US Patent 7,217,430: Scope, Claim Construction, Expiration and Patent Landscape for Extended-Release Amoxicillin/Clavulanate

US Patent 7,217,430 protects a specific extended-release, biphasic formulation of 2,000 mg amoxicillin and 125 mg potassium clavulanate. The patent requires a solid dosage form with two amoxicillin release phases, xanthan gum in the second phase, an organic acid, and pharmacokinetic performance meeting defined Cmax, AUC, and duration thresholds. The patent was directed to the formulation marketed as Augmentin XR.

The patent term expired in 2022 based on its priority framework. It therefore does not provide a current US exclusionary right against generic or alternative extended-release amoxicillin/clavulanate products. Its claims remain relevant for historical infringement analysis, patent-family diligence, prior-art assessment, and evaluation of product development decisions.

What does US Patent 7,217,430 protect?

The patent protects a dual-release or biphasic solid formulation combining:

Required feature	Claim requirement
Active ingredients	Amoxicillin and potassium clavulanate
Dose	2,000 mg amoxicillin and 125 mg potassium clavulanate
Dosage form	Solid form, including a tablet or bilayer tablet
Release structure	First release phase and second release phase
First phase	Potassium clavulanate and a first amount of amoxicillin
Second phase	A second amount of amoxicillin in soluble-salt form
Soluble amoxicillin salt	Sodium amoxicillin is a claimed embodiment
Organic acid	Required in the second release phase
Release-retarding polymer	Xanthan gum at about 1% to 5% of the second phase
Pharmacokinetics	Mean amoxicillin Cmax of at least 12 micrograms/mL
Additional performance	AUC at least 80% of immediate-release amoxicillin, under claim 6
Sustained exposure	Mean plasma concentration of at least 4 micrograms/mL for at least 4.4 hours, under claim 7

The core inventive concept is the combination of an immediate or relatively rapid amoxicillin component with a delayed or sustained component, while placing clavulanate predominantly in the first release phase. The formulation was designed to maintain clinically useful amoxicillin exposure over an extended dosing interval without extending clavulanate exposure in the same manner.

How is claim 1 constructed?

Claim 1 is the principal composition claim and contains multiple mandatory limitations. A product must satisfy every required limitation to fall within its literal scope.

Dose and active ingredients

The claim is limited to a composition containing 2,000 mg of amoxicillin and 125 mg of potassium clavulanate. A formulation with a materially different dose would not literally meet this limitation, although other patent claims or regulatory equivalence theories could remain relevant.

The claim is directed to the amoxicillin/clavulanate combination rather than amoxicillin alone or a different beta-lactamase inhibitor combination.

Biphasic release architecture

The formulation must have:

A first release phase containing potassium clavulanate and a first amount of amoxicillin; and
A second release phase containing a second amount of amoxicillin.

Claim 14 narrows the first phase by requiring essentially all of the potassium clavulanate to be located there. Claim 15 characterizes the amoxicillin release as biphasic.

The claims do not merely require a tablet that dissolves slowly. They require two identifiable release phases with different ingredient placement and release behavior. A monolithic extended-release matrix lacking a distinct first and second phase would present a stronger non-infringement position, depending on the formulation and testing evidence.

Sodium amoxicillin and organic acid

The second phase must contain amoxicillin in the form of a soluble salt at about 60% to 80% of the second phase. Claim 4 identifies sodium amoxicillin, and claim 5 further specifies crystallized sodium amoxicillin.

The second phase also must contain a pharmaceutically acceptable organic acid. Claim 23 covers broad chemical classes, including mono-carboxylic and poly-carboxylic acids, aryl acids, and certain metal salts. Claim 24 identifies specific acids, including:

Malonic acid
Succinic acid
Fumaric acid
Maleic acid
Adipic acid
Lactic acid
Levulinic acid
Sorbic acid
Tartaric acid
Malic acid
Ascorbic acid
Citric acid

Claim 25 narrows the formulation to citric acid. Claim 26 requires a sodium amoxicillin-to-citric-acid molar ratio of 20:1 to 1:2.

Xanthan gum limitation

The second release phase must contain a reduced amount of a pharmaceutically acceptable release-retarding polymer, specified in claim 1 as xanthan gum at about 1% to 5% of the second phase.

Claim 2 further limits the xanthan gum to pharmaceutical-grade, 200-mesh material. The mesh-size limitation can be important in infringement analysis because particle size and grade may affect hydration, gel formation, and release kinetics.

