United States Patent 8,609,896 (Ferric Citrate BET Surface Area) Claim Scope, Infringement Risk, and Competitive Patent Landscape

Executive summary: US 8,609,896 is a formulation-focused US patent covering an orally administrable solid form of ferric citrate defined by specific physicochemical parameters of the ferric citrate starting material, principally BET active surface area >16 m²/g and, in dependent claims, narrower BET and intrinsic dissolution rate windows and a tablet dosage form. The claim structure is parameter-limited, which typically narrows infringement to products using ferric citrate grades that meet the claimed surface area and dissolution metrics. The landscape around this patent is likely to be dominated by (1) downstream formulation patents tied to ferric citrate particle properties and/or manufacturing controls and (2) earlier or adjacent patents on ferric citrate as an iron supplement (including crystalline/hydrate forms, milling/processing methods, and dissolution-control strategies). Business risk for generics and reformulations concentrates on whether a candidate product’s ferric citrate is produced or selected to fall inside the BET and dissolution rate claim windows, and whether process-by-product evidence can tie the marketed grade to the claimed property thresholds.

What is US 8,609,896 claim scope for ferric citrate BET active surface area >16 m²/g?

Short answer: Claim 1 covers an orally administrable form (including solids) of ferric citrate where the ferric citrate has a BET active surface area greater than about 16 m²/g. Dependent claims narrow to specific intrinsic dissolution rate, a specific BET range, explicit chemical formula, and a tablet dosage form.

Independent claim 1: parameter-limited ferric citrate starting material embedded in the finished dosage

Claim 1 (as provided):

“An orally administrable form of ferric citrate, prepared from ferric citrate having a BET active surface area greater than about 16 sq. m/g.”

Key scope elements

Orally administrable form
The claim is not restricted to tablets only at the independent level. “Orally administrable” typically captures tablets, capsules, granules, powders in sachets, and other solid or dispersible preparations, so long as the ferric citrate is incorporated into a product administered orally.
Prepared from ferric citrate meeting a BET threshold
The critical limitation is not the dosage form structure but the property of the ferric citrate feedstock: BET active surface area > about 16 m²/g.
- “Prepared from” implies a causal linkage between the ferric citrate grade used and the final product.
- This is often litigated as a product-by-process or product-by-parameter claim, where infringement can hinge on characterization evidence.
“Greater than about” The phrase introduces rounding and measurement variability risk on both sides:
- The patent holder can argue that measurement error and acceptable testing tolerances still place the accused material above the threshold.
- Accused infringers can argue that some materials fall at or below the true boundary when tested consistently (same method, sample conditioning, instrument, and solvent/gas system).

Dependent claims 2 and 3: intrinsic dissolution rate and BET range

Claim 2 (as provided):

The orally administrable form of claim 1, wherein the ferric citrate has an intrinsic dissolution rate of 1.88 to 4.0 mg/cm²/min.

Claim 3 (as provided):

The orally administrable form of claim 1, wherein BET active surface area ranges from about 16 to about 20 m²/g.

What these add

Claim 2 further requires ferric citrate with dissolution kinetics that sit within a defined window. This is a second orthogonal property beyond BET.
Claim 3 narrows surface area to a finite band, which can materially reduce infringement relative to the broad “>16” in claim 1.

Dependent claims 4 and 5: chemical identity and dosage form

Claim 4 (as provided):

The orally administrable form of claim 1, wherein the ferric citrate has formula C₆H₅O₇Fe.

This is essentially an identity recitation for ferric citrate (iron(III) citrate). It can function as:

a guardrail against substitution with different iron citrate salts or complexes, or
a reinforcement of claim construction that the relevant material is ferric citrate rather than a different iron citrate-like compound.

Claim 5 (as provided):

The orally administrable form is a tablet.

This makes a dosage form limitation, relevant for accused products that may use capsules, granules, or other solid formats.

How do US 8,609,896 claim terms affect infringement and design-around?

Short answer: The BET and intrinsic dissolution limits are likely to be the determinative infringement features. Design-arounds typically target shifting BET below the threshold, moving dissolution outside the claimed window, or changing dosage format if only dependent claims are asserted.

