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Amifampridine Prior Authorization with Quantity Limit Program Summary
Policy Number: PH-1103
This program applies to Blue Partner, Commercial, GenPlus, NetResults A series, SourceRx and Health Insurance Marketplace.
POLICY REVIEW CYCLE
Effective Date |
Date of Origin |
10-01-2024 |
07-01-2019 |
FDA LABELED INDICATIONS AND DOSAGE
Agent(s) |
FDA Indication(s) |
Notes |
Ref# |
Firdapse® (amifampridine) Tablet |
Treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults and pediatric patients 6 years of age and older
|
|
1 |
See package insert for FDA prescribing information: https://dailymed.nlm.nih.gov/dailymed/index.cfm
CLINICAL RATIONALE
Lambert-Eaton myasthenic syndrome |
Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder characterized by the gradual onset of muscle weakness, especially of the pelvic and thigh muscles. Approximately 60 percent of LEMS cases are associated with a small cell lung cancer (SCLC), and the onset of LEMS symptoms often precedes the detection of the cancer. The LEMS patients with cancer tend to be older and nearly always have a long history of smoking. In cases in which there is no associated cancer, disease onset can be at any age.(3) LEMS may affect the patient’s ability to engage in strenuous exercise and may make such activities as climbing stairs or walking up a steep walkway difficult. Onset is gradual, typically taking place over several weeks to many months. There is often a progression of symptoms whereby the shoulder muscles, muscles of the feet and hands, speech and swallowing muscles and eye muscles are affected in a stepwise fashion. The symptoms progress more quickly when LEMS is associated with cancer. Most LEMS patients also exhibit the following autonomic symptoms: dry mouth, constipation, impotence, and decreased sweating. LEMS patients with or without cancer may also undergo significant weight loss. The tendon reflexes are diminished or absent on examination. In summary, LEMS is often described as a clinical “triad” of proximal muscle weakness, autonomic symptoms and reduced tendon reflexes.(3) LEMS occurs because autoantibodies damage the “voltage-gated calcium channels (VGCC)” on the motor nerve membrane at the neuromuscular junction. These channels normally conduct calcium into the nerve resulting in release of acetylcholine. Acetylcholine helps in the communication between nerve cells and muscles and is one of a group of chemicals known as neurotransmitters, which help to transmit nerve impulses. The autoantibodies attack the VGCC resulting in less acetylcholine release. In LEMS cases associated with cancer, it is believed that autoantibodies created against the VGCC on the small-cell lung tumor damage the VGCC on the nerve. It is unknown what causes autoantibody production in cases not associated with cancer.(3) A differential diagnosis of LEMS must be determined due to its similarities in presentation to myasthenia gravis. Diagnosis of LEMS is based on clinical signs and symptoms, electrophysiological studies, and antibody testing. LEMS can be diagnosed when the patient is positive for antibodies against voltage-gated calcium channels (VGCC) unlike myasthenia gravis which as anti-acetylcholine receptor (AChR) and anti-muscle-specific tyrosine kinase (MuSK) antibodies.(4) The triad of electrophysiologic abnormalities in LEMS consists of the following:
The most effective symptomatic treatment in LEMS is 3,4-diaminopyridine (3,4-DAP), also known as amifampridine. Through blocking voltage-gated potassium channels,3,4-DAP prolongs nerve terminal depolarization and increases acetylcholine release. In theory, pyridostigmine should be synergistic with 3,4-DAP but many patients with LEMS have no benefit from pyridostigmine either on its own or in combination with 3,4-DAP.(4) |
Efficacy |
The mechanism by which Firdapse (amifampridine) exerts its therapeutic effect in LEMS patients has not been fully elucidated. Amifampridine is a broad-spectrum potassium channel blocker. The efficacy of Firdapse for the treatment of LEMS was demonstrated in two randomized, double-blind, placebo-controlled discontinuation studies. A total of 64 adults with LEMS (confirmed by either neurophysiology studies or a positive anti-P/Q type voltage-gated calcium channel antibody test. Patients were required to be on an adequate and stable dosage (30 to 80 mg daily) of amifampridine prior to entering the randomized discontinuation phases of both studies.