United States Patent 5,972,967: Tirofiban Intravenous Formulation Claims, Patent Scope, and Competitive Landscape

U.S. Patent No. 5,972,967 protects specific intravenous aqueous formulations of tirofiban, principally tirofiban hydrochloride in citrate buffer with a tonicity-adjusting agent. The patent does not broadly claim tirofiban, its chemical structure, or every use of the compound. Its commercial value was concentrated in formulation protection for Aggrastat, an intravenous antiplatelet product.

The patent issued October 26, 1999. Based on the applicable 20-year U.S. patent term and the recorded priority framework, the patent expired in 2017, subject to any patent-term adjustment or extension reflected in the USPTO file. It is no longer an enforceable barrier to U.S. generic development. The claims remain relevant for freedom-to-operate analysis because they define the formulation architecture historically associated with tirofiban injection.

What drug and formulation does U.S. Patent 5,972,967 protect?

The patent covers an aqueous intravenous composition containing:

Tirofiban, identified chemically as 2-(S)-(n-butylsulfonylamino)-3-[4-(4-(piperidin-4-yl)butyloxy)phenyl]propionic acid, or a pharmaceutically acceptable salt;
A citrate buffer;
A tonicity-adjusting agent.

The claimed composition is intended for intravenous administration and platelet aggregation inhibition. The active ingredient is tirofiban, generally administered clinically as tirofiban hydrochloride.

The patent is directed to formulation properties rather than molecular discovery. Its technical focus is a stable, pharmaceutically acceptable, substantially isotonic aqueous injection at a mildly acidic pH.

Core formulation elements

Element	Claimed scope
Active ingredient	Tirofiban or pharmaceutically acceptable salt
Route	Intravenous administration
Dosage form	Aqueous pharmaceutical composition
Buffer	Citrate buffer
pH	Broadly about 5 to 7; narrower embodiments around pH 6
Tonicity	Approximately 50 to 500 mOsmol/L in broad claims
Preferred tonicity	Approximately 290 mOsmol/L
Active concentration	About 0.01 to 0.5 mg/mL in broad claims
Preferred concentration	About 0.05 to 0.25 mg/mL
Specific concentrations	Approximately 0.05 or 0.25 mg/mL
Buffer concentration	About 2 to 100 mM broadly; about 2 to 20 mM in narrower claims
Preferred buffer concentration	Approximately 10 mM citrate

How broad are the independent claims in U.S. Patent 5,972,967?

The principal composition claims are claims 1, 10, 11, 15 and 21. The principal method claims are claims 6 and 8.

Claim 1: basic intravenous formulation

Claim 1 requires all of the following:

An aqueous composition;
Intended for intravenous administration;
Tirofiban or a pharmaceutically acceptable salt;
Citrate buffer at a concentration providing a pharmaceutically acceptable pH;
A tonicity-adjusting agent sufficient to make the formulation substantially isotonic.

Claim 1 is relatively broad because it does not specify an exact pH, active concentration, buffer concentration, osmolarity, or particular tonicity agent. A formulation could fall within claim 1 even if it does not match the narrower examples, provided it satisfies the functional limitations.

The claim does not expressly require sodium citrate, citric acid, sodium chloride, a particular vial, a premixed bag, or a particular manufacturing process.

Claim 10: pH and osmolarity limitations

Claim 10 narrows claim 1 by requiring:

A pH of about 5 to 7; and
Osmolarity of about 50 to 500 mOsmol/L.

This claim remains commercially broad. The osmolarity range covers hypotonic, isotonic and moderately hypertonic solutions. The claim is not limited to a formulation at approximately physiologic osmolarity.

Claim 11: active concentration and buffer range

Claim 11 requires:

Tirofiban concentration of approximately 0.01 to 0.5 mg/mL;
Citrate buffer of approximately 2 to 100 mM; and
Osmolarity of approximately 50 to 500 mOsmol/L.

