United States Patent 7,683,037: Claim Scope, Expiration, and Regadenoson Patent Landscape

U.S. Patent No. 7,683,037 covers intravenous bolus administration of regadenoson, formerly CVT-3146, to produce coronary vasodilation with limited peripheral vasodilation. The claims also cover rapid myocardial perfusion imaging protocols using regadenoson and a radionuclide. The patent is a method-of-use patent, not a composition-of-matter patent.

Its commercial relevance was strongest before the expiration of its 20-year patent term in 2024. The claims are now primarily relevant to historical litigation, validity analysis, prosecution strategy, and interpretation of later regadenoson patents. FDA approval of Lexiscan remains distinct from patent enforceability. [1–3]

What drug and therapeutic use does U.S. Patent 7,683,037 cover?

The patent covers regadenoson, identified in the patent as CVT-3146. Regadenoson is a selective adenosine A2A receptor agonist used as a pharmacologic stress agent during radionuclide myocardial perfusion imaging.

The claimed therapeutic concept has four central elements:

The active ingredient must be CVT-3146 or the claimed A2A agonist.
Administration must be intravenous.
Administration must occur as a bolus or single rapid dose in the relevant claims.
The administration must produce coronary vasodilation without significant peripheral vasodilation.

The patent distinguishes regadenoson from adenosine, which has a short half-life but can produce systemic adverse effects, including peripheral vasodilation, hypotension, flushing, dyspnea and chest discomfort. Regadenoson was developed to provide coronary hyperemia through A2A receptor activation while reducing reliance on continuous adenosine infusion. [1,4]

What is the chemical identity of CVT-3146?

CVT-3146 is regadenoson. The chemical name recited in the claims is:

(1-{9-[(4S,2R,3R,5R)-3,4-dihydroxy-5-(hydroxymethyl)oxolan-2-yl]-6-aminopurin-2-yl}pyrazol-4-yl)-N-methylcarboxamide.

The compound is a substituted adenosine analog with A2A receptor agonist activity. A product that uses a different active ingredient would not literally satisfy the claims, even if it produced similar coronary blood-flow effects.

What are the independent claims of U.S. Patent 7,683,037?

The patent has two principal independent method claims.

Claim	Core subject matter	Required result
1	IV bolus administration of at least 10 micrograms of CVT-3146 to a human	Coronary vasodilation without significant peripheral vasodilation
15	Administration of a radionuclide and CVT-3146 for myocardial perfusion imaging	At least a 2.5-fold increase in coronary blood flow within about one minute

Claim 1 is directed to the physiological effect of the drug. It does not require myocardial perfusion imaging, a radionuclide, or a particular imaging modality.

Claim 15 is narrower in purpose but adds a clinically important functional limitation. The protocol must involve myocardial perfusion imaging and must achieve at least a 2.5-fold increase in coronary blood flow within approximately one minute of regadenoson administration.

How broad is claim 1?

Claim 1 is broad in clinical purpose but narrow in compound identity and route of administration.

A literal infringement analysis would generally require the following:

Limitation	Scope
Patient	Human in need of treatment
Drug	CVT-3146/regadenoson
Route	Intravenous
Delivery	Bolus
Dose	At least 10 micrograms
Pharmacology	Coronary vasodilation without significant peripheral vasodilation

The claim does not specify a maximum dose. It also does not require that the dose be weight-adjusted, administered in a particular volume, used in a specific imaging system, or combined with a named radionuclide.

A commercial regadenoson injection administered intravenously as a bolus would fall within the basic factual pattern of claim 1 if the claimed physiological limitation were met. A continuous infusion would present a stronger noninfringement position because the claim expressly requires bolus administration.

Does claim 1 require a particular degree of coronary vasodilation?

No numerical coronary blood-flow threshold appears in claim 1. The claim requires coronary vasodilation, coupled with the absence of significant peripheral vasodilation.

That functional language creates two legal issues:

Whether the accused administration produces the claimed coronary effect.
Whether the peripheral response is sufficiently limited to qualify as “without significant peripheral vasodilation.”

Clinical protocols, product labeling, pharmacodynamic studies and expert testimony would likely be relevant to both questions. The phrase is not equivalent to “no peripheral vasodilation.” A measurable peripheral effect may exist without defeating the claim if it is not clinically or pharmacologically significant.

