US Patent 10,519,252: Scope, Claims, Expiration, and Ferric Carboxymaltose Patent Landscape

US Patent 10,519,252 protects defined iron(III) carboxymaltodextrin complexes, pharmaceutical compositions, and treatment methods for iron deficiency. The central limitations are a weight-average molecular weight of 80 to 400 kDa and maltodextrin-derived carboxylate material with specified dextrose-equivalent ranges. The patent issued December 31, 2019, and its ordinary 20-year term appears to run from the earliest claimed priority date in 2007, producing an estimated expiration in 2028, subject to any patent-term adjustment.

The broadest commercial risk is concentrated in claims 1, 13, 18, 21, 24, and 25. Claims 5 through 12 are narrower molecular-weight species claims. Claim 26 is narrower still because it requires a 500-to-1,000-mg iron dose administered over one hour.

What does US Patent 10,519,252 cover?

US Patent 10,519,252 covers four connected subject areas:

A specific iron(III) carboxymaltodextrin complex.
Medicaments containing that complex.
Aqueous and brine formulations containing the complex.
Treatment of iron deficiency, including intravenous or intramuscular administration and single-dose therapy.

The patent is assigned to Vifor (International) AG in the public patent record. Its technical subject matter is associated with ferric carboxymaltose, an intravenous iron-carbohydrate complex marketed in the United States as Injectafer and outside the United States as Ferinject. The patent itself does not grant rights outside the United States.

What is the independent composition claim?

Claim 1 requires all of the following:

Limitation	Requirement
Active complex	Iron(III) carboxymaltodextrin complex
Iron structure	Polynuclear iron(III)-hydroxide
Ligand structure	4(R)-(poly-(1→4)-O-alpha-D-glucopyranosyl)-oxy-2(R),3(S),5(R),6-tetrahydroxy-hexanoate
Molecular weight	Weight-average molecular weight from 80 to 400 kDa
Source material	Ligand derived from oxidation of maltodextrin
Single maltodextrin	Dextrose equivalent of 5 to 20
Maltodextrin mixture	Mixture DE of 5 to 20, with each individual maltodextrin at DE 2 to 40

The claim is structurally and process-defined. It does not cover every iron-carbohydrate complex or every ferric iron formulation. A product must fall within the specified carboxymaltodextrin chemistry and molecular-weight range.

How should the molecular-weight limitations be interpreted?

The molecular-weight limitations are central to both infringement and validity analysis. Claim 1 uses a weight-average molecular-weight range of 80 to 400 kDa. Claims 2 through 4 narrow that range, while claims 5 through 12 identify specific values.

Claim	Molecular-weight limitation
1	80-400 kDa
2	80-350 kDa
3	80-300 kDa
4	118-271 kDa
5	271,000 Da
6	141,000 Da
7	140,000 Da
8	189,000 Da
9	118,000 Da
10	178,000 Da
11	137,000 Da
12	170,000 Da

The dependent claims are cumulative. A complex falling within claim 5 must also satisfy every limitation of claim 1. A product with a 271-kDa weight-average molecular weight is not within claim 5 unless it also uses the claimed iron(III)-carboxymaltodextrin structure and the specified maltodextrin DE conditions.

Weight-average molecular weight is not necessarily equivalent to a simple average, median, or peak molecular weight. Testing method, calibration standard, sample preparation, aggregation, and distribution profile can materially affect the reported value. In a patent dispute, the analytical protocol and the definition of the tested material would likely become significant evidence.

What formulations are protected by US 10,519,252?

Claim 13 covers a medicament comprising the claim 1 complex and a pharmaceutically acceptable carrier, excipient, or additive.

Claims 14 through 17 narrow the formulation:

Claim	Formulation limitation
13	Medicament with carrier, excipient, or additive
14	Aqueous solution
15	Brine solution
16	1%-20% complex by total solution weight
17	5% complex by total solution weight

The formulation claims are composition claims. They do not require a particular indication or route unless those features are added through a treatment claim.

