US Patent 10,188,637: Scope, Claims, Expiration and Pirfenidone Patent Landscape

US Patent 10,188,637 protects a granulated oral formulation of pirfenidone, the active ingredient in Esbriet. Its central limitation is the use of a glidant inside the pirfenidone-containing granules together with a second, extragranular glidant. The patent does not broadly claim pirfenidone, the treatment of idiopathic pulmonary fibrosis, or every pirfenidone tablet. It targets a specific solid-dose formulation architecture and, in claim 11, a measurable powder-flow performance threshold.

The patent was issued Jan. 29, 2019, and has a nominal expiration date in March 2034, subject to any patent-term adjustment or disclaimer recorded in the USPTO file. Its commercial relevance depends on whether a competing pirfenidone product uses the claimed granulation process and dual-glidant composition.

What drug and formulation does US Patent 10,188,637 protect?

The patent covers formulations containing 5-methyl-1-phenyl-2-(1H)-pyridone, the chemical name for pirfenidone.

Item	Patent relevance
Active ingredient	Pirfenidone
Drug class	Antifibrotic
Principal indication	Idiopathic pulmonary fibrosis
Commercial reference product	Esbriet
Dosage forms potentially implicated	Tablets, capsules, and other oral products containing granules
Patent type	Formulation and composition
Issue date	Jan. 29, 2019
Nominal expiry	March 2034
Core commercial issue	Whether a competing product contains both intra-granular and extragranular glidant

The patent is directed to manufacturing and performance problems associated with high-pirfenidone-load solid formulations. Claim 5 allows pirfenidone to constitute approximately 60% to 95% of the total formulation. That range indicates a high-drug-load product in which powder flow, blending, compression, content uniformity, and manufacturing consistency are material technical concerns.

How broad is independent claim 1 of US 10,188,637?

Claim 1 requires a granulate formulation with two structural components:

Granules containing pirfenidone and a glidant.
One or more extragranular excipients containing an extragranular glidant.

The claim uses “comprising,” which is an open-ended transition. A product can contain additional excipients, coatings, processing aids, or dosage-form components and still fall within the claim if the required elements are present.

Claim 1 element-by-element analysis

Claim limitation	Scope
“A granulate formulation”	Requires a formulation containing granules; a simple physical blend may not satisfy this limitation
Pirfenidone in the granules	The active ingredient must be present in the granulated portion
A glidant in the granules	At least one flow-enhancing excipient must be intra-granular
Extragranular excipients	At least one excipient must be outside the granules
An extragranular glidant	A second glidant must be located in the extragranular phase

The claim does not require a particular granulation method. It does not expressly require wet granulation, dry granulation, fluid-bed granulation, roller compaction, a specific tablet weight, or a particular release profile. The infringement analysis therefore turns primarily on the composition and the location of the glidants, not on the equipment used to manufacture the product.

A formulation with silica inside the granules and silica outside the granules is a straightforward example within the literal scope of claim 1, assuming the product contains pirfenidone in the granules. The claim can also cover different glidants in the two phases.

What formulations are protected by dependent claims 2 through 11?

The dependent claims add quantitative, compositional, and performance limitations.

Glidant concentration

Claim 2 requires the intra-granular glidant to be present at least about 1% by weight of the total formulation. Claim 3 requires the extragranular glidant to be present at about 0.1% to about 5% by weight.

Claim 10 provides a narrower formulation framework:

Intra-granular glidant: approximately 1% to 3%.
Binder: approximately 1% to 10%.
Filler: approximately 2% to 30%.
Extragranular disintegrant: 0% to approximately 10%.
Lubricant: approximately 0.05% to 2%.

Because the claims use “about,” ordinary claim-construction principles may allow some measurement tolerance around the stated numerical endpoints. The precise range will depend on the specification, prosecution history, analytical method, and the significance of the selected boundaries.

Permitted glidants

Claim 4 identifies a broad set of permitted materials, including:

Silica
Silicified cellulose
Sodium stearate
Magnesium aluminum silicate
Pyrogenic silica
Hydrated sodium silicoaluminate
Cellulose
Calcium phosphate
Sodium lauryl sulfate
Pregelatinized starch
Talc
Physical or coprocessed combinations

The list expands the patent beyond conventional colloidal silica. A design-around that replaces silica with talc, magnesium aluminum silicate, or another listed material may remain within the claim if the material is used in the required intra-granular or extragranular position.

