US Patent 8,513,259: Cetirizine Injection Claims, Exclusivity, Litigation Risk, and Patent Landscape

US Patent 8,513,259 protects a method of administering intravenous cetirizine for acute urticaria, angioedema, and related acute allergic reactions. Its core limitation is pharmacokinetic: the intravenous dose must produce a Cmax greater than twice that of an equivalent immediate-release oral cetirizine dose while maintaining substantially similar overall exposure. The patent does not broadly cover all cetirizine injections. It covers a defined intravenous dosing method, dose range, administration rate, patient population, and pharmacokinetic result.

The patent was assigned to JDP Therapeutics, the developer of Quzyttir, cetirizine hydrochloride injection. The patent issued on August 20, 2013, from an application claiming priority to a November 2009 filing. Its projected basic patent-term expiration is in November 2029, subject to any applicable patent-term adjustment or terminal disclaimer. Quzyttir received FDA approval in 2019 for the treatment of acute urticaria in adults and pediatric patients six months of age and older.[1][2]

What does US Patent 8,513,259 protect?

The patent protects a method with five central elements:

Claim element	Scope of US 8,513,259
Active ingredient	Cetirizine
Route	Intravenous injection
Dose	2 mg to 20 mg in claim 1; 5 mg to 20 mg in claim 10
Administration rate	10 mg per 1.0 to 1.5 minutes or faster
Indication	Acute urticaria or angioedema associated with an acute allergic reaction
Pharmacokinetic result	Cmax greater than twice the Cmax of an equivalent immediate-release oral dose
Total exposure	AUC0-36 and AUC0-inf substantially the same as the oral reference
Additional clinical result	No substantial increase in drowsiness or dry mouth compared with oral cetirizine

The patent is therefore a method-of-treatment patent combined with a pharmacokinetic limitation. A competing product would need to satisfy the full combination of limitations in at least one asserted claim to create a literal infringement case.

The claims do not require a particular excipient, container, manufacturing process, pH, preservative, or concentration. The claimed subject matter is centered on clinical use and pharmacokinetic performance rather than composition-of-matter protection.

How broad is independent claim 1?

Claim 1 is broad in dose and indication but narrow in its combined technical requirements. It requires:

An individual requiring treatment for acute urticaria or angioedema associated with an acute allergic reaction.
An injectable cetirizine composition.
Intravenous administration.
A dose containing 2 mg to 20 mg of cetirizine.
Administration at a rate of 10 mg per 1.0 to 1.5 minutes or faster.
A Cmax exceeding twice that of a same-dose immediate-release oral cetirizine reference.
Substantially equivalent AUC0-36 and AUC0-inf relative to that oral reference.

The phrase “or faster” is important. The minimum stated rate is approximately 6.67 mg per minute if the 10 mg dose is administered over 1.5 minutes. A 10 mg dose administered over one minute satisfies the rate limitation. A 10 mg dose administered over two minutes would not satisfy the literal rate requirement.

The claim also uses a dose-matched oral comparator. A 10 mg intravenous dose must be compared with a 10 mg immediate-release oral dose, not with a 5 mg or 20 mg oral dose. The comparison is central to the claim and creates potential design-around opportunities if a product uses a different dose, administration route, or reference methodology.

What do claims 2 through 10 add?

Claim 2: approximately 4.2-fold Cmax

Claim 2 narrows claim 1 by specifying that the intravenous Cmax is about 4.2 times the oral Cmax. This limitation corresponds to the pharmacokinetic result described for a 10 mg dose, where the intravenous Cmax was approximately 1,345 ng/mL versus approximately 318 ng/mL for oral cetirizine.

A product producing a materially lower or higher ratio could fall outside this dependent claim while still potentially implicating claim 1 if its Cmax remains greater than twice the oral comparator.

Claims 3 and 4: drowsiness and dry mouth

Claims 3 and 4 require that intravenous administration not substantially increase drowsiness or dry mouth compared with oral cetirizine.

These claims introduce factual and clinical-evidence issues. “Substantially increase” is not expressed as a fixed numerical threshold. Enforcement would likely depend on clinical-trial data, statistical analysis, adverse-event definitions, and the appropriate oral comparator.

These limitations are narrower than claim 1 because claim 1 does not expressly require the absence of increased drowsiness or dry mouth.

Claim 5: specified Cmax values

Claim 5 specifies:

Oral 10 mg mean Cmax: approximately 318 ng/mL.
Intravenous 10 mg mean Cmax: approximately 1,345 ng/mL.

The claim text supplied identifies the intravenous value as “1345 ng/ml hr.” Cmax is normally expressed as a concentration, such as ng/mL, rather than concentration-time units. The “hr” notation appears to be a drafting or transcription error. A court would likely examine the issued patent specification and prosecution history when interpreting the limitation.

