United States Patent 5,978,698: Claim Scope, Expiration, and GP IIb/IIIa Inhibitor Patent Landscape

U.S. Patent No. 5,978,698 protects a treatment protocol for coronary artery blockage during balloon angioplasty. The patent does not claim a fibrinogen receptor antagonist as a chemical compound. It claims the clinical sequence of coronary imaging, fibrinogen receptor antagonist administration before or during balloon inflation, angioplasty, and continued antagonist treatment after balloon inflation.

The broadest claim requires at least 70% inhibition of fibrinogen binding to platelet GP IIb/IIIa. Dependent claims narrow the protocol by specifying oral or intravenous administration, treatment for at least 24 hours, defined antagonist compounds, and, in claim 7, the eptifibatide-related peptide Mpr-(Har)-G-D-W-P-C-NH2.

The patent is historically important for the percutaneous coronary intervention use of GP IIb/IIIa inhibition. It is no longer a live U.S. exclusivity barrier. The patent issued on November 2, 1999, and its ordinary U.S. term has expired.

What does U.S. Patent 5,978,698 cover?

The patent covers a combination treatment method involving four technical elements:

Imaging a coronary blockage with a nonionic contrast dye.
Administering a fibrinogen receptor antagonist before or during balloon angioplasty.
Inflating a balloon catheter at the blocked site to revascularize the artery.
Continuing administration after balloon inflation at a dose providing at least 70% inhibition of fibrinogen binding to GP IIb/IIIa.

The claim is directed to a clinical method, not to:

The chemical structure of eptifibatide itself;
A generic formulation of a GP IIb/IIIa antagonist;
Balloon catheter hardware;
Contrast dye composition;
Coronary stent structure; or
Manufacturing of the antagonist.

The patent’s legal value therefore depended on whether a competing treatment protocol practiced all required method elements.

Patent identification

Field	Detail
U.S. patent	5,978,698
Issue date	November 2, 1999
Subject matter	Coronary angioplasty combined with fibrinogen receptor antagonism
Technology	GP IIb/IIIa platelet inhibition during coronary revascularization
Claim type	Medical treatment method
Core procedure	Coronary imaging plus balloon angioplasty
Core drug action	At least 70% inhibition of fibrinogen binding to GP IIb/IIIa
Key dependent duration	At least 24 hours after balloon inflation
Key specific agent	Mpr-(Har)-G-D-W-P-C-NH2, associated with eptifibatide
Current U.S. status	Expired

The patent’s claim text identifies multiple oral and intravenous antagonist candidates. Some are experimental compounds rather than marketed products. The list demonstrates the patent’s intended platform scope across small-molecule and peptide GP IIb/IIIa antagonists.

How broad is claim 1 of U.S. Patent 5,978,698?

Claim 1 is broad in drug identity but narrow in treatment sequence.

A practicing party would generally need to satisfy each of the following limitations:

Limitation	Required showing
Patient	Patient has coronary artery blockage
Imaging	Nonionic contrast dye is introduced into the coronary artery
Drug	A fibrinogen receptor antagonist is administered
Procedure	A balloon catheter is inserted into and inflated at the blockage
Timing	Antagonist is administered before or during balloon inflation and again following inflation
Pharmacology	Dose provides at least 70% inhibition of fibrinogen binding to GP IIb/IIIa

The claim does not require a particular named antagonist. It uses a functional limitation: the administered amount must provide at least 70% inhibition of fibrinogen binding to GP IIb/IIIa.

That functional language expands the potential drug coverage but creates proof issues. In an infringement dispute, the patent holder would need to establish that the accused dose and agent achieve the required inhibition level. Clinical dosing information, receptor-occupancy data, pharmacodynamic studies, product labeling, or expert testing could be relevant.

The claim also requires post-balloon administration. A protocol involving only a pre-procedure bolus would not satisfy the full claim unless the facts established a second administration after balloon inflation.

What do claims 2 through 7 add?

Claim 2: post-procedure duration

Claim 2 requires administration after balloon inflation for at least 24 hours. This is a narrower continuation-treatment claim.

A protocol that stops immediately after angioplasty may fall outside claim 2 but could still implicate claim 1 if post-inflation administration occurred for any period and the other limitations were met.

