FIRDAPSE Drug Patent Profile

When do Firdapse patents expire, and when can generic versions of Firdapse launch?

Firdapse is a drug marketed by Catalyst Pharms and is included in one NDA. There are six patents protecting this drug and one Paragraph IV challenge.

The generic ingredient in FIRDAPSE is amifampridine phosphate. There is one drug master file entry for this compound. One supplier is listed for this compound. Additional details are available on the amifampridine phosphate profile page.

DrugPatentWatch^® Generic Entry Outlook for Firdapse

Firdapse was eligible for patent challenges on November 28, 2022.

By analyzing the patents and regulatory protections it appears that the earliest date for generic entry will be February 25, 2037. This may change due to patent challenges or generic licensing.

There have been six patent litigation cases involving the patents protecting this drug, indicating strong interest in generic launch. Recent data indicate that 63% of patent challenges are decided in favor of the generic patent challenger and that 54% of successful patent challengers promptly launch generic drugs.

Indicators of Generic Entry

Summary for FIRDAPSE

US Patents:	6
Applicants:	1
NDAs:	1
Finished Product Suppliers / Packagers:	1
Raw Ingredient (Bulk) Api Vendors:	170
Clinical Trials:	3
Drug Prices:	Drug price information for FIRDAPSE
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for FIRDAPSE
What excipients (inactive ingredients) are in FIRDAPSE?	FIRDAPSE excipients list
DailyMed Link:	FIRDAPSE at DailyMed

See drug prices for FIRDAPSE

DrugPatentWatch^® Estimated Loss of Exclusivity (LOE) Date for FIRDAPSE

Constraining patent/regulatory exclusivity:

10,626,088

NDA:

208078

Dosage:

TABLET;ORAL

^*The generic entry opportunity date is the latter of the last compound-claiming patent and the last regulatory exclusivity protection. Many factors can influence early or later generic entry. This date is provided as a rough estimate of generic entry potential and should not be used as an independent source.

Recent Clinical Trials for FIRDAPSE

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
Wake Forest University Health Sciences	Phase 1
Augusta University	Phase 2
Centre Hospitalier Universitaire, Amiens	Phase 2/Phase 3

See all FIRDAPSE clinical trials

Pharmacology for FIRDAPSE

Drug Class	Potassium Channel Blocker
Mechanism of Action	Potassium Channel Antagonists

Paragraph IV (Patent) Challenges for FIRDAPSE

Tradename	Dosage	Ingredient	Strength	NDA	ANDAs Submitted	Submissiondate
FIRDAPSE	Tablets	amifampridine phosphate	10 mg	208078	3	2022-11-28

US Patents and Regulatory Information for FIRDAPSE

FIRDAPSE is protected by six US patents and one FDA Regulatory Exclusivity.

This potential generic entry date is based on patent 10,626,088.

Generics may enter earlier, or later, based on new patent filings, patent extensions, patent invalidation, early generic licensing, generic entry preferences, and other factors.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Catalyst Pharms	FIRDAPSE	amifampridine phosphate	TABLET;ORAL	208078-001	Nov 28, 2018		RX	Yes	Yes	11,274,332
Catalyst Pharms	FIRDAPSE	amifampridine phosphate	TABLET;ORAL	208078-001	Nov 28, 2018		RX	Yes	Yes
Catalyst Pharms	FIRDAPSE	amifampridine phosphate	TABLET;ORAL	208078-001	Nov 28, 2018		RX	Yes	Yes	11,268,128
Catalyst Pharms	FIRDAPSE	amifampridine phosphate	TABLET;ORAL	208078-001	Nov 28, 2018		RX	Yes	Yes	11,274,331
Catalyst Pharms	FIRDAPSE	amifampridine phosphate	TABLET;ORAL	208078-001	Nov 28, 2018		RX	Yes	Yes	10,793,893
Catalyst Pharms	FIRDAPSE	amifampridine phosphate	TABLET;ORAL	208078-001	Nov 28, 2018		RX	Yes	Yes	10,626,088		Y

International Patents for FIRDAPSE

See the table below for patents covering FIRDAPSE around the world.

Country	Patent Number	Title	Estimated Expiration
World Intellectual Property Organization (WIPO)	2017214504
Canada	2840591	METHODES D'ADMINISTRATION DE 3,4-DIAMINOPYRIDINE (METHODS OF ADMINISTERING 3,4-DIAMINOPYRIDINE)
World Intellectual Property Organization (WIPO)	2013003708

Last updated: July 25, 2026

FIRDAPSE market dynamics and financial trajectory: exclusivity, pricing, demand drivers, and revenue outlook

FIRDAPSE (amifampridine) is a specialty neuromuscular treatment with limited addressable prevalence, niche prescribing, and high monitoring intensity tied to symptom control in Lambert-Eaton myasthenic syndrome (LEMS). Financial trajectory has historically depended on (1) access and formulary coverage in a small patient base, (2) the timing of U.S. regulatory milestones and any label expansions, and (3) the degree of channel pull through specialty distribution. Competitive pressure is structurally muted by the drug’s regulatory and patent position in the U.S. but remains a key swing factor for future cash flows because the molecule is small-molecule oral therapy where generic entry, if enabled, can compress net prices quickly.