This claim captures a substantial range of plausible injectable concentrations and citrate-buffer strengths. A competing developer using tirofiban at a clinically conventional concentration could face literal infringement risk if it also uses citrate buffer and falls within the stated ranges.

Claim 15: mixing-based composition claim

Claim 15 covers a composition prepared by mixing:

Tirofiban hydrochloride;
Sodium citrate and citric acid sufficient to produce a pH of about 5 to 7; and
A tonicity-adjusting agent sufficient to produce osmolarity of about 50 to 500 mOsmol/L.

This claim is narrower in some respects because it identifies the citrate components as sodium citrate and citric acid. It is also directed to a composition prepared by mixing specified ingredients, which creates potential claim-construction issues concerning whether the preparation language imposes a meaningful product limitation.

The claim does not identify the tonicity-adjusting agent. Sodium chloride is a commercially plausible example, but the claim language is not limited to sodium chloride.

What formulations are protected by the dependent claims?

The dependent claims create multiple nested formulation positions.

Claims	Formulation limitations
2	Tirofiban free acid; citrate buffer about 2 to 20 mM
3	Tirofiban concentration about 0.05 to 0.25 mg/mL
4	0.25 mg/mL tirofiban; 10 mM citrate; about 290 mOsmol/L; pH about 6
5	0.05 mg/mL tirofiban; 10 mM citrate; about 290 mOsmol/L; pH about 6
12	2 to 20 mM citrate; about 290 mOsmol/L
13	0.25 mg/mL; 10 mM citrate; about 316 mOsmol/kg; pH about 6
14	0.05 mg/mL; 10 mM citrate; about 315 mOsmol/kg; pH about 6
16	0.05 to 0.25 mg/mL tirofiban
17	pH about 5.8 to 6.2
18	Osmolarity about 290 mOsmol/L
19	0.05 mg/mL; pH about 6; about 290 mOsmol/L
20	0.25 mg/mL; pH about 6; about 290 mOsmol/L
21	0.25 mg/mL; pH about 6; about 316 mOsmol/kg
22	0.05 mg/mL; pH about 6; about 315 mOsmol/kg

The most product-specific claims are claims 4, 5 and 19 through 22. They target formulations closely matching the claimed commercial concentration and buffer conditions. The broadest practical claims are claims 1, 10 and 11.

Does the patent cover tirofiban itself?

No. U.S. Patent 5,972,967 does not claim the tirofiban molecule as such.

The claims require an aqueous intravenous formulation containing tirofiban. Oral formulations, transdermal products, solid dosage forms, nonmedical laboratory compositions and formulations lacking citrate buffer are outside the literal scope of the composition claims, unless another claim or infringement theory applies.

A patent directed to the tirofiban chemical entity would be analytically separate. The principal earlier U.S. patent associated with the tirofiban compound is U.S. Patent No. 5,292,756, which covered nonpeptide platelet aggregation inhibitors including tirofiban-related chemistry. That earlier compound patent expired before U.S. Patent 5,972,967 and does not extend the enforceable life of the formulation patent (U.S. Patent No. 5,292,756).

What method-of-use protection does the patent provide?

Claims 6 through 9 cover intravenous treatment to inhibit platelet aggregation in a mammal.

Claim 6 requires:

A method for inhibiting platelet aggregation;
Intravenous treatment;
A therapeutically effective amount;
The composition of claim 2.

Claim 8 uses the broader composition of claim 1. Claims 7 and 9 limit the treated mammal to a human.

These claims are method-of-use claims, not claims to every use of tirofiban. They require intravenous administration of a formulation that satisfies the incorporated composition limitations. They are most relevant to direct treatment by a hospital or healthcare provider and to induced-infringement analysis involving a product label.

The method claims do not independently claim:

Oral antiplatelet treatment;
Prevention of thrombosis using a formulation outside the claim limitations;
Any particular procedure such as percutaneous coronary intervention;
A specific dosing rate or infusion duration;
Combination treatment with aspirin, heparin or another antithrombotic.