A commercially supplied ferric carboxymaltose solution containing 50 mg/mL iron, commonly described as a 5% w/v formulation, may present a strong issue under claims 14, 16, and 17 if the active complex also meets the structural, DE, and molecular-weight limitations of claim 1. The claim language refers to the complex percentage by total solution weight, so the analysis must distinguish the mass of the iron complex from the mass of elemental iron.

What treatment methods are protected?

Claim 18 covers treatment of an iron deficiency condition by administering the medicament of claim 13. Claims 19 through 26 narrow the therapy.

Claim	Treatment limitation
18	Treatment of an iron deficiency condition
19	Iron deficiency anemia
20	Parenteral or oral administration
21	Intravenous or intramuscular administration
22	Injection
23	Infusion
24	Single dose
25	Single dose containing 500-1,000 mg iron
26	Single dose administered during one hour

Claims 18 and 19 are comparatively broad because they do not require the intravenous route, a particular dose, or a specific administration schedule. They do, however, incorporate claim 13 and therefore require the claimed complex in a medicament with a pharmaceutically acceptable carrier, excipient, or additive.

Claim 21 is commercially important for intravenous iron products. Claims 24 and 25 are relevant to high-dose replacement regimens. Claim 26 has a narrower commercial fit because current ferric carboxymaltose labels commonly provide administration over a shorter period than one hour, depending on dose and jurisdiction.

When does US Patent 10,519,252 lose exclusivity?

The patent issued on December 31, 2019. The public family record indicates an earliest priority date in 2007. Under the US patent-term rule, a utility patent generally expires 20 years from the earliest effective nonprovisional filing date, not 20 years from issue. [1]

Event	Date or period
Earliest claimed priority	2007, according to public family records
US grant	December 31, 2019
Estimated ordinary expiration	2028
Estimated date based on a March 30, 2007 priority chain	March 30, 2028
Potential adjustment	Patent-term adjustment could extend the date

The precise enforceable expiration date must be taken from the USPTO patent-term calculation and the patent’s official continuity record. Patent-term extension under 35 U.S.C. § 156 is a separate issue from patent-term adjustment and depends on the relevant regulatory approvals. [2]

A terminal disclaimer, if present in the family, could also affect the expiration date. The patent’s issue date alone does not support a 2039 expiration date.

What is the Orange Book status of US 10,519,252?

Ferric carboxymaltose is an FDA-approved small-molecule drug product rather than a biologic. Relevant exclusivity is therefore handled through the New Drug Application and Abbreviated New Drug Application systems, including Orange Book patent listings and Paragraph IV certifications. [3]

Injectafer is approved in the United States under NDA 022020. The FDA label identifies ferric carboxymaltose injection as an intravenous iron replacement product. [4]

The commercial relevance of US 10,519,252 depends on whether it is listed against the relevant NDA, whether the listing covers the product being copied, and whether the patent remains listed during the ANDA approval process. An Orange Book listing does not itself establish that every claim is valid or infringed. It creates a statutory framework for notice, certification, and potential litigation.

What Paragraph IV challenges could target this patent?

An ANDA applicant seeking approval before the listed patent expires generally has four certification options:

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 certification concerning US 10,519,252 would require the applicant to evaluate at least:

Whether its iron-carbohydrate complex is structurally a carboxymaltodextrin complex.
Whether the complex has a weight-average molecular weight within 80-400 kDa.
Whether its maltodextrin starting material falls within the claimed DE ranges.
Whether its formulation contains the claimed complex and carrier.
Whether its proposed labeling induces use covered by claims 18 through 26.

If the NDA holder receives a compliant Paragraph IV notice and files suit within 45 days, FDA approval may be subject to a 30-month stay, subject to statutory exceptions and court developments. [5]

How strong is the patent estate for ferric carboxymaltose?

US 10,519,252 has a technically focused claim set. Its principal strength is that claim 1 combines several limitations rather than relying only on the general identity of ferric carboxymaltose.

Strengths

The patent has several features that can increase enforcement leverage:

The composition is defined by both chemical structure and manufacturing origin.
The molecular-weight range is broad enough to encompass multiple commercial or development batches.
The formulation and treatment claims create multiple infringement theories.
The dependent claims provide fallback positions at 118, 137, 140, 141, 170, 178, 189, and 271 kDa.
Claims 18 and 21 can reach treatment use even where formulation-specific claims are disputed.

