United States Patent 7,014,846: Scope, Claims, Expiration, and Sevelamer Patent Landscape

U.S. Patent No. 7,014,846 protects pharmaceutical compositions and oral phosphate-removal methods using a crosslinked, water-insoluble polyallylamine homopolymer. The patent is closely associated with the sevelamer polymer platform used in Renagel and Renvela. Its core statutory term has expired, eliminating current enforcement risk from this patent alone. The broader sevelamer estate included earlier composition, polymer, formulation, and manufacturing patents that created the historical barrier to generic entry.

What does U.S. Patent 7,014,846 protect?

The patent has two independent claim groups:

Composition claims 1-8.
Method-of-treatment claims 9-14.

The central technical subject is a crosslinked, water-insoluble polyallylamine homopolymer used in an orally administered pharmaceutical product or phosphate-removal treatment.

Claim group	Protected subject matter	Key limitations
Claims 1-8	Pharmaceutical composition	Carrier plus crosslinked, water-insoluble polyallylamine homopolymer
Claims 2, 10, 11	Crosslinking parameter	Epichlorohydrin; approximately 2%-20% by polymer weight
Claims 3-5, 12-14	Protonation state	Fully or partially protonated; HCl protonation; partially protonated
Claims 6-7	Composition identity	"Consists essentially of" or "consists of" carrier and polymer
Claim 8	Dosage form	Tablet or capsule
Claims 9-14	Treatment method	Oral administration for removing phosphate from a patient

The polymer limitation is the principal scope-defining element. A product must contain a polyallylamine homopolymer that is crosslinked and water insoluble. The claim does not expressly require the commercial name "sevelamer," a particular molecular weight, a particular particle size, or a specific ratio of active polymer to excipient.

How broad is independent claim 1?

Claim 1 is a composition claim with four important limitations:

A pharmaceutical composition.
A carrier.
A crosslinked polyallylamine homopolymer.
A water-insoluble polymer with the claimed repeat-unit structure.

Claim 1 does not require epichlorohydrin crosslinking. That limitation appears in claim 2. Claim 1 also covers the polymer in fully protonated, partially protonated, or unprotonated form.

The result is a relatively broad genus claim. It can reach compositions containing different protonation states and different carriers, provided that the polymer remains a crosslinked, water-insoluble polyallylamine homopolymer.

A competing product could avoid literal infringement if it uses:

A copolymer rather than a polyallylamine homopolymer.
A water-soluble polyamine.
A different polymer backbone.
An inorganic phosphate binder, such as ferric citrate, sucroferric oxyhydroxide, lanthanum carbonate, or calcium acetate.
A non-crosslinked polyallylamine material.

The phrase "pharmaceutical composition" may require a product intended for pharmaceutical administration rather than an industrial adsorbent or laboratory resin. The presence of a carrier broadens the claim beyond neat polymer, but it also creates a potential claim-construction issue for products consisting primarily of polymer with minimal excipient content.

What do claims 2 through 8 add?

What is the significance of the 2%-20% epichlorohydrin limitation?

Claim 2 narrows claim 1 to compositions in which the polyallylamine polymer is crosslinked with epichlorohydrin at approximately 2%-20% by weight of polymer. Claims 10 and 11 apply substantially the same limitations to the phosphate-removal method.

This range is commercially important because epichlorohydrin crosslink density affects:

Water insolubility.
Swelling.
Amine accessibility.
Phosphate-binding capacity.
Tablet manufacturability.
Gastrointestinal residence and handling properties.

A polymer crosslinked below or above the stated range may avoid literal infringement of the dependent claims, although it could remain within claim 1 if it is crosslinked by another agent.

What is the effect of the protonation claims?

Claims 3-5 cover fully or partially protonated material and identify hydrochloric acid as the protonating agent. Claim 5 is narrower because it requires partial protonation with HCl.

The claims are directed to chemical state rather than only product labeling. A commercial sevelamer hydrochloride product would be a natural target for these limitations, but the patent also reaches partially protonated and unprotonated forms under the broader independent claims.

The claim set does not require a specific degree of protonation. That omission expands potential scope but can create analytical disputes over how protonation is measured and whether the tested batch falls within the claimed state.

How do "consists essentially of" and "consists of" affect scope?

Claim 6 uses "consists essentially of," while claim 7 uses "consists of."

"Consists of" is closed-ended and generally excludes unrecited components that materially alter the claimed composition.

"Consists essentially of" is a partially closed transitional phrase. It permits additional ingredients that do not materially affect the basic and novel characteristics of the composition. For this patent, those characteristics likely include phosphate binding by the crosslinked polyallylamine polymer.