Excipient classes

Claim 6 permits a formulation containing one or more of four excipient classes:

Disintegrant
Binder
Filler
Lubricant

Claim 7 lists extensive species within each category. Claim 8 then supplies concentration ranges for each class.

Claim 9 identifies a preferred combination:

Component	Specified material
Filler	Microcrystalline cellulose
Intra-granular glidant	Silica
Extragranular glidant	Silica
Binder	Polyvinylpyrrolidone
Disintegrant	Croscarmellose sodium
Lubricant	Magnesium stearate

Claim 9 is commercially important because it describes a conventional pharmaceutical excipient platform. A generic manufacturer cannot avoid the claim merely by using commonly accepted excipients if it retains the claimed arrangement and concentration profile.

Flow-function coefficient

Claim 11 requires an effective amount of the two glidants sufficient to provide a flow function coefficient of at least approximately 4.

This limitation introduces a performance-based issue. The patent does not merely require the presence of two glidants. It requires the formulation to achieve a specified powder-flow result.

The litigation significance of claim 11 would depend on:

The instrument used to measure flow.
The consolidation stress applied.
Whether the coefficient is measured before or after granulation.
The sampling location.
The formulation lot tested.
The definition of “effective amount.”
Whether the specification identifies a standardized test method.

A formulation may satisfy the structural limitations of claim 1 but avoid claim 11 if it does not reach the claimed flow threshold. Conversely, a product that reaches a coefficient of at least 4 but lacks an extragranular glidant would not satisfy claim 11 because claim 11 depends on claim 1.

When does US Patent 10,188,637 lose exclusivity?

The patent’s nominal term runs to March 2034, calculated from the relevant nonprovisional or PCT filing date associated with the patent family. The exact enforceable expiration must be confirmed against the USPTO patent-term calculation and any terminal disclaimer.

Event	Date
Patent issued	Jan. 29, 2019
Nominal patent expiry	March 2034
FDA small-molecule exclusivity	Separate from patent term
Biosimilar exclusivity	Not applicable
Generic pathway	ANDA under section 505(j)

Pirfenidone is a small molecule, so biosimilar procedures do not apply. Competing products would generally use the ANDA pathway and may submit Paragraph IV certifications against listed patents.

The formulation patent does not automatically prevent all generic pirfenidone launches. A generic could seek approval for a formulation that does not use the claimed dual-glidant architecture, or it could launch after prevailing in litigation, obtaining a covenant not to sue, or reaching a settlement.

What is the Orange Book status of US Patent 10,188,637?

US Patent 10,188,637 is associated with the Esbriet pirfenidone product and is relevant to Orange Book patent analysis for the NDA. Orange Book listing establishes a statutory framework for patent certifications and potential ANDA litigation. It does not independently establish infringement.

For a generic applicant, the relevant certification options generally include:

Paragraph I: No patent information has been submitted.
Paragraph II: The listed patent has expired.
Paragraph III: The applicant will wait until patent expiration.
Paragraph IV: The listed patent is invalid, unenforceable, or will not be infringed.

A Paragraph IV notice concerning a listed Esbriet formulation patent can trigger an infringement action under the Hatch-Waxman Act. The resulting 30-month stay depends on the timing and statutory requirements applicable to the NDA holder and ANDA applicant.

The principal regulatory distinction is between patents covering:

The active ingredient.
The method of treating pulmonary fibrosis.
The formulation or dosage form.
Manufacturing or granulation technology.

US 10,188,637 belongs primarily to the third category.

Which companies are challenging pirfenidone exclusivity?

Pirfenidone has faced generic competition from multiple pharmaceutical manufacturers through ANDA filings and related Paragraph IV activity involving Esbriet patent listings. Public generic-market activity has included companies such as Cipla, Alembic, Torrent, Zydus, and other ANDA sponsors, depending on the dosage form and filing period.

The relevant distinction is whether an applicant challenged US 10,188,637 specifically, rather than another Esbriet patent. A generic applicant may certify Paragraph IV to some listed patents while using a Paragraph III certification or section viii statement for others. A public challenge to one patent does not establish a challenge to every patent in the Orange Book family.

For commercial diligence, the operative documents are:

The ANDA applicant’s Paragraph IV notice.
The NDA holder’s complaint.
The asserted-patent list in the complaint.
Any claim-construction or summary-judgment decision.
The settlement and license terms.
The FDA approval letter and tentative-approval record.

What patent litigation affects Esbriet and pirfenidone generics?

Patent litigation risk is concentrated in three areas.

