Drugs in MeSH Category Filaricides

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Lederle	HETRAZAN	diethylcarbamazine citrate	TABLET;ORAL	006459-001	Approved Prior to Jan 1, 1982		DISCN	No	No

Last updated: July 11, 2026

Market dynamics and patent landscape for filaricides (MeSH Class: Filaricides)

Filaricides are prescription medicines used to treat human lymphatic filariasis and onchocerciasis, with key competitors concentrated in a small number of active ingredients. Market structure is shaped by (1) dosing-seasonality, (2) mass drug administration (MDA) procurement contracts, (3) WHO treatment-program eligibility, and (4) a patent estate dominated by branded originator manufacturing, formulation, and method-of-use claims rather than broad active-ingredient monopolies. The current business risk is not “active-ingredient loss of exclusivity” across the whole category, but pipeline timing around repeat dosing regimens, pediatrics, and product-line expansions, plus biosafety and bioequivalence barriers for generics where originator manufacturing/formulation patents remain in force.

Market map of filaricides by program and active ingredient

MeSH “Filaricides” typically tracks products used for lymphatic filariasis (LLM), onchocerciasis (river blindness), and related nematode infections. The practical category is narrower than the label suggests because many antiparasitics fall outside MeSH “Filaricides” in major indexing.

Indication program	Primary parasites	Dominant filaricide actives in market	Commercial model that drives dynamics
Lymphatic filariasis (Wuchereria bancrofti, Brugia spp.)	Lymphatic nematodes	Diethylcarbamazine (DEC), Ivermectin (adjunct), Albendazole (MDA co-therapy)	WHO MDA procurement, tendered multi-year contracts; prices are low but volumes are large
Onchocerciasis (Onchocerca volvulus)	Skin and eye nematodes	Ivermectin	MDA procurement and national programs; dosing is periodic, which extends maintenance of demand
Scabies/strongyloides overlap in practice	Mixed NTD landscapes	Ivermectin can be adjacent depending on labeling	Patent and generic pressure is more acute when products overlap commercial channels

The patent landscape for the category is driven by three realities:

1. Active ingredient patents for legacy filaricides (especially ivermectin-era products and DEC-era products) are largely historic.
2. Product life-cycle protection tends to shift to formulations (dose forms, stability, pediatric suitability), manufacturing/process, and method-of-use (dose regimens for specific indications or combinations).
3. Exclusivity under the Hatch-Waxman and pediatric/market exclusivity frameworks can extend market protection even after core composition patents expire.

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What patents protect filaricides (ivermectin, diethylcarbamazine, albendazole) in the US and EU?

Featured-snippet answer: Protection for filaricides typically comes from (1) legacy composition claims that have largely expired, (2) formulation and process patents that survive longer, and (3) US exclusivity and Orange Book-listed patents tied to specific branded dosage forms and labeling regimens.

What is usually covered in the patent estate?

Across filaricides, patent filings cluster into these technical bins:

• Formulation patents
  • Solid oral forms adapted for pediatric use (tablet splits, dispersible tablets, granules)
  • Stability and dissolution improvements for poorly soluble components
  • Bioavailability-enabling excipient systems
• Manufacturing/process patents
  • API crystallization and polymorph control
  • Solid-state control (particle size distribution, amorphous/crystalline forms)
  • Tablet/compression process parameters and scale-up methods
• Method-of-use patents
  • Specific dosing schedules for MDA programs
  • Combination regimens (for example, adjunctive use with albendazole or targeting specific populations)
  • Eye disease endpoints in onchocerciasis (where claim scope is narrower and litigation is more common)

US patent-protection posture: “Orange Book-driven” per product

For most filaricides, business teams should treat the Orange Book as the operative map for:

• “Patents listed for approval” that must be addressed for abbreviated approvals
• Method-of-use and formulation listings that constrain generic entry even when composition patents are dead

However: generating a product-by-product Orange Book matrix with specific patent numbers and expiration dates requires product-level labeling and Orange Book listings, which are not provided in the prompt.

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When do filaricide patents lose exclusivity, and what drives the last-mile protection?

Featured-snippet answer: Filariicide category exclusivity is usually determined by the remaining validity of Orange Book-listed patents for the specific dosage form and labeling, plus any non-patent exclusivities (pediatric exclusivity, new clinical investigation exclusivity) rather than broad active-ingredient composition rights.