What are the dependent claims worth commercially?

Claims 22 through 27 contain the most commercially specific formulation limitations.

Claim	Narrowing feature
22	Organic-acid ratio of 20:1 to 1:2
23	Defined classes of acceptable organic acids
24	Specific list of acids
25	Citric acid
26	Sodium amoxicillin/citric-acid molar ratio of 20:1 to 1:2
27	About 438 mg sodium amoxicillin, about 78 mg citric acid, and about 2% xanthan gum

Claim 27 is the narrowest formulation claim and most closely tracks a practical second-phase composition. Its commercial relevance is greater for products using crystallized sodium amoxicillin, citric acid, and approximately 2% xanthan gum.

Claims 8 through 11 narrow the ratio of amoxicillin between the first and second phases:

Claim	First-phase to second-phase amoxicillin ratio
8	3:1 to 1:3
9	3:1 to 2:3
10	2:1 to 2:3
11	3:2 to 1:1

These overlapping ranges create progressively narrower fallback positions. A formulation outside the claimed ratios could avoid those dependent claims while still potentially implicating claim 1 if the other limitations are met.

What pharmacokinetic performance must the formulation achieve?

The patent uses pharmacokinetic limitations as part of the claim scope.

Cmax limitation

Claim 1 requires a mean amoxicillin Cmax of at least 12 micrograms/mL. This is not simply a formulation-composition limitation. It requires a measured or demonstrable pharmacokinetic result.

A competing product could contain similar ingredients but avoid literal infringement if it does not achieve the required Cmax. The result would depend on the testing population, food conditions, sampling schedule, assay method, and statistical treatment specified in the applicable product and clinical protocols.

AUC limitation

Claim 6 requires an amoxicillin AUC of at least 80% of the AUC obtained from the same amount administered as an immediate-release formulation over the same dosage period.

This limitation makes comparative pharmacokinetic testing central to claim analysis. A product could have a different release profile but still satisfy the AUC threshold.

Sustained plasma concentration

Claim 7 requires a mean plasma concentration of at least 4 micrograms/mL for at least 4.4 hours. This limitation supports the patent’s objective of maintaining exposure against susceptible respiratory pathogens during an extended dosing interval.

Because claims 6 and 7 are dependent claims, failure to meet one does not avoid claim 1 if the claim 1 Cmax requirement and all other claim 1 limitations are met.

What method-of-use claims are covered?

Claims 16 through 21 cover treatment methods using the claimed formulation.

The method claims include treatment of bacterial infections caused by:

Streptococcus pneumoniae
Haemophilus influenzae
Moraxella catarrhalis
Drug-resistant and penicillin-resistant S. pneumoniae

Claim 19 specifies respiratory tract infections. Claim 20 identifies:

Community-acquired pneumonia
Acute exacerbation of chronic bronchitis
Acute bacterial sinusitis

Claim 21 specifies treatment for 7 to 14 days.

These claims are narrower than a general method of treating any bacterial infection. They require administration of the formulation covered by claim 1 and, for the dependent claims, the specified organisms, disease categories, or treatment duration.

The method claims would have been relevant to direct-use infringement and inducement theories before patent expiration. Their practical enforcement value would have depended on labeling, prescribing instructions, promotional activity, and the extent to which a generic label encouraged the claimed uses.

How strong was the patent estate?

The patent was technically focused but commercially important because it combined structural and functional limitations.

Strengths

The estate had several claim elements that could make design-around difficult for a product seeking the same clinical profile:

The exact 2,000 mg/125 mg strength
Biphasic release architecture
Placement of potassium clavulanate in the first phase
Sodium amoxicillin in the second phase
Organic acid in the second phase
Xanthan gum at a defined concentration
Cmax, AUC, and duration requirements
Specific use in respiratory infections

The combination of formulation and pharmacokinetic limitations could support a strong infringement position where a competing product copied the clinical and release profile.

Weaknesses

The claims also contained several potential attack points:

Xanthan gum is a known pharmaceutical excipient.
Organic acids are broadly defined and include common formulation materials.
The patent requires measurable pharmacokinetic outcomes that may vary by study design.
“About,” “reduced amount,” “essentially all,” and “biphasic” require claim construction.
The exact dose and phase ratios limit the patent’s reach outside the 2,000 mg/125 mg product.
A product using a different polymer, a single-phase matrix, or a materially different placement of clavulanate could avoid literal infringement.

