US Patent 8,216,560: Scope, Claims, Expiration, and Patiromer Patent Landscape
US Patent No. 8,216,560 protects methods of removing potassium from patients with renal insufficiency or congestive heart failure using an orally administered, crosslinked alpha-fluoroacrylic acid polymer. The claims focus on patiromer-type calcium-containing polymers, patients receiving renally relevant medications, bead dosage forms, low swelling, and simultaneous administration with certain therapies.
The patent was assigned to Relypsa, Inc., the developer of patiromer, later acquired by Vifor Pharma. The patent issued July 10, 2012, and its ordinary patent term ran to April 11, 2024, based on the earliest claimed priority date. It is therefore no longer a live exclusion right against new commercial activity, absent an unusual term adjustment or other surviving right recorded in the official patent file.[1]
What does US Patent 8,216,560 cover?
The patent covers therapeutic methods rather than a broad composition of matter in isolation. A practicing party would need to satisfy the relevant limitations of the asserted claim, including:
| Claim element |
Scope |
| Therapeutic objective |
Removing potassium from a patient |
| Administration route |
Oral administration |
| Patient population |
Renal insufficiency or congestive heart failure |
| Polymer |
Crosslinked cation-exchange polymer or crosslinked alpha-fluoroacrylic acid polymer |
| Structural feature |
Fluorine attached to the carbon alpha to a carboxylic acid group |
| Counterion |
Calcium, in claims 6-11 and 17-22 |
| Physical form |
Beads in several independent and dependent claims |
| Clinical context |
Use with potassium-sparing diuretics, ACE inhibitors, ARBs, NSAIDs, heparin, or trimethoprim |
| Additional limitation |
Swelling ratio below about 3 in claims 7 and 18 |
| Administration timing |
Simultaneous administration in claims 5, 15, and 16 |
The claims are directed to treatment of hyperkalemia and potassium control in patients whose medications or disease state increase the risk of elevated serum potassium.
How are the independent claims structured?
Claim 1: renal insufficiency and concomitant medication
Claim 1 requires:
- A patient with renal insufficiency.
- Treatment of that patient with at least one listed medication.
- Oral administration of a potassium-binding polymer.
- A crosslinked cation-exchange polymer in bead form.
- A carboxylic acid group with fluorine attached to the alpha carbon.
The listed medications are potassium-sparing diuretics, ACE inhibitors, ARBs, NSAIDs, heparin, and trimethoprim. The claim does not require that the patient already have hyperkalemia, although claim 4 expressly adds that limitation.
The medication limitation narrows the claim but creates an infringement issue that turns on the patient’s actual treatment regimen. A product label alone would not establish infringement. The relevant question would be whether the accused treatment is administered to a patient who satisfies the listed renal and medication conditions.
Claim 6: calcium-containing alpha-fluoroacrylic polymer
Claim 6 is broader in physical-form language than claim 1 because it does not require beads. It requires:
- A patient with renal insufficiency;
- Treatment with one of the specified medications;
- Oral administration of a therapeutically effective amount; and
- A crosslinked alpha-fluoroacrylic acid polymer with a calcium cationic counterion.
This claim is the central composition-linked method claim. The calcium counterion distinguishes the claimed polymer from a protonated polymer, a sodium-only exchange resin, or a polymer using another counterion.
Claim 12: congestive heart failure
Claim 12 shifts the patient population from renal insufficiency to CHF. It requires oral administration of a potassium-binding polymer in bead form, with the same alpha-fluorinated carboxylic-acid polymer structure.
Unlike claim 1, claim 12 does not require concomitant treatment with a specified medication. Claims 13-16 add potassium-sparing diuretics, ACE inhibitors, and simultaneous administration.
Claim 17: CHF and calcium counterion
Claim 17 is the CHF counterpart to claim 6. It requires a crosslinked alpha-fluoroacrylic acid polymer containing a calcium cationic counterion but does not require beads.
What do dependent claims 2 through 22 add?
