US Patent 8,513,223: Scope, Claims, Expiration, and Tetracycline Patent Landscape
US Patent 8,513,223 is a method-of-treatment patent covering substituted tetracycline compounds for inflammatory skin disorders, particularly acne and rosacea. Its broadest independent claim uses a large Markush formula and reaches compounds administered topically or orally. The patent is commercially associated with sarecycline, the active ingredient in Seysara, although the supplied claim text omits the chemical structures embedded in claims 3, 13, 18, and 19.
The patent’s principal value is its combination of:
- Treatment claims directed to acne and rosacea.
- Broad substituted-tetracycline genus language.
- Biological activity limitations based on minimum inhibitory concentration.
- Coverage of both oral and topical administration.
- Potential Orange Book relevance for an approved acne product.
The expected US patent-term expiration is February 17, 2027, subject to any applicable patent-term adjustment. The patent does not independently block every tetracycline product because infringement requires practicing the claimed treatment method with a compound falling within the claimed chemical scope.
What does US Patent 8,513,223 cover?
US 8,513,223 covers treating an inflammatory skin disorder by administering an effective amount of a substituted tetracycline compound having the formula defined in claim 1. The patent was granted on August 20, 2013, and is assigned to Paratek Pharmaceuticals, Inc. [1]
The claims are method claims rather than broad composition-of-matter claims. A generic manufacturer or competitor would generally face infringement risk if it:
- Markets a compound within the claim 1 Markush structure;
- Promotes that compound for treating an inflammatory skin disorder; and
- Uses an administration route or disease indication covered by the asserted claim.
Claim 1 does not require a particular dose, formulation, treatment duration, patient age, or disease severity. It requires an effective amount and a qualifying inflammatory skin disorder.
Patent identification
| Item |
Detail |
| Patent |
US 8,513,223 |
| Grant date |
August 20, 2013 |
| Patent type |
Method of treatment |
| Primary subject |
Substituted tetracyclines for inflammatory skin disorders |
| Named disease examples |
Acne and rosacea |
| Administration |
Oral or topical under dependent claim 6 |
| Assignee |
Paratek Pharmaceuticals, Inc. |
| Expected expiration |
February 17, 2027, subject to patent-term adjustment |
| Commercial relevance |
Sarecycline and Seysara acne treatment |
How broad is claim 1 of US 8,513,223?
Claim 1 is chemically broad because it defines numerous substituent positions using alternative functional groups. The Markush structure allows substantial variation at the tetracycline scaffold and at side-chain positions.
The claim requires the following core elements:
- A subject suffering from an inflammatory skin disorder.
- Administration of an effective amount.
- A substituted tetracycline compound.
- A compound falling within formula I.
- A pharmaceutically acceptable salt as an alternative to the free compound.
- Treatment of the inflammatory skin disorder.
The claim does not require the compound to be sarecycline specifically. Sarecycline would be one potential species within the broader genus if its structure satisfies the claimed substituent definitions.
Chemical breadth
The formula permits variation involving:
- Carbon, sulfur, nitrogen, and oxygen at the X position.
- Amino, alkoxy, and related substituents at the E position.
- Alkyl, alkenyl, alkynyl, aryl, heterocyclic, and heteroaromatic groups.
- Halogens, hydroxyl, thiol, amino, amido, sulfonyl, sulfinyl, and thioether groups.
- Ring formation between specified side-chain positions.
- Free compounds and pharmaceutically acceptable salts.
This drafting approach creates a potentially large genus. Its enforceability depends on written description, enablement, claim construction, prosecution history, and whether the accused compound is structurally within the formula.
Disease scope
The term “inflammatory skin disorder” is broader than acne and rosacea. Claim 20 narrows the disease to acne or rosacea, but claim 1 is not expressly limited to those conditions.
Potentially relevant disorders could include inflammatory dermatologic conditions if the accused use satisfies the ordinary meaning of the claim and the evidentiary requirements for induced or contributory infringement. The approved commercial indication is narrower than the claim language.
What do the dependent claims add?
The dependent claims progressively narrow the chemical and therapeutic scope.
| Claim |
Limitation |
Strategic effect |
| 1 |
Broad substituted-tetracycline genus for inflammatory skin disorders |
Principal genus claim |
| 2 |
X is CR6'R6; R4 is dialkylamino; most other positions are hydrogen |
Narrows to a more conventional tetracycline scaffold |
| 3 |
Specific compound structure |
Species claim; structure omitted from supplied text |
| 4 |
MIC lower than doxycycline or minocycline against specified organisms |
Adds comparative antibacterial activity |
| 5 |
MIC below 32 µg/ml against S. aureus, P. acnes, or S. pneumoniae |
Adds quantitative microbiological threshold |
| 6 |
Oral or topical administration |
Directly relevant to commercial dosage forms |
| 7-17 |
Detailed substituent limitations involving E and ring formation |
Creates fallback species and subgenus claims |
| 18-19 |
Specific compound structures |
Species claims; structures omitted from supplied text |
| 20 |
Acne or rosacea |
Narrows disease indication to dermatology markets |
Claims 2 and 7 through 17 are important prosecution and litigation fallback positions. If a court limits the broad Markush language, a patentee may rely on narrower claims directed to specific substitution patterns.