The market is not “mass-market” by design: revenue is sensitive to incremental patients captured, persistence, and payor behavior, not to broad epidemiologic expansion. For investors and licensors, the core financial question is whether the brand maintains pricing power and prescription growth long enough to stay ahead of generic risk and whether payor dynamics shift in a way that forces rebates or restricts access.

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What is FIRDAPSE, who buys it, and what market segments drive revenue?

Snapshot answer: FIRDAPSE is an oral symptomatic therapy for LEMS, with buying concentrated in specialty neurology and payer channels that cover orphan or rare-disease use.

Indication and use that constrain addressable volume

• Primary FDA-approved use: Symptomatic treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults.
• Demand driver: Physician uptake depends on diagnostic certainty, documented symptom burden, and tolerability (amifampridine dosing and seizure-risk management shape initiation and persistence).

Where prescriptions concentrate

• Prescribers: Neuromuscular specialists, tertiary centers, and neurologists with rare-disease referral patterns.
• Patients: LEMS is rare; revenue is driven by the number of identified and treated patients, not broad incidence growth.
• Payers: Specialty pharmacy benefit managers, commercial rare-disease coverage plans, and government formularies where coverage is tied to medical criteria.

Net revenue sensitivity

Brand revenue in this category typically tracks:

• New starts (diagnosis and referral pipeline)
• Continuation/persistence (tolerability, efficacy perception, dosing stability)
• Access friction (prior authorization outcomes, step edits, and specialty pharmacy utilization)
• Payor price pressure (rebates and plan-level contracting)

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How do pricing, rebates, and specialty distribution shape FIRDAPSE net sales?

Snapshot answer: Net sales are dominated by payer contracting terms and specialty pharmacy economics rather than headline list price.

Price dynamics unique to rare-disease specialty brands

• Orphan dynamics: Payors often negotiate tighter rebate structures even for orphan therapies if budgets face pressure.
• Specialty channel mechanics: Distributors and specialty pharmacies influence dispensing velocity and adherence monitoring, which can affect monthly and quarterly sales reporting.
• Prior authorization burden: Each rejection cycle reduces effective demand; approvals drive claim conversions.

What to track for financial trajectory

• Gross-to-net ratio: A rising ratio signals worsening payer economics or higher concessions.
• Quarterly fill rates: Reveals whether uptake is accelerating or plateauing.
• Specialty pharmacy penetration: Correlates with conversion speed after approval.

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When does FIRDAPSE lose exclusivity, and how does that affect financial forecasts?

Snapshot answer: Generic entry timing is the dominant downside risk for future net sales. The market tends to reprice fast if generic manufacturers can substitute without meaningful barriers.

Exclusivity and patent risk framework

For oral small-molecule therapies like amifampridine, financial models should assume:

• Peak-to-generic compression: Net price can fall sharply after the first credible generic launch.
• Short-lived brand resilience: Without line extensions or formulation differentiation, brands typically lose share quickly.
• Litigation settlement impact: If a settlement triggers earlier-than-expected launch, the revenue step-down can arrive before the nominal end of market protection.

Scenario drivers for the trajectory

• U.S. patent life and Orange Book status: Determines the earliest Paragraph IV windows and potential litigation timelines.
• Number of listed patents per submission: More listed patents can slow entry or increase settlement complexity.
• Generic business model feasibility: If the generic sponsor can produce at scale and price competitively, substitution accelerates.

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What patents protect FIRDAPSE, and how strong is the patent estate for blocking generics?

Snapshot answer: Patent estate strength determines whether generics face a credible entry barrier. A dense Orange Book listing with enforceable claims can force carve-outs or settlements; a thin estate shortens the path to entry.

Patent estate assessment logic

A robust blocking position usually has:

• Multiple patent families covering compound, composition, and/or method-of-use
• Claims that remain valid post-challenge
• Active enforcement history or litigation signals

A weak position usually has:

• Fewer, narrow-use claims
• Near-expiration composition or formulation terms
• Claims susceptible to easy invalidation or design-around

Business use

This drives:

• License deal value for any branded or derivative commercialization
• Litigation cost curves for generic defense
• Time-to-market outcomes for generic competitors

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What generic entry risks exist for FIRDAPSE under Paragraph IV, and what are typical launch mechanics?

Snapshot answer: Paragraph IV challenges are a primary channel for generic entry risk, and launch mechanics are fast once approved if settlements or injunctions do not delay.

Generic launch mechanics

• Hatch-Waxman pathway: A Paragraph IV filing can produce an FDA approval timeline that depends on litigation and any court stays.
• 180-day exclusivity among challengers: The first-to-file Paragraph IV filer can capture early share, then pricing compresses as additional generics enter.
• Switching behavior: In rare disease, switching may be slower if clinicians require stability and insurers demand step edits.

Financial sensitivity

Forecasts should incorporate:

• Probabilistic generic date
• Share loss curve
• Net price erosion
• Payor formulary replacement speed

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How does FIRDAPSE compare with other LEMS therapies and symptomatic neuromuscular drugs on market dynamics?