Claim 6: specified AUC values

Claim 6 requires approximately:

AUC0-36: 2,550 to 2,640 ng·hr/mL.
AUC0-inf: 2,650 to 2,772 ng·hr/mL.

This claim narrows claim 1 by specifying numerical exposure ranges. The AUC requirement limits the patent’s reach to formulations and dosing conditions that preserve total systemic exposure despite the substantially higher early plasma concentration.

Claims 7 and 8: early exposure

Claim 7 requires AUC0-1hr to be approximately twice that of the oral reference. Claim 8 requires AUC0-2hr to be approximately 1.5 times the oral reference.

These claims protect the rapid-onset profile rather than only the total 36-hour or infinite exposure. They are commercially relevant because the intended value of intravenous cetirizine is rapid relief in acute-care settings.

Claim 9: anaphylaxis

Claim 9 adds anaphylaxis to the acute allergic reaction. The claim does not necessarily cover treatment of anaphylaxis as a substitute for epinephrine. It covers use of the claimed intravenous cetirizine method where the acute allergic reaction includes anaphylaxis.

Claim 10: 5 mg to 20 mg dose

Claim 10 narrows the dose range by excluding doses below 5 mg. It remains broad enough to cover the FDA-approved 10 mg dose and potential pediatric or alternative dosing regimens within the range.

What is the FDA regulatory status of injectable cetirizine?

The FDA approved Quzyttir, cetirizine hydrochloride injection, under NDA 211871 in 2019. The product is supplied as a 10 mg/mL intravenous injection. The FDA labeling describes administration by intravenous push over one to two minutes for acute urticaria.[1]

Regulatory item	Status
Product	Quzyttir
Active ingredient	Cetirizine hydrochloride
Dosage form	Intravenous injection
Strength	10 mg/mL
Applicant	JDP Therapeutics, Inc.
NDA	211871
FDA approval	2019
Approved use	Acute urticaria
Approved route	Intravenous
Approved administration	Intravenous push over approximately 1 to 2 minutes

The approved 10 mg dose administered over one to two minutes closely tracks the claimed dosing concept. A one-minute administration satisfies the express “10 mg per 1.0 to 1.5 minutes or faster” language. A two-minute administration may not satisfy that literal rate limitation, although infringement analysis would depend on the actual dose, timing, claim construction, and any asserted equivalents theory.

What is the Orange Book status of US 8,513,259?

US Patent 8,513,259 has been associated with the Quzyttir product and its intravenous cetirizine indication. The relevant Orange Book issue is not merely whether cetirizine is patented. Oral cetirizine has long been available generically. The protected commercial product is the approved intravenous formulation and its use in acute urticaria.

The patent’s expected basic term runs to approximately November 2029 based on the November 2009 priority period and the standard 20-year term from the earliest relevant nonprovisional filing. The exact enforceable date must be determined from the patent’s official term calculation, including any patent-term adjustment, terminal disclaimer, or other prosecution-specific event.[2][3]

The FDA Orange Book listing is commercially significant because an ANDA applicant referencing Quzyttir may need to address the listed patent through a Paragraph IV certification, a section viii statement where permitted, or a certification that the patent has expired or is not infringed.

When does cetirizine injection lose exclusivity?

The principal patent-based exclusivity risk point is approximately November 2029 for US 8,513,259. FDA regulatory exclusivity is separate from patent protection.

Quzyttir was approved in 2019. Any three-year clinical-investigation exclusivity associated with the NDA would generally expire before the patent term, depending on the specific FDA exclusivity code and approval basis. Cetirizine is not a new molecular entity in the United States, so five-year NCE exclusivity would not ordinarily apply to the injectable product.

The commercial exclusivity timeline is therefore dominated by the patent estate and any additional Orange Book-listed patents rather than by NCE exclusivity.

Protection type	Relevance to Quzyttir
NCE exclusivity	Generally unavailable because cetirizine was previously approved
Three-year clinical exclusivity	Potentially relevant after approval, but earlier than the principal patent expiry
US 8,513,259	Core method patent; projected expiration around November 2029
Formulation patents	Must be reviewed separately for additional term
Patent-term adjustment	Could alter the basic expiration date
Pediatric exclusivity	Depends on FDA grant and listed patent status

Are there formulation patents protecting Quzyttir?

US 8,513,259 is not primarily a formulation patent. Its claims do not recite a specific excipient system or manufacturing process. They recite an injectable cetirizine composition only as part of a method that produces defined pharmacokinetic results.

