U.S. Patent 11,446,246: Claim Scope, Baclofen Formulation Protection, and Generic Entry Risk

U.S. Patent 11,446,246 protects a method of treating spasticity with a specific 5 mg/mL liquid baclofen formulation. The patent is formulation-specific but claims use of the formulation, rather than merely the composition itself. The principal infringement risk concerns an ANDA or commercial product that uses the claimed excipient system, pH range, stability profile, and spasticity indication.

The patent does not broadly cover all oral baclofen liquids. A competing product may avoid literal infringement by changing a required concentration, omitting a listed ingredient, using a different stabilizer, falling outside the claimed pH range, or avoiding the claimed treatment method.

What does U.S. Patent 11,446,246 protect?

Claim 1 is the only independent claim supplied. It requires all of the following:

Required limitation	Claimed requirement
Therapeutic method	Treating spasticity in a subject
Dosage form	Liquid oral pharmaceutical composition
Active ingredient	Baclofen or a salt thereof
Baclofen concentration	5 mg/mL
Citric acid	0.12% w/v, anhydrous
Hydroxyethyl cellulose	0.5% w/v
Propylene glycol	5% w/v
Simethicone emulsion	0.15% w/v, 30% emulsion
Sodium benzoate	0.1% w/v
Sucralose	0.2% w/v
Vehicle	Water
pH	3.0 to 6.0
Stability	Less than +/-5% baclofen concentration variation by USP assay for at least 30 days at room temperature

The open-ended term “comprises” generally permits additional ingredients. Adding a flavor, color, buffer, preservative, or other excipient will not by itself avoid claim 1 if every listed limitation remains present in the claimed amounts. Claim construction and infringement analysis are governed by the patent claims, specification, prosecution history, and applicable Federal Circuit precedent. [1]

How broad is claim 1 for baclofen oral solutions?

Claim 1 is narrow in composition but potentially meaningful commercially because it combines composition and use limitations.

The claim does not require:

A particular brand name;
A particular bottle or container;
A specific dose administered to the patient;
A particular dosing frequency;
A particular age group;
Multiple sclerosis specifically;
A particular flavor or color;
A particular manufacturing process;
A particular baclofen salt, provided the salt satisfies the claimed baclofen requirement;
A particular room-temperature definition beyond the stability limitation.

The claim does require use of the liquid composition to treat spasticity. A product with the same composition but no use, labeling, promotion, or administration for spasticity presents a different infringement question from a product marketed with a spasticity indication.

Because the claim uses “comprises,” the ingredient list is a floor, not necessarily an exhaustive formulation. A generic manufacturer could add excipients and still fall within the claim.

Which dependent claims add the greatest commercial restrictions?

Claims 2 through 10 narrow the formulation or stability profile. Claims 11 through 16 narrow the treatment population or symptoms.

Claims	Added limitation	Commercial significance
2	Less than +/-5% variation after at least 30 days at 38-42°C	Requires accelerated or high-temperature stability performance
3	Less than +/-5% variation after at least 30 days at 15-30°C	Defines a separate temperature range
4	Less than +/-2% variation after at least 30 days at room temperature	Stronger stability limitation
5	Coloring agent, flavoring agent, or both	Broad dependent formulation limitation
6	0.0002% w/v D&C Yellow No. 10	Specific color formulation
7	About 0.000038% w/v FD&C Red No. 40	Specific color formulation with approximate language
8	0.0500% w/v flavor grape 59.266/A	Specific flavor formulation
9	pH 3.6-4.6	Narrower pH window
10	pH 4.0-4.3	Narrowest stated pH window
11	Alleviation of spasms, pain, stiffness, tightness, or cramping	Defines covered symptoms
12	Symptoms caused by multiple sclerosis	Multiple sclerosis limitation
13	Human subject	Excludes nonhuman treatment
14	Child	Pediatric limitation
15	Adult or elderly human	Adult population limitation
16	Human with multiple sclerosis	Multiple sclerosis and human limitations

Claims 6, 7, and 8 are commercially relevant if the reference product uses the specified coloring and flavoring system. They are vulnerable to straightforward formulation design-around if those excipients are not medically or commercially necessary.

What stability performance does the patent require?

The stability limitations are central to infringement and validity.

Claim 1 requires less than +/-5% variation in baclofen concentration, measured by a USP assay, after at least 30 days at room temperature. Claim 2 extends the requirement to 38-42°C. Claim 3 specifies 15-30°C. Claim 4 tightens the allowed variation to less than +/-2% at room temperature.

The claims raise several technical questions:

The baseline concentration must be identified before the 30-day comparison.
The USP assay method and applicable monograph or analytical procedure must be determined.
The meaning of “room temperature” must be established from the specification, prosecution history, or expert evidence.
The assay’s precision, sampling plan, and acceptance criteria may affect the result.
The claim does not state whether the variation is calculated from label claim, initial assay value, or average assay value.

