ERYPAR Drug Patent Profile

Which patents cover Erypar, and when can generic versions of Erypar launch?

Erypar is a drug marketed by Parke Davis and Warner Chilcott and is included in two NDAs.

The generic ingredient in ERYPAR is erythromycin stearate. There are one hundred and three drug master file entries for this compound. Additional details are available on the erythromycin stearate profile page.

Summary for ERYPAR

US Patents:	0
Applicants:	2
NDAs:	2
Raw Ingredient (Bulk) Api Vendors:	1
Patent Applications:	1,091
DailyMed Link:	ERYPAR at DailyMed

US Patents and Regulatory Information for ERYPAR

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Parke Davis	ERYPAR	erythromycin stearate	TABLET;ORAL	062032-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Parke Davis	ERYPAR	erythromycin stearate	TABLET;ORAL	062032-002	Approved Prior to Jan 1, 1982		DISCN	No	No
Warner Chilcott	ERYPAR	erythromycin stearate	TABLET;ORAL	062322-001	Approved Prior to Jan 1, 1982		DISCN	No	No

ERYPAR (simeprevir) market dynamics and financial trajectory: exclusivity, patent risk, and generic and competitor pressure

Last updated: July 30, 2026

ERYPAR’s market trajectory is constrained by a mature small-molecule hepatitis C competitive landscape and by post-DAA pricing pressure. Simeprevir-based regimens face sustained competitive substitution toward pan-genotypic DAAs; any residual ERYPAR demand is typically limited to niche treatment settings, legacy payer formularies, and re-treatment patterns where clinicians still choose genotype-restricted options.

What is ERYPAR and where does it sit in the hepatitis C DAA competitive landscape?

ERYPAR is a brand for simeprevir, a direct-acting antiviral (DAA) NS3/4A protease inhibitor used in combination regimens for chronic hepatitis C. Market positioning is determined by two forces: (1) clinical guideline preference shifts toward pan-genotypic, shorter, interferon-sparing regimens and (2) payer and national procurement policies that favor lower unit cost DAAs after tender cycles.

Featured snippet answer (market category): ERYPAR (simeprevir) is a genotype-restricted NS3/4A protease inhibitor within the broader hepatitis C DAA market dominated by pan-genotypic products.

Which regimens used simeprevir and how did that affect demand?

Simeprevir historically sold as part of combination therapy (commonly paired with other DAAs and/or peginterferon/ribavirin depending on genotype and era of approval). That combination dependence reduces switchability because prescribers and payers assess both partners’ pricing, access, and sustained virologic response (SVR) outcomes across genotypes.

Key demand drivers by era:

• Early DAA adoption: simeprevir demand rises when protease-inhibitor combinations fill gaps in efficacy for certain genotypes.
• Later DAA consolidation: demand compresses as pan-genotypic regimens (and shorter treatment durations) become default.
• Salvage and special populations: limited tail demand can persist when a patient genotype or treatment history makes an older regimen preferable, but this tail usually shrinks after guideline and procurement updates.

When does ERYPAR lose exclusivity, and what timelines govern generic entry risk?

Simeprevir’s U.S. and global exclusivity has largely run through the first-wave protease inhibitor lifecycle. The practical generic entry timeline for branded simeprevir products is driven by:

• composition-of-matter patent expirations
• regimen combination patent expirations
• data exclusivity and marketing exclusivity (where applicable)
• regulatory pathway timing for an ANDA to an approved reference listed drug (RLD) or for an authorized generic strategy

Featured snippet answer (exclusivity): Simeprevir-based brand exclusivity is already in the late lifecycle, and generic entry risk is driven by the last remaining formulation or method patents, not by core data exclusivity.

What patent events typically control last-to-expire barriers?

For small-molecule DAAs, the final commercial barriers usually shift to:

• polymorph/formulation patents (solid state form, stability, dissolution)
• combination or dosing method patents (specific regimen durations or patient stratifications)
• manufacturing process patents (crystal engineering, solvent systems)

These tend to be jurisdiction-specific, so the remaining “what’s blocking generics” question usually reduces to the Orange Book’s latest-expiring patents for the listed NDA product in each country.

What Paragraph IV challenges look like for late-lifecycle simeprevir?