Claims 3, 13, 18, and 19 cannot be chemically mapped from the supplied text because the relevant structures are absent. Their value may be substantial if they identify sarecycline or another commercially relevant species, but the exact scope cannot be determined from the text alone.
Does the patent cover sarecycline and Seysara?
US 8,513,223 is associated with the sarecycline patent estate and is relevant to Seysara, an oral sarecycline product approved for the treatment of moderate-to-severe acne vulgaris in patients nine years of age and older. The FDA approved Seysara on October 1, 2018, under NDA 209699. [2]
Sarecycline is a tetracycline-class antibiotic designed for acne treatment. Its commercial positioning emphasizes a narrower antibacterial spectrum than older tetracyclines, although the patent claims are not limited to a narrow-spectrum pharmacological profile.
Claim 4 requires the substituted tetracycline to have an MIC lower than doxycycline or minocycline against S. aureus, P. acnes, or S. pneumoniae. Claim 5 adds an MIC threshold below 32 µg/ml. These claims create a factual infringement issue that may depend on:
- The tested bacterial strain.
- The assay methodology.
- The measured MIC value.
- Whether the accused product’s labeling or marketing establishes the claimed activity.
- Whether the MIC comparison is inherent in the accused compound.
The broad treatment claim does not require the MIC limitation. Claims 4 and 5 therefore provide narrower alternatives rather than necessary elements of the principal infringement theory.
What is the Orange Book status of US 8,513,223?
US 8,513,223 has been listed in the FDA Orange Book in connection with Seysara. The listing is relevant because it can support a patent certification requirement for an ANDA applicant seeking approval of a generic sarecycline product. [3]
Because the patent is a method-of-use patent, an ANDA applicant may attempt to use a section viii statement if the generic labeling omits the patented method. That strategy depends on the scope of the listed use code and the remaining approved indications. If the patented method corresponds to the only relevant labeled use, a Paragraph IV certification may be necessary.
Regulatory milestones
| Milestone |
Date |
| US patent grant |
August 20, 2013 |
| Seysara NDA approval |
October 1, 2018 |
| Estimated five-year NCE exclusivity end |
October 1, 2023 |
| Expected US patent expiration |
February 17, 2027 |
| Potential generic entry absent litigation or other barriers |
After applicable exclusivity and patent barriers |
The five-year new chemical entity exclusivity period would have expired before the patent term. Any pediatric exclusivity, if granted and applicable, could have extended regulatory protection by six months. FDA regulatory exclusivity and patent protection are separate rights. [2,4]
When does sarecycline lose exclusivity?
Sarecycline’s principal US patent protection is expected to end in 2027 under US 8,513,223, subject to patent-term adjustment. FDA NCE exclusivity ended in 2023 unless an extension applied.
The practical generic-entry date depends on:
- Whether Orange Book-listed continuation or related patents remain enforceable.
- Whether an ANDA applicant files a Paragraph IV certification.
- Whether the patent owner sues within the statutory period.
- Whether litigation triggers a 30-month stay.
- Whether the generic applicant obtains approval with a restricted label.
- Whether other formulation, manufacturing, or crystalline-form patents apply.
The expiration of one patent does not necessarily establish immediate market entry. A generic company must clear the entire relevant patent estate and complete FDA approval requirements.
Are there Paragraph IV challenges or generic litigation?
The supplied record does not identify a specific Paragraph IV notice, ANDA number, district court complaint, settlement agreement, or final judgment involving US 8,513,223. No litigation conclusion should be drawn solely from the existence of the patent or its Orange Book listing.
For a generic sarecycline applicant, the most likely legal routes would be:
- Paragraph IV challenge alleging invalidity or noninfringement.
- Section viii carve-out if the patented method can be omitted from labeling.
- Paragraph III certification with launch after patent expiry.
- A negotiated entry agreement with the patent holder or marketing authorization holder.
The patent’s method-of-use character may make a section viii strategy commercially important. A carve-out would be difficult if the patented acne indication is the product’s principal or only approved use.
How strong is the patent estate?
US 8,513,223 has moderate-to-strong commercial relevance but narrower legal breadth than a classic composition-of-matter patent.
Strengths
- Broad Markush genus covering many substituted tetracycline structures.
- Direct coverage of inflammatory skin disorders.
- Express coverage of acne and rosacea in claim 20.
- Oral and topical administration in claim 6.