A separate formulation patent could create additional barriers if it claims:

A stable cetirizine hydrochloride solution.
A defined pH range.
Specific buffers or tonicity agents.
A preservative-free presentation.
A particular concentration or vial configuration.
A manufacturing process that limits degradation products.
A ready-to-use syringe or infusion presentation.

The existence of a formulation patent would materially change generic-entry analysis. A generic applicant could avoid the '259 method claims yet remain exposed to a separate composition or manufacturing patent. Conversely, the absence of a formulation claim would leave the principal barrier concentrated in the method patent.

How does the patent estate compare with oral cetirizine patents?

Issue	Oral cetirizine	Intravenous cetirizine
Active ingredient	Cetirizine	Cetirizine
Primary patent category	Historical compound and formulation patents	Method-of-treatment and pharmacokinetic claims
Generic availability	Broadly generic	Limited approved injectable competition
Route	Oral	Intravenous
Acute-care use	Less suited to immediate intervention	Designed for rapid onset in acute allergic conditions
Main patent risk	Generally expired or weak for basic cetirizine	Concentrated in product-specific method and formulation rights
Biosimilar pathway	Not applicable	Not applicable
ANDA pathway	Established	Potentially available, subject to listed patents and sameness requirements

The patent does not restore exclusivity to the cetirizine molecule itself. It protects a new route, dosing method, and pharmacokinetic profile. That distinction limits the patent’s reach against ordinary oral cetirizine products but strengthens its relevance against an injectable generic designed for the same acute-care use.

What Paragraph IV challenges and litigation affect US 8,513,259?

A Paragraph IV challenge would likely allege that the patent is invalid, unenforceable, or not infringed. The most likely theories would include:

Lack of written description or enablement for the full 2 mg to 20 mg dose range.
Obviousness based on intravenous antihistamine delivery, oral cetirizine pharmacokinetics, and known acute allergic-reaction treatment.
Indefiniteness of “substantially the same,” “about,” and “substantially increase.”
Noninfringement based on administration over a slower period, a different dose, or failure to meet the Cmax and AUC limitations.
Failure to satisfy the acute urticaria or angioedema indication.
Inability to reproduce the claimed pharmacokinetic comparison using the required reference product or study design.

The strongest invalidity pressure is likely obviousness. Intravenous delivery generally raises Cmax and reduces time to peak concentration. The patent’s counterposition is that the claimed method produces a specific combination: materially higher peak concentration, immediate onset, substantially equivalent total exposure, and no substantial increase in drowsiness or dry mouth.

The strongest noninfringement route is likely failure to satisfy the complete pharmacokinetic profile or administration-rate limitation. A product administered over two minutes, by infusion rather than injection, or at a dose outside the claimed range may create a meaningful design-around position.

No widely reported federal patent litigation involving US 8,513,259 is identified in the core public regulatory materials cited here. The absence of reported litigation does not eliminate Paragraph IV risk. ANDA litigation may arise only after a notice letter, and some commercial disputes resolve through confidential settlement agreements.

Which companies are challenging injectable cetirizine?

The main commercial competitor set includes:

Generic manufacturers with injectable development capabilities.
Hospital-focused injectable suppliers.
Contract manufacturers capable of sterile liquid production.
Developers of alternative intravenous antihistamines.
Sponsors pursuing acute-care allergy products with different active ingredients.

No biosimilar competition applies. Cetirizine is a small-molecule drug, so competing products would use the ANDA pathway rather than the biosimilar pathway under the Public Health Service Act.

The lack of an identified public challenger does not indicate that the estate is uncontested. Generic companies may conduct Paragraph IV diligence without filing, pursue a non-infringing product, or wait for patent expiration.

How strong is the patent estate for intravenous cetirizine?

The '259 patent has moderate commercial strength and narrower legal breadth.

Strengths

It covers the clinically valuable intravenous route.
It aligns closely with the Quzyttir dosing concept.
It includes pharmacokinetic results that can be measured in a clinical or bioequivalence program.
It covers acute urticaria and angioedema, the principal acute-care use cases.
It can be asserted against a product intentionally designed to replicate Quzyttir’s rapid-onset profile.

Weaknesses

It does not claim cetirizine itself.
It does not expressly claim a unique excipient or manufacturing platform.
Several terms are relative, including “about,” “substantially the same,” and “substantially increase.”
The claim depends on comparison with an oral reference product.
A competing product may be able to alter dose, infusion time, indication, or PK profile.
Obviousness arguments may rely on predictable pharmacokinetic effects of intravenous administration.

The estate is strongest against a direct Quzyttir substitute that uses a 10 mg intravenous dose administered rapidly for acute urticaria and produces a comparable Cmax and AUC profile. It is weaker against slower infusions, different clinical indications, alternative dose levels, or products that do not reproduce the claimed PK relationship.

What generic launch scenarios exist?

