Details for Patent: 8,309,112

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Summary for Patent: 8,309,112

Title:	Coatings for implantable medical devices comprising hydrophilic substances and methods for fabricating the same
Abstract:	A segmented polyurethane and an amphiphilic random or block copolymer are disclosed. The segmented polyurethane and the amphiphilic random or block copolymer can be used for fabricating a coating for an implantable medical device such as a stent.
Inventor(s):	Thierry Glauser, Connie S. Kwok, Charles D. Claude, Eugene T. Michal, Yiwen Tang, Irina Astafieva, John Whatley, Stephen D. Pacetti, Ashok Shah
Assignee:	Abbott Cardiovascular Systems Inc
Application Number:	US10/746,483
Patent Claim Types: see list of patent claims	Compound;

US Patent 8,309,112: Claim Scope, Patent Term, Infringement Risk and Medical-Coating Landscape

US Patent 8,309,112 covers implantable medical articles with drug-bearing coatings made from amphiphilic copolymers. The claims focus on four cumulative limitations: an implantable substrate, a polymer coating, specified hydrophobic and sulfonated hydrophilic components, and a therapeutic agent incorporated into the coating. Claim 1 is limited by a therapeutic-agent-to-polymer mass ratio of approximately 1:10 to 1:3. Claim 9 covers a narrower polymer architecture centered on 3-sulfopropyl methacrylate, including PSPMA-PBMA and PSPMA-PBMA-PSPMA systems.

The patent is most relevant to drug-eluting stents, implantable scaffolds, catheters, orthopedic implants, vascular grafts and other devices using water-compatible polymer coatings. Its strongest protection is directed to specific polymer chemistry and drug-loading relationships, rather than to every drug-eluting implant.

What does US Patent 8,309,112 protect?

The claims protect a coated implantable article in which the coating contains:

1. An amphiphilic copolymer;
2. At least one hydrophobic moiety;
3. At least one hydrophilic moiety selected from specified sulfonated monomers;
4. A therapeutic agent incorporated or dispersed in the coating; and
5. For independent claim 1, a drug-to-polymer mass ratio of about 1:10 to about 1:3.

The patent does not claim an uncoated implant, a coating lacking the specified amphiphilic copolymer, or a coating containing only a conventional hydrophobic polymer without the claimed sulfonated monomer chemistry.

The principal independent claims are claim 1 and claim 9.

Claim	Claim type	Principal scope
1	Independent	Implantable substrate coated with an amphiphilic copolymer containing specified hydrophilic monomers and a therapeutic agent at a 1:10 to 1:3 mass ratio
2	Dependent	Acrylic copolymer
3	Dependent	Block or random acrylic copolymer
4	Dependent	ABA or AB block copolymer
5	Dependent	Specified hydrophobic monomers
6	Dependent	Living free-radical copolymerization
7	Dependent	Specific peptide or polypeptide therapeutic agents
8	Dependent	Small-molecule water-soluble drug
9	Independent	Formula-defined amphiphilic copolymer containing 3-sulfopropyl as R or R2, with a therapeutic agent
10	Dependent	ABA or AB block copolymer
11	Dependent	PSPMA-PBMA or PSPMA-PBMA-PSPMA
12	Dependent	Specific peptide or polypeptide therapeutic agents

How broad is claim 1 of US 8,309,112?

Claim 1 is broad at the device level but narrow at the materials level.

Required elements of claim 1

An accused product would need to satisfy each of the following limitations:

Limitation	Scope
Medical article	An implantable medical article or device
Implantable substrate	A structural substrate capable of implantation
Coating	A coating disposed on at least part of the substrate
Amphiphilic copolymer	A copolymer having hydrophobic and hydrophilic moieties
Hydrophilic moiety	At least one of AMPS, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate or 3-allyloxy-2-hydroxypropanesulfonic acid
Therapeutic agent	Agent incorporated or dispersed in the coating
Mass ratio	Therapeutic agent to amphiphilic copolymer of about 1:10 to about 1:3

The claim does not require a stent, vascular use, a particular release profile, a particular coating thickness, or a particular therapeutic indication. The term “medical article” therefore potentially reaches several implant categories, subject to the requirement that the article have the claimed coating.

