US Patent 8,273,795: Scope, Claims, Expiration, Litigation, and Tranexamic Acid Patent Landscape

US Patent 8,273,795 protects a specific method of treating menorrhagia with two 650-mg oral modified-release tranexamic acid dosage forms. Its core limits are cumulative: the accused product must satisfy the dose, formulation composition, modified-release, dissolution, and treatment-method requirements. The patent is materially narrower than a broad composition patent covering tranexamic acid or a generic extended-release tablet.

The commercial product most closely associated with the claimed technology is Lysteda, an oral tranexamic acid product marketed for heavy menstrual bleeding. The patent’s practical value depends on whether a competing product has the same two-tablet dosing regimen and falls within the claimed dissolution profile.

What does US Patent 8,273,795 protect?

US 8,273,795 protects a method of treating menorrhagia by administering a modified-release tranexamic acid formulation in two oral dosage forms, each containing approximately 650 mg of tranexamic acid.

The independent claim requires all of the following:

Claim limitation	Required scope
Therapeutic use	Treatment of menorrhagia
Route	Oral administration
Active ingredient	Tranexamic acid or a pharmaceutically acceptable salt
Dosage	Two oral dosage forms
Dose per unit	About 650 mg tranexamic acid per dosage form
Active concentration	About 50% to 95% by weight
Modified-release material	About 5% to 50% by weight
Dissolution at 15 minutes	Less than about 40% released
Dissolution at 45 minutes	Less than about 70% released
Dissolution at 90 minutes	At least 50% released
Test method	USP 27 Apparatus II, paddle, 50 rpm, 900 mL water, 37 +/- 0.5 degrees C

The claim is therefore directed to a clinical dosing method tied to a pharmaceutical formulation with defined in-vitro performance. It is not a general monopoly over tranexamic acid, oral tranexamic acid, menorrhagia treatment, or modified-release technology.

How should claim 1 of US 8,273,795 be construed?

Claim 1 is a combination claim. Each limitation must be met for literal infringement.

Method-of-treatment limitation

The claim requires administration to a patient in need of treatment for menorrhagia. A product sold only for trauma, surgery, dental bleeding, hemophilia, or other indications would not necessarily satisfy the claimed use.

The treatment limitation creates a divided-risk analysis:

A manufacturer must make, use, or sell a product capable of infringing the formulation limitations.
Infringement of the method claim generally depends on evidence that the product is intended, directed, or used for menorrhagia.
Labeling, promotional materials, prescribing information, physician instructions, and actual use may be relevant.

A generic product with an FDA label for heavy menstrual bleeding presents substantially greater method-of-use risk than a product labeled only for non-gynecologic bleeding indications.

Two-dose, 650-mg regimen

The claim requires two oral dosage forms, each providing approximately 650 mg of tranexamic acid. This corresponds to a total administration of approximately 1,300 mg per dose.

A product administered as:

one 1,300-mg tablet;
four 325-mg tablets;
two tablets with materially different strengths; or
a different dosing schedule

may avoid literal infringement of this limitation, depending on the product’s actual labeling and formulation.

The phrase “about 650 mg” introduces a range rather than an absolute 650-mg requirement. The relevant range would be assessed in light of the specification, prosecution history, industry practice, and the patent’s disclosure.

Weight-percentage limitations

Claim 1 requires tranexamic acid or its salt to represent about 50% to 95% of the formulation by weight. The modified-release material must represent about 5% to 50%.

The dependent claims narrow these ranges:

Claim 8: active ingredient from about 60% to about 90%.
Claim 9: active ingredient from about 60% to about 80%.
Claim 10: modified-release material from about 10% to about 35%.
Claim 11: active ingredient from about 60% to about 90%, modified-release material from about 10% to about 35%, with a matrix-tablet configuration.

The claim does not require the active ingredient and modified-release material to account for 100% of the tablet. Excipients, binders, lubricants, fillers, coatings, and other materials can be present.

Dissolution limitations

The dissolution profile is central to the patent. Claim 1 requires:

less than about 40% release at 15 minutes;
less than about 70% release at 45 minutes; and
at least 50% release at 90 minutes.