Claim 3: oral administration

Claim 3 narrows the antagonist route to oral administration. This limitation is commercially significant because the named oral compounds were investigational candidates rather than the principal approved GP IIb/IIIa therapy used in PCI.

Claim 4: listed oral compounds

Claim 4 limits claim 3 to four specified compounds:

A tetrahydropyrazolodiazepine derivative;
A formamidinophenyl isoxazoline derivative;
An aminoiminomethyl phenyl-containing acetylenic compound; and
An isoxazoline derivative identified as an acetate salt.

These compounds are claimed by chemical identity rather than by a generic Markush formula. The claim is therefore narrower than claim 3 and would not cover every oral GP IIb/IIIa antagonist.

Claim 5: intravenous administration

Claim 5 narrows the administration route to intravenous delivery. This is the commercially relevant branch for eptifibatide and other parenteral GP IIb/IIIa inhibitors used during PCI.

Claim 6: listed intravenous compounds

Claim 6 lists six intravenous antagonists, including:

Four disulfide-linked peptide derivatives;
N-Methyl-D-phenylalanyl-N-[(1S)-1-formyl-4-guanidinobutyl]-L-prolinamide;
A benzamidine-containing piperidine derivative; and
A sulfonamide-substituted phenylpropionic acid derivative.

Because claim 6 depends on claim 5, the listed compound must be administered intravenously in the claimed coronary intervention protocol.

Claim 7: eptifibatide-related peptide

Claim 7 specifies Mpr-(Har)-G-D-W-P-C-NH2. The abbreviation refers to a cyclic peptide-type GP IIb/IIIa antagonist associated with eptifibatide, marketed by Millennium Pharmaceuticals and later by Cor Therapeutics’ successor commercial organizations as Integrilin.

Claim 7 remains limited by the parent claim’s procedural requirements. It does not independently claim eptifibatide in all uses, doses, or formulations. It requires intravenous administration in the coronary blockage and balloon angioplasty context covered by claim 5 and claim 1.

What drugs and technologies are implicated by the patent?

The patent sits within the GP IIb/IIIa inhibitor field. These agents inhibit the final common pathway of platelet aggregation by blocking fibrinogen binding to activated platelet glycoprotein IIb/IIIa receptors.

Agent	Commercial status	Relationship to Patent 5,978,698
Eptifibatide	FDA-approved intravenous GP IIb/IIIa inhibitor	Most direct commercial relevance, particularly claim 7
Abciximab	FDA-approved intravenous GP IIb/IIIa inhibitor	Potentially relevant to broad claim 1, but not necessarily listed in claims 6 or 7
Tirofiban	FDA-approved intravenous small-molecule GP IIb/IIIa inhibitor	Potentially relevant to broad functional claim 1
Oral GP IIb/IIIa candidates	Generally discontinued or not commercially adopted	Relevant to claims 3 and 4
Balloon angioplasty	Established revascularization procedure	Required procedural component
Nonionic contrast media	Standard coronary imaging agents	Required imaging component under claim 1

The claim language may reach approved antagonists not expressly listed in the dependent claims if they satisfy the broad functional requirements of claim 1. A named drug need not appear in claim 1 to fall within that claim.

When did U.S. Patent 5,978,698 lose exclusivity?

The patent issued on November 2, 1999. Under the U.S. patent-term rules applicable to the relevant filing period, the patent’s ordinary term ran for 17 years from grant or 20 years from the applicable earliest nonprovisional filing date, depending on the governing transition rules and filing history. Public patent records identify the patent as expired, and it no longer creates enforceable U.S. exclusionary rights.

Event	Date or status
Patent issued	November 2, 1999
Patent term	Expired
Current enforceability	No enforceable ordinary patent term
Current generic-entry barrier	None from this patent
Historical litigation value	Potentially relevant before expiration
Current Orange Book significance	No live exclusivity based on this patent

The expiration of this method patent does not establish freedom to operate for every eptifibatide product. Separate composition, formulation, manufacturing, dosing, or regulatory exclusivities would require independent review.

What is the Orange Book status of Patent 5,978,698?

