United States Patent 8,957,113: Scope, Claim Architecture, and US Landscape for Oral Tranexamic Acid in Menorrhagia

United States Patent US 8,957,113 claims an oral, fixed-dose tranexamic acid (TXA) dosage form and a treatment regimen for menorrhagia defined by (i) dose strength, (ii) USP dissolution release kinetics under a specified test, and (iii) optional pharmacokinetic and formulation limitations (Tmax, transit time, Cmax, excipient classes, film coatings). The independent claim set is bifurcated into two near-identical dosage-form scopes that differ materially in dissolution endpoints at 30 and 45 minutes (claim set 1 vs. claim set 2), plus method claims for twice-a-day regimens achieved by administering “two oral dosage forms” per dose.

What is the core claim scope?

1) Dosage form: fixed strength and dissolution kinetics (independent claim)

Claim 1 recites an oral dosage form comprising:

Active: tranexamic acid (or a pharmaceutically acceptable salt)
Dose strength: provides a dose of about 650 mg of tranexamic acid
Excipient: pharmaceutically acceptable excipient
Dissolution method: USP 27 Apparatus Type II Paddle @ 50 RPM in 900 mL water at 37 ± 0.5°C
Release profile constraints (weight % released):
- 0–95% released by ~15 minutes
- 30–95% released by ~30 minutes
- 70–95% released by ~45 minutes
- ~100% released by ~60 minutes

Claim 23 is the second independent dosage-form claim and is the same structure except it expands dissolution ceilings:

0–95% by 15 minutes
30–100% by 30 minutes (note the upper bound changes from 95% to 100%)
70–100% by 45 minutes (note the upper bound changes from 95% to 100%)
~100% by 60 minutes

Practical scope consequence: Both claim sets are release-kinetics-defined. Competitors that match the 650 mg strength and excipient presence are still at risk if they fall within the claimed dissolution envelopes under the specified USP paddle conditions.

2) Methods of treatment: menorrhagia with “two oral dosage forms”

Claim 7: treating a patient for menorrhagia by:

Orally administering two oral dosage forms according to claim 1

This yields a claimed per-dose total TXA amount of about 1,300 mg (two units of ~650 mg).

Claim 30 mirrors Claim 7 for the second dissolution variant:

administering two dosage forms according to claim 23

How broad are the dissolution limits and what do they practically cover?

Dissolution constraints are the claim’s gating element

The independent dosage-form claims lock in:

Strength: about 650 mg TXA per unit
Test conditions: USP 27 Apparatus 2 Paddle, 50 RPM, 900 mL water, 37 ± 0.5°C
Timepoints: 15, 30, 45, 60 minutes
Weight-percent release bands: with specific ranges and a “substantially complete release” at 60 minutes

Claim set difference	Parameter	Claim 1 (tight ceiling)
Release at ~30 min	30% to 95%	30% to 100%
Release at ~45 min	70% to 95%	70% to 100%
Release at ~15 min	0% to 95% (same)	0% to 95% (same)
Release at ~60 min	~100% (same)	~100% (same)

Release envelope implication

A product that releases TXA faster (toward 100% by 30 and/or 45 minutes) may avoid Claim 1 but can still be captured by Claim 23 because that claim relaxes upper bounds.
A product that releases TXA slower (below the lower bounds at 30 and/or 45 minutes) may fall outside both independent claims.

What additional limitations narrow the scope?

A. Pharmacokinetic narrowing is present in dependent claims

Claims 2, 3, and 11 tie the dosage form to PK parameters after a single oral dose of 1,300 mg TXA:

Claim 2: mean transit time = 7.21 ± 1.01 hours
Claim 3: mean absorption time = 3.70 ± 0.94 hours
Claim 8: mean Tmax about 2 to 4 hours
Claim 9: transit time = 7.21 ± 1.01 hours (repeated from claim 2 but anchored to the method)
Claim 10: absorption time = 3.70 ± 0.94 hours
Claim 11: mean Cmax about 9 to 15 mcg/mL

Scope note: These are method/dosing performance limitations layered onto the treatment claims. They matter most in infringement theories for a regimen, where claim construction can treat them as functional outcomes rather than formulation-only features.