Launch after patent expiration

A generic applicant can launch after the patent expires, assuming FDA approval and no separate enforceable patent remains. This is the lowest litigation-risk path but offers limited time for market entry before competitors.

Paragraph IV launch

A Paragraph IV applicant could challenge validity or infringement before expiration. A timely patent-owner lawsuit could trigger a 30-month stay of approval under the Hatch-Waxman framework, subject to statutory conditions and FDA determinations.[4]

Carve-out or section viii strategy

If the relevant patent claim is limited to an indication not included in the proposed label, an applicant may attempt a section viii statement. This strategy is less useful if the generic label includes acute urticaria or if the patented method is inseparable from the approved intravenous use.

Design-around launch

A competitor could seek to avoid the patent by using:

A different administration rate.
A dose outside 2 mg to 20 mg.
A different acute-allergy indication.
A formulation that does not achieve the claimed Cmax relationship.
A dosing regimen that does not preserve the claimed AUC relationship.

Each design-around must still satisfy FDA requirements for safety, efficacy, sterility, concentration, and clinical labeling.

What manufacturing and geographic barriers affect competition?

Sterile injectable manufacturing is a practical barrier separate from patent rights. A competing company needs validated aseptic processing, container-closure integrity, stability data, particulate control, and a compliant supply chain for cetirizine hydrochloride injection.

US patent rights are territorial. US 8,513,259 does not block manufacture, sale, or use outside the United States unless corresponding foreign patents exist. A global launch requires separate review of patent families in Europe, Canada, Japan, China, and other target markets. The FDA approval and Orange Book effects are also US-specific.

For a US generic, the principal barriers are:

Patent certification and possible Paragraph IV litigation.
Demonstration of pharmaceutical equivalence.
Injectable-product quality requirements.
Sterile manufacturing capacity.
Potential additional formulation or process patents.
Hospital purchasing and formulary adoption.

Key Takeaways

US 8,513,259 is a method patent covering rapid intravenous cetirizine for acute urticaria, angioedema, and related acute allergic reactions.
Claim 1 requires a 2 mg to 20 mg dose, rapid intravenous administration, more than double the oral Cmax, and substantially equivalent total AUC.
The patent is closely aligned with Quzyttir’s 10 mg/mL intravenous product and rapid-push administration.
Claims 2 through 8 add specific Cmax, AUC, early-exposure, and tolerability limitations.
The patent is not a broad cetirizine composition-of-matter patent.
The projected basic expiration is approximately November 2029, subject to official term adjustments and other patent-estate events.
No biosimilar pathway applies; competing products would use the ANDA framework.
The principal generic strategies are Paragraph IV litigation, section viii labeling, or a design-around based on administration rate, dose, indication, or PK profile.
The patent is strongest against a direct Quzyttir substitute and weaker against a product that does not reproduce the claimed pharmacokinetic relationship.

FAQs

Does US 8,513,259 cover oral cetirizine tablets?

No. The claims require an injectable cetirizine composition administered intravenously. Ordinary oral cetirizine tablets and solutions do not satisfy the route limitation.

Does the patent cover intramuscular cetirizine?

The claims recite intravenous injection. Intramuscular administration would not literally satisfy that limitation.

Can a generic administer cetirizine over two minutes?

Possibly, but a two-minute administration may fall outside the express rate limitation requiring 10 mg per 1.0 to 1.5 minutes or faster. The full claim language and any additional patents would still require review.

Is Quzyttir protected by a new-molecular-entity exclusivity period?

No. Cetirizine was previously approved, so the principal protection is patent-based and product-specific rather than five-year NCE exclusivity.

Does a generic need to reproduce the 4.2-fold Cmax?

Not necessarily. The 4.2-fold result appears in dependent claim 2. A generic could avoid claim 2 while still implicating claim 1 if it produces a Cmax greater than twice the oral reference and satisfies the other claim limitations.

References

U.S. Food and Drug Administration. (2019). Quzyttir (cetirizine hydrochloride injection) prescribing information. https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/211871s000lbl.pdf
United States Patent and Trademark Office. (2013). U.S. Patent No. 8,513,259, methods of treating allergic reactions using injectable cetirizine. https://patents.google.com/patent/US8513259B2/en
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book
U.S. Food and Drug Administration. (2023). ANDA submissions: Refuse-to-receive standards. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/abbreviated-new-drug-application-anda-submissions-questions-and-answers("")]

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	⤷ Start Trial	⤷ Start Trial				METHOD OF INCREASING PEAK PLASMA OR ONSET OF PLASMA CONCENTRATION BY INTRAVENOUS INJECTION IN INDIVIDUALS IN NEED OF TREATMENT FOR ACUTE URTICARIA	⤷ 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: 8,513,259