The Orange Book is relevant to patents submitted for approved drug products under the Hatch-Waxman framework. Patent 5,978,698 is a method-of-treatment patent and is not itself a composition-of-matter patent for eptifibatide.

The patent’s practical Orange Book significance would have depended on whether it was listed against an approved product and whether the listed claims corresponded to an approved method of use. For a marketed intravenous GP IIb/IIIa inhibitor such as Integrilin, relevant Orange Book analysis must distinguish:

Drug substance patents;
Drug product or formulation patents;
Method-of-use patents;
Expired patents; and
Delisted or no-longer-effective patent entries.

Because Patent 5,978,698 is expired, it does not presently support a paragraph IV litigation strategy or block an ANDA applicant. An applicant could still face other listed patents for eptifibatide or its product presentation, but this patent would not provide a current statutory stay or enforceable Orange Book barrier.

Were paragraph IV challenges likely under this patent?

A paragraph IV certification would have been relevant only while the patent was listed against an approved drug and had unexpired claims that an ANDA product allegedly infringed.

The patent presented several possible paragraph IV vulnerabilities:

It claimed a treatment method rather than the drug compound.
Claim 1 required a specific imaging and angioplasty sequence.
It required administration both before or during balloon inflation and after inflation.
It included a quantitative 70% inhibition limitation.
Dependent claims required particular routes, durations, or chemical identities.
Some named antagonists were not commercially adopted.

An ANDA applicant seeking approval for eptifibatide could argue that the proposed label did not instruct the complete claimed sequence, particularly the contrast-dye limitation, repeated administration requirement, or 24-hour continuation period in claim 2.

Under the modern skinny-label framework, a generic applicant may seek approval for uses that avoid patented indications. The practical strength of such a defense would depend on the approved label, physician practice, induced-infringement evidence, and the precise Orange Book listing.

How strong was the patent estate for eptifibatide?

Patent 5,978,698 was a use patent, not the central composition patent for eptifibatide. Its commercial strength was therefore narrower than a valid composition-of-matter patent.

Strengths

It covered a clinically important PCI protocol.
It used a functional inhibition threshold rather than limiting claim 1 to one molecule.
It included both oral and intravenous treatment branches.
Claim 7 addressed the eptifibatide-related peptide directly.
The claimed protocol aligned with the clinical use of intravenous GP IIb/IIIa inhibitors during coronary intervention.

Weaknesses

The claim required multiple sequential procedural steps.
The nonionic contrast-dye limitation created a potential noninfringement issue.
The 70% inhibition threshold required pharmacodynamic proof.
Claims 4, 6, and 7 were limited to specified compounds.
The patent did not protect eptifibatide across unrelated indications or formulations.
The patent has expired.

The patent was more valuable as a historical method-of-use layer around PCI than as a durable platform patent for the drug class.

What patent litigation and settlement risks applied?

Before expiration, potential litigation would have centered on whether a drug label or clinical protocol instructed:

Coronary angioplasty;
Use of a nonionic contrast agent;
Administration before or during balloon inflation;
Continued administration after balloon inflation; and
A dose producing at least 70% GP IIb/IIIa inhibition.

The patent does not appear, from the claim text provided, to create a manufacturing dispute. A manufacturer could produce a GP IIb/IIIa antagonist without practicing the claimed method. Risk would arise principally from product labeling, promotional materials, clinical trial protocols, or induced use by hospitals and physicians.

No current settlement or litigation agreement can preserve an expired patent’s exclusionary effect. Any historical settlement would be relevant to past market entry, not to current enforcement.

How does this patent compare with composition and formulation patents?

Patent category	Typical protection	Relative value
Composition patent	Chemical structure of eptifibatide or another antagonist	Broadest product-level protection
Formulation patent	Concentration, excipients, stability, container, or presentation	Product-specific protection
Manufacturing patent	Peptide synthesis, purification, cyclization, or scale-up	Supply-chain protection
Method-of-use patent	Treatment protocol during PCI	Narrower, label- and conduct-dependent protection
Patent 5,978,698	Imaging, angioplasty, antagonist timing, and receptor inhibition	Expired method-of-use layer

For eptifibatide, composition and manufacturing rights would generally have provided stronger barriers than the claims in Patent 5,978,698. The patent’s value depended on enforcing clinical use rather than controlling the product itself.