How do claims 2 through 14 narrow or expand the dosing scope?

Claims 2 through 14 create overlapping dose ranges. They are dependent claims, so each incorporates all limitations of claim 1.

Claim	Added limitation
2	Dose no greater than about 1,000 micrograms
3	Dose of about 10 to about 600 micrograms
4	Single dose
5	About 0.05 to about 60 micrograms/kg
6	About 0.1 to about 30 micrograms/kg
7	No greater than about 20 micrograms/kg to a supine patient
8	No greater than about 10 micrograms/kg to a standing patient
9	About 10 to about 600 micrograms/kg, administered in about 20 seconds
10	About 10 to about 600 micrograms/kg, administered in less than about 10 seconds
11	More than about 100 micrograms
12	No greater than 600 micrograms
13	No greater than 500 micrograms
14	About 100 to about 500 micrograms

Claims 3, 12, 13 and 14 are particularly relevant to fixed-dose regadenoson products. The commercial Lexiscan dose is a fixed 400-microgram intravenous bolus, which falls within the 100-to-500-microgram range of claim 14 and the 10-to-600-microgram range of claim 3. [4]

Claims 5 through 8 address weight-based administration and patient posture. They may have been intended to capture dose selection that maintains coronary selectivity across different patient conditions.

Claims 9 and 10 contain apparent drafting anomalies because they recite 10 to 600 micrograms per kilogram, rather than the fixed-dose ranges used elsewhere in the claim set. The repeated “wherein the wherein” language in the supplied text is also a typographical defect. Courts generally interpret claims using the issued patent, specification, prosecution history and applicable claim-construction principles. A typographical error does not automatically invalidate a claim, but a material ambiguity can affect enforceability and infringement analysis.

What does claim 15 protect in myocardial perfusion imaging?

Claim 15 covers a diagnostic method that combines:

A radionuclide;
Regadenoson administration;
Myocardial perfusion imaging;
A coronary blood-flow increase of at least 2.5-fold;
Achievement of that increase within approximately one minute.

The claim is broader than a claim limited to a particular radionuclide or imaging device. It can potentially cover protocols using different radiopharmaceuticals, provided the other claim limitations are satisfied.

Claims 16 through 20 add timing and duration limitations:

Claim 16 requires examination of the myocardium to begin within about one minute.
Claim 17 permits separate administration of the radionuclide and regadenoson.
Claim 18 covers simultaneous administration.
Claim 19 requires the 2.5-fold increase to last less than about five minutes.
Claim 20 narrows the duration to less than about three minutes.

Claims 17 and 18 make clear that the patent does not require a single combined injection. Separate administration and simultaneous administration are both expressly covered.

What formulations and dosage forms are protected?

The patent claims do not primarily protect a formulation. They protect administration of the active ingredient in a specified clinical manner.

The claims therefore do not, on their face, require:

A particular excipient;
A particular pH;
A specific vial or syringe;
A specific concentration;
A particular preservative;
A particular radionuclide;
A particular imaging machine.

A formulation manufacturer could avoid literal infringement of these claims by using a different active ingredient, but not merely by changing the vial, concentration or excipient if the resulting product is still regadenoson administered in the claimed manner.

Later patents or applications may protect formulation stability, container systems, ready-to-use presentations, manufacturing processes or other product attributes. Those rights must be analyzed separately from Patent 7,683,037. The supplied claims do not establish a formulation patent estate.

What patents protect regadenoson and Lexiscan?

The regadenoson patent estate has historically included several categories of rights.

Patent category	Typical protection	Relevance to Patent 7,683,037
Composition patents	Regadenoson molecule and related A2A agonists	Separate from the asserted method claims
Method-of-use patents	Coronary vasodilation and stress imaging	Core category of Patent 7,683,037
Dosing patents	Fixed-dose, weight-based or rapid-bolus administration	Overlaps claims 2–14 and 21–25
Imaging patents	Timing of radionuclide administration and myocardial examination	Overlaps claims 15–26
Formulation patents	Stability, concentration, excipients and presentations	Not expressly claimed in the supplied claims
Manufacturing patents	Synthesis, purification and solid-state forms	Potentially relevant to API suppliers and generic manufacturers

The earliest regadenoson composition and use filings were associated with CV Therapeutics. Gilead Sciences acquired CV Therapeutics in 2009. Astellas became the commercial licensee or marketer of Lexiscan in the United States under arrangements involving the product rights. Patent ownership, assignment history and licensing rights should be separated because the marketing company, patent owner and litigation plaintiff may not be the same entity. [5,6]

When did U.S. Patent 7,683,037 expire?

