United States Drug Patent 9,446,057: Scope, Claims, Expiration, and Doxycycline Patent Landscape

U.S. Patent No. 9,446,057 protects multiparticulate modified-release doxycycline dosage forms containing 60 mg, 90 mg, or 120 mg of doxycycline. Its core requirements are doxycycline-containing pellets, a polymer coating controlling release, pH-dependent dissolution behavior, and pharmacokinetic exposure within specified Cmax and AUC ranges. Dependent claims add enteric and water-soluble polymers, plasticizer, stabilizing coatings, dosage strengths, and once-daily treatment of acne, rosacea, and related skin conditions.

The patent is directed to a formulation platform rather than doxycycline as an active ingredient. A generic or follow-on product would face its strongest infringement risk if it uses coated doxycycline pellets that reproduce the claimed pH 5 dissolution profile and delivers the claimed exposure ranges.

What does U.S. Patent 9,446,057 protect?

The patent protects a multiparticulate oral dosage form in which doxycycline is incorporated into pellets and covered with a controlled-release polymer composition. The independent formulation claim requires all of the following:

Claim element	Required feature
Active ingredient	Doxycycline
Dosage architecture	A plurality of modified-release pellets
Pellet structure	Doxycycline-containing pellet with polymer composition disposed over the doxycycline
Strength	60 mg, 90 mg, or 120 mg
Dissolution	Release under USP <711> at pH 5 sufficient to provide a clinically effective plasma level
Pharmacokinetics	Further specified in dependent claims through Cmax and AUC ranges

Claim 1 is the principal composition claim. It does not require a particular capsule, tablet, excipient, pellet size, coating weight, or manufacturing process. The claim instead combines structural limitations with functional dissolution and clinical-performance language.

Claims 19 through 24 extend the patent to methods of treating skin conditions with the claimed dosage form. The listed conditions include acne, rosacea, skin infection, papules, pustules, open comedones, and closed comedones.

How do the claims divide between formulation, performance, and treatment?

Structural formulation claims

Claims 1 and 14 through 18 define the physical dosage form.

Claim 14 requires a doxycycline-containing core with the controlled-release polymer composition applied as a layer over that core. This narrows claim 1 by requiring a layered pellet architecture.

Claim 15 requires the controlled-release layer to contain:

An enteric polymer
A water-soluble polymer

Claim 16 adds a plasticizer. Claim 17 narrows the composition further by requiring that the coating consist essentially of an enteric polymer, a water-soluble polymer, and a plasticizer.

Claim 18 requires a stabilizing coating between the doxycycline core and the controlled-release layer. This intermediate layer may be relevant to chemical stability, drug-polymer compatibility, or prevention of migration of doxycycline into the release-controlling layer.

Dissolution-profile claims

Claim 5 requires at least one of five pH 5 release characteristics:

Time point	Claimed doxycycline release
10 minutes	About 45% to about 50%
20 minutes	About 55% to about 65%
30 minutes	About 65% to about 70%
45 minutes	About 70% to about 75%
60 minutes	About 75% to about 80%

Claims 10 through 13 progressively require at least two, three, four, or all five release characteristics. Claim 13 is the narrowest dissolution-profile claim because it requires the complete sequence.

The pH limitations are commercially important. Claim 6 requires release levels to remain low at pH values up to 4.5. Claims 7 through 9 apply the same feature to dosage forms that also meet the Cmax or AUC limitations.

This creates a two-stage release concept:

Low release in acidic conditions through approximately pH 4.5.
Controlled release at pH 5, with the specified release trajectory.

That profile is consistent with a formulation designed to limit release in the stomach while controlling dissolution after the dosage form reaches a less acidic environment.

Pharmacokinetic claims

Claims 2 through 4 define exposure ranges for 60 mg, 90 mg, and 120 mg products.