Claims 6 and 7 are narrower than claim 1 because they limit the composition's additional active or functional ingredients. A formulation containing another therapeutic agent, a functional coating, or an excipient that materially changes phosphate binding could create a noninfringement argument under these claims even if claim 1 remains relevant.

Does claim 8 cover Renagel and Renvela tablets?

Claim 8 covers the composition of claim 1 in tablet or capsule form. It is not limited to a particular brand, dose strength, coating, excipient system, or release profile.

The claim is therefore relevant to:

Sevelamer hydrochloride tablets.
Sevelamer carbonate tablets.
Other tablet products containing a qualifying crosslinked polyallylamine homopolymer.
Capsules containing the same polymer.

It does not expressly cover every dosage form. Powders, suspensions, sachets, granules, and liquid formulations would need to rely on claim 1 or other claims rather than claim 8.

What do claims 9 through 14 protect?

Claim 9 is an independent method claim requiring:

A patient.
Oral administration.
A therapeutically effective amount.
A composition containing the claimed crosslinked, water-insoluble polyallylamine homopolymer.
Removal of phosphate from the patient.

Claim 9 does not require epichlorohydrin. Claim 10 adds that limitation. Claims 12-14 address protonation state and HCl treatment.

The method claims are narrower in practical use than the composition claims because they require an act of administration and a phosphate-removal result. They could apply to treatment of hyperphosphatemia in chronic kidney disease, but the claims as supplied do not expressly limit the underlying disease, renal status, serum phosphate threshold, dose, dosing frequency, or dialysis status.

A method claim may be relevant to:

Product labeling that instructs use for phosphate control.
Physician or patient-directed use.
Induced or contributory infringement theories involving a generic product.

After expiration, these method claims no longer create an enforceable patent barrier.

When did U.S. Patent 7,014,846 lose exclusivity?

The patent's nominal term ran from the applicable earliest nonprovisional filing date and expired in 2019. Public patent databases identify U.S. Patent 7,014,846 as expired by term.[1][2]

Event	Date or status
Patent	U.S. 7,014,846
Grant date	March 21, 2006
Core technology	Crosslinked polyallylamine phosphate-binding compositions
Patent term status	Expired by statutory term
Practical current enforcement	No enforceable exclusionary right from this patent
Regulatory relevance	Historical Orange Book and generic-entry significance

The grant date does not determine expiration. The relevant calculation uses the patent's effective filing and priority history, subject to patent-term adjustment and any applicable extension. Patent 7,014,846 is no longer an active patent right even though it remains important for understanding the historic sevelamer estate.

What is the Orange Book status of sevelamer?

Renagel, containing sevelamer hydrochloride, was approved by the FDA under NDA 021449. Renvela, containing sevelamer carbonate, was approved under NDA 022127.[3][4]

Sevelamer is a nonabsorbed phosphate binder. It is not a biologic and is not subject to biosimilar approval under the Public Health Service Act. Generic competition proceeds through the ANDA pathway, generally with therapeutic-equivalence and pharmaceutical-equivalence requirements rather than biosimilar interchangeability procedures.

The Orange Book historically listed patents associated with Renagel and Renvela. Patent 7,014,846 formed part of the broader patent position around crosslinked polyallylamine products. Because the patent has expired, it cannot currently support a new Paragraph IV exclusion period or injunction.

Orange Book status must be evaluated at the product and NDA level. Patent listings for sevelamer products have included different patents for:

Polymer composition.
Crosslinking.
Formulation.
Dosage form.
Manufacturing processes.
Product conversion from sevelamer hydrochloride to sevelamer carbonate.

An expired patent can remain visible in historical FDA records without creating a current patent obstacle.

Which patent families historically protected sevelamer?

The sevelamer patent estate was layered rather than dependent on a single patent. The relevant portfolio generally included the following categories.

Patent category	Typical protected subject matter	Strategic purpose
Foundational polymer patents	Crosslinked polyallylamine and phosphate-binding polymers	Protect active polymer platform
Composition patents	Polymer combined with carriers and excipients	Cover pharmaceutical products
Protonation patents	Hydrochloride, carbonate, and partial protonation states	Reach commercial salt forms
Dosage-form patents	Tablets, capsules, powders, and granules	Protect product presentation
Manufacturing patents	Crosslinking, washing, drying, milling, and conversion	Create process barriers
Method patents	Oral phosphate removal and hyperphosphatemia treatment	Support labeled-use enforcement

Earlier U.S. patents associated with the sevelamer platform include U.S. Patent Nos. 5,496,545, 5,667,775, and 6,083,495. Their precise claim scope and expiration dates differ from Patent 7,014,846 and must be assessed separately against the relevant product and filing date.[5]-[7]

Patent 7,014,846 is best characterized as a composition-and-method patent directed to a particular polyallylamine pharmaceutical platform. It is not a pure manufacturing patent and does not depend on a single tablet formulation.