The dependent claims fall into five categories:
| Claims |
Added limitation |
| 2, 10, 14, 22 |
ACE-inhibitor treatment |
| 3, 11 |
ARB treatment |
| 4 |
Hyperkalemia |
| 5, 15, 16 |
Simultaneous administration |
| 7, 18 |
Swelling ratio below about 3 |
| 8, 19 |
Specified crosslinkers |
| 9, 20 |
Bead form |
| 13, 21 |
Potassium-sparing diuretic treatment |
Claims 8 and 19 identify a wide group of possible crosslinkers, including divinylbenzene, ethylene bisacrylamide, N,N'-methylenebisacrylamide, vinylsulfone-based materials, polyvinyl ether, and polyallyl ether.
The dependent claims add fallback positions but also increase design-around opportunities. A competing product using a noncalcium counterion, a nonfluorinated acrylic polymer, a nonbead morphology, or a different swelling profile would fall outside at least some of these claims.
What polymer does the patent cover?
The claimed polymer is a crosslinked alpha-fluoroacrylic acid polymer. In practical commercial terms, the claims correspond closely to patiromer technology.
Patiromer is a nonabsorbed potassium-binding polymer administered orally. The approved product, Veltassa, contains patiromer sorbitex calcium and is supplied as an oral powder that is mixed with water before administration.[2] The regulatory product is not marketed as a conventional tablet or capsule. The patent’s “bead” language therefore requires careful product-characterization analysis. Polymer particle morphology, manufacturing specifications, and the meaning of “bead” would be material in any infringement dispute.
The calcium counterion is functionally important. Patiromer exchanges calcium for potassium in the gastrointestinal tract. This distinguishes it from sodium polystyrene sulfonate and from sodium zirconium cyclosilicate, which use different binding mechanisms and chemical architectures.[2][3]
What is the patent expiration date for US 8,216,560?
US Patent 8,216,560 expired on April 11, 2024, based on the earliest priority date publicly associated with the family.[1] The patent issued on July 10, 2012.
| Event |
Date |
| Earliest priority date |
April 11, 2003 |
| US filing |
May 27, 2011 |
| Patent issued |
July 10, 2012 |
| Ordinary expiration |
April 11, 2024 |
The patent’s expiration removes the ordinary patent-barrier value of the claimed methods. It does not invalidate later patents covering patiromer formulations, manufacturing processes, dosing regimens, administration instructions, or other product attributes.
Was US 8,216,560 listed in the Orange Book?
US 8,216,560 is part of the patiromer patent estate, but the commercially significant Orange Book analysis for Veltassa must be performed patent by patent and product by product. The Orange Book records patents submitted by the NDA holder and identifies expiration information, use codes, and whether a patent is listed for a particular dosage form or indication.[4]
The key commercial issue is that an expired method patent does not remove later-listed Veltassa patents. A generic applicant must address every applicable listed patent through certification or a statement under the Hatch-Waxman framework.
The Orange Book is not a complete record of every patent relevant to a drug. It generally does not capture all manufacturing patents, foreign rights, unpublished applications, trade secrets, or patents that the sponsor did not submit for listing.[4]
What later patents protect patiromer and Veltassa?
The later patiromer estate is more commercially important than US 8,216,560 because it includes patents directed to the commercial product and its manufacture. Publicly identified Relypsa/Vifor patent families include patents relating to:
- Patiromer polymer compositions;
- Calcium-containing counterion forms;
- Particle and bead characteristics;
- Oral formulations;
- Manufacturing and purification processes;
- Dosing and administration;
- Reduced gastrointestinal drug-interaction risk;
- Product specifications used in Veltassa.
Representative US patents associated with the broader Veltassa estate include US 8,501,698 and later continuation or related patents. Exact scope depends on each patent’s issued claims, terminal disclaimers, maintenance history, and Orange Book listing.[5]
| Patent category |
Commercial relevance |
Typical design-around |
| Core polymer composition |
High, where claim scope reaches calcium patiromer |
Different polymer chemistry or counterion |
| Bead and particle claims |
Medium to high |
Alter particle morphology or size distribution |
| Formulation claims |
High for the marketed dosage form |
Alternative excipients or dosage form |
| Manufacturing claims |
High if the process is difficult to replace |
Develop an independent process |
| Dosing claims |
Variable |
Use a nonclaimed dose or schedule |
| Drug-separation instructions |
Regulatory and labeling relevance |
Alternative administration timing |
The strongest barriers are usually the claims that read directly on the commercial active ingredient and the manufacturing process, not the expired patient-population claims in US 8,216,560.