Claim 2 adds a more detailed profile:

Time point	Claimed release
15 minutes	About 0% to about 40%
30 minutes	About 20% to about 60%
45 minutes	About 40% to about 65%
60 minutes	About 50% to about 95%
90 minutes	At least about 60%

The specified dissolution method is not incidental. Differences in apparatus, paddle speed, medium volume, temperature, sampling, agitation, or analytical method may affect the result. A non-infringement position based on dissolution would require validated testing under the claimed conditions.

What do claims 2 through 12 add?

Claims 2 through 12 define narrower embodiments and provide alternative infringement positions.

Claim 2: multitime-point dissolution profile

Claim 2 requires release ranges at five separate time points. It is narrower than claim 1 because a formulation must satisfy the complete profile, not simply the three points specified in the independent claim.

A competing product that fails the 30-, 60-, or 90-minute limitations may avoid claim 2 while remaining potentially exposed under claim 1.

Claims 3 and 4: substantially controlled release

Claim 3 requires release of approximately 10% to 25% of the active ingredient every 15 minutes.

Claim 4 requires release of approximately 1% per minute.

These limitations describe a substantially linear release profile. They may present measurement and claim-construction issues because the claims do not expressly define whether the release rate must be maintained across the entire 90-minute period or evaluated over specified intervals.

Claim 5: tranexamic acid rather than a salt

Claim 5 narrows the active ingredient to tranexamic acid itself. A pharmaceutically acceptable salt that otherwise falls within claim 1 may not satisfy claim 5.

Claim 6: pharmacokinetic limitation

Claim 6 requires a mean maximum plasma concentration, or Cmax, of approximately 5 to 17.5 micrograms per milliliter following administration.

This limitation shifts part of the infringement analysis from formulation testing to clinical or pharmacokinetic evidence. A generic applicant could attempt to design around this claim by producing materially different exposure characteristics while retaining similar dissolution behavior.

Claims 7 and 11: matrix tablet and granulation

Claim 7 requires a matrix tablet in which the drug is mixed with granulated modified-release material.

Claim 11 narrows the formulation further by requiring:

60% to 90% active ingredient;
10% to 35% modified-release material;
a matrix tablet; and
granulated drug mixed with modified-release material.

These claims are vulnerable to design-around strategies involving coated multiparticulates, layered tablets, osmotic systems, capsule-based systems, or other release technologies that do not use the claimed matrix and granulation structure.

What formulation technologies are covered by US 8,273,795?

The claims are broad enough to cover multiple modified-release matrix formulations, provided the product meets the compositional and dissolution limitations.

Potentially covered technologies include:

hydrophilic polymer matrix tablets;
hydrophobic matrix tablets;
granulated tranexamic acid blended with release-controlling excipients;
polymer-based erosion matrices;
diffusion-controlled tablets; and
combinations of release-modifying excipients.

The claims do not identify a single mandatory polymer in the language provided. The patent’s enforceable scope therefore turns on the functional dissolution profile and the weight percentages, not solely on the identity of the excipient.

A formulation using the same active ingredient but an immediate-release design would generally be outside the literal scope of these claims. A modified-release formulation with a faster 15-minute release or slower 90-minute release could also avoid claim 1 if the deviation is outside the “about” ranges.

What is the FDA and Orange Book relevance of US 8,273,795?

Lysteda is an FDA-approved oral tranexamic acid product for the treatment of cyclic heavy menstrual bleeding. The FDA approved Lysteda in 2009 under NDA 022430. Its dosage form is a 650-mg tablet, and the labeled regimen uses two tablets taken twice daily during menstruation. FDA, Drugs@FDA.

A patent listed in the Orange Book can create an ANDA certification issue. A generic applicant referencing the NDA may need to provide:

Paragraph I certification if no patent is listed;
Paragraph II certification if the patent has expired;
Paragraph III certification accepting delayed approval until patent expiration; or
Paragraph IV certification asserting that the patent is invalid, unenforceable, or not infringed.