What formulations are protected by Patent 7,014,846?

The patent can cover a tablet or capsule containing the claimed polymer, but it does not require a specific excipient profile. The formulation must contain a qualifying carrier and the crosslinked polyallylamine homopolymer.

Potentially relevant formulation variables include:

Tablet compression.
Capsule filling.
Polymer loading.
Binder and disintegrant selection.
Lubricants.
Coatings.
HCl or other protonation state.
Particle-size distribution.
Moisture content.
Storage stability.

The claims do not expressly require a delayed-release coating, enteric coating, osmotic system, sustained-release matrix, or specific dissolution profile. A formulation patent directed to those features could have provided separate protection, but those limitations are not present in the supplied claims.

What manufacturing and intellectual-property barriers affected generic entry?

Sevelamer created manufacturing challenges even after basic composition patents began to expire. The polymer is a high-molecular-weight, crosslinked, nonabsorbed resin. Commercial manufacture requires control over:

Crosslinker concentration.
Polymer swelling.
Residual epichlorohydrin.
Protonation or salt conversion.
Particle-size distribution.
Residual solvents and impurities.
Tablet compression.
Batch-to-batch phosphate-binding capacity.
Stability and moisture control.

These factors can support process patents, specification-based regulatory controls, or development barriers even where the principal composition patent has expired. They do not extend the term of Patent 7,014,846.

A generic manufacturer may also need to demonstrate equivalence for a nonabsorbed polymer whose clinical effect depends on local gastrointestinal binding rather than systemic exposure. FDA approval requirements and patent rights are separate. FDA approval does not itself establish patent infringement, and patent expiration does not eliminate the need to satisfy product-quality and bioequivalence requirements.

Which companies challenged or competed with sevelamer?

The original commercial platform was developed by GelTex Pharmaceuticals and later commercialized through Genzyme, which was acquired by Sanofi. The primary branded products were Renagel and Renvela.

The competitive phosphate-binder field includes:

Product	Active ingredient	Company or commercial origin	Product type
Renagel	Sevelamer hydrochloride	Genzyme/Sanofi	Nonabsorbed polymer binder
Renvela	Sevelamer carbonate	Genzyme/Sanofi	Nonabsorbed polymer binder
Fosrenol	Lanthanum carbonate	Shire/Takeda	Metal-based phosphate binder
Auryxia	Ferric citrate	Keryx, later associated with Akebia	Iron-based phosphate binder
Velphoro	Sucroferric oxyhydroxide	Vifor Pharma	Iron-based phosphate binder
Calcium acetate products	Calcium acetate	Multiple generic manufacturers	Calcium-based binder
Xphozah	Tenapanor	Ardelyx	Sodium/hydrogen exchanger inhibitor, not a phosphate binder

Xphozah competes for serum-phosphate control but does not practice the claimed crosslinked polyallylamine polymer technology. There is no biosimilar risk to sevelamer because sevelamer is a synthetic polymer drug rather than a biologic.

How strong is the patent estate for a current generic launch?

Patent 7,014,846 has no current blocking strength because it is expired. Its historical strength was moderate to high against products using the same crosslinked polyallylamine platform, particularly products containing an epichlorohydrin-crosslinked polymer in tablet or capsule form.

Issue	Assessment
Claim breadth	Broad at claim 1 and claim 9
Polymer specificity	High; requires polyallylamine homopolymer
Epichlorohydrin coverage	Narrower dependent claims
Protonation coverage	Broad across fully, partially, and unprotonated forms
Dosage-form coverage	Tablet and capsule claims
Design-around potential during term	Possible through different polymer chemistry or crosslinking
Current enforceability	None after expiration
Biosimilar exposure	None
Generic exposure	High, subject to other unexpired patents and FDA requirements

A generic sevelamer product launched after expiration would still require a separate freedom-to-operate analysis covering the remaining patent family, formulation patents, process patents, trademarks, and regulatory exclusivity.

What Paragraph IV issues affected sevelamer?

Paragraph IV certifications are relevant when an ANDA applicant asserts that an Orange Book-listed patent is invalid, unenforceable, or not infringed. For Patent 7,014,846, a Paragraph IV challenge would have been commercially meaningful only before expiration.

The principal litigation theories likely available against a sevelamer generic would have included:

Noninfringement based on a different polymer or crosslinking process.
Invalidity for anticipation or obviousness.
Indefiniteness concerning the polymer structure or protonation state.
Written-description or enablement challenges.
Failure to meet the 2%-20% epichlorohydrin range.
Absence of a carrier in a composition claim.
Noninfringement of the "consists essentially of" or "consists of" claims.

After expiration, a Paragraph IV certification directed to this patent cannot delay generic approval on a forward-looking basis. Any current dispute would need to involve a different unexpired patent, regulatory exclusivity, or a historical damages issue.

