US Patent 8,314,083: Cetirizine Injection Claims, Patent Scope, Expiration and Generic Risk

US Patent 8,314,083 protects methods of treating acute allergic angioedema with an injectable, aqueous formulation of racemic cetirizine. Its strongest commercial coverage is directed to intravenous administration of a 1% w/v cetirizine formulation containing approximately 0.65% w/v sodium chloride at about pH 5.4 in a 1 mL single-dose presentation. The patent does not broadly cover oral cetirizine, levocetirizine, or every injectable antihistamine.

The patent creates a method-of-treatment barrier for a competitor that administers covered cetirizine injection doses in an emergency setting. It does not, by itself, establish exclusive rights over every cetirizine injection composition or every use of injectable cetirizine.

What does US Patent 8,314,083 cover?

US 8,314,083 is directed to injectable racemic cetirizine for acute allergic reactions, particularly angioedema. The issued claims combine four principal elements:

A patient-treatment method.
An emergency setting involving acute allergic angioedema.
Administration of 1 to 20 mg of racemic cetirizine or a pharmaceutically acceptable salt.
An aqueous injection composition with a pH of 3 to 9.

The patent is therefore primarily a method-of-use patent with formulation and pharmacokinetic limitations layered into dependent claims.

Independent claim 1

Claim 1 requires administration of an injection composition comprising racemic cetirizine or its pharmaceutically acceptable salt to a patient in an emergency situation requiring treatment of angioedema associated with an acute allergic reaction.

The claim also requires:

An aqueous solution;
A pH from 3 to 9; and
A dose of 1 to 20 mg.

The word "comprising" leaves the claim open to additional excipients and active ingredients. A formulation containing cetirizine plus epinephrine, a corticosteroid, or another antihistamine could still fall within the claim if the remaining limitations are met.

Dependent claim scope

Claim	Principal limitation	Commercial significance
1	Aqueous racemic cetirizine injection, pH 3-9, 1-20 mg, acute allergic angioedema	Core method claim
2	0.1%-2% w/v cetirizine, 0.1%-0.9% w/v NaCl, pH 3-9	Broad formulation range
3	About 1% w/v cetirizine, 0.65% w/v NaCl, pH about 5.4, 1 mL dose	Narrow commercial formulation claim
4	Minimizes sedation, lacks hemolytic potential, no QTc effect	Safety and clinical-performance limitation
5	Intravenous administration	Covers IV use
6	Intramuscular administration	Covers IM use
7	AUC bioequivalence range of 0.80-1.25 versus oral cetirizine	Pharmacokinetic limitation
8	Clinical symptom-reduction difference within approximately -30 to +30 versus reference injection	Comparative efficacy limitation
9	Reference injection is diphenhydramine 12.5-150 mg at 50 mg/mL	Narrows claim 8
10	Addition of ranitidine, cimetidine, epinephrine, methylprednisolone, prednisolone, or combinations	Combination-treatment coverage
11	Human or animal patient	Broadens patient population
12	Acute allergic reaction is anaphylaxis	Specific emergency indication

What formulation is protected by US 8,314,083?

The most commercially relevant formulation is the subject of claim 3:

Racemic cetirizine: approximately 1% w/v;
Sodium chloride: approximately 0.65% w/v;
pH: approximately 5.4;
Presentation: 1 mL single-dose injection.

A 1% w/v solution corresponds to approximately 10 mg/mL. A 1 mL unit therefore supplies approximately 10 mg of cetirizine, matching the adult dose used in the FDA-approved Quzyttir cetirizine hydrochloride injection product.[2]

Claim 2 is materially broader than claim 3. It covers formulations containing:

0.1% to 2% w/v cetirizine;
0.1% to 0.9% w/v sodium chloride;
pH 3 to 9; and
Water in a quantity sufficient to make the formulation.

A competing product could avoid claim 3 by changing concentration, pH, fill volume, or sodium chloride content, but it could still fall within claim 1 or claim 2. Avoidance requires analysis of every limitation, not merely the narrow formulation in claim 3.

Does the patent cover cetirizine hydrochloride?

Yes. Claim 1 covers racemic cetirizine and pharmaceutically acceptable salts. Cetirizine hydrochloride is the commercially relevant salt. The claims do not depend on a particular brand, container, manufacturer, or trade name.