What FDA exclusivity applied to patiromer?
FDA approved Veltassa on October 21, 2015, for the treatment of hyperkalemia.[6] Patiromer was approved under the drug pathway, not as a biologic. Accordingly, biosimilar litigation does not apply. A competitor would generally pursue an abbreviated new drug application, subject to the applicable reference-product exclusivity and patent certifications.
The FDA approval history is:
| Regulatory item |
Information |
| Product |
Veltassa |
| Active ingredient |
Patiromer sorbitex calcium |
| Sponsor at approval |
Relypsa, Inc. |
| Current commercial owner |
Vifor Pharma, now within CSL Vifor |
| Approval date |
October 21, 2015 |
| Dosage form |
Oral powder for suspension |
| FDA pathway |
NDA |
| Therapeutic area |
Hyperkalemia |
The original five-year new chemical entity exclusivity period would have ended in October 2020. The principal remaining barriers have therefore been patent-based rather than FDA exclusivity-based.[6]
Were there Paragraph IV challenges to this patent?
A Paragraph IV certification is relevant only while an Orange Book-listed patent remains enforceable. Because US 8,216,560 expired in 2024, it is no longer a meaningful standalone Paragraph IV barrier.
Generic applicants seeking to market patiromer would need to address the later, unexpired Veltassa patents. Public patent disputes involving Veltassa have focused on the broader Relypsa/Vifor estate rather than treating US 8,216,560 as the sole commercial barrier.
A Paragraph IV challenge could produce:
- A 30-month stay if the statutory requirements are met;
- Hatch-Waxman litigation in federal district court;
- A possible 180-day generic exclusivity period for the first qualified filer;
- Settlement terms governing launch timing;
- Product-specific restrictions tied to labeling or formulation.
No biosimilar pathway is available because patiromer is a small-molecule polymer drug rather than a biologic.
Which companies compete with patiromer?
The principal potassium-control competitors are Veltassa, Lokelma, and older sodium polystyrene sulfonate products.
| Product |
Active ingredient |
Company |
Key distinction |
| Veltassa |
Patiromer sorbitex calcium |
CSL Vifor |
Calcium-exchange polymer |
| Lokelma |
Sodium zirconium cyclosilicate |
AstraZeneca |
Inorganic crystalline potassium trap |
| Kayexalate and generics |
Sodium polystyrene sulfonate |
Multiple generic companies |
Older sodium-containing ion-exchange resin |
Lokelma received FDA approval in May 2018.[3] Its chemistry is materially different from patiromer, so US 8,216,560 does not read directly on Lokelma merely because both products remove potassium orally.
The older sodium polystyrene sulfonate products also do not satisfy the alpha-fluoroacrylic acid and calcium-counterion limitations in claims 6 and 17.
How strong is the patent estate for patiromer?
US 8,216,560 had moderate historical value and limited current value.
Strengths
- It expressly covers calcium-containing alpha-fluoroacrylic acid polymers.
- It connects the polymer to clinically important renal-insufficiency and CHF populations.
- It includes ACE inhibitors, ARBs, potassium-sparing diuretics, and other high-risk medications.
- It contains both polymer-structure claims and patient-treatment claims.
- It provides multiple dependent claim positions involving beads, swelling, and crosslinkers.
Weaknesses
- The patent expired in April 2024.
- Several claims require a specific patient disease state and concomitant treatment.
- Claims 1 and 12 require bead form.
- The “therapeutically effective amount” and “patient in need thereof” language may create proof issues.
- The claims do not by themselves cover every patiromer formulation, manufacturing process, or product label.
- A competitor using a different polymer architecture would avoid the central chemical limitation.