What generic launch risks exist today?

Patent 5,978,698 creates no current generic launch risk because it is expired. A current entrant would instead evaluate:

FDA approval requirements for an abbreviated application or 505(b)(2) application;
Current Orange Book listings for the reference product;
Drug-substance and drug-product patents;
Sterility and injectable manufacturing requirements;
Peptide identity and impurity specifications;
Stability and container-closure requirements;
Labeling differences from the reference product; and
Institutional purchasing and substitution practices.

Eptifibatide is an injectable peptide product. Manufacturing and regulatory execution may remain commercially important even without an enforceable method patent. Those barriers are operational and regulatory, not based on Patent 5,978,698.

What is the geographic scope of the patent?

The patent’s enforceability was limited to the United States. It did not directly control:

European angioplasty protocols;
Canadian eptifibatide use;
Japanese GP IIb/IIIa products;
Manufacturing performed entirely outside the United States; or
Foreign clinical practice.

Foreign counterparts, if any, required separate review by jurisdiction. Patent term, prosecution history, claim construction, supplementary protection certificates, and national litigation outcomes could differ materially from the U.S. position.

Key Takeaways

U.S. Patent 5,978,698 is a method-of-treatment patent for coronary angioplasty combined with GP IIb/IIIa inhibition.
Claim 1 requires nonionic contrast imaging, balloon angioplasty, antagonist administration before or during balloon inflation, post-inflation administration, and at least 70% inhibition of fibrinogen binding.
Claim 2 adds at least 24 hours of post-inflation treatment.
Claims 3 and 4 address oral antagonists and specified oral compounds.
Claims 5 through 7 address intravenous antagonists, with claim 7 identifying the eptifibatide-related peptide Mpr-(Har)-G-D-W-P-C-NH2.
The patent does not claim eptifibatide as a composition across all uses.
The patent has expired and is not a current U.S. exclusivity barrier.
Historical infringement risk would have depended heavily on the drug label, procedural sequence, contrast-agent use, dosing, and clinical practice.
Current eptifibatide market entry analysis must focus on any separate live composition, formulation, manufacturing, regulatory, or Orange Book-listed rights.

FAQs

Does Patent 5,978,698 claim eptifibatide itself?

No. Claim 7 identifies an eptifibatide-related peptide in the context of the claimed intravenous coronary angioplasty treatment. It does not claim the compound for every medical use, formulation, or manufacturing process.

Does using tirofiban or abciximab automatically infringe Patent 5,978,698?

No. The drug must be used in the claimed procedural sequence and satisfy all limitations of claim 1. The broad claim may reach unlisted antagonists, but infringement would require analysis of the specific protocol and inhibition level.

Can a hospital infringe the patent by giving a GP IIb/IIIa inhibitor during PCI?

The patent is expired, so it cannot presently support an infringement action. Before expiration, hospital conduct could have been relevant if the full claimed sequence was practiced.

Does the 70% inhibition requirement limit the patent to a particular dose?

It limits the claim to an administered amount that provides at least 70% inhibition of fibrinogen binding to GP IIb/IIIa. The limitation is functional rather than tied to one fixed dose.

Is a separate patent search required for a generic eptifibatide launch?

Yes. Expiration of Patent 5,978,698 does not resolve separate rights covering eptifibatide composition, injectable formulation, manufacturing, stability, packaging, or FDA-listed methods of use.

References

U.S. Patent No. 5,978,698. (1999). Method for treating a patient having coronary artery blockage. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.
U.S. Food and Drug Administration. (2024). Integrilin (eptifibatide) prescribing information. Center for Drug Evaluation and Research.
U.S. Patent and Trademark Office. (2024). Patent Center: U.S. Patent No. 5,978,698. https://patentcenter.uspto.gov/
U.S. Code, 35 U.S.C. §§ 154, 271, and 282. (2024). Patent term, infringement, and validity provisions.
U.S. Food and Drug Administration. (2024). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
United Kingdom	2318053	⤷ Start Trial
United Kingdom	9626396	⤷ Start Trial
United Kingdom	9720996	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,978,698

Summary for Patent: 5,978,698