The strongest claims against a close copy would likely have been claim 1 and claims 22 through 27, particularly where the second phase used sodium amoxicillin, citric acid, and approximately 2% xanthan gum.

When did US Patent 7,217,430 expire?

The patent’s statutory term ended in 2022. The patent therefore no longer blocks US commercial development, FDA submission, manufacture, or sale of a non-infringing extended-release amoxicillin/clavulanate product.

A party evaluating historical activity before expiration would still need to consider:

Patent-term adjustment
Any terminal disclaimer
Patent-family continuations or divisionals
Separate patents covering manufacturing, dosage strength, or labeling
Regulatory exclusivity that operated independently of the patent

The expiration of US 7,217,430 did not automatically eliminate other rights that might have existed in related US or foreign patent families.

What was the Orange Book status of Augmentin XR?

Augmentin XR was marketed by GlaxoSmithKline as an extended-release amoxicillin/clavulanate product. The product was approved under NDA 050755 and was identified as an extended-release tablet containing 2,000 mg of amoxicillin and 125 mg of clavulanate per tablet [2].

The Orange Book treats patents and regulatory exclusivity separately. Patent listing does not extend after patent expiration, and expiration of a listed patent does not itself establish that a competing product is therapeutically equivalent or eligible for a standard ANDA pathway.

For a generic applicant, the relevant regulatory routes would depend on whether Augmentin XR remained an active reference listed drug and whether FDA had accepted the product as a suitable reference for an ANDA. If the reference product was withdrawn for reasons other than safety or effectiveness, the applicant might pursue an ANDA. If no suitable reference listed drug remained available, a 505(b)(2) application could become more relevant.

Were Paragraph IV challenges required?

A Paragraph IV certification would have been relevant while US 7,217,430 was listed and unexpired. A generic applicant seeking approval before expiration could certify that the patent was invalid, unenforceable, or would not be infringed.

After expiration, a Paragraph IV challenge to this patent would no longer create a meaningful commercial launch advantage because the patent would not delay launch. The applicant could instead rely on patent-expiration timing or certify that the patent had expired, subject to FDA’s applicable certification requirements.

No reliable conclusion can be drawn from the patent number alone regarding whether a particular generic company filed a Paragraph IV notice, whether litigation occurred, or whether a settlement was executed. Such events would need to be established from FDA records and federal court filings.

Which companies challenged or licensed the patent?

The patent was associated with the GlaxoSmithKline/SmithKline Beecham amoxicillin-clavulanate franchise. The patent record identifies the branded-product originator and its predecessor entities as the relevant rights holders.

There is no basis in the claim text alone to identify:

A particular Paragraph IV challenger
A litigation settlement
A royalty-bearing license
A covenant not to sue
A transfer of the patent to a generic manufacturer

Any such transaction would be separate from the patent’s prosecution history and claim language.

What design-around strategies were available?

A competing formulation could target several claim limitations.

Release-system design around

Potential approaches included:

A single-phase extended-release matrix
A multilayer tablet with a different phase architecture
Placement of a material amount of clavulanate in the second phase
A release profile that is not biphasic
A different first-to-second phase amoxicillin ratio

Excipient design around

A product could use a different release-retarding polymer, such as a cellulose derivative or another hydrophilic matrix former, rather than xanthan gum. This approach would avoid the express xanthan-gum limitation, although other patents or regulatory performance requirements could apply.

Salt and acid design around

Potential alternatives included:

A non-sodium amoxicillin form
Amoxicillin trihydrate in both phases
A different organic acid
No organic acid in the second phase
A different acid-to-amoxicillin ratio

The broader claim language means that changing citric acid alone would not necessarily avoid claim 1, because claim 1 covers a pharmaceutically acceptable organic acid generally. It could, however, avoid claims 25 through 27.

Dose and pharmacokinetic design around

A product using a different amoxicillin/clavulanate dose could fall outside claim 1. A formulation that failed to achieve the specified Cmax or sustained-concentration threshold could also avoid particular claims, but relying solely on pharmacokinetic failure would require controlled comparative testing.

How does this patent compare with the broader Augmentin patent landscape?

US 7,217,430 is a formulation patent, not a basic composition-of-matter patent for amoxicillin or clavulanate. The underlying antibacterial agents were known well before this patent. The commercial value came from extending the formulation and dosing profile of the established combination.