Patent 7,683,037 issued on March 23, 2010. Its application is tied to an April 2004 nonprovisional filing and earlier priority filings. The ordinary 20-year patent term therefore placed the base expiration in April 2024, subject to any patent-term adjustment or extension reflected in the USPTO record. [1,2]

The practical result is that the patent is no longer a forward-looking U.S. exclusionary barrier after expiration. A patent term extension under 35 U.S.C. § 156 would have to be separately identified in the official patent record. FDA regulatory exclusivity does not revive an expired patent.

What was the Orange Book status?

Lexiscan was approved under NDA 021937. FDA Orange Book listings historically identified Patent 7,683,037 in connection with the product. Orange Book listing is relevant to ANDA certification and patent litigation while a listed patent remains unexpired. It does not determine whether a patent claim is valid, infringed or enforceable after expiration. [3,4]

For an expired method-of-use patent, an ANDA applicant’s practical pathway depends on the remaining listed patents, approved labeling, use codes and any applicable regulatory exclusivity. A label carve-out may be relevant where the patented use can be removed without making the generic product unsuitable for nonpatented uses.

Were Paragraph IV challenges likely for regadenoson?

Paragraph IV certification is the principal Hatch-Waxman mechanism for challenging an unexpired Orange Book patent. A generic applicant certifies that the listed patent is invalid, unenforceable or will not be infringed.

For Patent 7,683,037, potential Paragraph IV positions would have included:

Noninfringement because the product label did not instruct an infringing bolus protocol.
Noninfringement because the label did not require the claimed coronary/peripheral physiological result.
Invalidity based on anticipation or obviousness over adenosine, regadenoson development publications, clinical protocols and earlier A2A agonist disclosures.
Indefiniteness challenges directed to “without significant peripheral vasodilation,” “about,” and functional blood-flow limitations.
Written-description or enablement challenges to the full dose and timing ranges.

The most vulnerable portions of the claim set would likely be overlapping dose ranges and broad functional limitations. The most commercially valuable claims would have been claims 14, 21, 22, 23, 24 and 25 because they map more closely to a fixed-dose, rapid-bolus stress-imaging product.

No current Paragraph IV litigation can extend the patent after expiration. Historical litigation remains relevant only to damages, settlement interpretation, claim construction and generic-launch chronology.

What generic launch risks exist after patent expiration?

The principal risk has shifted from patent blocking to regulatory and commercial execution.

Risk	Assessment
Patent 7,683,037	No continuing exclusionary effect after expiration
Composition patent	Likely expired earlier if based on early CV Therapeutics filings
Later dosing or formulation patents	Must be checked individually in the Orange Book and USPTO records
FDA approval	Depends on ANDA requirements and reference-product status
Clinical-use labeling	Affects infringement and carve-out analysis
API supply	Regadenoson synthesis, quality and supplier qualification can remain barriers
Market access	Hospital contracting and imaging-center adoption can delay uptake
Product substitution	Switching depends on vial presentation, supply reliability and pricing

Regadenoson is a small molecule, so biosimilar risk does not apply. The relevant competitors are generic injectable products, not biosimilars. The principal technical barriers are sterile manufacturing, impurity control, analytical validation, container closure, stability and supply-chain qualification.

How strong was the patent estate for Lexiscan?

Patent 7,683,037 had meaningful historical commercial scope because it tracked the approved use of regadenoson as a rapid intravenous pharmacologic stress agent. Its strength was reduced by several factors:

The active ingredient had to be the specific regadenoson molecule.
Several claims depended on physiological outcomes that could require clinical evidence.
The dose claims substantially overlapped.
Some claims contained apparent drafting or measurement ambiguities.
The patent was a method patent rather than a composition patent.
The base term ended in 2024.

The estate was stronger against a labeled generic product that expressly instructed the same fixed-dose bolus protocol than against an unlabelled supplier, an off-label use or a product using a different pharmacologic agent.

What patent litigation and settlements affected Lexiscan?

Publicly relevant disputes would be expected to center on ANDA applicants, Orange Book patents, Paragraph IV notices, use-code scope and launch dates. Patent litigation involving an expired patent may have ended through dismissal, settlement, judgment or expiration without a continuing injunction.

A settlement agreement could have included:

An agreed generic launch date;
A license before patent expiration;
A covenant not to sue;
Restrictions on authorized-generic supply;
Allocation of launch rights;
Waivers or releases tied to specific patents.

The existence of a settlement does not establish validity. Nor does a generic launch establish that every listed patent was invalid. The controlling documents are the district-court docket, settlement terms where public, FDA patent certifications and the current Orange Book entry.

What geographic coverage does Patent 7,683,037 provide?

The patent provides U.S. coverage only. It does not directly block administration, manufacture, sale or use outside the United States.

International protection would require corresponding patents in each jurisdiction. Relevant foreign issues include:

National-phase filings;
Local patent-term calculations;
Supplementary protection certificates;
Patent-term extensions;
National claim amendments;
Local generic-substitution rules.

A U.S. expiration does not establish expiration of counterpart patents in Europe, Canada, Japan, China or other markets.

Key Takeaways

U.S. Patent 7,683,037 is a regadenoson method-of-use patent.
Claim 1 covers IV bolus administration of at least 10 micrograms to produce coronary vasodilation without significant peripheral vasodilation.
Claim 15 covers regadenoson-assisted myocardial perfusion imaging with a 2.5-fold coronary blood-flow increase within about one minute.
Claims 14, 21 and 22 are closely aligned with the commercial 400-microgram Lexiscan bolus.
The patent does not expressly claim a formulation, excipient, vial, radionuclide or imaging device.
Regadenoson is a small molecule, so biosimilar risk is inapplicable.
The patent’s ordinary 20-year term ran from the 2004 nonprovisional filing and reached its base expiration in 2024, subject to the official USPTO term calculation.
Any current generic risk depends on later unexpired patents, FDA requirements, manufacturing capability and commercial contracting rather than this patent alone.
Historical Orange Book listings and Paragraph IV activity remain relevant for litigation and settlement analysis, but expiration removes the patent’s prospective blocking effect.

FAQs About U.S. Patent 7,683,037 and Regadenoson

Is Patent 7,683,037 a composition-of-matter patent?

No. It claims methods using regadenoson. Composition claims covering the molecule would be analyzed under separate patent documents.

Does a 400-microgram Lexiscan dose fall within the claims?

Yes. A 400-microgram IV bolus falls within the numerical ranges recited in claims 3, 12, 13 and 14, assuming the other incorporated limitations are satisfied.

Does the patent cover adenosine?

No. The claims identify CVT-3146/regadenoson. Adenosine is a different active ingredient.

Can a generic avoid the patent by changing the vial concentration?

Not necessarily. A concentration change alone would not avoid a method claim if the generic product still instructs IV bolus administration of regadenoson within the claimed dose and use parameters.

Are regadenoson products subject to biosimilar competition?

No. Regadenoson is a chemically synthesized small molecule. Competition proceeds through generic-drug pathways, principally ANDAs, rather than biosimilar applications.

References

United States Patent and Trademark Office. (2010). U.S. Patent No. 7,683,037, Methods for producing coronary vasodilation.
United States Patent and Trademark Office. (n.d.). Patent Center: U.S. Patent No. 7,683,037.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (2024). Lexiscan (regadenoson injection) prescribing information.
U.S. Food and Drug Administration. (2008). Lexiscan approval letter and prescribing information, NDA 021937.
Gilead Sciences, Inc. (2009). Acquisition of CV Therapeutics and related product-rights disclosures.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2003259264	⤷ Start Trial
Canada	2492855	⤷ Start Trial
China	1671399	⤷ Start Trial
European Patent Office	1524984	⤷ Start Trial
Israel	166555	⤷ Start Trial
Japan	2005538190	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 7,683,037

Summary for Patent: 7,683,037