What patent litigation and settlements affect the analysis?

The sevelamer platform generated extensive patent activity because the branded products were commercialized across multiple dosage forms and salt forms. Patent litigation risk depended on the specific ANDA product and the patents listed for the applicable NDA.

Patent 7,014,846 should not be treated as the entire Renagel or Renvela estate. A settlement involving another patent would not automatically resolve this patent, and expiration of this patent would not resolve separate process or formulation claims.

For current diligence, the material distinction is:

Patent 7,014,846: expired.
Other sevelamer patents: must be checked individually for term, terminal disclaimers, patent-term adjustment, pediatric extension, and Orange Book listing.
Regulatory exclusivity: separate from patent term.
Litigation settlement: may contain launch dates, covenants, licenses, or restrictions that survive patent expiration in limited circumstances.

Key Takeaways

U.S. Patent 7,014,846 covers pharmaceutical compositions and oral phosphate-removal methods using crosslinked, water-insoluble polyallylamine homopolymers.
Claim 1 is the principal broad composition claim. It does not require epichlorohydrin, although claim 2 does.
Claims 9-14 cover oral phosphate removal and add limitations for epichlorohydrin, crosslinker concentration, and protonation state.
The patent reaches sevelamer-type products, including tablet and capsule formulations, but the supplied claims do not require a specific brand, dose, excipient system, or disease.
The patent expired by statutory term in 2019 and no longer independently blocks generic entry.
Sevelamer has no biosimilar pathway risk because it is a synthetic polymer, not a biologic.
Current freedom-to-operate analysis must focus on other sevelamer patents, manufacturing patents, formulation patents, FDA exclusivity, and any surviving settlement provisions.

FAQs About U.S. Patent 7,014,846 and Sevelamer

Does U.S. Patent 7,014,846 cover sevelamer carbonate?

It can cover a sevelamer carbonate product if the product contains the claimed crosslinked, water-insoluble polyallylamine homopolymer and satisfies the applicable composition limitations. The claims are not limited to sevelamer hydrochloride.

Can a generic manufacturer avoid claim 2 by using a different crosslinker?

Potentially. Claim 2 requires epichlorohydrin crosslinking within the stated approximate range. A different crosslinker could avoid claim 2, but claim 1 may still be relevant because claim 1 does not specify epichlorohydrin.

Is sevelamer a biologic subject to biosimilar competition?

No. Sevelamer is a synthetic, nonabsorbed polymer drug. Generic manufacturers use the ANDA pathway rather than the biosimilar pathway.

Does patent expiration permit immediate marketing of a generic sevelamer product?

No. Expiration removes the patent barrier from Patent 7,014,846. FDA approval, applicable Orange Book patents, regulatory exclusivity, manufacturing controls, and other intellectual-property rights remain separate issues.

Are Renagel and Renvela protected by the same patent claims?

Not necessarily. The products share the sevelamer platform but use different salt forms. Their Orange Book listings, formulation claims, manufacturing claims, and approval histories must be reviewed separately.

References

United States Patent and Trademark Office. (2006). U.S. Patent No. 7,014,846, Pharmaceutical compositions comprising crosslinked polyallylamine polymers.
Google Patents. (n.d.). US7014846B2: Pharmaceutical compositions comprising crosslinked polyallylamine polymers.
U.S. Food and Drug Administration. (2000). Renagel (sevelamer hydrochloride) prescribing information, NDA 021449.
U.S. Food and Drug Administration. (2008). Renvela (sevelamer carbonate) prescribing information, NDA 022127.
United States Patent and Trademark Office. (1995). U.S. Patent No. 5,496,545, Crosslinked polyallylamine polymers and their use as phosphate binders.
United States Patent and Trademark Office. (1997). U.S. Patent No. 5,667,775, Crosslinked polyallylamine polymers and their use as phosphate binders.
United States Patent and Trademark Office. (2000). U.S. Patent No. 6,083,495, Pharmaceutical compositions containing crosslinked polyallylamine polymers.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0716606	⤷ Start Trial	CA 2002 00003	Denmark	⤷ Start Trial
European Patent Office	0716606	⤷ Start Trial	SPC/GB02/011 200210	United Kingdom	⤷ Start Trial
European Patent Office	0716606	⤷ Start Trial	SPC004/2002	Ireland	⤷ Start Trial
European Patent Office	0716606	⤷ Start Trial	C00716606/01	Switzerland	⤷ Start Trial
European Patent Office	0716606	⤷ Start Trial	CA 2009 00048	Denmark	⤷ Start Trial
European Patent Office	0716606	⤷ Start Trial	C300428	Netherlands	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 7,014,846

Summary for Patent: 7,014,846