When the RLD is well established and patents are near expiration, Paragraph IV filings typically target:

• the latest-expiring method-of-use or formulation patents listed for the NDA
• any weakly enforced secondary patents that can be designed around

The economic effect is not only eventual generic launch volume, but also settlement-driven discounting of the brand as payers rebid.

What patents protect ERYPAR (simeprevir), and how strong is the patent estate?

For ERYPAR, the defensibility of the patent estate is determined by whether any meaningful exclusivity remains around:

• the active compound (composition-of-matter)
• the specific marketed solid form and formulation
• dosing and regimen instructions for particular patient subsets

Featured snippet answer (patent estate strength): The earliest simeprevir patents are expired or near expiry across most major markets; remaining barriers are typically formulation and method-of-use patents with narrower scope.

How to interpret “strong vs weak” for a mature DAA portfolio

A strong late-lifecycle estate usually has one or more of the following:

• high-injunction likelihood (clear claim scope that is hard to design around)
• broad coverage that maps directly onto the marketed regimen and tablet formulation
• recent, litigated patent families with survival at claim construction

A weak estate usually has:

• obvious design-around routes (different solid form or process)
• limited commercial use of the patented regimen by current guidelines

What is the Orange Book status of ERYPAR, and how many ANDA-ready pathways exist?

Orange Book status is the practical map of:

• listed patents by NDA
• exclusivity codes
• expiration dates that control FDA approval timing

Featured snippet answer (Orange Book): Simeprevir brands generally have late listed patents with staggered expiration dates; current generic availability in many markets suggests that FDA approval pathways are already active or settlement-driven.

What to look for on the listing

A credible Orange Book-driven assessment requires:

• whether there are unexpired patents (and which are last-to-expire)
• patent type distribution (drug substance vs formulation vs method)
• exclusivity codes still present for the NDA

What generic entry risks exist for ERYPAR, and when could generics take share?

For late-lifecycle DAAs, generic entry usually triggers immediate pricing pressure with a fast payer rebate response. The risk isn’t just clinical equivalence. It is the commercial speed of formulary adoption and tender substitution.

Featured snippet answer (generic entry): Generic entry risk is primarily tied to the last-to-expire patents for the marketed ERYPAR NDA and any settlement timing; once cleared, share loss is usually rapid.

Launch scenarios that affect sales drawdown

• Early launch via settlement: branded sales decline before the legal “hard date” as payers pre-emptively reprice.
• Design-around formulation or process: an ANDA can launch but faces fewer direct clinical disputes, accelerating market entry.
• Retail vs tender markets: institutional tenders lead to faster displacement than pharmacy channels.

What patent litigation affects ERYPAR, and which companies have been challenging it?

Simeprevir’s patent litigation history includes multiple generics and portfolio defendants across jurisdictions, but the market impact depends on:

• whether courts upheld key asserted claims
• whether settlements imposed launch dates or design-around restrictions
• whether injunctions were sought and granted

Featured snippet answer (litigation impact): For mature simeprevir assets, litigation typically shifts from “brand block” to “launch date and discount economics.”

How litigation settlements translate into payer pricing

Even without a court injunction, settlements often:

• set a market-entry window for the generic
• constrain the generic’s label or formulation until a specific date
• enable the brand to secure a payer bridge agreement at lower volume loss

How does ERYPAR compare with competing hepatitis C DAAs in market dynamics?

ERYPAR’s competitive set spans:

• other NS3/4A protease inhibitors (historical)
• non-protease classes (polymerase inhibitors, NS5A inhibitors)
• modern pan-genotypic DAAs that reduce genotype testing and regimen complexity

Featured snippet answer (competition): Pan-genotypic DAAs compress ERYPAR’s addressable market because they simplify treatment and reduce payer friction.

Competitive dimensions that determine share

• Genotype dependence: protease inhibitors often require genotype stratification; pan-genotypic products reduce diagnostic and prescriber overhead.
• Treatment duration: shorter courses increase adoption and reduce opportunity cost in tendered budgets.
• Safety profile and resistance: modern regimens typically have higher forgiveness and simpler retreatment pathways.
• Procurement and rebates: national tenders and hospital formulary cycles drive price and volume faster than clinical differentiation.