Formulation infringement

A generic product may be vulnerable if its tablets or capsules contain pirfenidone granules with a glidant in the granules and another glidant outside the granules. The risk increases when the product uses silica in both locations and falls within the claimed excipient ranges.

Invalidity challenges

The principal invalidity theories against US 10,188,637 would likely involve:

Obviousness over pirfenidone formulations combined with known glidants.
Anticipation by an earlier granulated composition.
Lack of written description for the full breadth of the glidant and excipient lists.
Lack of enablement for the full range of formulations.
Indefiniteness concerning “about,” “effective amount,” or the flow-function coefficient.

The patent’s strongest position is likely the combination of dual glidant placement and a high-pirfenidone-load granulate. Its weaker position is the breadth of the generic excipient lists, particularly where the prior art describes common glidants and standard oral-tablet excipients.

Manufacturing-process evidence

Even where the final product does not disclose its manufacturing process, reverse engineering and discovery can examine:

Granule morphology.
Particle-size distribution.
Excipient localization.
Dissolution behavior.
Elemental or spectroscopic markers.
Manufacturing records obtained through litigation.

A product label generally will not reveal whether silica was added intra-granularly or extragranularly. That issue can make formulation claims more difficult to enforce than claims directed to a labeled active ingredient or a stated dosage regimen.

How strong is the patent estate for pirfenidone?

The pirfenidone estate is layered rather than dependent on US 10,188,637 alone.

Patent layer	Commercial function	Relevance to US 10,188,637
Composition patents	Protect pirfenidone or related pyridone compounds	Generally older and more vulnerable to expiration
Method-of-use patents	Protect treatment of IPF or fibrotic disease	Can create separate ANDA certification issues
Formulation patents	Protect tablet, capsule, granule, or excipient systems	Directly relevant
Manufacturing patents	Protect processing or granulation conditions	May create process or discovery risks
Regulatory exclusivity	Controls FDA approval timing	Independent of patent infringement

The formulation patent strengthens the estate by moving beyond the expired or expiring chemical-entity layer. Its protection is narrower than a composition patent but may be harder to avoid for a high-dose product designed around the same manufacturing objectives.

The estate is less robust against a generic that uses a different granulation architecture, for example:

No glidant in the granules.
Only one glidant in the entire formulation.
A non-granulated direct-compression formulation.
A different excipient system outside the claimed ranges.
A formulation whose granules contain pirfenidone but whose extragranular phase lacks a glidant.

Those approaches can create manufacturing or bioequivalence challenges, but they reduce literal infringement exposure.

What generic launch scenarios exist for pirfenidone?

Scenario 1: Formulation design-around

A generic manufacturer develops a formulation outside claim 1. This is the cleanest legal path but may require new development work to achieve acceptable flow, content uniformity, compressibility, and dissolution.

Scenario 2: Paragraph IV litigation

The applicant certifies that US 10,188,637 is invalid, unenforceable, or not infringed. The NDA holder files suit, potentially delaying approval through the statutory 30-month period.

Scenario 3: Settlement and licensed launch

The parties agree to a license, launch date, authorized-generic arrangement, or other commercial terms. The launch date may precede patent expiry but remain subject to confidential or restricted conditions.

Scenario 4: Post-expiry launch

The applicant waits until the patent’s enforceable expiry date. This eliminates formulation-patent litigation risk but delays revenue capture.

Scenario 5: Product-specific non-infringement

The applicant argues that its formulation does not contain granules, does not use an extragranular glidant, or does not meet the claimed quantitative or flow-performance limitations.

How does US 10,188,637 compare with method-of-use patents?

A method-of-use patent can be avoided through a section viii “skinny label” if the protected indication or dosing instruction can be carved out of the generic labeling. A formulation patent is different. If the approved generic product itself embodies the claimed composition, labeling changes may not eliminate infringement.

US 10,188,637 therefore creates a product-level risk. Its importance is greatest when:

The generic has the same or similar granulation design as Esbriet.
The product is a high-dose tablet or capsule.
The formulation uses silica or another listed glidant in both phases.
The product documentation confirms the claimed excipient levels.
The product achieves the claim 11 flow threshold.

What geographic coverage does the patent provide?

US Patent 10,188,637 provides protection only in the United States. It does not directly block products in Europe, Japan, China, Canada, or other markets.

The patent family may include corresponding applications in other jurisdictions. Each national right requires separate analysis of:

Grant status.
Claim scope.
Patent-term adjustments.
Supplementary protection certificates.
Opposition or post-grant proceedings.
Local generic-launch rules.
Settlement terms applicable to the jurisdiction.