How strong were the patent claims?

The patent had meaningful historical formulation value but a narrower technical moat than a compound patent.

Strengths

The claims identify the active ingredient by a specific chemical identity.
Intravenous use narrows the field to a commercially important dosage form.
Citrate buffer is a required formulation element in the principal claims.
The claims combine composition parameters with functional pharmaceutical requirements.
The preferred claims align closely with practical injectable concentrations and physiologic tonicity.
Claims 15 through 22 provide ingredient-mixing and formulation-specific fallback positions.

Vulnerabilities

The active pharmaceutical ingredient was known from earlier compound patents.
Citrate buffering and tonicity adjustment are conventional formulation techniques.
Many ranges are broad and may face validity scrutiny for obviousness or written-description issues, depending on the prior art.
Functional language such as "effective to provide" and "sufficient to achieve" may create claim-construction and proof issues.
Claims 13, 14, 21 and 22 use osmolality in mOsmol/kg, while other claims use osmolarity in mOsmol/L. That distinction can create measurement and infringement disputes.
The exact product may be difficult to distinguish from a competing formulation if the manufacturer uses undisclosed process conditions or excipient quantities.
The patent expired in 2017, eliminating current injunction and damages exposure for post-expiration conduct.

The narrowest claims are likely more defensible against a formulation that precisely matches the disclosed concentrations, pH and tonicity. The broad claims create more prior-art and obviousness exposure but would have covered a larger set of commercial formulations during their enforceable term.

When did U.S. Patent 5,972,967 lose exclusivity?

The patent issued October 26, 1999 and expired in 2017 under the ordinary U.S. patent-term framework. The relevant term is measured from the earliest applicable nonprovisional filing date, not from the issue date.

The patent's exclusivity timeline is:

Event	Date or status
Patent filing and priority chain	Before the October 1999 issue date
U.S. patent grant	October 26, 1999
Commercial relevance	Intravenous tirofiban formulation for Aggrastat
Patent expiration	2017 under the applicable 20-year term
Current status	Expired; no enforceable patent exclusivity
Current generic barrier	Regulatory and commercial, not this patent

Patent-term adjustment, terminal disclaimers and any patent-term extension must be checked in the USPTO Patent Center record for a formal terminal date. The patent is not an active U.S. formulation barrier today.

What is the Orange Book status of tirofiban and Aggrastat?

Aggrastat is the brand associated with tirofiban hydrochloride injection. The product was approved by the FDA under NDA 020912. The regulatory product is an injectable antiplatelet agent used to reduce thrombotic cardiovascular events in acute coronary syndrome settings and during related interventional treatment.

FDA Orange Book analysis separates three concepts:

FDA approval of the reference product;
Listed patents and their expiration dates;
Regulatory exclusivity periods.

A patent can appear in the Orange Book without remaining enforceable if it has expired. Conversely, an expired patent does not block an abbreviated new drug application.

For tirofiban, the principal commercial patent risks historically included:

The earlier chemical patent estate;
Formulation patents such as U.S. Patent 5,972,967;
Potential later patents covering manufacturing, salts, dosage regimens or product-specific improvements.

U.S. Patent 5,972,967 is not a current Orange Book-based obstacle to an ANDA because its patent term has ended. A generic applicant would still need to address any other unexpired listed patents, applicable exclusivity, labeling requirements and product-quality standards under the ANDA pathway (FDA, 2025a; FDA, 2025b).

Which companies challenged or could challenge the patent?

No current Paragraph IV challenge to U.S. Patent 5,972,967 is commercially material because the patent has expired.

During its enforceable period, a generic tirofiban applicant could have used an ANDA certification strategy based on:

Paragraph III certification, stating that the applicant would wait until patent expiration;
Paragraph IV certification, alleging that the patent was invalid, unenforceable or not infringed;
A section viii statement, if the patented method of use could be carved out of the proposed labeling.