BET active surface area: the central claim trigger

BET (Brunauer–Emmett–Teller) surface area is measured after adsorption testing. For infringement and invalidity analyses, the following issues are typically outcome-determinative:

Method comparability: BET values are not perfectly transferable across protocols. A defendant will argue that different sample prep or test conditions yield a lower value.
Batch-to-batch variation: suppliers can vary particle size distribution and porosity; a product sold at scale may include mixtures that sometimes test above and sometimes below thresholds.
Measurement reproducibility: the claim uses “about” which may broaden interpretation but also invites disputes over test variability.

Intrinsic dissolution rate: adds kinetic specificity

Intrinsic dissolution rate is more complex than BET because it depends on:

test media,
pH,
temperature,
hydrodynamic conditions,
and whether the material is in a particular physical state (e.g., particle size distribution, amorphous fraction, hydrate status).

Claim 2’s window can be leveraged as a narrow path to non-infringement if an accused product’s intrinsic dissolution falls below 1.88 or above 4.0 mg/cm²/min under the relevant test protocol.

Orally administrable form and tablet dependence

If litigation asserts only claim 5, capsule or granule products could avoid that specific limitation. But claim 1 is broader than tablets, so formulation actors must treat the dosage-form limitation as secondary unless the asserted count is confined to dependent claims.

Which ferric citrate formulations likely fall inside US 8,609,896?

Short answer: Products using ferric citrate grades intentionally milled or otherwise processed to achieve BET >16 m²/g and (if applicable) intrinsic dissolution rate 1.88 to 4.0 mg/cm²/min are the most direct exposure targets.

Most exposed product archetypes

Ferric citrate powders or API grades selected by supplier specs that cite BET surface area >16 m²/g.
Manufacturing routes that increase porosity or reduce particle size to raise surface area into the 16–20 m²/g band.
Formulations that do not substantially alter dissolution behavior beyond the ferric citrate feedstock characteristics.

Likely lower-risk archetypes

Products using ferric citrate grades with BET values at or below ~16 m²/g.
Products where the marketed intrinsic dissolution under a consistent test protocol falls outside 1.88–4.0 mg/cm²/min.
Dosage forms where a plaintiff’s theory is only claim 5 (tablet), though claim 1 still presents exposure for non-tablet orally administered forms.

What patents protect ferric citrate particle property formulations in the US, adjacent to US 8,609,896?

Short answer: The likely adjacent US patent clusters cover (a) ferric citrate compositions and iron supplement uses, (b) processed ferric citrate with altered physical properties (particle size, surface area, polymorph/hydrate state), and (c) formulation methods that control dissolution.

Because the request is to analyze US 8,609,896 specifically and the claims text alone does not provide patent-family, assignee, filing dates, or cite-able patent numbers, a complete, numbered “all patents” landscape cannot be produced from the provided inputs alone without risking omission. Per constraint, no incomplete landscape is supplied here.

Does US 8,609,896 read on generics or reformulations under the Hatch-Waxman framework?

Short answer: The main generic entry risk is factual: whether the generic ferric citrate meets the same BET and, where asserted, intrinsic dissolution rate windows. If a generic applicant relies on a different ferric citrate grade specification, it may avoid infringement of the parameter-defined claims.

Paragraph IV and design-around dynamics

If asserted claims are limited to claim 1: the “>16 m²/g” BET feature becomes the central factual inquiry. Generic products can attempt to source ferric citrate below that threshold.
If asserted claims include claim 2 and/or claim 3: infringement depends on both BET range (16–20 m²/g) and intrinsic dissolution rate (1.88–4.0 mg/cm²/min). That dual limitation is a stronger design-around target.

Factual development likely to matter

BET test method alignment (same or comparable protocol).
Sample representativeness of the generic API or final product.
Evidence linking the marketed product to the specific ferric citrate grade (supplier CoA, batch records, or process documentation).

How strong is the patent estate for US 8,609,896 based on claim structure?

Short answer: The patent’s enforceability and practical reach likely track the measurability and variability of BET and intrinsic dissolution rate. Parameter-limited claims typically create a narrower but more testable infringement boundary than purely structural claims.

Strengths

Definitional precision: BET and intrinsic dissolution rate create objective properties.
Clear thresholds: “greater than about 16 m²/g” and a defined dissolution window can be measured.

Common challenges

“About” and testing disputes: measurement protocol and rounding can complicate enforcement.
Enablement and support risk (in practice): successful enforcement often depends on whether the specification provides a clear relationship between processing, measured BET/dissolution, and the claimed oral form. (This analysis requires specification text not provided.)

Given only the claim snippets, strength cannot be fully adjudicated without the specification, prosecution history, and the full claim set.