Strength	Reference Cmax range	Reference AUC0-∞ range
60 mg	625 to 1,600 ng/mL	10,000 to 24,000 ng·hr/mL
90 mg	940 to 2,400 ng/mL	15,000 to 36,500 ng·hr/mL
120 mg	1,250 to 3,200 ng/mL	20,000 to 48,500 ng·hr/mL

The claims apply an 80% to 125% multiplier to these reference ranges. Read literally, the resulting numerical boundaries are broad:

Strength	Approximate claimed Cmax boundary	Approximate claimed AUC boundary
60 mg	500 to 2,000 ng/mL	8,000 to 30,000 ng·hr/mL
90 mg	752 to 3,000 ng/mL	12,000 to 45,625 ng·hr/mL
120 mg	1,000 to 4,000 ng/mL	16,000 to 60,625 ng·hr/mL

The claim language uses “about,” which creates potential scope disputes over measurement variability, study design, subject population, fasting conditions, and statistical treatment. The claims specify single-dose administration under fasting conditions for Cmax and AUC. A bioequivalence study conducted under fed conditions would not necessarily test the same limitations.

What is the strongest independent claim?

Claim 1 is the key composition claim. It is stronger commercially than claims 19 through 24 because it can potentially reach manufacture, sale, importation, or commercial distribution of the dosage form without requiring proof of a particular physician’s treatment decision.

The principal limitations that a challenger would likely test are:

Whether the product contains a “plurality” of modified-release pellets.
Whether the polymer composition is disposed over the doxycycline.
Whether the product contains exactly one of the claimed strengths.
Whether the product maintains the required release at pH 5.
Whether the product provides a clinically effective doxycycline plasma level.

Claims 14 through 18 provide narrower fallback positions. They are more difficult to read on a product that uses a different architecture, but they may be easier to defend if the broad pellet claim is challenged.

What formulation technology is protected?

The patent’s formulation protection centers on a coated-pellet system using pH-responsive and water-permeable polymers.

Enteric polymer

An enteric polymer generally remains relatively impermeable or insoluble in strongly acidic media and becomes more permeable or soluble as pH rises. The patent does not limit the claims to a named enteric polymer in the claim text supplied. A product may therefore face claim risk even if it uses a different commercial polymer, provided the formulation satisfies the claimed structural and performance requirements.

Water-soluble polymer

The water-soluble polymer can modify coating permeability, hydration, pore formation, and release rate. It is relevant to the gradual pH 5 release sequence.

Plasticizer

The plasticizer limitation may affect film flexibility, coating integrity, and permeability. It is required only in claims 16 and 17, not in claim 1.

Stabilizing coating

The intermediate stabilizing layer in claim 18 adds a distinct manufacturing and formulation limitation. A product using a direct drug-core-to-release-coating interface may avoid claim 18 while remaining exposed to broader claims.

When does U.S. Patent 9,446,057 lose exclusivity?

The patent issued September 20, 2016. A U.S. utility patent generally expires 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and any applicable priority-chain issues.[1]

The nominal expiration date should be determined from the USPTO Patent Center record and the patent’s term-adjustment calculation. Patent 9,446,057 should not be treated as expiring merely on the 20th anniversary of its issue date. The relevant date is the effective filing date of the application or earliest claimed nonprovisional priority, not September 20, 2036.

A patent-term extension under 35 U.S.C. § 156 would require a qualifying regulatory review and a granted extension. Doxycycline products generally do not receive the type of regulatory exclusivity associated with new molecular entities because doxycycline is an established active ingredient.

What is the Orange Book status of patent 9,446,057?

Orange Book listing is product-specific. The existence of patent 9,446,057 does not by itself establish that the patent is listed for every doxycycline product or for every 60 mg, 90 mg, or 120 mg dosage form.

For an Orange Book analysis, the relevant questions are:

Orange Book issue	Relevance
Listed reference product	Determines the applicable NDA and patent listing
Listed patent	Determines whether an ANDA applicant must make a patent certification
Use code	Determines whether a method-of-use claim is implicated
Listed expiration date	Determines the timing of a Paragraph IV challenge
Approved strength	Determines whether the patent covers the ANDA product

The structural formulation claims are more likely to be relevant to an ANDA than the skin-condition method claims unless the reference product’s labeling includes a corresponding use code. FDA’s Orange Book should be checked by NDA, product name, and active ingredient rather than by patent number alone.[2]

How does patent 9,446,057 affect Paragraph IV challenges?

