Drugs in MeSH Category Anti-Allergic Agents

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Perrigo R And D	CETIRIZINE HYDROCHLORIDE ALLERGY	cetirizine hydrochloride	TABLET;ORAL	078336-001	Dec 27, 2007		OTC	No	No
Micro Labs	DIPHENHYDRAMINE HYDROCHLORIDE	diphenhydramine hydrochloride	INJECTABLE;INJECTION	219845-001	Aug 22, 2025	AP	RX	No	No
Vitarine	TRIPROLIDINE HYDROCHLORIDE	triprolidine hydrochloride	TABLET;ORAL	085610-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Chartwell Rx	PROMETHAZINE HYDROCHLORIDE	promethazine hydrochloride	SYRUP;ORAL	040026-001	Sep 25, 1998	AA	RX	No	No
Perrigo	DIPHENHYDRAMINE HYDROCHLORIDE	diphenhydramine hydrochloride	CAPSULE;ORAL	083061-001	Approved Prior to Jan 1, 1982		DISCN	No	No

Market dynamics and patent landscape for NLM MeSH Class: Anti-Allergic Agents

Last updated: June 27, 2026

Anti-allergic agents is a broad MeSH class that spans multiple pharmacologic families, with distinct patent and exclusivity dynamics by molecule and FDA pathway. Patent risk is dominated by (1) whether the drug is still protected by unexpired formulation or method-of-use patents listed in the FDA Orange Book, (2) whether biologic/biobiosimilar entry applies (less common in this MeSH bucket), and (3) whether generics face Paragraph IV litigation around active ingredient and dosage form patents. Commercially, the category is split between high-volume, mature oral generics in allergic rhinitis and asthma subsets, and premium, patent-protected immunology and targeted therapies that can extend exclusivity windows through layered method-of-use and device-adjacent IP.

What drives market dynamics for NLM MeSH “Anti-Allergic Agents” by drug class?

Broadly, anti-allergic agents market dynamics follow three engines: seasonal demand elasticity (allergic rhinitis and urticaria), guideline-based migration to newer mechanisms, and payer control through step therapy and formulary design.

Which product segments dominate anti-allergic revenues?

• Allergic rhinitis: intranasal corticosteroids (e.g., fluticasone, mometasone, budesonide), H1 antihistamines (oral and intranasal), and combination sprays.
• Chronic urticaria and atopic disease: second-generation antihistamines, leukotriene pathway agents, and biologics in a subset of chronic spontaneous urticaria and severe allergic phenotypes.
• Asthma with allergic components: anti-IgE and other immunomodulators in overlap cohorts, plus controller therapies that are not always tagged as “anti-allergic” in retail marketing but are clinically positioned in allergic asthma.

How do exclusivity and lifecycle management typically work in this MeSH bucket?

Most “anti-allergic agents” are small molecules with long-established active ingredients. Patent leverage often shifts away from the original composition and into:

• Formulation patents (extended-release, taste-masking, intranasal delivery, particle engineering).
• Method-of-use patents (specific dosing regimens, patient subpopulations, maintenance schedules).
• Combination patents (fixed-dose combinations and dosing algorithms).
• Device and administration patents for nasal sprays and inhalers (where the device is integral to the claimed product experience).

How many patents cover anti-allergic agents, and what types of IP are most common?

Patent estates in anti-allergic categories concentrate into repeatable clusters: composition-of-matter, formulations, and method-of-use claims tied to clinical endpoints. In practice, the Orange Book is the operational map for generic entry risk, while non-Orange-Book patents often govern settlement structures and “skinny label” negotiations.

What patent types are most common for small-molecule antihistamines and intranasal steroids?

Most common claim buckets:

1. Composition of matter for active ingredients and specific salts/polymorphs.
2. Pharmaceutical compositions for intranasal sprays or extended-release tablets.
3. Manufacturing/process claims for particle size, dissolution profile, or encapsulation.
4. Method of use for specific indications and dosing schedules.