The principal vulnerability for enforcement is the combination of broad device language and narrow chemical limitations. A competitor can potentially avoid literal infringement by using:

• A hydrophilic monomer outside the four named categories;
• A non-amphiphilic polymer system;
• A polymer containing a different sulfonated monomer;
• A drug-to-polymer ratio outside the claimed range;
• A drug-free topcoat over a separate drug reservoir, depending on claim construction and product architecture;
• A nonimplantable delivery article.

What formulations are protected by claims 2 through 8?

The dependent claims narrow claim 1 into specific polymer structures, monomers and drug classes.

Acrylic copolymers

Claims 2 through 4 cover acrylic copolymers and distinguish between random and block configurations. Claim 4 expressly includes AB and ABA block copolymers.

The claims therefore reach both:

• Random acrylic copolymers containing hydrophobic and hydrophilic repeat units; and
• Segmented block copolymers in which hydrophilic and hydrophobic blocks are arranged as AB or ABA structures.

The block-copolymer language may be commercially important because block architecture can affect coating morphology, water uptake, drug partitioning, adhesion and release kinetics.

Hydrophobic monomers

Claim 5 identifies:

• Methyl methacrylate;
• Ethyl methacrylate;
• n-Butyl methacrylate; and
• Lauryl methacrylate.

These limitations narrow the hydrophobic component but do not require a single hydrophobic monomer. A formulation using one or more listed monomers could fall within the dependent claim if all claim 1 limitations are also met.

Polymerization process

Claim 6 covers a copolymer produced through living free-radical copolymerization with initiation-transfer-agent termination of living macrochains.

This claim adds a manufacturing limitation. It is potentially difficult to prove from the finished product alone unless the resulting polymer has identifiable structural characteristics or production records reveal the process. Process evidence, polymer molecular-weight distribution and sequence architecture may become relevant in discovery.

Therapeutic agents

Claim 7 covers peptide and polypeptide agents, including:

• Cyclic-RGD peptide;
• Poly(L-arginine);
• Poly(D-arginine);
• Poly(D,L-arginine);
• Poly(L-lysine);
• Poly(D-lysine);
• Poly(δ-guanidino-α-aminobutyric acid);
• Racemic mixtures of poly(L-arginine) and poly(D-arginine);
• Elastin mimetic polypeptides; and
• Blends of those materials.

Claim 8 separately covers a small-molecule water-soluble drug. The claim set therefore addresses both biological macromolecules and conventional small-molecule agents.

What does claim 9 add to the patent?

Claim 9 is a separate independent claim directed to a formula-defined amphiphilic copolymer. It requires a polymer having three independently positive integer parameters, m, n and p, and substituent groups defined through R, R1 and R2. At least one of R and R2 must be 3-sulfopropyl.

The claim also requires a therapeutic agent incorporated or dispersed in the coating, but, unlike claim 1 as provided, it does not expressly state the 1:10 to 1:3 drug-to-polymer mass ratio.

That difference creates a potentially important scope distinction:

Issue	Claim 1	Claim 9
Named sulfonated monomers	Four expressly listed options	Formula requiring at least one 3-sulfopropyl substituent
Drug-to-polymer ratio	About 1:10 to about 1:3	No express ratio in the provided text
Polymer structure	General amphiphilic copolymer	Formula-defined polymer
PSPMA-PBMA species	Reached through dependent claims if limitations are met	Expressly addressed by claim 11
Therapeutic agent	Required	Required

The chemical formula associated with claim 9 is central to claim construction. The text supplied does not reproduce the formula drawing or structural notation. The explicit limitation requiring 3-sulfopropyl remains clear, but the full reach of claim 9 depends on the complete formula and its written-description support.

What polymer systems are specifically protected by claim 11?

Claim 11 identifies:

• PSPMA-PBMA, and
• PSPMA-PBMA-PSPMA.

PSPMA is poly(3-sulfopropyl methacrylate), while PBMA is poly(butyl methacrylate).

These structures combine:

• A sulfonated, hydrophilic PSPMA block; and
• A hydrophobic PBMA block.