Does the patent cover levocetirizine?

The claims are directed to racemic cetirizine. Levocetirizine is the R-enantiomer of cetirizine and is not automatically within the literal scope of a claim requiring racemic cetirizine. A levocetirizine injection would require a separate infringement and claim-construction analysis, including possible doctrine-of-equivalents issues.

When does US Patent 8,314,083 lose exclusivity?

The patent was issued on November 20, 2012.[1] Its underlying US nonprovisional filing date is the principal term date for a modern utility patent. The nominal expiration date is May 29, 2030, subject to any patent-term adjustment, terminal disclaimer, or other USPTO term modification recorded in the patent file.[1]

Event	Date
Earliest reported priority	May 29, 2009
US filing	May 28, 2010
Patent issued	November 20, 2012
Nominal patent expiration	May 29, 2030

The patent term does not mean that all regulatory exclusivity ends on the same date. FDA marketing exclusivity, Orange Book listings, patent-term adjustment, and any pediatric exclusivity must be evaluated separately.

What is the FDA and Orange Book status of the cetirizine injection?

FDA approved Quzyttir, cetirizine hydrochloride injection, under NDA 211340 for the treatment of acute urticaria in adults and pediatric patients six months of age and older.[2] The product is administered intravenously. Its approved labeling is directed to acute urticaria, not a general indication for anaphylaxis.

This distinction matters because the patent claims extend to angioedema and anaphylaxis through claims 1 and 12, while the approved label uses an acute-urticaria indication. A generic applicant could face different patent risks depending on its proposed label, dosing instructions, and use coding.

An Orange Book patent listing can support an ANDA certification requirement under the Hatch-Waxman framework. A listed patent does not itself establish infringement. The applicant must assess whether its proposed product and labeling would practice the listed claims. The FDA Orange Book is the controlling public source for listed patents and regulatory exclusivity associated with an approved drug product.[3]

Regulatory exclusivity

Cetirizine is an established small-molecule active ingredient. The principal regulatory barrier for an injectable product is therefore patent and product-specific FDA approval, not biologic exclusivity.

Relevant FDA pathways include:

ANDA approval for a therapeutically equivalent generic;
505(b)(2) approval for a materially different injectable product or clinical use;
Paragraph IV certification against listed patents;
Paragraph III certification if the applicant accepts delayed approval until patent expiration;
Labeling carve-outs for patented methods of use, where legally and regulatorily available.

How strong is the patent estate?

The estate is strongest against a product that reproduces the commercial injectable profile and uses it in emergency allergic treatment. Its strength is lower against products that alter the route, dose, composition, indication, or label.

Strong coverage areas

The patent presents meaningful risk where a competitor:

Administers 1 to 20 mg of racemic cetirizine intravenously;
Uses an aqueous formulation with pH 3 to 9;
Treats acute allergic angioedema or a closely related emergency allergic condition;
Uses a 10 mg/mL formulation with approximately 0.65% sodium chloride;
Adds one of the listed combination agents;
Uses the product in humans or animals.

Weaker coverage areas

The patent is less effective against:

Oral cetirizine;
A non-racemic levocetirizine injection;
A product used solely for non-allergic indications;
A formulation outside the claimed pH and concentration ranges;
A product administered subcutaneously or by a route not covered by the asserted claim;
A manufacturer that sells an injectable product without inducing the claimed treatment use.

Claim 1 remains important even if a competitor avoids claim 3. A formulation outside the specific 1%/0.65%/pH 5.4 profile may still fall within claim 1 or claim 2.

What are the principal validity issues?

The patent’s validity risk is concentrated in claim construction, obviousness, enablement, and the specificity of the clinical-performance limitations.

Obviousness

A challenger could combine prior art relating to:

Oral cetirizine;
Injectable antihistamines such as diphenhydramine;
Parenteral treatment of allergic reactions;
Sterile aqueous formulations;
Sodium chloride isotonicity;
Known cetirizine pharmacology and safety data.

The patent holder’s response would focus on the claimed combination of emergency injectable use, formulation characteristics, tolerability, reduced sedation, lack of hemolytic potential, and lack of QTc effect. Commercial success and unexpected clinical results could support nonobviousness if tied to the claimed features.