What patent types most often trigger Paragraph IV filings?

• Orange Book listed composition and formulation patents tied to the dosage form.
• Method-of-use patents when a generic seeks to launch into the same labeled indication.
• Combination product patents where the generic must certify to multiple patents per listed drug.

When does exclusivity end for major anti-allergic drugs, and what timelines matter for generics?

Exclusivity timelines for anti-allergic agents follow a two-layer model:

• Regulatory exclusivity (e.g., new chemical entity, new clinical investigation, pediatric exclusivity).
• Patent expiry and Orange Book listing (composition, formulation, and method-of-use).

What timeline milestones typically govern generic entry risk?

• Patent expiration: earliest end of enforceable patent coverage for a given listed patent family.
• Regulatory exclusivity expiry: limits approval timing in FDA processes even if patents expire (less common for older actives but critical for truly new molecules).
• Last Orange Book patent expiry: often sets the effective launch window because settlement agreements commonly require non-launch until a later date.

What is the practical “launch window” approach?

For market planning and litigation exposure, the relevant date is typically the latest of:

• the last listed Orange Book patent for the relevant drug product,
• any period stayed by litigation or settlement under Hatch-Waxman,
• and any remaining regulatory exclusivity constraints on approval.

What is the Orange Book status of anti-allergic agents, and which patents are usually listed?

Orange Book coverage is molecule-specific, but the listing pattern for anti-allergic products is consistent: each drug product (strength, dosage form) can list multiple patents across categories.

How to read Orange Book listings for this category

• Patent number and expiration date identify the legal “hard stop.”
• Patent type in Orange Book disclosures (composition, method, formulation) helps predict whether generic entry can rely on design-around or label carve-outs.
• Multiple listed patents per product is the rule, not the exception, in combination and device-enabled nasal products.

Which generic entry risks exist for anti-allergic agents, including Paragraph IV challenges?

Generic entry risks are driven by:

• how many Orange Book patents remain at the time of ANDA filing,
• the strength and enforceability posture (as reflected by litigation outcomes and settlement terms),
• and whether the generic can launch with a carve-out (skinny label) that avoids method-of-use claims.

What does Paragraph IV typically target in anti-allergic launches?

• Formulation patents controlling intranasal delivery and performance.
• Method-of-use patents tied to labeled indications (e.g., allergic rhinitis seasons or dosing schedules).
• Combination patents that prevent generic substitution without matching the claimed regimen.

How do settlements usually play out in this therapeutic area?

Settlements in mature anti-allergic categories frequently include:

• agreed non-launch dates aligned to the last-in-force patent,
• sometimes authorized brand switching limitations,
• and occasionally provisions allowing launch of non-infringing strengths or formulations earlier if the settlement carves around specific claims.

What patent litigation affects anti-allergic agents, and how do outcomes change market timing?

Litigation drives delayed market entry and sets precedent on claim construction and validity. For business planning, the “market effect” is usually measurable as a gap between:

• ANDA acceptance/approval timing, and
• actual commercial launch after final judicial or settlement terms.

What are typical litigation themes in antihistamine and intranasal steroid patent disputes?

• Validity challenges around obviousness or prior art.
• Non-infringement based on formulation differences (particle size, excipient profile) or dosing regimen differences.
• Indication carve-outs when method-of-use patents are asserted.

How do biologics or biosimilars affect the anti-allergic agents patent landscape?

Biologics appear within allergic disease adjuncts, but they are not uniformly tagged under the MeSH “Anti-Allergic Agents” grouping in all datasets. Where biologics apply, biosimilar dynamics are governed by:

• biosimilar exclusivity and interchangeability pathways,
• manufacturer-specific IP on molecules, formulations, and manufacturing processes,
• and patent thickets around Fc variants, glycosylation, and dosing regimens.

What is the business impact of biosimilar readiness in allergic indications?

Biosimilar launches typically compress price and shift share quickly, but timing is often delayed by:

• patent litigation and stay arrangements,
• complex CMC comparability activities,
• and payer contracting cycles for biosimilar adoption.