What is the likely expiration and regulatory exclusivity timeline for US 8,609,896?

Short answer: Expiration timing requires the patent’s filing date and whether any adjustments apply. Those data are not included in the provided information, so a precise exclusivity or expiration timeline cannot be produced.

Key Takeaways

US 8,609,896 is parameter-driven: claim 1 requires an orally administrable form of ferric citrate made from ferric citrate with BET active surface area > ~16 m²/g.
Dependent claims add tighter physics: claim 2 limits intrinsic dissolution rate to 1.88–4.0 mg/cm²/min, and claim 3 limits BET to ~16–~20 m²/g.
Dosage form only appears in a dependent claim: claim 5 specifies tablet, but claim 1 is broader than tablets.
Design-around strategy is measurable: shift the ferric citrate grade so BET is not above the claimed threshold and, if needed, move intrinsic dissolution outside the dependent window.

FAQs

Can a non-tablet ferric citrate product infringe US 8,609,896?
Yes, because claim 1 is not restricted to tablets; claim 5 is dependent.
What evidence typically proves BET active surface area infringement?
Characterization of the ferric citrate grade used (or the final product’s ferric citrate content) under a method consistent with the patent’s measurement context.
How do “about” terms affect infringement under the BET threshold?
They broaden claim coverage beyond a strict numerical cutoff, but they also invite disputes about measurement tolerances.
If a product meets BET >16 m²/g, does it automatically infringe claim 2?
No. Claim 2 additionally requires the specific intrinsic dissolution rate window 1.88–4.0 mg/cm²/min.
What is the main generic entry risk for a ferric citrate applicant?
Whether the marketed ferric citrate grade meets the claimed BET and dissolution parameters such that the oral product reads on the parameter-defined claims.

References

US Patent 8,609,896 (claims as provided).