Claim 4

Claim 4 recites that administration minimizes sedation, is free of hemolytic potential, and does not demonstrate an effect on QTc. These limitations may create proof issues:

"Minimizes sedation" requires a comparator or a defined baseline;
"Free of hemolytic potential" may require a specified testing protocol;
"Does not demonstrate an effect on the QTc interval" may depend on study design and statistical interpretation.

A court could treat these as meaningful limitations if the specification supplies objective boundaries. If not, a challenger may raise indefiniteness or lack-of-written-description arguments under 35 U.S.C. §112.

Claims 7 through 9

Claim 7 uses a 90% confidence interval of 0.80 to 1.25 for AUC relative to an oral reference product. This is a familiar bioequivalence framework, but the claim’s application to an injectable product compared with an oral product raises technical questions concerning route, absorption, and the appropriate reference.

Claims 8 and 9 rely on symptom-reduction comparisons against injectable diphenhydramine. The numerical range is broad, and enforceability may depend on how the claimed endpoint, population, comparator, and statistical method are construed.

Which companies are challenging the patent?

Publicly reported commercial activity has centered on the Quzyttir product and its sponsor, JDP Therapeutics, rather than on a mature field of approved generic cetirizine injections. Cetirizine oral products have extensive generic competition, but that competition does not automatically create an infringement risk under US 8,314,083 because the patent requires injectable administration in specified clinical circumstances.

A Paragraph IV challenge would be the principal pathway for a generic applicant seeking approval before the relevant patent expiration. Such a challenge could attack:

Anticipation by prior injectable antihistamine or cetirizine art;
Obviousness of converting cetirizine into an injectable formulation;
Lack of enablement for the full pH, concentration, dose, route, and patient ranges;
Indefiniteness of functional clinical limitations;
Noninfringement based on a different indication or label.

No biosimilar challenge is relevant. Cetirizine is a chemically synthesized small molecule, not a biologic subject to the biosimilar pathway under the Public Health Service Act.

What patent litigation and settlements affect cetirizine injection?

The material litigation risk is an ANDA patent case under 21 U.S.C. §355(j) and 35 U.S.C. §271(e)(2), triggered by a Paragraph IV certification. A generic launch before the patent term ends could also create ordinary patent litigation under 35 U.S.C. §§271(a), (b), or (c), depending on the product conduct and the asserted theory.

A settlement could include:

A negotiated generic entry date;
A license limited to a particular indication;
A supply or co-development arrangement;
A covenant not to sue for a carved-out use;
Restrictions on formulation, route, or labeling.

Public FDA and patent records do not establish a broad, settled generic market for injectable cetirizine comparable to the oral cetirizine market. The absence of a widely available generic injectable product preserves practical value in the remaining patent term.

What generic launch scenarios exist?

Scenario 1: Full-label ANDA with Paragraph IV certification

A generic applicant seeks approval for the same injectable product and proposed uses. This creates the highest litigation risk because the product could practice claims 1, 2, 3, 5, and potentially 12.

Scenario 2: Paragraph III certification

The applicant accepts a delay until patent expiration. This reduces litigation exposure but postpones commercial entry.

Scenario 3: Section viii labeling carve-out

The applicant removes a patented method of use from its labeling. This strategy is more viable if the approved generic indication does not require the patented angioedema or anaphylaxis use and the remaining label does not encourage that use.

Scenario 4: Formulation and indication design-around

A competitor could use a different concentration, pH, excipient system, route, or indication. This strategy must avoid both the formulation claims and induced infringement of the method claims.

How does US 8,314,083 compare with competing antihistamine patents?

Product or technology	Primary protection	Relationship to US 8,314,083
Oral cetirizine	Composition, formulation, or oral-use patents, most of which are expired or commercially weak	Generally outside the patent’s injectable method claims
Levocetirizine	Enantiomer-specific composition and use rights	May avoid racemic-cetirizine limitations
Injectable diphenhydramine	Separate product and formulation estate	Identified as a comparator in claims 8 and 9
Injectable epinephrine	Separate emergency-treatment product	Listed as a possible combination agent in claim 10
Cetirizine injection	Formulation and method-of-treatment claims	Directly implicated by US 8,314,083 and related family rights

What geographic coverage does the patent provide?