- Specific compound claims that may provide fallback protection.
- Commercial linkage to an FDA-approved acne product.
Vulnerabilities
- Claim 1 is a method claim, not an unrestricted compound claim.
- The broad genus may face written-description and enablement scrutiny.
- Infringement may depend on labeling, prescribing, physician conduct, or inducement evidence.
- The “effective amount” limitation can create factual disputes.
- MIC claims require reproducible laboratory evidence.
- The supplied record does not establish the status of every continuation, terminal disclaimer, or related formulation patent.
The estate is stronger against a labeled generic acne product than against an off-label or non-dermatologic use of a structurally qualifying tetracycline.
What manufacturing and formulation barriers remain?
US 8,513,223 does not principally claim a manufacturing process or a dosage-form technology. Its claims target therapeutic use and chemical structure. Competitors could therefore attempt to design around the patent through:
- A tetracycline outside the Markush definition.
- A noninfringing indication.
- Labeling that omits the patented use.
- A different salt or formulation, if the resulting compound is outside the claims.
- A compound lacking the specified microbiological activity, while recognizing that this may not avoid claim 1.
Separate patents could cover crystalline forms, salts, impurities, tablet compositions, controlled-release systems, or manufacturing methods. Those rights cannot be inferred from US 8,513,223 alone.
How does US 8,513,223 compare with competing acne patents?
| Protection type |
Typical claim focus |
Relevance to generic entry |
| US 8,513,223 |
Substituted tetracyclines used for inflammatory skin disorders |
High for sarecycline acne use |
| Doxycycline patents |
Formulation, modified release, or low-dose anti-inflammatory treatment |
Depends on product and formulation |
| Minocycline patents |
Extended-release formulations and acne treatment |
Often formulation-driven |
| Topical retinoid patents |
Specific active ingredients and combinations |
Product-specific |
| Isotretinoin patents |
Formulation and risk-management systems |
Regulatory and formulation barriers |
| Sarecycline continuation patents |
Species, formulations, or additional treatment methods |
Could extend practical protection beyond one patent |
Sarecycline competes clinically with doxycycline and minocycline, but those products have different patent profiles. The key distinction is that US 8,513,223 combines a new substituted tetracycline genus with a dermatology method claim, whereas many older acne estates rely on formulation or delivery technologies.
Key Takeaways
- US 8,513,223 is a method-of-treatment patent for substituted tetracyclines used against inflammatory skin disorders.
- Claim 1 is broad and covers a large Markush genus, but it is not an unrestricted composition claim.
- Claim 20 specifically covers acne and rosacea.
- Claim 6 covers both oral and topical administration.
- Claims 4 and 5 add comparative MIC limitations but are narrower than claim 1.
- The patent is commercially relevant to sarecycline and Seysara.
- The expected patent expiration is February 17, 2027, subject to patent-term adjustment.
- FDA NCE exclusivity ended before the expected patent expiry.
- A generic sarecycline applicant may consider Paragraph IV litigation or a section viii carve-out.
- The exact scope of claims 3, 13, 18, and 19 cannot be determined because their chemical structures are missing from the supplied claim text.
- Separate continuation, formulation, salt, crystalline-form, and manufacturing patents must be reviewed before estimating a definitive generic launch date.
FAQs About US Patent 8,513,223
Does US 8,513,223 claim sarecycline itself?
The patent is associated with the sarecycline patent estate and is relevant to Seysara, but the supplied text does not include the structures in several species claims. The exact claim covering sarecycline requires review of the issued patent drawings and chemical structures.
Can a generic manufacturer avoid US 8,513,223 by using a topical product?
Not necessarily. Claim 6 expressly covers topical or oral administration. A topical product could still infringe if its active compound falls within the claimed formula and the product is used for a covered inflammatory skin disorder.
Does claim 20 cover all acne products?
No. Claim 20 covers treatment of acne or rosacea with a qualifying substituted tetracycline compound. It does not cover unrelated acne drugs such as benzoyl peroxide, isotretinoin, topical retinoids, or nonqualifying antibiotics.
Is US 8,513,223 a composition-of-matter patent?
No. The supplied claims are method claims. The patent protects specified therapeutic use of qualifying compounds rather than every manufacture, sale, or use of the chemical compound regardless of indication.
Could a generic launch before February 2027?
Potentially, but only if the generic applicant clears applicable FDA exclusivity and all enforceable patent barriers. Possible routes include a successful Paragraph IV challenge, a noninfringing label carve-out, settlement-based entry, or a product outside the relevant patent claims.
References
- United States Patent and Trademark Office. (2013). US Patent No. 8,513,223, substituted tetracycline compounds and methods of use.
- U.S. Food and Drug Administration. (2018). Seysara prescribing information.
- U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
- U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs database, Seysara NDA 209699.