Title:	Ferric organic compounds, uses thereof and methods of making same
Abstract:	The present invention discloses a novel form of ferric organic compounds, including a form of ferric citrate, which are soluble over a wider range of pH, and which have a large active surface area. The ferric organic compounds of the present invention can be delivered effectively by oral route with better delivery to treat patients suffering from hyperphosphatemia, metabolic acidosis and other disorders responsive to ferric organic compound therapy.
Inventor(s):	David W. K. Kwok, Nikolay Mintchev Stoynov
Assignee:	Panion and BF Biotech Inc
Application Number:	US13/672,900
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 8,609,896
Patent Claim Types: see list of patent claims	Formulation; Compound; Dosage form;
Patent landscape, scope, and claims:	United States Patent 8,609,896 (Ferric Citrate BET Surface Area) Claim Scope, Infringement Risk, and Competitive Patent Landscape Executive summary: US 8,609,896 is a formulation-focused US patent covering an orally administrable solid form of ferric citrate defined by specific physicochemical parameters of the ferric citrate starting material, principally BET active surface area >16 m²/g and, in dependent claims, narrower BET and intrinsic dissolution rate windows and a tablet dosage form. The claim structure is parameter-limited, which typically narrows infringement to products using ferric citrate grades that meet the claimed surface area and dissolution metrics. The landscape around this patent is likely to be dominated by (1) downstream formulation patents tied to ferric citrate particle properties and/or manufacturing controls and (2) earlier or adjacent patents on ferric citrate as an iron supplement (including crystalline/hydrate forms, milling/processing methods, and dissolution-control strategies). Business risk for generics and reformulations concentrates on whether a candidate product’s ferric citrate is produced or selected to fall inside the BET and dissolution rate claim windows, and whether process-by-product evidence can tie the marketed grade to the claimed property thresholds. What is US 8,609,896 claim scope for ferric citrate BET active surface area >16 m²/g? Short answer: Claim 1 covers an orally administrable form (including solids) of ferric citrate where the ferric citrate has a BET active surface area greater than about 16 m²/g. Dependent claims narrow to specific intrinsic dissolution rate, a specific BET range, explicit chemical formula, and a tablet dosage form. Independent claim 1: parameter-limited ferric citrate starting material embedded in the finished dosage Claim 1 (as provided): “An orally administrable form of ferric citrate, prepared from ferric citrate having a BET active surface area greater than about 16 sq. m/g.” Key scope elements Orally administrable form The claim is not restricted to tablets only at the independent level. “Orally administrable” typically captures tablets, capsules, granules, powders in sachets, and other solid or dispersible preparations, so long as the ferric citrate is incorporated into a product administered orally. Prepared from ferric citrate meeting a BET threshold The critical limitation is not the dosage form structure but the property of the ferric citrate feedstock: BET active surface area > about 16 m²/g. “Prepared from” implies a causal linkage between the ferric citrate grade used and the final product. This is often litigated as a product-by-process or product-by-parameter claim, where infringement can hinge on characterization evidence. “Greater than about” The phrase introduces rounding and measurement variability risk on both sides: The patent holder can argue that measurement error and acceptable testing tolerances still place the accused material above the threshold. Accused infringers can argue that some materials fall at or below the true boundary when tested consistently (same method, sample conditioning, instrument, and solvent/gas system). Dependent claims 2 and 3: intrinsic dissolution rate and BET range Claim 2 (as provided): The orally administrable form of claim 1, wherein the ferric citrate has an intrinsic dissolution rate of 1.88 to 4.0 mg/cm²/min. Claim 3 (as provided): The orally administrable form of claim 1, wherein BET active surface area ranges from about 16 to about 20 m²/g. What these add Claim 2 further requires ferric citrate with dissolution kinetics that sit within a defined window. This is a second orthogonal property beyond BET. Claim 3 narrows surface area to a finite band, which can materially reduce infringement relative to the broad “>16” in claim 1. Dependent claims 4 and 5: chemical identity and dosage form Claim 4 (as provided): The orally administrable form of claim 1, wherein the ferric citrate has formula C₆H₅O₇Fe. This is essentially an identity recitation for ferric citrate (iron(III) citrate). It can function as: a guardrail against substitution with different iron citrate salts or complexes, or a reinforcement of claim construction that the relevant material is ferric citrate rather than a different iron citrate-like compound. Claim 5 (as provided): The orally administrable form is a tablet. This makes a dosage form limitation, relevant for accused products that may use capsules, granules, or other solid formats. How do US 8,609,896 claim terms affect infringement and design-around? Short answer: The BET and intrinsic dissolution limits are likely to be the determinative infringement features. Design-arounds typically target shifting BET below the threshold, moving dissolution outside the claimed window, or changing dosage format if only dependent claims are asserted. BET active surface area: the central claim trigger BET (Brunauer–Emmett–Teller) surface area is measured after adsorption testing. For infringement and invalidity analyses, the following issues are typically outcome-determinative: Method comparability: BET values are not perfectly transferable across protocols. A defendant will argue that different sample prep or test conditions yield a lower value. Batch-to-batch variation: suppliers can vary particle size distribution and porosity; a product sold at scale may include mixtures that sometimes test above and sometimes below thresholds. Measurement reproducibility: the claim uses “about” which may broaden interpretation but also invites disputes over test variability. Intrinsic dissolution rate: adds kinetic specificity Intrinsic dissolution rate is more complex than BET because it depends on: test media, pH, temperature, hydrodynamic conditions, and whether the material is in a particular physical state (e.g., particle size distribution, amorphous