The broader landscape should be divided into four categories:

Patent category	Typical subject matter
Active-ingredient patents	Amoxicillin, clavulanate, salts, crystalline forms
Formulation patents	Immediate-release, sustained-release, bilayer, multiparticulate and taste-masked products
Method-of-use patents	Respiratory infections, resistant organisms and dosing regimens
Manufacturing patents	Granulation, blending, compression, coating, salt preparation and stability control

US 7,217,430 is strongest against products that reproduce the Augmentin XR architecture. It is less relevant to conventional immediate-release amoxicillin/clavulanate tablets, suspensions, chewables, or unrelated extended-release designs.

Biosimilar risk is not applicable. Amoxicillin/clavulanate is a small-molecule drug, so the relevant competitive pathways are generic ANDA products and, where appropriate, 505(b)(2) products rather than biosimilars.

What is the current commercial risk?

The patent itself presents no current US launch barrier because it expired in 2022. Current risk instead turns on:

FDA reference-product status
Bioequivalence requirements
Product-specific formulation complexity
Stability of clavulanate
Manufacturing control of the two release phases
Patent rights in other jurisdictions
Any unexpired continuation or related formulation patent

The manufacturing barrier is primarily technical rather than patent-based. A successful product must control phase separation, release kinetics, sodium amoxicillin stability, clavulanate degradation, tablet compression, dissolution, and pharmacokinetic performance.

Key Takeaways

US 7,217,430 covers a 2,000 mg/125 mg biphasic extended-release amoxicillin/clavulanate solid dosage form.
Claim 1 requires two release phases, xanthan gum in the second phase, an organic acid, and amoxicillin Cmax of at least 12 micrograms/mL.
Claims 4, 5, and 22 through 27 focus on sodium amoxicillin, crystallized sodium amoxicillin, citric acid, phase ratios, and approximately 2% xanthan gum.
Claims 16 through 21 cover treatment of respiratory infections, including community-acquired pneumonia, acute exacerbation of chronic bronchitis, and acute bacterial sinusitis.
The patent expired in 2022 and does not currently block US generic or alternative formulation development.
The patent was a formulation patent, not a basic amoxicillin or clavulanate patent.
Biosimilar analysis is not relevant; generic and 505(b)(2) pathways are the applicable competitive frameworks.
Current commercial barriers are more likely to involve FDA reference-product status, bioequivalence, formulation complexity, and manufacturing control than this expired patent.

FAQs

Does US 7,217,430 cover ordinary Augmentin tablets?

No. The claims are directed to a specific 2,000 mg/125 mg biphasic extended-release formulation. Conventional immediate-release Augmentin products generally fall outside the claimed architecture.

Does using citric acid alone infringe US 7,217,430?

Not necessarily. Claim 1 covers a broad pharmaceutically acceptable organic acid, so citric acid is not the only relevant limitation. Claims 25 through 27 specifically narrow the claims to citric acid and defined sodium amoxicillin, acid, and xanthan-gum amounts.

Is xanthan gum required in every claim?

Xanthan gum is expressly required by claim 1 and therefore carries into every dependent claim. A formulation using another release-retarding polymer would have a potential non-infringement position against the literal claims, subject to analysis of other patent rights.

Can a generic manufacturer launch after expiration without a Paragraph IV challenge?

A Paragraph IV challenge is generally not needed to overcome an expired patent. The applicant must still satisfy FDA’s applicable ANDA or 505(b)(2) requirements and address any other unexpired patents or regulatory exclusivities.

Does the patent protect the treatment of resistant Streptococcus pneumoniae indefinitely?

No. The method claims expired with the patent term. They do not create a continuing exclusivity period for treatment of drug-resistant or penicillin-resistant S. pneumoniae.

References

United States Patent No. 7,217,430. (2007). Pharmaceutical compositions comprising amoxicillin and clavulanic acid. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2001). Augmentin XR prescribing information. GlaxoSmithKline.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.
U.S. Food and Drug Administration. (2019). Orange Book: Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.
United States Code, 35 U.S.C. § 154. Patent term and patent-term adjustment.
U.S. Food and Drug Administration. (2023). Abbreviated new drug application submissions and patent certifications. Center for Drug Evaluation and Research.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
African Regional IP Organization (ARIPO)	1806	⤷ Start Trial
Argentina	031068	⤷ Start Trial
Austria	242629	⤷ Start Trial
Austria	4327	⤷ Start Trial
Australia	5702000	⤷ Start Trial
Australia	5837500	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 7,217,430

Summary for Patent: 7,217,430