Typical exclusivity timeline mechanics for category players

1. Composition/IP expires first
   • Active ingredient monopoly ends on the last composition patent expiration.
2. Formulation/process claims remain
   • Strengthening around dissolution, stability, pediatric suitability, and manufacturing yield.
3. Method-of-use claims constrain “label-only” changes
   • If claims are tied to dosing regimens, generics can be forced into “carve-out” labeling or launch delays.
4. Exclusivity is label-dependent
   • Non-patent exclusivity can bar an approval or bar marketing for a branded product even if some patents are expiring.

MDA procurement contracts extend practical exclusivity

Even after legal exclusivity ends, supply chain and procurement tenders can delay substitution. Contracting in NTD programs can produce a practical lag:

• incumbent supply reliability
• QA validation
• tenders that lock in pricing and qualification

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Which Paragraph IV challenges matter for filaricides, and how often do they succeed?

Featured-snippet answer: Paragraph IV activity in filaricides is less about “hundreds of distributed filings” and more about targeted challenges against specific Orange Book-listed formulation or method-of-use patents protecting a branded dosage form.

What claim types typically trigger Paragraph IV

• Formulation patents
  • Generic can challenge patent validity or non-infringement based on different excipient system, manufacturing, or bioequivalence strategy.
• Method-of-use patents
  • Generics attempt to seek approval on a narrower label that avoids the claimed regimen. Litigations can hinge on how FDA-approved labeling aligns with patent claim language.

What outcomes typically drive category market dynamics

• Settlement agreements often convert patent risk into entry timing commitments (launch date) and/or labeling carve-outs.
• Court invalidation is less common than settlements; the business effect is still market access shift.

Missing data constraint: Without a specific list of filaricide brand names and target Orange Book products, it is not possible to produce a factual Paragraph IV docket table (case names, court dates, asserted patents, and settlement terms).

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How strong is the patent estate for filaricides, and which claim buckets dominate?

Featured-snippet answer: The filaricide patent estate is usually dominated by formulation and manufacturing claims at the product level, with method-of-use claims playing a smaller but high-impact role during generic transition.

Patent-strength drivers for investors and challengers

• Remaining claim life: composition patents are mostly expired; remaining years depend on formulation/process continuations.
• Claim breadth:
  • Narrow process conditions reduce generic inhibition if design-around is possible.
  • Broad formulation composition claims can force product redesign.
• Litigation history:
  • If originators have previously enforced similar formulation patents, infringement theories and claim construction tend to be predictable.
• Regulatory alignment:
  • If patents are listed for a specific dosing regimen and FDA labeling matches the regimen, non-infringement defenses are harder.

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What formulations are protected for filaricides, and what generic entry risks exist?

Featured-snippet answer: Generic entry risk is highest when Orange Book-listed patents cover the exact dosage form and bioequivalence-critical formulation characteristics, or when method-of-use patents match FDA labeling for endemic-program dosing.

Dosage-form pressure points

• Pediatric suitability
  • Tablets that can be split or dispersible/granulated dosage forms can be the basis for formulation patent differentiation.
• Stability and shelf-life
  • MDA programs require robust cold-chain optionality; stability claims can drive patent strength.
• Bioavailability
  • For oral agents, formulation changes that affect exposure can lead to additional bridging studies and patent non-infringement scrutiny.

Generic entry risk categories

• Regulatory risk: label carve-outs required to avoid method-of-use infringement.
• CMC/IP risk: process patent infringement based on crystallization or solid-state steps that are hard to redesign.
• Procurement qualification risk: even after legal entry, program adoption can lag.

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How does the competitive landscape differ across lymphatic filariasis vs onchocerciasis?

Featured-snippet answer: Onchocerciasis markets are usually more concentrated around ivermectin-like recurring MDA use, while lymphatic filariasis markets involve combination program structures (including co-administered albendazole) and broader regimen adaptation.

Competitive dynamics: what changes by program

• Onchocerciasis
  • periodic dosing drives stable recurring demand
  • product switching requires program-level tender requalification
• Lymphatic filariasis
  • combination regimens create multiple “anchor” products; substitutability depends on procurement and regimen guidelines

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What FDA status and Orange Book status apply to filaricides?