Which companies hold the strongest patent estates in anti-allergic agents?

In anti-allergic categories, patent strength generally tracks with R&D intensity in:

• intranasal delivery technology,
• combination regimens,
• and immunology adjacent therapeutics.

What company profiles tend to show dense IP in this space?

• Originator brands with active lifecycle management (formulation and regimen patents).
• Device-integrated product owners where nasal administration technology is tied to claimed performance.
• Immunology developers where method-of-use and patient stratification patents remain active.

How does anti-allergic agents patent strength compare between small molecules and immunology therapies?

Small molecules tend to be constrained by clear patent expiration schedules and predictable generic entry routes through ANDA plus carve-outs.

Immunology therapies tend to produce longer-lived and more heterogeneous patent thickets:

• biologic-specific molecule protection can be complemented by dosing and regimen IP,
• and manufacturing process claims can complicate “design-around” efforts.

Which formulation patents for anti-allergic agents are most likely to block generic substitution?

Formulation patents in this class usually target:

• intranasal particle engineering,
• dissolution and bioavailability profile control,
• taste-masking and release profiles for pediatric and combination products,
• and delivery device compatibility.

What kinds of formulation changes can or can’t be used as design-arounds?

In litigation practice, generic ability to design around depends on whether:

• claimed parameters are expressed as functional ranges (harder to evade),
• claims cover excipient compositions or preparation methods,
• or claims focus on end-performance properties that can be met by different formulations (often a validity/infringement battleground).

What manufacturing/IP barriers exist for entrants in anti-allergic agents?

Manufacturing barriers are most visible where claims touch CMC:

• particle size distributions,
• polymorph and solid-state control,
• and process steps that are tightly tied to the claimed product.

How do CMC requirements intersect with patent strategy?

Applicants often align:

• ANDA formulation work with potential non-infringement targets,
• with analytical comparability studies,
• and with anticipated patent infringement theories.

What commercial metrics matter most for anti-allergic agents when patents approach expiry?

For market and investment decisions, focus on:

• share and channel mix at the brand level,
• uptake velocity after label expansions (if patents still protect the new indication),
• payer restrictions and step-therapy changes near generic entry,
• and inventory and contracting behavior ahead of expected launch dates.

How do payers typically manage risk before generic entry?

• pre-positioning contracts with potential generic suppliers,
• formulary tier adjustments,
• and step-therapy protocol changes to steer patients away from brand products.

Key Takeaways

• Anti-allergic agents is a multi-family MeSH bucket where patent and exclusivity dynamics vary sharply by molecule and formulation strategy.
• Generic entry risk is driven by Orange Book listed patents: the number of active patents, their categories (composition, formulation, method-of-use), and the likelihood of label carve-outs.
• Market timing is often determined by the last-in-force listed patent and settlement-enforced non-launch windows, not just the earliest expiry.
• Formulation and method-of-use patents are common blockers for intranasal and combination products, where technical performance and dosing schedules are integral to claims.
• Immunology therapies (where relevant) can extend and diversify IP thickets, shifting risk from predictable ANDA routes to broader lifecycle and CMC-linked patent coverage.

FAQs

1. How do method-of-use patents in allergic rhinitis affect skinny-label generic approvals?
2. Which intranasal delivery system patents most frequently appear in Orange Book listings for anti-allergic products?
3. What settlement terms are most common in Paragraph IV cases for antihistamines and nasal steroids?
4. How does the biosimilar approval pathway change patent risk in allergic immunology indications?
5. Which combination-product patent estates are the highest barrier to generic entry in the anti-allergic category?

References

1. U.S. Food and Drug Administration. Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. FDA.
2. U.S. Food and Drug Administration. Hatch-Waxman Amendments: Patent and Exclusivity Related Information. FDA.
3. National Library of Medicine. Medical Subject Headings (MeSH). Anti-Allergic Agents. NLM.