A generic applicant challenging a listed patent would typically submit one of four certifications under the Hatch-Waxman framework:

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

A Paragraph IV challenge to this patent would likely focus on claim construction and noninfringement rather than the identity of doxycycline. Potential arguments include:

The generic uses a single matrix tablet rather than a plurality of pellets.
The doxycycline is not covered by a polymer composition “disposed over” the drug.
The product does not maintain low release through pH 4.5.
The pH 5 release profile does not satisfy claim 5 or claims 10 through 13.
The product does not meet the claimed pharmacokinetic ranges.
The reference product or prior art renders the pellet and enteric-coating combination obvious.
The terms “clinically effective plasma level” or “low” lack sufficient objective boundaries.

A generic applicant could also use a section viii statement where the proposed label omits a patented method of use. That strategy would not necessarily avoid a formulation patent covering the dosage form itself.

Which companies are likely to face the patent?

The competitive risk is greatest for companies developing delayed-release or modified-release doxycycline products in strengths aligned with the claims. Potentially affected parties include:

Generic doxycycline manufacturers filing ANDAs for delayed-release tablets or capsules.
Manufacturers using multiparticulate pellet technology.
Companies developing acne or rosacea products with 60 mg, 90 mg, or 120 mg strengths.
Contract manufacturers supplying coated doxycycline pellets.
Licensees commercializing an authorized generic or reformulated product.

A conventional immediate-release doxycycline tablet is less likely to fall within the claims because it would not ordinarily contain modified-release pellets or the claimed pH-dependent profile.

How strong is the patent estate?

Patent 9,446,057 has meaningful commercial value because claim 1 combines formulation structure with in vitro and in vivo performance. A design-around must avoid either the pellet architecture or the specified release and pharmacokinetic characteristics.

Its strengths are:

Coverage of three commercially useful strengths.
Broad independent coverage of modified-release pellets.
Dependent claims directed to coating chemistry.
Pharmacokinetic limitations that can be tested in clinical studies.
Method claims covering acne, rosacea, and related conditions.

Its weaknesses are:

The core concept depends on a technically specific multiparticulate architecture.
Some functional terms, including “clinically effective” and “low,” may create construction and definiteness disputes.
The “about” ranges may complicate infringement testing.
A product that changes pellet structure, coating sequence, or release environment may avoid the narrow dependent claims.
Doxycycline has extensive prior art, increasing obviousness risk for broad formulation concepts.

What design-around strategies exist?

A competing product could reduce risk by using one or more of the following approaches:

Design-around route	Potential effect
Immediate-release tablet or capsule	Avoids modified-release pellet limitations
Single matrix dosage form	May avoid “plurality of pellets”
Non-coated drug particles	May avoid the polymer-over-core limitation
Different pH release behavior	May avoid claims 5 and 10 through 13
Release that is not low through pH 4.5	May avoid claims 6 through 9
Strengths outside 60, 90, and 120 mg	May avoid the express strength limitations
Different pharmacokinetic profile	May avoid claims 2 through 4
Non-acne or non-rosacea labeling	May reduce method-of-use exposure, but not formulation exposure

A design-around must be evaluated against claim 1 before relying on narrower claim limitations. Avoiding claim 17, for example, does not avoid claim 1 if the product still uses coated modified-release doxycycline pellets.

What litigation and settlement issues matter?

The critical litigation events would include:

A Paragraph IV notice letter.
A patent infringement complaint under 35 U.S.C. § 271(e)(2).
A 30-month FDA approval stay.
Claim-construction proceedings.
Preliminary injunction or launch-at-risk activity.
ANDA settlement and any agreed generic-entry date.
A possible authorized-generic arrangement.