A competitor could challenge infringement by showing that its product does not meet the claimed stability threshold, even if the formulation otherwise matches. Conversely, a patentee may rely on batch records, stability protocols, assay data, and product specifications to establish the limitation.

What formulation design-arounds could avoid the patent?

The strongest design-arounds change a required element rather than merely adding an ingredient.

Design-around	Likely effect
Use a baclofen concentration other than 5 mg/mL	Avoids the concentration limitation
Replace hydroxyethyl cellulose	Avoids a required excipient
Use a different preservative instead of sodium benzoate	Avoids a required excipient
Omit simethicone emulsion	Avoids a required excipient
Replace sucralose	Avoids a required sweetener
Use a pH below 3.0 or above 6.0	Avoids claim 1’s pH range
Use a nonaqueous or materially different vehicle	May avoid the water limitation, depending on formulation
Demonstrate failure of the claimed 30-day stability threshold	May avoid the stability limitation
Market exclusively for a non-spasticity indication	May reduce method-of-use risk, subject to actual conduct
Use a tablet, capsule, injectable, or intrathecal formulation	Avoids the liquid oral dosage-form limitation

A minor change in flavor or color is less effective against claim 1 because claims 5 through 8 are dependent claims. Removing the specified flavor or color may avoid those dependent claims but will not avoid claim 1 if the base formulation remains unchanged.

How do the method-of-treatment claims affect generic infringement?

The claims are directed to treatment methods, not directly to the manufacture or sale of a composition. A generic product can create infringement exposure through:

An ANDA label that includes treatment of spasticity;
Instructions directing administration of the claimed formulation;
Promotional materials identifying spasticity treatment;
Physician or pharmacy use that is encouraged or induced by the applicant;
A product whose approved labeling necessarily directs the claimed use.

Under 35 U.S.C. § 271(e)(2), submission of an ANDA with a Paragraph IV certification can create patent litigation exposure before commercial launch. [2] Induced infringement under 35 U.S.C. § 271(b) depends on evidence of intent and encouragement of infringing use. [3]

A label carve-out may reduce risk only if the omitted indication or use is separable and the remaining label does not still encourage the patented method. A generic that retains a broad “spasticity” indication would face a materially stronger infringement case than one that removes the relevant patented use, subject to FDA approval and the product’s actual labeling.

What is the Paragraph IV risk for a generic baclofen oral solution?

A generic applicant could challenge the patent through a Paragraph IV certification asserting that the patent is invalid, unenforceable, or not infringed. The principal challenge theories would likely involve:

Anticipation

A challenger would need prior art disclosing every limitation, including the exact or legally equivalent ingredient concentrations, pH range, liquid oral form, spasticity treatment, and 30-day USP assay stability result. General disclosures of baclofen oral solutions would not necessarily anticipate the full combination.

Obviousness

Obviousness would likely be the more substantial validity issue. A challenger could combine prior art relating to:

Baclofen oral liquids;
Hydroxyethyl cellulose as a suspending or thickening agent;
Propylene glycol;
Sodium benzoate;
Sucralose;
Simethicone;
Acidified formulations;
Stability testing.

The strongest defense would focus on unexpected stability, compatibility, palatability, dosing accuracy, or preservation results. The precise stability limitation may provide the principal basis for distinguishing routine formulation optimization from a patentable result. The analysis would depend on the prior-art combinations and the patent’s experimental data. [4]

Written description and enablement

The exact concentrations and color/flavor options appear to require support in the specification. The stability limitations must also be enabled across the claimed formulation and temperature ranges. A challenge could focus on whether the disclosure supports the full breadth of “baclofen or a salt thereof,” all pH values from 3.0 to 6.0, and the claimed stability performance without undue experimentation.

Indefiniteness

Potential issues include the meaning of “room temperature,” the calculation of “variation,” the relevant USP assay, and the scope of “about” in claim 7. These terms may be sufficiently definite if the specification or industry practice supplies objective boundaries.

What is the Orange Book status of U.S. Patent 11,446,246?

A patent’s Orange Book status cannot be established from the claims alone. FDA listing depends on whether the patent is submitted for an approved drug product and whether FDA accepts the listing under its patent-listing rules. FDA’s Orange Book identifies patents and regulatory exclusivities associated with approved drug products, but a patent number by itself does not establish that it is currently listed, accurately listed, or enforceable. [5]

For a baclofen oral solution, the relevant regulatory pathway is generally an abbreviated new drug application for a therapeutically equivalent generic product. A 505(b)(2) applicant could face a different certification and patent strategy if it relies partly on an existing product while introducing formulation or labeling differences.

When does U.S. Patent 11,446,246 lose exclusivity?

The patent’s expiration date cannot be calculated from the patent number or claims. U.S. utility patent term generally runs 20 years from the effective nonprovisional filing date, subject to patent-term adjustment, terminal disclaimers, patent-term extension, and applicable priority rules. [6]

The issue date, September 20, 2022, does not establish the expiration date. Any commercial exclusivity analysis should distinguish:

Patent expiration;
FDA three-year or five-year exclusivity;
Pediatric exclusivity;
Regulatory stays arising from Paragraph IV litigation;
Any terminal disclaimer tying the patent to an earlier-expiring patent.