For a method-of-use patent, a generic applicant may also use a section viii statement to carve out the patented indication, if the FDA-approved labeling permits a commercially meaningful non-infringing use.

The regulatory importance of US 8,273,795 depends on its Orange Book listing, expiration date, pediatric exclusivity, patent-term adjustment, and whether the FDA accepted a use carve-out for a generic applicant. Those facts must be evaluated against the current Orange Book entry and FDA regulatory history rather than the patent document alone.

When does US 8,273,795 lose exclusivity?

The patent’s base term is determined by the earliest effective nonprovisional priority date and the applicable 20-year patent term rules. The actual expiration date may be modified by patent-term adjustment, terminal disclaimers, or other USPTO-record events.

Public patent records should be used to confirm:

Date item	Relevance
Earliest effective filing date	Establishes the base patent term
Nonprovisional filing date	Determines the statutory term framework
Patent issuance date	Relevant to enforceability before issuance
Patent-term adjustment	Can extend the base expiration
Terminal disclaimer	Can restrict expiration to another patent
Orange Book expiration entry	Relevant to ANDA certification and approval
Pediatric exclusivity	Can add six months to listed patent or exclusivity protection

The issuance of US 8,273,795 in 2012 did not create a new 20-year term from the issue date. The patent term is tied primarily to the applicable filing and priority framework.

Which companies are exposed to this patent?

The highest-risk products are generic or follow-on products that match all of the following:

Tranexamic acid as the active ingredient.
Two 650-mg tablets per administration.
An indication or labeling for heavy menstrual bleeding.
Modified-release matrix technology.
Active and excipient percentages within the claimed ranges.
A dissolution profile within the claimed release windows.

Companies selling immediate-release tranexamic acid products for surgery or other bleeding disorders face a different risk profile. Their products may use the same active ingredient but lack the modified-release, dose-form, treatment-use, or dissolution limitations.

Biosimilar risk

Biosimilar analysis is not applicable. Tranexamic acid is a chemically synthesized small molecule, not a biologic. Competitive entry occurs through the ANDA pathway for a generic drug, not through a 351(k) biosimilar application.

What patent litigation affects Lysteda and tranexamic acid entry?

The principal litigation risk would arise when an ANDA applicant files a Paragraph IV certification against an Orange Book-listed patent covering Lysteda’s formulation or menorrhagia use.

A Paragraph IV notice can trigger litigation under the Hatch-Waxman statute. If the NDA holder files an infringement action within the statutory period, FDA approval may be subject to a 30-month stay, subject to statutory exceptions and court decisions.

Relevant disputes typically focus on:

whether the generic formulation meets the dissolution profile;
whether the generic label induces treatment of menorrhagia;
whether “about 650 mg” is satisfied;
whether the formulation contains the required modified-release material;
whether the patent claims are anticipated or obvious;
whether the patent adequately describes and enables the claimed release profile; and
whether prosecution-history statements narrow the meaning of “about” or “modified release.”

Settlement agreements can permit an earlier generic launch, but the commercial date depends on the agreement, court approval where required, patent status, FDA approval, and any other listed patents.

How strong is the patent estate for this technology?

US 8,273,795 has meaningful but concentrated strength.

Strengths

It combines method-of-use and formulation limitations.
The two-tablet, 650-mg regimen maps closely to the commercial dosing configuration.
The dissolution limitations provide an objective testing framework.
The claims cover multiple possible modified-release materials.
Dependent claims add matrix, granulation, composition, and pharmacokinetic fallbacks.

Weaknesses

The claims do not broadly cover all tranexamic acid products.
A generic can potentially design around the two-tablet regimen.
A different release technology may avoid the matrix claims.
Dissolution results can vary with testing conditions and manufacturing process.
Method-of-use infringement depends heavily on labeling and actual use.
“About” limitations create a boundary dispute around numerical ranges.
Prior-art risk is potentially significant because controlled-release tablets and tranexamic acid were known technologies.

The strongest enforcement position is against a product that deliberately replicates the Lysteda dose, dosage form, indication, and release characteristics. The weakest position is against an immediate-release or differently dosed product marketed for a non-menorrhagia indication.