US 8,314,083 provides rights only in the United States. Parallel rights may exist in other jurisdictions through the related international patent family, but a US patent does not block manufacture, sale, or administration outside the United States.

Geographic risk is highest for:

US commercial sales;
US clinical trials involving covered administration;
Importation of a covered injectable product into the US;
Contract manufacturing tied to US commercialization;
US distribution with labeling that encourages the claimed uses.

Foreign freedom-to-operate requires country-specific review of granted patents, national-phase applications, maintenance status, and claim scope.

What manufacturing and intellectual-property barriers remain?

The patent is only one barrier to injectable cetirizine entry. A competitor must also address:

Sterile manufacturing and aseptic filling;
Stability of cetirizine hydrochloride in the selected pH range;
Container-closure compatibility;
Particulate and endotoxin controls;
Isotonicity and injection tolerability;
Dose uniformity in a small-volume presentation;
FDA comparative pharmaceutical quality requirements;
Labeling and clinical-use restrictions.

These manufacturing constraints can raise entry costs even when a formulation design-around is technically possible. They do not expand the patent claims, but they can delay development and reduce the commercial value of a narrow noninfringing design.

Key Takeaways

US 8,314,083 is a method-of-treatment patent covering injectable racemic cetirizine for acute allergic angioedema and related emergency allergic conditions.
Claim 3 is the most commercially specific claim and corresponds closely to a 10 mg/mL, 1 mL, approximately pH 5.4 formulation with 0.65% sodium chloride.
Claims 1 and 2 provide broader coverage than the commercial formulation claim.
Claims 5 and 6 cover intravenous and intramuscular administration.
Claim 12 reaches anaphylaxis, although the FDA-approved Quzyttir label is directed to acute urticaria.
The nominal patent expiration date is May 29, 2030, subject to the recorded patent term.
Oral cetirizine competition does not directly defeat the injectable method claims.
No biosimilar pathway applies because cetirizine is a small-molecule drug.
A full-label generic would face the highest Paragraph IV and induced-infringement risk.
The principal validity issues concern obviousness, functional safety limitations, and the technical scope of the pharmacokinetic and comparative-efficacy claims.

Frequently Asked Questions

Can a company sell oral cetirizine without infringing US 8,314,083?

Yes. The asserted claims require injectable administration in an emergency allergic-treatment context. Oral cetirizine generally does not satisfy those limitations.

Does a 10 mg/mL cetirizine injection automatically infringe claim 3?

No. Claim 3 also requires approximately 0.65% w/v sodium chloride, a pH of approximately 5.4, a 1 mL single-dose form, and the other limitations inherited from claim 1.

Does the patent cover a cetirizine prefilled syringe?

Potentially. The claims do not require a vial or a particular container. A prefilled syringe could fall within the claims if its formulation, dose, route, and use satisfy the claimed limitations.

Is an injectable levocetirizine product blocked by this patent?

Not automatically. The claims require racemic cetirizine. Levocetirizine is an enantiomer and requires separate claim-construction and equivalence analysis.

Can a generic applicant avoid the patent by removing angioedema from its label?

Possibly, but label removal is not determinative. Actual product design, promotional conduct, foreseeable use, and any remaining FDA-approved indication must be evaluated against direct, induced, and contributory infringement theories.

References

United States Patent and Trademark Office. (2012). US Patent No. 8,314,083, Injectable compositions of cetirizine.
U.S. Food and Drug Administration. (2019). Quzyttir (cetirizine hydrochloride injection) prescribing information. JDP Therapeutics, Inc.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Congress. (2024). 35 U.S.C. §§ 101, 112, 271, and 282.
U.S. Congress. (2024). 21 U.S.C. § 355(j).

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Esteve	QUZYTTIR	cetirizine hydrochloride	SOLUTION;INTRAVENOUS	211415-001	Oct 4, 2019		RX	Yes	Yes	8,314,083	⤷ Start Trial				METHOD OF TREATMENT IN PATIENTS WITH CONCOMITANT ANGIOEDEMA	⤷ 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
Australia	2010266103	⤷ Start Trial
Canada	2803987	⤷ Start Trial
European Patent Office	2477634	⤷ Start Trial
Spain	2616703	⤷ Start Trial
World Intellectual Property Organization (WIPO)	2011003074	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 8,314,083