The ABA version, PSPMA-PBMA-PSPMA, places the hydrophobic PBMA block between two hydrophilic PSPMA blocks. The AB version, PSPMA-PBMA, contains one hydrophilic block and one hydrophobic block.

Claim 11 is narrower than claim 9 because it names specific block-copolymer compositions. It may be more defensible against invalidity attacks based on generic breadth, but it also creates a straightforward design-around path using:

• A different hydrophobic block;
• A different sulfonated hydrophilic block;
• A random rather than block architecture;
• A different block order;
• A chemically similar monomer that does not satisfy the 3-sulfopropyl limitation.

How would infringement of US 8,309,112 be analyzed?

A literal infringement analysis would begin with the marketed device and its coating specification, not with the device’s therapeutic label.

Claim 1 infringement checklist

A product presents the highest claim 1 risk if it has all of the following:

1. An implantable substrate;
2. A coating on at least part of the substrate;
3. An acrylic or other amphiphilic copolymer;
4. A hydrophilic monomer within the listed sulfonated group;
5. A therapeutic agent in the coating; and
6. A drug-to-polymer ratio between approximately 1:10 and 1:3.

The ratio limitation is likely to be a major technical issue. “About” introduces claim-construction flexibility, but it does not eliminate the need for quantitative evidence. Batch formulation records, coating weight, polymer content, drug loading and analytical release data would be relevant.

Claim 9 infringement checklist

Claim 9 presents the strongest risk for a product using a PSPMA-containing block copolymer. The key questions would be:

• Does the polymer contain the required 3-sulfopropyl substituent?
• Does the polymer satisfy the complete formula?
• Is the polymer amphiphilic?
• Is the article implantable?
• Is the therapeutic agent incorporated or dispersed in the coating?

A product using a different sulfonated monomer may avoid literal infringement of claim 9 even if its coating has similar charge density, hydrophilicity or drug-release behavior.

When does US Patent 8,309,112 lose exclusivity?

A US utility patent generally expires 20 years after the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension and terminal disclaimers under 35 U.S.C. §§ 154 and 156.

US Patent 8,309,112 issued on November 13, 2012. The issue date does not determine expiration. The controlling date is the applicable earliest nonprovisional filing date in the patent family, adjusted by any USPTO patent-term adjustment.

Event	Date or rule
Patent grant	November 13, 2012
Standard term rule	20 years from earliest effective nonprovisional filing date
Possible adjustment	Patent-term adjustment under 35 U.S.C. § 154
Possible extension	Patent-term extension under 35 U.S.C. § 156, if statutory requirements are met
Post-expiration effect	No enforceable patent exclusion after expiration, subject to any separate unexpired continuation or related patent

The patent number and claims alone do not establish a final expiration date. A freedom-to-operate conclusion should use the USPTO Patent Center term calculation, the front-page filing data, maintenance-fee history and the complete continuation/divisional family.

What is the Orange Book status of US 8,309,112?

US Patent 8,309,112 is not an Orange Book patent merely because it claims a therapeutic-agent-containing medical coating.

The Orange Book lists patents submitted for approved human drug products under the Hatch-Waxman framework. A patent directed to an implantable article, coating composition or device construction is generally outside Orange Book listing unless it is properly tied to an approved drug product and satisfies FDA listing requirements.[2]

The patent is more appropriately evaluated through:

• Medical-device regulatory records;
• FDA product classifications;
• Device master files and 510(k), PMA or De Novo records;
• Patent-family searches; and
• Direct product and coating analysis.

The patent does not create an automatic Paragraph IV filing pathway for a generic drug applicant.

Do Paragraph IV challenges apply to this patent?

Paragraph IV challenges generally do not apply directly to US 8,309,112 because the claims are directed to a medical article and coating, not to an FDA-approved drug product listed in the Orange Book.

A company developing a drug-eluting device could face patent litigation through:

• A direct infringement action under 35 U.S.C. § 271;
• A declaratory-judgment action;
• An invalidity defense;
• A licensing negotiation; or
• A patent-clearance dispute involving related patents.

A generic drug applicant might encounter the patent only indirectly if the drug product is supplied for use in a patented device or if a separate drug patent family is also asserted.

Is there biosimilar risk under US 8,309,112?