The practical Paragraph IV targets would have been the composition claims, particularly claims 1, 10 and 11, and the specific formulation claims 15 through 22. A generic applicant using a noncitrate buffer, a materially different pH or a formulation outside the claimed concentration and osmolarity ranges could have pursued a noninfringement position.

The relevant commercial parties include the brand sponsor or its licensees, generic injectable manufacturers, contract manufacturers and the FDA. The patent record supplied does not establish a current litigation or settlement dispute affecting the patent.

What generic launch risks exist for tirofiban?

The patent-related generic launch risk is low because the patent is expired. The remaining risks are manufacturing, regulatory and commercial.

Regulatory risks

A tirofiban generic must demonstrate pharmaceutical equivalence and bioequivalence or otherwise satisfy the applicable FDA requirements for an injectable product. The applicant must address:

Active ingredient identity and strength;
Sterility and endotoxin control;
Container-closure integrity;
Particulate matter;
Stability;
Extractables and leachables;
Labeling and administration instructions;
Compatibility with infusion systems and co-administered products.

Manufacturing risks

The formulation patent does not block all manufacturing approaches, but injectable products remain sensitive to:

pH drift;
precipitation;
degradation during storage;
adsorption to containers or tubing;
tonicity variation;
mixing order;
sterilization conditions;
scale-up reproducibility.

A generic can design around the patent's historical claim set by changing one or more of the following:

Design-around variable	Potential effect
Buffer system	Use phosphate, acetate or another suitable buffer
pH	Move outside the claimed pH range where clinically acceptable
Active concentration	Use a concentration outside the claimed ranges
Osmolarity	Use a materially different osmolarity
Salt form	Use a form not captured by the relevant claim language
Manufacturing process	Avoid the sodium citrate/citric acid mixing limitations
Packaging	Use a different container or presentation

A design-around must still satisfy FDA quality requirements and clinical usability. A technically noninfringing formulation may be commercially unattractive if it creates stability, compatibility or dosing problems.

Is biosimilar risk relevant to tirofiban?

No. Tirofiban is a chemically synthesized small molecule, not a biologic. Biosimilar provisions under the Public Health Service Act do not apply.

The relevant competitive pathway is an ANDA for a generic drug, not a biosimilar application under section 351(k). The key legal framework is the Hatch-Waxman Act, including patent certifications, labeling carve-outs and potential 30-month stays if a valid Orange Book patent is timely litigated (21 U.S.C. § 355(j)).

How does the patent compare with the broader tirofiban patent estate?

Patent category	Scope	Current status
Compound patent	Tirofiban chemical structure and related analogs	Expired
Formulation patent, including U.S. 5,972,967	Aqueous intravenous citrate-buffered formulations	Expired
Method-of-use patents	Platelet aggregation inhibition and cardiovascular indications	Must be assessed individually
Manufacturing patents	Synthesis, purification, salt formation or process controls	Must be assessed individually
Packaging or device patents	Vials, infusion bags, delivery systems or administration sets	Must be assessed individually
Regulatory exclusivity	FDA exclusivity tied to approval history	Separate from patent rights

The patent estate was strongest when compound and formulation rights overlapped. Once the compound patent expired, a formulation patent could delay direct copying of the branded injectable but could not prevent all tirofiban products. After formulation-patent expiration, the remaining competitive differentiation shifted to FDA approval, manufacturing capacity, supply reliability and contracting.

What litigation and settlement issues affect U.S. Patent 5,972,967?

The supplied record does not establish active U.S. litigation, a current Paragraph IV case or a settlement agreement involving this patent. Because the patent expired in 2017, any historical dispute would now have limited prospective relevance except for damages, claim-construction precedent or settlement terms affecting historical launch dates.