B. Formulation excipients are defined by category lists

Claims 4–6 define an excipient composition conceptually:

Claim 4: excipient comprises a diluent
Claim 5: diluent selected from:
- dextrose, sucrose, starch, powdered cellulose, lactose, mannitol, microcrystalline cellulose, or combinations
Claim 6: excipient comprises at least one of:
- glidant, surface active agent, coloring agent, flavoring agent, lubricant, or combination

Dependent claims 13–15 replicate the same excipient categories for the method claims.

C. Solid form and composition ratio narrowing

Claims 17–20 specify:

Claim 17: dosage form is a tablet
Claim 18: active is tranexamic acid (not salt)
Claim 19: TXA present 50% to 95% by weight of dosage form
Claim 20: TXA present 60% to 90% by weight

D. Film coating limitation is categorical

Claims 21–22 and 28–29 specify coating and film-former families:

Claim 21 / 28: dosage form is coated with a film
Claim 22 / 29: film comprises one or more film-forming agents selected from:
- hydroxypropyl cellulose
- a cellulose ester
- a cellulose ether
- one or more acrylic polymers
- hydroxypropyl methylcellulose
- cationic methacrylate copolymers

E. Dosing frequency

Claim 12: dosage forms administered three times a day.

This aligns with common TXA menorrhagia regimens in practice, but here it is explicitly claimed as a dependent method limitation.

How does the claim architecture affect infringement risk for competitors?

Design-around options are mainly dissolution-timing based

Because the independent claims are driven by:

unit strength (~650 mg),
USP dissolution paddle profile (15/30/45/60 min points),
and “about 100% at 60 minutes,”

a competitor’s safest design-around is to shift dissolution timing such that:

release at 30 minutes falls below 30% or above the claimed envelope by selecting an alternative profile relative to claim set 1 and/or 23; and/or
release at 45 minutes falls below 70% or shifts beyond the claim’s upper bound constraints.

PK-matched products still face product-by-process style dispute

Even if a competitor matches the dissolution curve, their ability to avoid infringement may depend on whether the infringement theory asserts the dependent PK limitations or uses only the independent dosage-form claim coverage.

If a claim construction treats PK-dependent language as limiting, a competitor may attempt to shift systemic exposure to fall outside (transit time, absorption time, Tmax, Cmax) ranges.
If infringement is pursued on the dosage form itself under claim 1/23, excipient and coating limitations can be optional because independent claims do not require any particular excipient identity beyond “pharmaceutically acceptable excipient.”

What does the US landscape likely look like for this family?

US 8,957,113 is in a well-populated therapy area: oral TXA for heavy menstrual bleeding/menorrhagia is widely used and increasingly supported by clinical guidance. The patent value in this context typically concentrates on:

oral formulations with controlled dissolution that achieve a specific absorption and exposure pattern, and
method-of-use regimens for menorrhagia that fit dosing schedules.

Claim-driven landscape archetypes in US TXA reformulation

Even without enumerating every US patent in the family here, the claim structure points to the main risk buckets a competitor will face in freedom-to-operate work:

Immediate-release TXA tablets
- Usually fail dissolution-envelope matching if they do not align with the specific percent released at 15/30/45 minutes under USP 2 at 50 RPM.
- May still be implicated if their dissolution falls within the claimed ranges.
Modified-release or controlled-release TXA
- Often designed to regulate dissolution and absorption.
- These are more likely to be engineered to target the claimed dissolution timepoints and can be directly captured by claim 1 or claim 23.
Dose-unit strategies (650 mg unit + two-unit regimen)
- If a competitor sells a regimen of two 650 mg units that is administered to total 1,300 mg per dose, method claims become harder to avoid.
- Dosing frequency (three times a day) can create an additional method infringement hook.
Formulation variants using different excipients or film systems
- Independent claims are tolerant to excipient identity, so these variations do not avoid claim 1/23 if dissolution is within bounds.
- Film-former and diluent lists are mainly narrowing only for dependent claims, unless a competitor’s label or product design is used to pin infringement to those dependent features.