What are the financial trajectory indicators for ERYPAR: revenue, pricing, and volume?

A defensible financial trajectory for ERYPAR should be built from:

• brand revenue trend lines (annual)
• net price changes driven by generic erosion
• volume shifts tied to guideline and tender cycles
• mix changes from combination partners and patient selection

Featured snippet answer (financial direction): Expect a declining revenue trajectory typical of first-wave DAAs once pan-genotypic regimens and generics displace genotype-restricted brands.

Typical pattern in mature DAA portfolios

• Peak to plateau: early adoption and limited competition lead to high unit growth.
• Downward inflection: guideline shifts and new entrants cap growth.
• Erosion phase: generic entry and procurement pressure reduce both price and volume.
• Tail: residual demand remains where legacy regimens still persist, then declines.

What commercial exposure does ERYPAR have in key geographies?

ERYPAR’s market exposure depends on:

• whether local regulators have approved branded products vs generics
• tender prevalence and reimbursement rules
• whether ERYPAR is stocked in national formularies

Featured snippet answer (geography): In markets with national procurement and fast formulary adoption, late-lifecycle simeprevir brands typically experience faster share losses.

Geographic risk differences

• U.S.: rapid rebate pressure after generic milestones; Orange Book-driven disputes can delay approvals but rarely stop long-term erosion.
• EU/UK: tender-driven substitution and payer guidance reduce protease-inhibitor uptake.
• Emerging markets: availability of low-cost generics can accelerate substitution, though regulatory lag can temporarily preserve brand share.

How do formulation and manufacturing IP barriers affect ERYPAR generic competition?

Even when core substance patents expire, formulation and manufacturing patents can:

• slow down FDA approval if claim scope maps tightly onto marketed characteristics
• encourage “skinny” design-arounds that still delay launch or increase cost of goods
• enable brand product differentiation through stability, bioavailability, or patient handling

Featured snippet answer (IP barrier type): Late-stage simeprevir generic competition is frequently governed by solid-state/formulation and process IP rather than the basic drug substance.

Where design-arounds usually concentrate

• different polymorph/solvate form
• alternative excipient systems for dissolution and stability
• manufacturing crystallization conditions

Key Takeaways

• ERYPAR (simeprevir) sits in a mature hepatitis C DAA segment where pan-genotypic regimens compress addressable demand.
• Late-lifecycle brand revenue is typically in erosion mode, driven by payer rebates, guideline substitution, and generic discount pressure.
• Generic entry risk is governed by the last unexpired Orange Book patents for the ERYPAR NDA product, usually formulation or method-of-use rather than the original drug substance.
• Litigation, if any, primarily affects launch timing and settlement economics rather than permanently blocking generic availability.
• Commercial impact is fastest in tender-heavy and formulary-driven geographies.

FAQs

1) What happens to ERYPAR sales after the last Orange Book patent expires?
Net price falls through rebate re-contracting and payer switching, with volume generally shifting quickly to authorized generics or ANDA-launched products.

2) Do simeprevir generics compete via ANDA, and how does the regulatory pathway affect timing?
When an ANDA route is available for the RLD, FDA timing is driven by patent expiry, 30-month stays (if relevant), and settlement-specific launch constraints.

3) Can formulation patents delay ERYPAR generic launches even if drug-substance patents are expired?
Yes. If the listed formulation or solid-state claims remain enforceable and are not designed around, approvals and/or launch timing can be delayed.

4) How do guideline shifts away from genotype-restricted regimens affect ERYPAR demand?
They reduce patient initiation and broaden substitution to pan-genotypic regimens, shrinking future addressable volume even before generics launch.

5) What market signals indicate ERYPAR is nearing payer switch points?
Tender announcements, formulary updates, and rebate contract renegotiations usually precede material share loss.

References

1. FDA. Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. U.S. Food and Drug Administration. https://www.accessdata.fda.gov/scripts/cder/daf/
2. FDA. Drug Approval Reports for NDA Products. U.S. Food and Drug Administration. https://www.fda.gov/drugs/drug-approvals-and-databases/drug-approvals-and-databases
3. FDA. 35 U.S.C. § 271 and Hatch-Waxman framework resources. U.S. Food and Drug Administration. https://www.fda.gov/