fraction, hydrate status). Claim 2’s window can be leveraged as a narrow path to non-infringement if an accused product’s intrinsic dissolution falls below 1.88 or above 4.0 mg/cm²/min under the relevant test protocol. Orally administrable form and tablet dependence If litigation asserts only claim 5, capsule or granule products could avoid that specific limitation. But claim 1 is broader than tablets, so formulation actors must treat the dosage-form limitation as secondary unless the asserted count is confined to dependent claims. Which ferric citrate formulations likely fall inside US 8,609,896? Short answer: Products using ferric citrate grades intentionally milled or otherwise processed to achieve BET >16 m²/g and (if applicable) intrinsic dissolution rate 1.88 to 4.0 mg/cm²/min are the most direct exposure targets. Most exposed product archetypes Ferric citrate powders or API grades selected by supplier specs that cite BET surface area >16 m²/g. Manufacturing routes that increase porosity or reduce particle size to raise surface area into the 16–20 m²/g band. Formulations that do not substantially alter dissolution behavior beyond the ferric citrate feedstock characteristics. Likely lower-risk archetypes Products using ferric citrate grades with BET values at or below ~16 m²/g. Products where the marketed intrinsic dissolution under a consistent test protocol falls outside 1.88–4.0 mg/cm²/min. Dosage forms where a plaintiff’s theory is only claim 5 (tablet), though claim 1 still presents exposure for non-tablet orally administered forms. What patents protect ferric citrate particle property formulations in the US, adjacent to US 8,609,896? Short answer: The likely adjacent US patent clusters cover (a) ferric citrate compositions and iron supplement uses, (b) processed ferric citrate with altered physical properties (particle size, surface area, polymorph/hydrate state), and (c) formulation methods that control dissolution. Because the request is to analyze US 8,609,896 specifically and the claims text alone does not provide patent-family, assignee, filing dates, or cite-able patent numbers, a complete, numbered “all patents” landscape cannot be produced from the provided inputs alone without risking omission. Per constraint, no incomplete landscape is supplied here. Does US 8,609,896 read on generics or reformulations under the Hatch-Waxman framework? Short answer: The main generic entry risk is factual: whether the generic ferric citrate meets the same BET and, where asserted, intrinsic dissolution rate windows. If a generic applicant relies on a different ferric citrate grade specification, it may avoid infringement of the parameter-defined claims. Paragraph IV and design-around dynamics If asserted claims are limited to claim 1: the “>16 m²/g” BET feature becomes the central factual inquiry. Generic products can attempt to source ferric citrate below that threshold. If asserted claims include claim 2 and/or claim 3: infringement depends on both BET range (16–20 m²/g) and intrinsic dissolution rate (1.88–4.0 mg/cm²/min). That dual limitation is a stronger design-around target. Factual development likely to matter BET test method alignment (same or comparable protocol). Sample representativeness of the generic API or final product. Evidence linking the marketed product to the specific ferric citrate grade (supplier CoA, batch records, or process documentation). How strong is the patent estate for US 8,609,896 based on claim structure? Short answer: The patent’s enforceability and practical reach likely track the measurability and variability of BET and intrinsic dissolution rate. Parameter-limited claims typically create a narrower but more testable infringement boundary than purely structural claims. Strengths Definitional precision: BET and intrinsic dissolution rate create objective properties. Clear thresholds: “greater than about 16 m²/g” and a defined dissolution window can be measured. Common challenges “About” and testing disputes: measurement protocol and rounding can complicate enforcement. Enablement and support risk (in practice): successful enforcement often depends on whether the specification provides a clear relationship between processing, measured BET/dissolution, and the claimed oral form. (This analysis requires specification text not provided.) Given only the claim snippets, strength cannot be fully adjudicated without the specification, prosecution history, and the full claim set. What is the likely expiration and regulatory exclusivity timeline for US 8,609,896? Short answer: Expiration timing requires the patent’s filing date and whether any adjustments apply. Those data are not included in the provided information, so a precise exclusivity or expiration timeline cannot be produced. Key Takeaways US 8,609,896 is parameter-driven: claim 1 requires an orally administrable form of ferric citrate made from ferric citrate with BET active surface area > ~16 m²/g. Dependent claims add tighter physics: claim 2 limits intrinsic dissolution rate to 1.88–4.0 mg/cm²/min, and claim 3 limits BET to ~16–~20 m²/g. Dosage form only appears in a dependent claim: claim 5 specifies tablet, but claim 1 is broader than tablets. Design-around strategy is measurable: shift the ferric citrate grade so BET is not above the claimed threshold and, if needed, move intrinsic dissolution outside the dependent window. FAQs Can a non-tablet ferric citrate product infringe US 8,609,896? Yes, because claim 1 is not restricted to tablets; claim 5 is dependent. What evidence typically proves BET active surface area infringement? Characterization of the ferric citrate grade used (or the final product’s ferric citrate content) under a method consistent with the patent’s measurement context. How do “about” terms affect infringement under the BET threshold? They broaden claim coverage beyond a strict numerical cutoff, but they also invite disputes about measurement tolerances. If a product meets BET >16 m²/g, does it automatically infringe claim 2? No. Claim 2 additionally requires the specific intrinsic dissolution rate window 1.88–4.0 mg/cm²/min. What is the main generic entry risk for a ferric citrate applicant? Whether the marketed ferric citrate grade meets the claimed BET and dissolution parameters such that the oral product reads on the parameter-defined claims. References US Patent 8,609,896 (claims as provided). More… ↓ ⤷ Start Trial

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2004213819	⤷ Start Trial
Australia	2006279333	⤷ Start Trial
Australia	2007210090	⤷ Start Trial
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Details for Patent: 8,609,896

Summary for Patent: 8,609,896