No litigation conclusion should be inferred from the patent’s issuance or Orange Book presence alone. Litigation and settlement status must be confirmed through PACER, FDA Paragraph IV listings, SEC filings, and the Orange Book’s current patent table.

Key Takeaways

U.S. Patent 9,446,057 is a formulation patent covering modified-release doxycycline pellets.
Claim 1 is the central commercial claim and requires pellets, a polymer coating, 60/90/120 mg strength, and controlled release at pH 5.
Claims 2 through 4 add fasting-state Cmax and AUC performance requirements.
Claims 5 through 13 protect specified pH 5 dissolution profiles.
Claims 14 through 18 cover core-layer construction, enteric and water-soluble polymers, plasticizer, and stabilizing coatings.
Claims 19 through 24 cover treatment of acne, rosacea, infections, and related skin conditions.
The patent does not protect doxycycline generally. It targets a particular delivery architecture and pharmacokinetic profile.
Generic risk is highest for multiparticulate delayed-release doxycycline products in 60 mg, 90 mg, or 120 mg strengths.
Orange Book listing, expiration, Paragraph IV activity, and settlements must be assessed against the specific reference NDA and product listing.

FAQs

Does patent 9,446,057 cover immediate-release doxycycline?

Generally, no. The claims require modified-release pellets and a polymer composition disposed over the doxycycline. A conventional immediate-release tablet would ordinarily fall outside those structural limitations.

Can a generic avoid the patent by using a different enteric polymer?

Possibly, but changing the polymer alone may not avoid claim 1. The generic would also need to avoid the claimed pellet architecture, dissolution behavior, and other limitations. Claims 15 through 17 are narrower than claim 1.

Do the claims cover doxycycline hyclate?

The supplied claims recite doxycycline rather than limiting the active ingredient to a particular salt or hydrate. Doxycycline hyclate may therefore be relevant if the finished product satisfies the remaining claim limitations.

Are the 60 mg, 90 mg, and 120 mg strengths separately protected?

Yes. Claims 25, 26, and 27 separately recite the 60 mg, 90 mg, and 120 mg embodiments. Claims 1 through 4 also address those strengths through formulation and pharmacokinetic limitations.

Is a biosimilar pathway relevant to this patent?

No. Doxycycline is a small-molecule drug. A competing product would generally proceed through an ANDA or, depending on the formulation and regulatory strategy, an NDA pathway rather than a biosimilar application under section 351(k) of the Public Health Service Act.

References

United States Patent and Trademark Office. (2016). U.S. Patent No. 9,446,057, Doxycycline compositions and methods of use thereof.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (2024). Approved drug product labeling for doxycycline delayed-release products.
United States Code. 35 U.S.C. §§ 154, 156, 271(e)(2).
United States Code. 21 U.S.C. § 355(j).

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Mayne Pharma	DORYX MPC	doxycycline hyclate	TABLET, DELAYED RELEASE;ORAL	050795-007	May 20, 2016		RX	Yes	No	⤷ Start Trial	⤷ Start Trial	Y			TO TREAT OR PREVENT INFECTIONS CAUSED BY SUSCEPTIBLE BACTERIA USING DELAYED-RELEASE TABLETS CONSISTING OF DOXYCYCLINE HYCLATE COATED PELLETS IN A TABLET	⤷ Start Trial
Mayne Pharma	DORYX MPC	doxycycline hyclate	TABLET, DELAYED RELEASE;ORAL	050795-008	May 20, 2016		DISCN	Yes	No	⤷ Start Trial	⤷ Start Trial	Y			TO TREAT OR PREVENT INFECTIONS CAUSED BY SUSCEPTIBLE BACTERIA USING DELAYED-RELEASE TABLETS CONSISTING OF DOXYCYCLINE HYCLATE COATED PELLETS IN A TABLET	⤷ 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

Details for Patent: 9,446,057

Which drugs does patent 9,446,057 protect, and when does it expire?

Summary for Patent: 9,446,057