The patent was more valuable as part of a layered portfolio than as an isolated right. Its commercial protection depended on later composition, formulation, manufacturing, and regulatory-listing patents.
What generic launch risks exist for patiromer?
A generic applicant faces four principal risks:
- Core composition patents. These may cover calcium patiromer or closely related polymer forms after expiration of the older method patent.
- Manufacturing patents. A noninfringing process may be necessary even if the active polymer is no longer protected.
- Orange Book litigation. Listed patents can delay approval or launch through Hatch-Waxman litigation.
- Regulatory labeling. A skinny label may be required if patented uses remain listed.
Commercial substitution also depends on product performance. Patiromer has product-specific requirements involving preparation, administration, and separation from certain orally administered drugs.[2] A generic must demonstrate pharmaceutical equivalence and bioequivalence or satisfy the applicable FDA requirements for the reference product.
What geographic rights exist?
US 8,216,560 provided rights only in the United States. Corresponding applications may have been filed in other jurisdictions through the related international family, but each national right had its own examination, claim scope, maintenance requirements, and expiration date.
A US expiration did not automatically terminate corresponding European, Canadian, Japanese, or other national rights. For current licensing or freedom-to-operate work, the relevant analysis must separate:
- US composition patents;
- US formulation patents;
- US manufacturing patents;
- European patent validations;
- Supplementary protection certificates;
- Canadian and Japanese counterparts;
- Pending continuation applications.
The United States remains the most important market for Orange Book and Paragraph IV analysis because FDA-listed patents can directly delay generic approval.
Key Takeaways
- US 8,216,560 covers oral potassium removal using crosslinked alpha-fluoroacrylic acid polymers, particularly calcium-containing patiromer-type polymers.
- Claims 1-5 focus on renal insufficiency, high-risk concomitant medications, bead form, and hyperkalemia.
- Claims 6-11 focus on calcium-containing polymers, swelling ratio, and specified crosslinkers.
- Claims 12-22 apply similar polymer limitations to patients with CHF.
- The patent issued July 10, 2012, and expired April 11, 2024.
- It is not a biosimilar patent because patiromer is not a biologic.
- The principal current patent risk lies in later Veltassa composition, formulation, manufacturing, and dosing patents.
- Lokelma and sodium polystyrene sulfonate do not fall within the core alpha-fluoroacrylic acid/calcium-counterion limitations.
- A generic patiromer applicant must address the remaining Orange Book-listed patents, not only US 8,216,560.
Frequently Asked Questions
Does US 8,216,560 cover Veltassa?
It covers treatment methods using a polymer with characteristics associated with patiromer technology. It does not necessarily cover every aspect of the Veltassa product, and the patent expired in April 2024.
Does the patent cover Lokelma?
No. Lokelma contains sodium zirconium cyclosilicate, a different chemical entity from the claimed crosslinked alpha-fluoroacrylic acid polymer with a calcium counterion.
Does the patent require hyperkalemia?
Not in every independent claim. Claim 4 adds hyperkalemia expressly, while the independent claims require potassium removal from a patient in need thereof.
Can a generic avoid the patent by using sodium instead of calcium?
A sodium-counterion product would not satisfy the calcium-counterion limitation in claims 6-11 and 17-22. Other claims must be analyzed separately because claim 1 does not expressly recite calcium.
Is patiromer subject to biosimilar competition?
No. Patiromer is regulated as a drug rather than a biologic. Competition proceeds through the generic-drug and Hatch-Waxman framework.
References
- United States Patent and Trademark Office. (2012). US Patent No. 8,216,560, Methods for treatment of hyperkalemia.
- U.S. Food and Drug Administration. (2023). Veltassa (patiromer) prescribing information.
- U.S. Food and Drug Administration. (2018). Lokelma (sodium zirconium cyclosilicate) prescribing information.
- U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
- United States Patent and Trademark Office. (2024). Patent Center and Patent Examination Data System records for Relypsa/Vifor patiromer patent families.
- U.S. Food and Drug Administration. (2015). FDA approves Veltassa to treat hyperkalemia.
