypeClarified diagnostic confirmationcosmetic wordingadjusted conditions

Effective DateN/A

Next Review DateN/A

Key ActionObtain prior authorization and document genetic or enzymatic confirmation of a urea cycle disorder (or elevated ammonia) and that therapy is prescribed with a protein‑restricted diet.

SourceLink

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Recommended Authorization Criteria

Urea Cycle Disorders (initial authorization)

Approve if ALL of the following are met:

UCD approval criteria

Patient has a diagnosis of a urea cycle disorder (examples: deficiencies of carbamylphosphate synthetase, ornithine transcarbamylase, or argininosuccinic acid synthetase).
A) Diagnostic confirmation (ONE of):
- i: Genetic or enzymatic testing confirming a urea cycle disorder (approval duration: 1 year).
- ii: Hyperammonemia with an ammonia level above the upper limit of the normal reference range for the reporting laboratory (approval duration: 3 months).
B) Medication is prescribed in conjunction with a protein-restricted diet.
C) Patient will not receive concurrent therapy with another phenylbutyrate product (examples: sodium phenylbutyrate [Buphenyl, generic], Pheburane, Olpruva, glycerol phenylbutyrate [Ravicti, generic]).
D) Medication is prescribed by or in consultation with a metabolic disease specialist (or specialist who focuses on treatment of metabolic diseases).

Olpruva-specific weight/BSA requirement: patient weight > 20 kg and body surface area > 1.2 m2 (when applicable).

Phenylbutyrate products (including but not limited to Buphenyl®, Olpruva®, Pheburane®, and Ravicti®/glycerol phenylbutyrate) are considered not medically necessary for any uses that are not listed in the Recommended Authorization Criteria.

Coverage is not recommended for circumstances that are not included in the Recommended Authorization Criteria; the list of non-covered uses may be updated as new published data become available.

Product Listing, Dosing Limits, and Diagnostic Thresholds

Covered Products (trade/generic names listed)mixed

Buphenyl	sodium phenylbutyrate tablets and powder for oral solution - Horizon, generic
Olpruva	sodium phenylbutyrate for oral suspension - Acer
Pheburane	sodium phenylbutyrate oral pellets - Medunik
Ravicti	glycerol phenylbutyrate oral liquid - Horizon, generic

Olpruva (weight / BSA requirements)

Weight requirementPatient must weigh > 20 kg

BSA requirementBody surface area > 1.2 m2

Product-specific noteOlpruva is indicated for use in patients meeting both weight and BSA criteria

Ammonia level diagnostic threshold

Diagnostic thresholdAmmonia level above the upper limit of the normal reference range for the reporting laboratory

Reference range considerationReference ranges are dependent upon patient age

Prior Authorization, Documentation, and Billing Rules

Prior Authorization

Prior Authorization Required

Prior authorization is recommended for phenylbutyrate products. Approvals are time-limited: when approval is based on genetic or enzymatic confirmation of a urea cycle disorder, authorization may be granted for 1 year; when approval is based solely on hyperammonemia (an ammonia level above the laboratory's upper limit of normal), authorization may be granted for 3 months. Approvals expressed in months use 30-day months. Prescriptions must be written by or in consultation with a physician who specializes in the treated condition.

Documentation Required

Concurrent Therapy and Diet Requirement

The medication must be prescribed in conjunction with a protein-restricted diet and must not be used concurrently with another phenylbutyrate product.

Medication must be given with a protein-restricted diet.
Do not administer concurrently with other phenylbutyrate products (e.g., sodium phenylbutyrate [Buphenyl, generic], Pheburane, Olpruva, glycerol phenylbutyrate [Ravicti, generic]).

Clinical Background

Urea cycle disorders (UCDs) are inherited enzyme deficiencies (examples include carbamoyl phosphate synthetase, ornithine transcarbamylase, and argininosuccinate synthetase deficiencies) that impair the urea cycle and lead to accumulation of ammonia. Elevated blood ammonia (hyperammonemia) can cause encephalopathy and severe neurologic injury; chronic management strategies may include dietary protein restriction, amino acid supplementation, and adjunctive alternative nitrogen excretion therapies such as oral phenylbutyrate products.

Key Terms and Product Definitions

Urea cycle disorders (UCDs)

DefinitionInherited enzyme deficiencies leading to impaired urea cycle function and elevated blood ammonia (examples: CPS, OTC, AS)

Clinical consequenceElevated ammonia may cause encephalopathy and severe neurologic damage

Diagnosis methodsDiagnosis may involve clinical suspicion, enzymatic diagnosis, and/or genetic testing

Phenylbutyrate products

Drug classOral phenylbutyrate products (e.g., sodium phenylbutyrate formulations, glycerol phenylbutyrate)

Role in therapyUsed as adjunctive chronic therapy to provide alternative nitrogen excretion pathways in UCDs