For present diligence, the main questions are:

Whether any pre-expiration settlement delayed a generic launch;
Whether a license covered the formulation claims;
Whether a generic entered before or after the patent expiry date;
Whether later patents covered the marketed presentation;
Whether any patent-term adjustment changed the terminal date.

None of those issues changes the current conclusion that U.S. Patent 5,972,967 is expired.

What is the revenue exposure from this patent?

The patent's historical revenue exposure was linked to Aggrastat sales and the premium associated with a ready-to-use or commercially stable intravenous formulation. The patent did not control the entire tirofiban market because:

The compound itself was separately protected;
Alternative formulations could potentially be developed;
Hospital products can be supplied through different presentations;
The claims did not cover every antiplatelet product or every tirofiban use.

Current revenue exposure attributable specifically to U.S. Patent 5,972,967 is zero from an exclusivity perspective. Any present commercial value lies in know-how, validated manufacturing, regulatory history and market access, not enforceable patent rights.

Key Takeaways

U.S. Patent 5,972,967 is a formulation patent for intravenous tirofiban.
Its core requirement is tirofiban in an aqueous citrate-buffered, tonicity-adjusted composition.
Claims 1, 10 and 11 provide the broadest formulation coverage.
Claims 4, 5 and 19 through 22 target specific concentrations, pH values and osmolarity or osmolality levels.
Claims 6 through 9 cover intravenous platelet aggregation inhibition using the claimed compositions.
The patent does not claim tirofiban as a chemical entity.
The patent issued October 26, 1999 and expired in 2017 under the ordinary U.S. term framework.
It is not a current U.S. barrier to generic tirofiban entry.
Tirofiban is a small molecule, so biosimilar analysis is not applicable.
Current generic risk is concentrated in FDA approval, sterile manufacturing, stability, supply and commercial contracting.
Any surviving blocking rights would have to come from separate patents, not U.S. Patent 5,972,967.

FAQs

Does U.S. Patent 5,972,967 cover sodium chloride as the tonicity agent?

The claims do not expressly require sodium chloride. They require a tonicity-adjusting agent sufficient to achieve a specified osmolarity or isotonic condition. Sodium chloride is a likely example, but other agents can fall within the functional language.

Can a generic avoid the patent by using phosphate buffer instead of citrate?

A phosphate-buffered formulation would have a strong noninfringement position against claims requiring citrate buffer, provided no other claim or patent covers the alternative formulation and the product remains pharmaceutically acceptable.

Are claims 13 and 14 limited by osmolarity or osmolality?

Claims 13 and 14 use osmolality, expressed in mOsmol/kg, while other claims use osmolarity, expressed in mOsmol/L. That wording can affect claim scope and the analytical method used to evaluate infringement.

Does expiration of the formulation patent eliminate all tirofiban patent risk?

No. It eliminates the barrier created by this patent. Separate patents covering manufacturing, salts, dosing regimens, packaging or later product improvements must be reviewed independently.

Would an ANDA applicant need to file a Paragraph IV certification today?

Not for this expired patent. An applicant would address any currently listed, unexpired patents in the Orange Book. An expired patent cannot support a current 30-month stay or a prospective injunction based on patent expiration.

References

U.S. Patent No. 5,972,967. (1999). Pharmaceutical compositions comprising tirofiban. United States Patent and Trademark Office.
U.S. Patent No. 5,292,756. (1994). Non-peptide platelet aggregation inhibitors. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2025a). Approved drug products with therapeutic equivalence evaluations. FDA.
U.S. Food and Drug Administration. (2025b). Aggrastat (tirofiban hydrochloride) prescribing information. FDA.
Hatch-Waxman Act, 21 U.S.C. § 355(j). (1984). Abbreviated applications for new drugs.
United States Patent and Trademark Office. (2025). Patent term adjustment and patent term calculation guidance. USPTO.

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Details for Patent: 5,972,967

Summary for Patent: 5,972,967