(1) The two co-primary measures of efficacy in both studies were the change from baseline to the end of the discontinuation period in the Quantitative Myasthenia Gravis (QMG) score and in the Subject Global Impression (SGI) score. The QMG is a 13-item physician-rated categorical scale assessing muscle weakness. Each item is assessed on a 4-point scale, where a score of 0 represents no weakness, and a score of 3 represents severe weakness. Higher scores represent greater impairment. The SGI is a 7-point scale on which patients rated their global impression of the effects of the study treatment on their physical well-being. Lower scores on the SGI represent lower perceived benefit with the study treatment.(1) A key secondary efficacy endpoint was the clinical global impression improvement (CGI-I) score, a 7-point scale on which the treating physician rated the global impression of change in clinical symptoms. A higher CGI-I score indicates a perceived worsening of clinical symptoms.(1) |
Safety |
|
REFERENCES
Number |
Reference |
1 |
Firdapse Prescribing Information. Catalyst Pharmaceuticals. May 2023. |
2 |
Reference no longer used. |
3 |
National Organization for Rare Disorders (NORD). Rare Disease Database. Lambert-Eaton Myasthenic Syndrome. |
4 |
Nicolle MW. Myasthenia Gravis and Lambert-Eaton Myasthenic Syndrome. Continuum (Minneap Minn) 2016;22(6): 1978-2005. |
POLICY AGENT SUMMARY PRIOR AUTHORIZATION
Target Brand Agent(s) |
Target Generic Agent(s) |
Strength |
Targeted MSC |
Available MSC |
Final Age Limit |
Preferred Status |
|
||||||
Firdapse |
amifampridine phosphate tab |
10 MG |
M ; N ; O ; Y |
N |
|
|
POLICY AGENT SUMMARY QUANTITY LIMIT
Target Brand Agent Name(s) |
Target Generic Agent Name(s) |
Strength |
QL Amount |
Dose Form |
Day Supply |
Duration |
Addtl QL Info |
Allowed Exceptions |
Targeted NDCs When Exclusions Exist |
|
|||||||||
Firdapse |
Amifampridine Phosphate Tab 10 MG (Base Equivalent) |
10 MG |
300 |
Tablets |
30 |
DAYS |
|
|
|
CLIENT SUMMARY – PRIOR AUTHORIZATION
Target Brand Agent Name(s) |
Target Generic Agent Name(s) |
Strength |
Client Formulary |
Firdapse |
amifampridine phosphate tab |
10 MG |
Blue Partner ; Commercial ; GenPlus ; Health Insurance Marketplace ; NetResults A Series ; SourceRx |
CLIENT SUMMARY – QUANTITY LIMITS
Target Brand Agent Name(s) |
Target Generic Agent Name(s) |
Strength |
Client Formulary |
Firdapse |
Amifampridine Phosphate Tab 10 MG (Base Equivalent) |
10 MG |
Blue Partner ; Commercial ; GenPlus ; Health Insurance Marketplace ; NetResults A Series ; SourceRx |
PRIOR AUTHORIZATION CLINICAL CRITERIA FOR APPROVAL
Module |
Clinical Criteria for Approval |
|
Initial Evaluation Target Agent(s) will be approved when ALL of the following are met:
Length of Approval: 6 months Note: If Quantity Limit applies, please see Quantity Limit criteria
Renewal Evaluation Target Agent(s) will be approved when ALL of the following are met:
Length of Approval: 12 months Note: If Quantity Limit applies, please see Quantity Limit criteria |
QUANTITY LIMIT CLINICAL CRITERIA FOR APPROVAL
Module |
Clinical Criteria for Approval |
QL with PA |
Quantity Limits for the Target Agent(s) will be approved when the requested quantity (dose) does NOT exceed the program quantity limit Length of Approval: 6 months for initial 12 months for renewal |
This pharmacy policy is not an authorization, certification, explanation of benefits or a contract. Eligibility and benefits are determined on a case-by-case basis according to the terms of the member’s plan in effect as of the date services are rendered. All pharmacy policies are based on (i) information in FDA approved package inserts (and black box warning, alerts, or other information disseminated by the FDA as applicable); (ii) research of current medical and pharmacy literature; and/or (iii) review of common medical practices in the treatment and diagnosis of disease as of the date hereof. Physicians and other providers are solely responsible for all aspects of medical care and treatment, including the type, quality, and levels of care and treatment.
The purpose of Blue Cross and Blue Shield of Alabama’s pharmacy policies are to provide a guide to coverage. Pharmacy policies are not intended to dictate to physicians how to practice medicine. Physicians should exercise their medical judgment in providing the care they feel is most appropriate for their patients.
Neither this policy, nor the successful adjudication of a pharmacy claim, is guarantee of payment.
Commercial _ PS _ Amifampridine__PAQL _ProgSum_ 10-01-2024