Vulnerabilities

The same limitations create potential design-around and validity issues:

Weight-average molecular weight may vary by analytical method and batch.
The maltodextrin DE requirement may be difficult to establish from finished-product testing alone.
Prior art may disclose iron-carbohydrate complexes with overlapping molecular-weight distributions.
The oxidation process and starting-material limitations may raise written-description, enablement, or claim-construction disputes.
A generic may attempt to use a different carbohydrate ligand or an iron-carbohydrate complex outside the claimed structural definition.
A method-of-treatment claim may face inducement arguments if the proposed label does not expressly recommend the claimed dosing schedule or indication.

The key question is not whether a product is marketed as ferric carboxymaltose. The key question is whether the accused material satisfies the patent’s structural, molecular-weight, and DE limitations.

How does US 10,519,252 compare with related ferric carboxymaltose patents?

Ferric carboxymaltose products can be subject to overlapping patent categories:

Patent category	Typical protected subject matter	Relevance to US 10,519,252
Core composition	Iron-carbohydrate chemical complex	Directly relevant
Molecular-weight profile	Defined molecular-weight range or distribution	Directly relevant
Starting material	Maltodextrin DE and oxidation conditions	Directly relevant
Formulation	Concentration, carrier, pH, stability, container	Relevant to claims 13-17
Method of treatment	Iron deficiency, dosing, route, infusion	Relevant to claims 18-26
Manufacturing	Oxidation, complexation, purification, sterilization	Relevant to freedom to operate
Regulatory exclusivity	NDA exclusivity and Orange Book listing	Separate from patent scope

Earlier and related US patents in the ferric carboxymaltose field include US 7,612,109 and US 8,895,612, while later family members and continuation patents may cover overlapping composition, formulation, or use subject matter. [6,7] A complete freedom-to-operate analysis must review the entire continuation and divisional family rather than treating US 10,519,252 as the sole relevant right.

What generic entry risks exist?

The most likely generic entry scenarios are:

Scenario 1: Paragraph III delay

The applicant accepts the patent and waits for expiration. This avoids early patent litigation but delays approval until the listed patent barriers expire.

Scenario 2: Paragraph IV challenge

The applicant argues that the proposed product does not meet one or more limitations, or that the claims are invalid or unenforceable. The highest-value defenses would likely focus on:

Molecular weight outside the claimed range.
Non-maltodextrin carbohydrate chemistry.
Maltodextrin DE outside the claimed range.
Lack of proof that the finished product retains the claimed structure.
Prior-art overlap.
Non-infringing labeling for treatment claims.

Scenario 3: Design-around product

A competitor could pursue a different iron-carbohydrate complex, such as ferric derisomaltose or another carbohydrate ligand. Such a product would not automatically fall outside all related patent families, but it would not ordinarily satisfy the carboxymaltodextrin limitation of claim 1.

Scenario 4: Same active complex with process differences

Changing the manufacturing process alone may not avoid infringement if the final product still meets the product limitations of claim 1. Process changes are more useful where the claims require a particular starting material or where the resulting complex falls outside the molecular-weight or structural limitations.

Are biosimilar challenges relevant?

No. Ferric carboxymaltose is regulated as a drug product, not as a reference biological product under the biosimilar pathway. The relevant competitive pathway is an ANDA for a generic drug, not a 351(k) biosimilar application. [3]

A competing iron replacement product may still create commercial pressure without directly copying ferric carboxymaltose. Ferric derisomaltose, iron sucrose, ferumoxytol, and other parenteral iron products compete in overlapping treatment markets but have different active complexes, regulatory histories, dosing profiles, and patent estates.

What litigation and settlement issues affect this patent?

A patent-specific litigation assessment should distinguish three issues:

Whether US 10,519,252 was listed in the Orange Book for the relevant NDA.
Whether an ANDA applicant served a Paragraph IV notice.
Whether the NDA holder filed a timely infringement action.

A filed case may trigger a 30-month stay, but a settlement can change the practical launch date. Settlement agreements may include:

Delayed generic entry.
A license to a specified formulation or manufacturer.
No-challenge provisions.
Authorized-generic terms.
Restrictions tied to patent expiration or court judgment.