A US freedom-to-operate conclusion cannot be applied to an international pirfenidone launch without reviewing the corresponding foreign families.

What manufacturing and intellectual-property barriers remain?

The main technical barrier is achieving a high-load pirfenidone product with acceptable powder flow and tablet manufacturability without copying the claimed architecture.

A competing manufacturer may need to solve:

Poor flow of a high-pirfenidone blend.
Segregation during hopper and feeder transfer.
Granule friability.
Tablet tensile strength.
Disintegration and dissolution.
Dose uniformity.
Scale-up reproducibility.
Moisture sensitivity.
Compatibility between glidants, binders, and lubricants.

The patent converts those technical objectives into claim limitations. It does not monopolize the objectives themselves. A competitor remains free to solve the same manufacturing problem through a different composition or process, subject to other patents and regulatory requirements.

Key Takeaways

US 10,188,637 is a pirfenidone formulation patent, not a broad active-ingredient patent.
Claim 1 requires pirfenidone-containing granules with an intra-granular glidant and an extragranular glidant.
The claims can cover tablets or capsules containing the claimed granulate.
Claims 2 through 10 add glidant, binder, filler, lubricant, disintegrant, and pirfenidone concentration limits.
Claim 11 adds a flow-function coefficient of at least approximately 4.
The nominal patent expiry is in March 2034, subject to USPTO term adjustments or disclaimers.
Pirfenidone has no biosimilar pathway because it is a small molecule.
Generic applicants may use Paragraph IV, Paragraph III, or section viii strategies depending on the listed patent and labeling position.
The strongest design-around is a formulation without both intra-granular and extragranular glidant.
The principal litigation issues are obviousness, claim construction, glidant localization, numerical ranges, and measurement of powder flow.

FAQs

Does US 10,188,637 cover all pirfenidone tablets?

No. It covers tablets or capsules only when the dosage form contains the claimed granulate structure, including a glidant in the granules and an extragranular glidant.

Can a generic use silica and avoid the patent?

Potentially, but only if silica is not used in the claimed intra-granular and extragranular arrangement or if another claim limitation is absent. The use of silica alone does not determine infringement.

Does claim 11 require testing every commercial batch?

The claim requires the formulation to provide the specified flow-function coefficient. Whether batch testing is necessary in litigation depends on the product evidence, testing protocol, and claim-construction record.

Is a pirfenidone capsule automatically outside the patent?

No. The claims are directed to a granulate formulation, not solely to tablets. A capsule containing the claimed granules can fall within the patent.

Does patent expiry eliminate all pirfenidone launch barriers?

No. Expiry of US 10,188,637 removes that patent as a blocking right, but other listed patents, regulatory requirements, settlement restrictions, manufacturing patents, and market-approval timing may remain relevant.

References

United States Patent and Trademark Office. (2019). US Patent No. 10,188,637, Granulate formulations of pirfenidone. https://patents.google.com/patent/US10188637B2/en
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/
U.S. Food and Drug Administration. (2014). Esbriet (pirfenidone) prescribing information. https://www.accessdata.fda.gov/drugsatfda_docs/label/
U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application approvals and patent certifications. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/anda-approvals
United States Patent and Trademark Office. (n.d.). Patent term adjustment and patent term calculation. https://www.uspto.gov/patents/laws/patent-term-adjustment-patent-term-extension-prioritizing-examination-Track-One<|end|>

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Legacy	ESBRIET	pirfenidone	TABLET;ORAL	208780-001	Jan 11, 2017	AB	RX	Yes	No	10,188,637	⤷ Start Trial	Y				⤷ Start Trial
Legacy	ESBRIET	pirfenidone	TABLET;ORAL	208780-002	Jan 11, 2017		DISCN	Yes	No	10,188,637	⤷ Start Trial	Y				⤷ Start Trial
Legacy	ESBRIET	pirfenidone	TABLET;ORAL	208780-003	Jan 11, 2017	AB	RX	Yes	Yes	10,188,637	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	107990	⤷ Start Trial
Australia	2017241530	⤷ Start Trial
Australia	2022275529	⤷ Start Trial
Canada	2937365	⤷ Start Trial
China	108883072	⤷ Start Trial
China	114533688	⤷ Start Trial
European Patent Office	3435985	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,188,637

Which drugs does patent 10,188,637 protect, and when does it expire?

Summary for Patent: 10,188,637