Biosimilar risk is not a primary issue. The claims do not cover an antibody, recombinant protein, cell line, biologic manufacturing process or biologic formulation as such. Claim 7 lists peptide and polypeptide therapeutic agents, but the claimed invention remains a coated implantable article.

A biologic used in a coated implant could create product-specific patent questions, but the patent is not a conventional biologic composition-of-matter patent. Biosimilar applicants would normally focus on biologic patents, formulation patents, manufacturing patents and device-use patents separately.

What patent landscape surrounds amphiphilic drug-eluting coatings?

The relevant landscape contains several overlapping patent categories.

Polymer composition patents

These claims cover the chemical identity of the coating polymer, including:

• Sulfonated acrylic polymers;
• Zwitterionic or ionic copolymers;
• Block copolymers;
• Random copolymers;
• Hydrophobic methacrylate copolymers; and
• Water-compatible polymer networks.

US 8,309,112 is strongest where the product uses a specified sulfonated monomer, particularly PSPMA, in combination with an implantable article and therapeutic agent.

Device-coating patents

Separate patents may claim:

• A stent with a polymer coating;
• A catheter with a drug-eluting layer;
• A scaffold having a reservoir coating;
• A multilayer coating;
• A primer, drug layer or topcoat;
• A defined coating thickness or porosity; or
• A release profile.

A product can therefore face multiple patent families even if it avoids US 8,309,112.

Therapeutic-use patents

Separate method-of-use patents may cover:

• Prevention of restenosis;
• Reduction of thrombosis;
• Promotion of endothelialization;
• Treatment of vascular disease;
• Bone integration; or
• Local delivery of a particular peptide or small molecule.

The claims provided for US 8,309,112 are product claims, not treatment-method claims.

Manufacturing patents

The patent landscape may also include process claims directed to:

• Living free-radical polymerization;
• Initiation-transfer-agent termination;
• Sequential block formation;
• Coating deposition;
• Solvent selection;
• Curing; and
• Drug incorporation.

Claim 6 makes manufacturing method evidence relevant, but it does not by itself cover every process used to make a chemically similar coating.

Which companies could face competitive overlap?

The commercial overlap is greatest among companies developing drug-eluting vascular and implantable devices, including Abbott Vascular, Boston Scientific, Medtronic, Cordis, Biotronik and specialized coating suppliers.

The existence of a product in the same therapeutic category does not establish infringement. Competitive risk depends on the polymer identity, monomer composition, block architecture, drug loading, coating location and implant status.

Product strategy	Risk under US 8,309,112
PSPMA-PBMA block coating with drug	High claim 9 and claim 11 risk
PSPMA-PBMA-PSPMA coating with drug	High claim 9 and claim 11 risk
Random acrylic copolymer using PSPMA	Potential claim 1 risk; claim 9 requires formula analysis
Sulfonated polymer using a nonlisted monomer	Reduced literal claim 1 risk
Hydrophobic polymer without a sulfonated monomer	Lower literal risk
Drug-free implant coating	Lower risk under the provided claims
Drug-to-polymer ratio outside 1:10 to 1:3	Potentially lower claim 1 risk, but claim 9 remains relevant
Nonimplantable article	Outside the express implantable-substrate limitation

How strong is the patent estate for US 8,309,112?

The provided claims indicate a focused but technically meaningful estate.

Strengths

• Covers both broad amphiphilic copolymer concepts and specific PSPMA/PBMA embodiments;
• Reaches multiple implantable medical articles;
• Includes peptide, polypeptide and small-molecule drug embodiments;
• Claims both random and block copolymer architectures through dependent claims;
• Includes a quantitative drug-loading limitation that may distinguish prior art.

Limitations

• Independent claim 1 requires specified sulfonated hydrophilic monomers;
• Claim 1 includes a potentially limiting drug-to-polymer ratio;
• Claim 9 depends heavily on the complete, unabridged chemical formula;
• Claim 6 may require proof of a particular polymerization process;
• Device-level infringement may require access to confidential formulation and manufacturing data;
• Similar coating performance does not necessarily establish chemical claim coverage.

The practical strength of the patent is highest against products that deliberately use PSPMA-PBMA chemistry or a closely corresponding formula. Its strength is lower against products using unrelated hydrophilic monomers, nonacrylic polymers or separate drug-reservoir architectures.