The patent number should be searched in the FDA Orange Book, USPTO Patent Center, and federal court docket systems when assessing current litigation status. The controlling commercial date is the earliest date permitted by the patent, regulatory stay, settlement, and any court order.

What manufacturing and geographic barriers apply?

The patent’s geographic scope is limited to the United States. Foreign counterparts may have different claim wording, prosecution histories, validity outcomes, and expiration dates.

Manufacturing risk is material because the claims include both:

A defined chemical product; and
A maltodextrin oxidation origin with specified DE values.

A competitor cannot reliably avoid the patent merely by changing the supplier of maltodextrin. If the supplied material still falls within the claimed DE range and produces the claimed complex within the claimed molecular-weight range, the sourcing change may have no practical effect.

Conversely, a supplier certificate reporting only DE or only molecular weight may not establish the full claim analysis. The relevant evidence may include carbohydrate characterization, oxidation conditions, iron-to-ligand ratios, molecular-weight distribution, process records, and batch-specific analytical data.

Key Takeaways

US 10,519,252 is a composition, formulation, and method-of-treatment patent for iron(III) carboxymaltodextrin complexes.
Claim 1 requires a 80-400 kDa weight-average molecular weight and defined maltodextrin DE parameters.
Claims 5-12 provide narrower molecular-weight fallback positions from 118 to 271 kDa.
Claims 13-17 cover medicaments, aqueous solutions, brine solutions, and 1%-20% complex concentrations.
Claims 18-26 cover treatment of iron deficiency, including intravenous administration, single doses, and 500-1,000 mg iron dosing.
The patent issued December 31, 2019, with an estimated ordinary expiration in 2028 based on the public 2007 priority chain.
Ferric carboxymaltose is subject to the ANDA and Orange Book framework, not the biosimilar pathway.
The principal generic defenses are non-infringement based on structure, molecular weight, DE, or labeling, together with validity challenges based on prior art and disclosure.
A full freedom-to-operate review must include related composition, formulation, manufacturing, continuation, and method-of-use patents.

FAQs About US Patent 10,519,252

Does US Patent 10,519,252 cover Injectafer?

It may cover Injectafer products if the marketed iron(III) carboxymaltodextrin complex satisfies the claimed molecular-weight, structural, and maltodextrin DE limitations. Product branding alone does not determine infringement.

Does the patent cover ferric derisomaltose?

The claims are directed to iron(III) carboxymaltodextrin. Ferric derisomaltose is a different iron-carbohydrate complex and would require a separate claim comparison.

Can a generic avoid the patent by using a different molecular-weight average?

Potentially. A product outside the 80-400 kDa range would not literally satisfy claim 1, although other patents, equivalence theories, or related family claims could remain relevant.

Is a 5% ferric carboxymaltose solution within the formulation claims?

It may be. Claims 16 and 17 require the claimed complex to constitute 1%-20% or 5% by total solution weight, respectively. The chemical identity and molecular-weight requirements of claim 1 still apply.

Does a one-hour infusion fall within claim 26?

Yes, if the product also satisfies every incorporated limitation and the single dose contains 500-1,000 mg of iron. Claim 26 is narrower than claims 18, 21, 23, 24, and 25.

References

United States Patent and Trademark Office. (n.d.). Patent term calculator and patent term provisions. https://www.uspto.gov/patents/laws/patent-term-calculator
35 U.S.C. §§ 154, 156.
U.S. Food and Drug Administration. (n.d.). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/
U.S. Food and Drug Administration. (2023). Injectafer prescribing information. American Regent, Inc.
21 U.S.C. § 355(j).
U.S. Patent No. 7,612,109.
U.S. Patent No. 8,895,612.
U.S. Patent No. 10,519,252. (2019). Iron (III) carboxymaltose complex. United States Patent and Trademark Office.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Germany	102 49 552	Oct 23, 2002

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	1554315	⤷ Start Trial	C01554315/01	Switzerland	⤷ Start Trial
Argentina	041472	⤷ Start Trial
Austria	507246	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,519,252

Summary for Patent: 10,519,252