Claim-by-claim scope map (US 8,957,113 text provided)

Dosage form

Claim 1: 650 mg TXA oral dosage form; USP 2 dissolution profile with 30/45 minute ceilings at 95%; ~100% at 60 min.
Claim 4–6: diluent and excipient functional category lists (dextrose/sucrose/starch/cellulose/lactose/manitol/microcrystalline cellulose; glidant/surface active agent/color/flavor/lubricant).
Claim 17–20: tablet; TXA active; TXA content 50–95% and preferred 60–90% by weight.
Claim 21–22: film coated; film formers in the listed cellulose/acrylic/cationic methacrylate families.
Claim 23–29: second independent dosage profile; same structure as claim 1 but 30 and 45 minute ceilings extend to 100%.

Methods (menorrhagia)

Claim 7 / 30: administer two dosage forms per claimed dosage profile (total ~1,300 mg per dose).
Claim 8 / 11: Tmax 2 to 4 hours; Cmax 9 to 15 mcg/mL (after single 1,300 mg dose to humans).
Claim 9 / 10 / 2 / 3: transit time 7.21 ± 1.01 hours and absorption time 3.70 ± 0.94 hours.
Claim 12: dosing frequency three times a day.
Claim 13–15: diluent and excipient category lists carried into method claims.

Where is the practical leverage in these claims?

Leverage 1: dissolution-profile gating

The independent claims embed a quantifiable in-vitro performance test. This is often used in litigation because it can be repeated and can be tied to product batches.

Leverage 2: total regimen strength is fixed by the “two dosage forms” structure

By claiming “two” units of 650 mg each, the method claims target a specific regimen dose arithmetic.

Leverage 3: optional dependent PK anchors

Dependent PK bounds (Tmax, Cmax, absorption time, transit time) are specific enough to support performance comparisons in infringement, while being broad enough to avoid requiring exact point estimates outside a range.

Key Takeaways

US 8,957,113 claims oral TXA tablets at ~650 mg per unit with USP 2 (50 RPM, 900 mL water, 37 ± 0.5°C) dissolution targets at 15, 30, 45, and 60 minutes.
The independent claim set splits into two dissolution envelopes:
- Claim 1 caps release at 30 and 45 minutes at 95%,
- Claim 23 extends those ceilings to 100%.
Menorrhagia treatment claims use a “two dosage forms” construct, creating a ~1,300 mg per dose regimen; one dependent claim fixes three times daily dosing.
Formulation narrowing in dependent claims includes specific excipient categories, tablet format, TXA wt% ranges, and film-coating film former families.
Performance narrowing via dependent PK metrics (Tmax, Cmax, absorption time, transit time) increases claim coverage specificity for regimen infringement theories where clinical performance is compared.

FAQs

1) What is the most important claim feature for product design around US 8,957,113?

The most important feature is the USP 2 dissolution release profile at 15, 30, 45, and 60 minutes under the specified test conditions, because it is built into both independent dosage-form claims.

2) Why are there two independent dosage-form claims (1 and 23) if both are 650 mg TXA?

They differ in the upper bounds for dissolution at 30 minutes and 45 minutes: 95% in claim 1 versus 100% in claim 23.

3) Does the patent require a particular excipient in the independent dosage-form claims?

No. The independent claims require a “pharmaceutically acceptable excipient,” while the specific diluent and other excipient categories appear in dependent claims.

4) How does the patent define the menorrhagia treatment dose?

By requiring administration of two oral dosage forms of the claimed 650 mg unit, yielding about 1,300 mg per dose. A dependent claim also fixes dosing as three times a day.

5) What dependent claims add exposure-based constraints?

Claims include ranges for Tmax (about 2 to 4 hours), Cmax (about 9 to 15 mcg/mL), absorption time (3.70 ± 0.94 hours), and transit time (7.21 ± 1.01 hours) after a single 1,300 mg oral dose.

References

USP 27 Apparatus 2 Paddle dissolution method conditions as stated in the claims provided by the user.

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

Details for Patent: 8,957,113

Summary for Patent: 8,957,113