What generic launch and design-around scenarios exist?

Because the patent covers a device coating rather than a conventional drug product, “generic launch” is better understood as a competing device launch or follow-on device strategy.

Scenario 1: Same polymer architecture

A competitor uses PSPMA-PBMA or PSPMA-PBMA-PSPMA with a therapeutic agent. This presents the highest infringement exposure, particularly under claims 9 and 11.

Scenario 2: Different sulfonated monomer

A competitor substitutes another hydrophilic monomer not identified in claim 1 and not containing the claimed 3-sulfopropyl structure. This may reduce literal infringement risk, subject to equivalents analysis.

Scenario 3: Different polymer class

A competitor uses a nonacrylic amphiphilic polymer or a conventional biodegradable polymer. This may avoid the acrylic and sulfonated-monomer limitations.

Scenario 4: Separate drug reservoir

A competitor places the drug in a distinct reservoir or layer and uses the amphiphilic polymer only as a drug-free barrier or topcoat. The outcome depends on whether the drug is legally “incorporated or dispersed in the coating” and whether the product has multiple coatings that collectively satisfy the claim.

Scenario 5: Altered loading ratio

A competitor changes the drug-to-polymer ratio outside the 1:10 to 1:3 range. This is potentially effective against claim 1 but may not avoid claim 9, which does not include the stated ratio in the supplied text.

Key Takeaways

• US 8,309,112 protects implantable articles with drug-loaded amphiphilic copolymer coatings.
• Claim 1 requires specified sulfonated hydrophilic monomers and a drug-to-polymer ratio of about 1:10 to 1:3.
• Claims 9 and 11 create focused protection for 3-sulfopropyl-containing polymers, including PSPMA-PBMA and PSPMA-PBMA-PSPMA.
• Claim 7 covers specified peptide and polypeptide agents; claim 8 reaches small-molecule water-soluble drugs.
• The patent is not a conventional Orange Book drug patent and is not ordinarily subject to a standalone Paragraph IV challenge.
• Biosimilar exposure is peripheral because the patent claims a coated medical article, not a biologic composition.
• The most effective design-around options are changing the sulfonated monomer, polymer class, coating architecture or drug-placement strategy.
• The final expiration date depends on the patent family’s earliest effective nonprovisional filing date and any patent-term adjustment or extension.

FAQs

Does US 8,309,112 cover drug-eluting stents?

Potentially. A drug-eluting stent can fall within the claims if its implantable substrate has a coating containing the required amphiphilic copolymer, sulfonated hydrophilic component and therapeutic agent.

Does the patent cover coatings with poly(L-arginine)?

Yes, claim 7 expressly lists poly(L-arginine), provided the product also satisfies the limitations of claim 1, including the claimed polymer, implantable article and drug-to-polymer ratio.

Can a coating using poly(butyl methacrylate) alone infringe?

Not necessarily. PBMA alone does not satisfy the amphiphilic copolymer and specified hydrophilic-moiety limitations. Risk increases if PBMA is combined with PSPMA or another claimed hydrophilic block.

Does changing the drug avoid the patent?

Changing the drug may avoid claim 7 if the replacement is not one of the listed agents, but it will not necessarily avoid claim 1, which is not limited to the claim 7 drug list. The polymer, implant and loading-ratio limitations remain decisive.

Is a license required to commercialize a PSPMA-PBMA-coated implant?

A license may be required if an unexpired claim covers the specific product and no invalidity, noninfringement or exhaustion defense applies. The commercial assessment must evaluate the complete patent family, term status, prosecution history, continuation patents and the product’s actual coating composition.

References

1. United States Patent No. 8,309,112. (2012). Claims 1-12. United States Patent and Trademark Office.

2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. FDA.

3. United States Code, 35 U.S.C. § 154. Patent term.

4. United States Code, 35 U.S.C. § 156. Extension of patent term.

5. United States Code, 35 U.S.C. § 271. Infringement of patent.

6. United States Patent and Trademark Office. (2024). Manual of Patent Examining Procedure, §§ 2111 and 2710. USPTO.

Drugs Protected by US Patent 8,309,112

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate