United States Patent 6,503,911: Ranolazine Formulation Claims, Scope, Expiration and Patent Landscape

U.S. Patent No. 6,503,911 covers high-load ranolazine pharmaceutical dosage forms containing both a pH-independent binder and a pH-dependent binder. The core commercial formulation is a solid oral dosage form with approximately 70% to 80% ranolazine, methacrylic acid copolymer, and hydroxypropyl methylcellulose.

The patent’s practical significance was tied to Ranexa extended-release tablets. Its principal composition claims are now expired, eliminating current U.S. patent-based exclusion for products that practice the issued claims. The patent remains relevant for historical Orange Book analysis, prior-art review, freedom-to-operate assessments, and claim construction.

What does U.S. Patent 6,503,911 cover?

U.S. Patent 6,503,911 claims pharmaceutical dosage forms containing ranolazine at a high weight percentage with two different binders:

A pH-independent binder, principally hydroxypropyl methylcellulose, or HPMC.
A pH-dependent binder, principally methacrylic acid copolymer.
Ranolazine generally at 50 wt% or more.
In the narrower claims, ranolazine at 70 wt% to 80 wt%.
A dosage strength of approximately 350 mg to 800 mg in claim 7.
Optional microcrystalline cellulose and magnesium stearate.

The claims focus on composition, not on a particular disease indication, dosing regimen, tablet shape, manufacturing site, or brand name.

The patent issued January 7, 2003, from an application filed in 2001 and claims priority to an earlier ranolazine formulation disclosure. The listed assignee was CV Therapeutics, Inc., later acquired by Gilead Sciences, Inc. [1]

How do the claims of Patent 6,503,911 differ in scope?

The claims form a dependent hierarchy. Claim 1 is the broadest independent claim, while claim 7 is a separate, narrower independent claim directed to a specific formulation range.

Claim	Type	Required elements	Relative scope
1	Independent	At least about 50 wt% ranolazine; pH-independent and pH-dependent binders	Broadest composition claim
2	Dependent	Claim 1; 70 wt% to 80 wt% ranolazine	Narrows ranolazine loading
3	Dependent	Claim 1; methacrylic acid copolymer as pH-dependent binder	Narrows polymer identity
4	Dependent	Claim 3; 5 wt% to 12.5 wt% methacrylic acid copolymer	Narrows polymer concentration
5	Dependent	Claim 1; HPMC as pH-independent binder	Narrows binder identity
6	Dependent	Claim 5; 1 wt% to 3 wt% HPMC	Narrows HPMC concentration
7	Independent	70 wt% to 80 wt% ranolazine; 5 wt% to 12.5 wt% methacrylic acid copolymer; 1 wt% to 3 wt% HPMC; 350 mg to 800 mg ranolazine	Narrow but commercially important combination
8	Dependent	Claim 7; microcrystalline cellulose	Adds filler or compressibility component
9	Dependent	Claim 7; magnesium stearate	Adds lubricant

The commercial center of gravity is claim 7. It combines the active-ingredient loading, polymer identities, concentration ranges, and dosage-strength limitation most closely associated with a high-strength ranolazine extended-release tablet.

What formulation elements are required for infringement?

A product must satisfy every limitation of at least one asserted claim for literal infringement. The relevant elements are summarized below.

Ranolazine concentration

Claim 1 requires at least approximately 50 wt% ranolazine. Claims 2 and 7 require approximately 70 wt% to 80 wt%.

The phrase “about” introduces a numerical boundary issue. Courts generally interpret “about” in view of the specification, prosecution history, analytical precision, and technical context. A product containing 69% or 81% ranolazine would not automatically avoid claim 7. The relevant question would be whether the value falls within the patent’s scientifically and legally understood tolerance.

The concentration is calculated by weight of the dosage form. It is not necessarily the percentage of the active pharmaceutical ingredient relative to the tablet core alone unless the patent’s specification or claim construction establishes that convention.

pH-independent binder

Claim 1 requires an admixture containing a pH-independent binder. Claim 5 identifies HPMC as the pH-independent binder, and claim 6 requires HPMC at approximately 1 wt% to 3 wt%.

The claim does not require HPMC in every formulation unless claim 5 or claim 6 is asserted. Other pH-independent binders could potentially satisfy claim 1 if they perform the claimed function and fall within the claim’s construction.

pH-dependent binder

Claim 1 requires a pH-dependent binder. Claims 3, 4, and 7 identify methacrylic acid copolymer and, in the relevant dependent claims, specify a concentration of approximately 5 wt% to 12.5 wt%.

Methacrylic acid copolymers are enteric or pH-responsive polymers whose dissolution characteristics vary by gastrointestinal pH. The claim language does not appear limited to one commercial grade unless the specification or prosecution record imposed that restriction.

Admixture requirement

The two binders must be present in an admixture with ranolazine. This is important because a formulation containing only an enteric coating, but no pH-dependent binder in the dosage form as claimed, may not satisfy the limitation.

The distinction between an internal tablet binder, a matrix former, a coating polymer, and an excipient used in a separate layer can affect infringement analysis. A coating applied after tablet compression may raise a claim-construction issue if the claim requires the binder to be part of the dosage form but does not expressly require it to be in the tablet core.

What is the likely claim scope for Ranexa tablets?

Ranexa is an extended-release ranolazine product marketed by Gilead and originally developed by CV Therapeutics. The FDA-approved product was supplied in 500 mg and 1,000 mg extended-release tablets. [2]

A 500 mg tablet containing approximately 70% to 80% ranolazine would contain approximately 350 mg to 400 mg ranolazine by weight if the claim’s weight percentage is applied to the entire dosage form. A 1,000 mg tablet containing the same active percentage would contain approximately 700 mg to 800 mg ranolazine.

That relationship explains the claim 7 range:

Tablet strength	Ranolazine range under 70% to 80% loading
500 mg tablet	Approximately 350 mg to 400 mg
1,000 mg tablet	Approximately 700 mg to 800 mg

Claim 7 does not claim every 500 mg or 1,000 mg ranolazine tablet. It requires the tablet to contain the specified ranolazine percentage and the stated polymer ranges. A product with the same strength but a materially different excipient system would require a separate infringement analysis.

When did U.S. Patent 6,503,911 expire?

The patent’s ordinary 20-year term ran from its earliest effective nonprovisional filing date. Public patent records identify the expiration date as January 25, 2021, subject to any applicable patent-term adjustment or terminal disclaimer reflected in the official file history. [1]

Event	Date or status
Earliest priority date	January 25, 2000
U.S. application filing	January 25, 2001
Patent issued	January 7, 2003
Approximate ordinary term end	January 25, 2021
Current status	Expired

The patent therefore does not presently block a generic or authorized-generic formulation under U.S. patent law. A separate patent could still matter if it claims a different formulation, manufacturing process, dosage regimen, polymorph, or approved method of use.

What was the Orange Book status of Patent 6,503,911?

Patent 6,503,911 was listed in the FDA Orange Book for Ranexa. Orange Book listing gave the patent regulatory relevance for abbreviated new drug applications, including potential Paragraph IV certifications. [3]

An Orange Book listing does not itself prove that every generic product infringes. It identifies patents that the NDA holder represented as claiming the drug, a method of using the drug, or an approved product formulation.

The patent’s regulatory impact ended with expiration. After expiration, an ANDA applicant no longer faces a live patent term for this patent, although the applicant may still need to address other listed patents or regulatory exclusivities.

Did Patent 6,503,911 create a Paragraph IV risk?

Yes. During its term, a generic applicant could have certified under Paragraph IV that the patent was invalid, unenforceable, or would not be infringed by the proposed product. A Paragraph IV notice could trigger patent litigation and a 30-month FDA approval stay under the Hatch-Waxman framework, subject to the statutory conditions applicable at the time. [4]

The commercial risk depended on:

Whether the ANDA formulation used at least 50% ranolazine.
Whether it used both pH-dependent and pH-independent binders.
Whether it used methacrylic acid copolymer and HPMC within the narrower ranges.
Whether the listed claims covered the product as approved.
Whether other Ranexa patents remained unexpired.

A design-around could have reduced the risk by using a different release-control architecture, changing binder chemistry, moving the pH-responsive polymer to a separate coating, or lowering ranolazine loading below the relevant claim threshold. The validity and infringement outcome would have depended on the complete ANDA formulation and the patent’s prosecution history.

What other patents were relevant to ranolazine exclusivity?

The Ranexa patent estate included more than one patent family. The relevant categories were:

Patent category	Typical subject matter	Business significance
High-load formulation patents	Ranolazine with pH-dependent and pH-independent binders	Core tablet composition protection
Extended-release formulation patents	Controlled dissolution and release profiles	Potential product-specific barriers
Method-of-use patents	Treatment of chronic angina and related cardiovascular conditions	Potential indication-based protection
Process patents	Granulation, compression, coating, or manufacturing steps	Manufacturing and supply-chain barriers
Follow-on formulation patents	Alternative excipients, release systems, or dosage forms	Potential lifecycle management

The presence of a patent in the broader ranolazine estate does not establish that it covers the claims supplied by the user. Patent-by-patent review is required because claim scope, expiration, terminal disclaimers, and Orange Book status vary.

Patent 6,503,911 is a formulation patent. It does not, based on the quoted claims, claim:

Ranolazine as a chemical compound generally.
Every oral dosage form containing ranolazine.
Every extended-release ranolazine product.
A specific angina treatment regimen.
A particular dissolution profile.
A manufacturing process.
A specific tablet coating.
A formulation without both claimed binder types.

How strong was the patent estate for ranolazine tablets?

The estate was strongest against products closely resembling the high-load commercial tablet architecture. Claim 7 gives the patent a concentrated infringement theory because it specifies the principal quantitative features and excipient classes.

Its limitations also create design-around opportunities. A competitor could seek to avoid one or more elements by:

Using less than approximately 70% ranolazine.
Using a different pH-dependent polymer.
Eliminating HPMC.
Using a different pH-independent binder.
Using a different extended-release mechanism.
Separating the pH-responsive component into a coating or distinct layer.
Selecting polymer concentrations outside the claimed ranges.
Using a dosage strength outside the 350 mg to 800 mg ranolazine range.

The broadest claim, claim 1, creates more risk because it starts at 50 wt% ranolazine and does not specify HPMC or methacrylic acid copolymer. Its practical enforceability would depend heavily on how the terms “pH-independent binder,” “pH-dependent binder,” and “admixture” were construed.

The narrower claims are easier to assess analytically but easier to design around. That tradeoff is typical of formulation patents.

What is the FDA regulatory status of ranolazine?

FDA approved Ranexa, containing ranolazine, as an extended-release tablet for the treatment of chronic angina. [2] Ranolazine is not a biologic, so biosimilar approval under the Public Health Service Act is not the relevant pathway. Generic competitors use the ANDA pathway under the Federal Food, Drug, and Cosmetic Act. [4]

The relevant regulatory categories are:

Issue	Ranolazine status
Reference product	Ranexa extended-release tablets
Active ingredient	Ranolazine
Dosage form	Extended-release oral tablet
Generic pathway	ANDA
Biosimilar pathway	Not applicable
Orange Book relevance	Product and method-of-use patent listings
New chemical entity exclusivity	Expired
Patent 6,503,911	Expired

FDA approval of a generic ranolazine product does not establish that the generic practices every claim of Patent 6,503,911. Regulatory approval and patent infringement are separate inquiries.

What generic launch risks exist after expiration?

The direct risk from Patent 6,503,911 is no longer a launch barrier because the patent expired in January 2021. Current generic entry analysis must instead examine:

Any unexpired Orange Book patents covering Ranexa.
Any litigation settlement restrictions.
Approved-product specifications and bioequivalence requirements.
Manufacturing patents not listed in the Orange Book.
Trade-secret controls over granulation and coating processes.
Supply constraints involving ranolazine API.
State substitution and contracting conditions.
Commercial erosion from multiple ANDA entrants.

Once the relevant formulation patent expired, generic manufacturers could use the claimed combination of ranolazine, methacrylic acid copolymer, and HPMC without infringing this patent, assuming no other enforceable patent applied.

Which companies challenged or competed against Ranexa?

The competitive field consisted primarily of:

Gilead Sciences, as successor to CV Therapeutics and holder of the Ranexa franchise.
Generic manufacturers filing ANDAs for ranolazine extended-release tablets.
Potential authorized-generic or contract-manufacturing participants.
Other antianginal therapies, including beta blockers, calcium-channel blockers, and nitrates.

Public FDA approval records are the most reliable source for identifying approved generic applicants and marketing status. Patent litigation and settlement analysis must be tied to individual defendants, ANDA numbers, asserted patents, and docket outcomes rather than inferred from FDA approval alone.

What revenue exposure did the patent protect?

Patent 6,503,911 protected the formulation architecture supporting Ranexa’s commercial tablet, not all ranolazine revenue as a matter of claim scope. Its economic value came from the ability to delay or manage generic substitution for the marketed extended-release tablets.

Revenue exposure depends on:

Ranexa net sales before generic entry.
The number and timing of ANDA approvals.
The availability of 500 mg and 1,000 mg strengths.
The degree of therapeutic substitution.
Payer formulary placement.
Settlement dates and authorized-generic strategy.
The expiration of other Ranexa patents.

Because the patent expired in 2021, its present revenue contribution is historical. The relevant current valuation question is whether any separate unexpired patent, regulatory exclusivity, or contractual arrangement continues to affect ranolazine sales.

Key Takeaways

U.S. Patent 6,503,911 covers high-load ranolazine dosage forms containing both pH-dependent and pH-independent binders.
Claim 1 requires at least approximately 50 wt% ranolazine and both binder classes.
Claim 7 is the most commercially targeted claim, requiring 70% to 80% ranolazine, 5% to 12.5% methacrylic acid copolymer, 1% to 3% HPMC, and 350 mg to 800 mg ranolazine.
Claims 8 and 9 add microcrystalline cellulose and magnesium stearate.
The patent is associated with the formulation technology used for Ranexa extended-release tablets.
The patent expired approximately January 25, 2021.
It is no longer a current U.S. patent barrier to generic ranolazine products.
Paragraph IV risk was material during the patent term but is now historical for this patent.
Ranolazine is a small-molecule drug subject to the ANDA pathway, not the biosimilar pathway.
Current market-entry analysis must focus on other patents, FDA records, manufacturing constraints, and commercial contracting.

FAQs About U.S. Patent 6,503,911 and Ranolazine

Does Patent 6,503,911 cover all Ranexa tablets?

No. It covers only dosage forms meeting the specific claim limitations, including ranolazine loading and the required binder system.

Can a generic use HPMC after Patent 6,503,911 expired?

Yes. The expired patent no longer prevents use of HPMC in a ranolazine formulation. Other patents must still be reviewed independently.

Does a tablet need methacrylic acid copolymer to infringe claim 1?

Not necessarily. Claim 1 broadly requires a pH-dependent binder, while claim 3 and claim 7 specifically identify methacrylic acid copolymer.

Is Patent 6,503,911 a method-of-use patent?

No. The quoted claims are composition claims directed to pharmaceutical dosage forms.

Does the patent cover the 1,000 mg Ranexa tablet automatically?

No. The 1,000 mg strength alone is insufficient. The formulation must also satisfy the applicable ranolazine percentage, binder, polymer, and dosage-form limitations.

References

United States Patent and Trademark Office. (2003). U.S. Patent No. 6,503,911: Pharmaceutical dosage forms containing ranolazine. U.S. Department of Commerce.
U.S. Food and Drug Administration. (2006). Ranexa (ranolazine) extended-release tablets: Prescribing information.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (2018). Approved drug products with therapeutic equivalence evaluations, 38th ed. U.S. Department of Health and Human Services.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	1109558	⤷ Start Trial	PA2008017	Lithuania	⤷ Start Trial
European Patent Office	1109558	⤷ Start Trial	CA 2008 00051	Denmark	⤷ Start Trial
European Patent Office	1109558	⤷ Start Trial	91504	Luxembourg	⤷ Start Trial
European Patent Office	1109558	⤷ Start Trial	PA2008017,C1109558	Lithuania	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,503,911

Summary for Patent: 6,503,911