How does US 8,273,795 compare with a broad tranexamic acid patent?

Issue	US 8,273,795	Broad active-ingredient patent
Subject matter	Menorrhagia treatment using a specific modified-release formulation	Tranexamic acid compound or broad therapeutic use
Dosage form	Two oral dosage forms, approximately 650 mg each	May be unrestricted
Dissolution	Required release profile	Usually not required
Formulation	Modified-release material and weight ranges	May not require formulation limits
Infringement proof	Requires formulation and use evidence	Often simpler if compound claims apply
Design-around potential	Moderate to high	Lower if the compound claim remains valid
Relevance to Lysteda generics	Direct	Depends on expiration and claim scope

What generic launch scenarios exist?

Scenario 1: Same 650-mg modified-release product

This is the highest-risk scenario. A generic matching the Lysteda formulation and labeling may face a Paragraph IV challenge, infringement litigation, or a settlement delaying launch.

Scenario 2: Same indication, different release profile

A product with a materially different dissolution curve may avoid some or all claims, but the formulation must be tested under the patent’s specified method.

Scenario 3: Different dose architecture

A one-tablet 1,300-mg product or another dosage schedule could avoid the express two-dosage-form limitation, subject to regulatory and clinical constraints.

Scenario 4: Label carve-out

A generic could seek approval for non-menorrhagia uses while excluding the patented heavy-menstrual-bleeding indication. This strategy depends on whether the remaining uses are commercially viable.

Scenario 5: Immediate-release tranexamic acid

An immediate-release product is less likely to meet the modified-release and dissolution limitations, although it may face other patents, regulatory requirements, or labeling-based issues.

Key Takeaways

US 8,273,795 is a narrow combination patent, not a broad tranexamic acid patent.
Its core protection is a two-tablet, 650-mg oral modified-release regimen for menorrhagia.
The dissolution profile is a principal infringement gate.
Claims 7 and 11 focus on matrix-tablet and granulation structures.
Claim 6 adds a Cmax limitation that may require pharmacokinetic evidence.
Immediate-release products and products for non-menorrhagia indications present lower direct risk.
Generic applicants are likely to focus on Paragraph IV invalidity, non-infringement, label carve-outs, or formulation design-arounds.
Biosimilar analysis does not apply because tranexamic acid is a small-molecule drug.
Current enforceability and generic timing depend on the USPTO patent file, FDA Orange Book listing, patent-term adjustment, litigation docket, and any settlement agreement.

FAQs

Does US 8,273,795 cover all oral tranexamic acid tablets?

No. The claims require modified release, specific dose architecture, defined composition ranges, and dissolution performance.

Can a generic avoid the patent by using one 1,300-mg tablet?

Potentially. The independent claim expressly requires two oral dosage forms, each providing approximately 650 mg. The product would still require analysis against other patents and regulatory requirements.

Does an FDA label for heavy menstrual bleeding create infringement risk?

Yes. A label directing use for menorrhagia or cyclic heavy menstrual bleeding can support the method-of-treatment element, particularly when the formulation and dosing limits also match.

Can a formulation outside the dissolution range infringe under the doctrine of equivalents?

Potentially, but the analysis would depend on prosecution history, the significance of the numerical limits, prior art, and whether applying equivalents would effectively eliminate a negotiated claim boundary.

Is a tranexamic acid biosimilar required for market entry?

No. Tranexamic acid is a small molecule. A competing product would generally use the ANDA pathway, subject to applicable patents, exclusivity, bioequivalence, and labeling requirements.

References

United States Patent and Trademark Office. (2012). United States Patent No. 8,273,795: Modified release tranexamic acid formulations.
U.S. Food and Drug Administration. (2009). Lysteda (tranexamic acid) tablets, NDA 022430: Prescribing information. Drugs@FDA.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Orange Book.
United States Code. (2018). 35 U.S.C. §§ 154, 271, and 283-285.
United States Code. (2018). 21 U.S.C. § 355(j).

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Japan	2008508275	⤷ Start Trial
Japan	2008508276	⤷ Start Trial
Japan	2011168596	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 8,273,795