Featured-snippet answer: FDA regulatory status for filaricides is typically anchored by whether specific branded dosage forms are listed in the Orange Book and whether their listed patents are active. Without specific brand/product inputs, a definitive Orange Book status matrix cannot be produced.

What to check for each product (operational checklist)

• Orange Book entry: listed patents, patent use codes (method-of-use vs formulation vs composition)
• Approval pathway: NDA vs ANDA
• Exclusivity codes: pediatric, orphan (if applicable), and any clinical investigation exclusivities tied to labeling expansions
• Labeling regimen: matches to method-of-use claim language

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What patent litigation affects filaricides, and which settlements shift launch dates?

Featured-snippet answer: Litigation typically focuses on product-level Orange Book patents and method-of-use labeling alignment. Settlement outcomes usually set an agreed launch date and label carve-outs.

Constraint: Building a litigation table requires specific case identifiers and asserted patents, which are not included in the prompt. Producing it without verified docket data would be non-actionable.

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Which companies are most exposed to generic entry in filaricides?

Featured-snippet answer: Exposure concentrates among originators with still-active Orange Book-listed patents for branded dosage forms used in endemic-program dosing, plus companies expanding product lines via pediatric and formulation upgrades.

Exposure drivers

• Share of sales tied to a dosage form with listed patents still within term
• Strength of formulation/process patents relative to generic design-around feasibility
• Reliance on MDA tender contracts that can switch suppliers quickly once legally eligible

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Revenue exposure and timing: how to map generics risk to product life-cycle events?

Featured-snippet answer: For filaricides, generic risk should be modeled around (1) last Orange Book expiration of the exact marketed dosage form, (2) any remaining pediatric exclusivity, and (3) settlement-driven launch covenants.

Category-level planning template (what a business team should model)

• Event 1: earliest Orange Book patent expiration per dosage form
• Event 2: latest Orange Book patent expiration (method-of-use can extend)
• Event 3: exclusivity cliffs tied to clinical pediatric labeling
• Event 4: settlement triggers (agreed entry dates)
• Event 5: procurement requalification time horizon (practical delay)

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How do filaricides compare with other antiparasitics in patent durability?

Featured-snippet answer: Filaricides show higher persistence of product-level formulation and method-of-use IP than many single-molecule antiparasitics because mass-program dosing drives stable product-specific demand and creates incentives to keep pediatric-appropriate formulations and regimen-specific labeling protected.

Key comparison axes

• MDA tender cadence vs hospital/retail prescribing
• Label regimen specificity vs generalized dosing
• Formulation differentiation vs pure active-ingredient equivalence

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Key Takeaways

• Filaricides are structurally shaped by endemic-program procurement, periodic dosing cycles, and product-level regulatory labeling.
• Patent protection in the category is typically last-mile: formulation, process, and method-of-use claims plus Orange Book-listed patents, not composition monopolies.
• The highest generic-entry risk points are the still-active Orange Book patent listings tied to specific dosage forms and dosing regimens.
• Litigation and Paragraph IV events, when they occur, are usually targeted at product-level patents that block label-accurate generic launches.
• For business planning, the actionable timing input is the per-dosage-form Orange Book expiration and the effect of any settlement agreements, not a generic “active ingredient” expiration view.

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FAQs

1) What do Orange Book patent use codes indicate for filaricide generic challenges?
The use codes identify whether the listed patent covers composition, formulation, or method-of-use, which determines whether a generic can design around by changing formulation or must change labeling/regimen.

2) Do filaricide method-of-use patents block generics even if the active ingredient is generic-eligible?
Yes when the generic seeks approval with labeling that reads on the claimed regimen; otherwise, carve-out labeling can sometimes avoid infringement.

3) How do pediatric formulations change patent strategy in filaricides?
They create distinct dosage forms and stability/exposure targets that are often protected by formulation patents and supported by pediatric exclusivity and bridging study data.

4) Why do MDA tender qualification timelines slow generic substitution?
Procurement qualification, QA testing, and multi-year contract pricing can delay real-world switching even after legal entry.

5) What patent claim types are hardest to design around for oral filaricides?
Solid-state and process-controlled claims tied to specific crystallization/polymorph outcomes can be difficult to replicate without triggering infringement theories, especially where the generic uses similar CMC steps.

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References

1. National Library of Medicine (MeSH). MeSH descriptor: Filaricides. https://meshb.nlm.nih.gov/
2. FDA. Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/