Snapshot answer: FIRDAPSE competes on efficacy-per-tolerability and access. In LEMS, therapeutic alternatives may include symptomatic agents or off-label neurologic regimens, but brand differentiation still matters because payer coverage is selective.

Competitive set logic

• Direct comparators: Other symptomatic treatments used in neuromuscular disease may reduce urgency to switch if they meet access or clinical needs.
• Off-label dynamics: If off-label options are covered more broadly, payors can steer demand, increasing rebate pressure on FIRDAPSE.

What matters for market share

• Treatment response speed
• Monitoring burden
• Provider comfort with titration and seizure risk management
• Insurance approval likelihood

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What is the FDA regulatory status of FIRDAPSE, and how can it change demand?

Snapshot answer: FDA status affects manufacturing continuity, label confidence, and prescriber willingness, which translate into fill patterns and channel demand.

Key regulatory elements to monitor

• Label stability: Changes in dosing guidance can alter persistence and claim conversion.
• Manufacturing compliance: Any quality events interrupt supply and can create delayed reorder cycles.
• Post-approval commitments: Can drive market disruptions if timelines slip.

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What FIRDAPSE financial indicators track growth vs. plateau in specialty pharma?

Snapshot answer: Growth tends to show up first in physician starts and specialty pharmacy fill rate acceleration, while plateau often reflects access constraints and small patient base ceiling effects.

Metrics that map to revenue trajectory

• Quarterly prescription count
• Average days of therapy
• Customer mix by channel (specialty pharmacy vs. retail specialty programs)
• Gross-to-net trend
• Inventory movements (avoid overstating demand through channel stocking)

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What patent litigation or settlements could alter FIRDAPSE earnings risk?

Snapshot answer: Injunctions, settlement-triggered carve-outs, and court stays are earnings swing factors because they can shift the probability distribution of generic entry.

Litigation variables

• Paragraph IV outcomes: Dismissal, win, settlement, or invalidation can each materially alter generic timing.
• Scope of settlement: A narrow settlement can allow generic launch in limited conditions, while a broad one can trigger earlier carve-out entry.
• Design-around effectiveness: If claims are easy to design around, the injunction’s economic value can shrink.

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Where does FIRDAPSE revenue sit in the specialty portfolio economics, and what does that imply for investors?

Snapshot answer: FIRDAPSE revenue should be valued like a niche cash-flow stream with high downside convexity to generic substitution, and upside to improved access and persistence.

Portfolio implications

• High fixed cost base: Specialty brands often carry manufacturing and pharmacovigilance costs that can limit margin resilience if unit demand softens.
• Contracting leverage: Limited patient counts reduce volume leverage with payors, raising the probability of margin pressure during renewals.

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Key financial trajectory framework: base case, downside, and bull case

Snapshot answer: In rare-disease specialty, the base case usually assumes steady net price and modest starts growth, while downside assumes rapid price compression if generic entry occurs earlier or with strong substitution.

Base case (access-stable, no major IP event)

• Modest patient capture growth
• Stable gross-to-net
• Limited supply interruptions
• Revenue increases mostly from volume, not price

Downside case (generic or market access disruption)

• Net price compression after first credible generic launch
• Share loss accelerates through formulary replacement
• Gross-to-net rises due to intensified contracting tactics to defend share
• Revenue declines in step function within 1 to 4 quarters after entry

Bull case (improved access, label confidence, persistence)

• Prior authorization throughput improves
• More prescriptions convert from diagnosis to therapy
• Persistence improves with better tolerability management
• Revenue growth modestly outpaces starts expectations

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Key Takeaways

• FIRDAPSE is revenue-constrained by rare LEMS prevalence, so financial trajectory is driven by patient starts, persistence, and payor access, not epidemiologic expansion.
• The dominant earnings risk is generic entry timing and substitution speed, typically determined by Orange Book patent coverage and Paragraph IV litigation/settlement outcomes.
• Net sales trajectory should be modeled around gross-to-net trends, specialty pharmacy fill velocity, and channel inventory behavior to avoid overstating demand.
• Investors should treat FIRDAPSE as a niche cash-flow asset with high convexity: small changes in access or IP timing can create large swings in quarterly revenue.

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FAQs

1. What drives specialty pharmacy fills for FIRDAPSE more than list price?
2. How quickly do LEMS patients switch from amifampridine to a generic if one launches?
3. What are the common payer barriers for LEMS drugs like FIRDAPSE (prior authorization, step edits, evidence requirements)?
4. How do manufacturing interruptions for oral rare-disease drugs affect quarterly revenue recognition?
5. Which patent claim types (compound, composition, method-of-use) most influence generic launch timelines for amifampridine?

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References

1. FDA. Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. (U.S. FDA database).
2. FDA. Drug Approval Package and Prescribing Information for FIRDAPSE (amifampridine). (U.S. FDA).
3. FDA. Paragraph IV Certification and Hatch-Waxman framework overview. (U.S. FDA guidance and resources).
4. U.S. Patent and Trademark Office. Patent application and assignment records for amifampridine-related families (public patent data).
5. FDA. Specialty drug distribution and prescribing information resources (U.S. FDA).