Does biosimilar risk apply to this patent?

No. Baclofen is a small-molecule active ingredient. The relevant competitive pathway is generic substitution through an ANDA or, in some circumstances, a 505(b)(2) application. The Biologics Price Competition and Innovation Act biosimilar pathway does not apply to an ordinary baclofen oral solution. [7]

How strong is the patent estate based on the supplied claims?

The supplied claims create a focused formulation patent position rather than a broad baclofen monopoly.

Strength factor	Assessment
Exact excipient combination	Strong against close copies
Open “comprises” language	Expands coverage to formulations with added ingredients
Treatment-method requirement	Can support use-based infringement but complicates enforcement
Exact concentration limits	Creates clear design-around opportunities
Stability limitation	Potentially valuable if supported by robust data
pH ranges	Provides practical but avoidable formulation boundaries
Color and flavor claims	Narrow and relatively easy to design around
Multiple sclerosis claims	Adds use specificity but does not broaden the base claim
Pediatric and adult claims	Population-specific, not composition-broadening
Manufacturing protection	None apparent in the supplied claims
Composition-only claim	None supplied

The patent’s commercial value therefore depends on whether the marketed reference formulation is difficult to reproduce without the claimed excipient system and whether a generic must use the formulation to obtain comparable palatability, stability, and dosing characteristics.

What patent litigation and licensing deals affect this patent?

No litigation, settlement agreement, license, assignment, or current Orange Book listing can be established from the claim text supplied. The claims identify technical coverage, not ownership history, transaction history, or litigation status. Those issues are separate from claim construction and require the official patent, FDA, court, and assignment records.

Key Takeaways

Claim 1 covers use of a specific 5 mg/mL liquid baclofen formulation to treat spasticity.
The required excipient system includes citric acid, hydroxyethyl cellulose, propylene glycol, simethicone, sodium benzoate, sucralose, and water.
The principal technical limitation is less than +/-5% baclofen assay variation after 30 days at room temperature.
Claims 2 through 4 add high-temperature, controlled-temperature, and tighter stability requirements.
Claims 6 through 8 protect specific color and flavor embodiments.
Claims 12 and 16 target multiple sclerosis-related spasticity; claims 14 and 15 divide the human population by age.
A generic using the same formulation and a spasticity label faces the highest risk.
Concentration, excipient, pH, dosage form, and indication changes provide the clearest design-around paths.
The patent is not a biosimilar issue because baclofen is a small molecule.
The patent expiration date and Orange Book status cannot be determined from the claims or patent number alone.

Frequently Asked Questions

Can a generic use the same 5 mg/mL baclofen concentration with different excipients?

Yes, but it must avoid every limitation of at least one asserted claim. Replacing a required excipient may avoid literal infringement, although the stability, pH, and treatment-method limitations must also be evaluated.

Does adding an extra preservative avoid U.S. Patent 11,446,246?

No. The claims use “comprises,” so additional ingredients generally do not avoid infringement if the required ingredients and other limitations remain present.

Can a generic avoid the patent by changing the baclofen salt?

Not necessarily. Claim 1 covers “baclofen or a salt thereof.” A different pharmaceutically acceptable baclofen salt may remain within the claim.

Are the color and flavor claims likely to block all generic oral solutions?

No. Claims 6 through 8 are narrow dependent claims. A generic can omit the specified dyes and grape flavor, but it would still need to avoid claim 1 and any other asserted claims.

Is a Paragraph IV certification required for every generic baclofen product?

No. The certification depends on which patents are listed for the relevant reference product and whether those patents are applicable to the proposed product and use. A product that does not rely on the listed formulation or patented method may pursue a different certification position.

References

United States Patent and Trademark Office. (2022). U.S. Patent No. 11,446,246.
35 U.S.C. § 271(e)(2) (2023).
35 U.S.C. § 271(b) (2023).
35 U.S.C. §§ 102, 103, 112 (2023).
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
35 U.S.C. § 154(a)(2) (2023).
Biologics Price Competition and Innovation Act of 2009, Pub. L. No. 111-148, §§ 7001-7002, 124 Stat. 119, 804-821.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Azurity	FLEQSUVY	baclofen	SUSPENSION;ORAL	215602-001	Feb 4, 2022	AB	RX	Yes	Yes	11,446,246	⤷ Start Trial				INDICATED FOR THE TREATMENT OF SPASTICITY RESULTING FROM MULTIPLE SCLEROSIS	⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Canada	3036356	⤷ Start Trial
China	109922801	⤷ Start Trial
European Patent Office	3509592	⤷ Start Trial
European Patent Office	4755373	⤷ Start Trial
World Intellectual Property Organization (WIPO)	2018049184	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 11,446,246

Which drugs does patent 11,446,246 protect, and when does it expire?

Summary for Patent: 11,446,246