Drugs in MeSH Category Astringents

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Stira	ZINC SULFATE	zinc sulfate	SOLUTION;INTRAVENOUS	217624-002	Jun 10, 2025	AP	RX	No	No
Gland	ZINC SULFATE	zinc sulfate	SOLUTION;INTRAVENOUS	216249-002	May 3, 2022	AP	RX	No	No
Apotex	ZINC SULFATE	zinc sulfate	SOLUTION;INTRAVENOUS	218059-002	Oct 28, 2024	AP	RX	No	No

Last updated: July 29, 2026

Market dynamics and patent landscape for drugs in NLM MeSH Class: Astringents

Executive summary

Astringents is a broad NLM MeSH class covering topical and oral agents used to reduce discharge, irritate less, or transiently contract tissue. The patent landscape is dominated by (1) legacy small-molecule actives with limited remaining exclusivity, (2) formulation and device-adjacent IP (vehicles, delivery systems, combinations, and concentration ranges), and (3) relatively low litigation intensity compared with high-revenue branded categories. Market dynamics skew toward OTC availability and pharmacy/retail private label, which compresses pricing and lowers incentives for new NCEs. Net consequence: most “patentable” value sits in product-specific reformulation rather than core active-ingredient exclusivity.

The actionable patent takeaway across the class is that buyers and litigators usually confront freedom-to-operate risk from formulation patents and combination patents tied to specific dosage forms (creams, gels, solutions, pastes) and specific actives (notably metal salts, tannins/astringent botanicals, and barrier-forming actives), not from long-lived method-of-use claims on a single flagship drug.

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What drugs are included in NLM MeSH “Astringents,” and which actives drive the patent and revenue pool?

The MeSH term “Astringents” spans multiple therapeutic and commercial segments. In practice, the competitive set clusters around:

• Topical wound and skin protectants (barrier and drying agents; metal salts and polymeric films)
• Hemorrhoid and anorectal preparations with local astringent components (often OTC)
• Mouth and throat astringent products (tannins, phenolic derivatives, styptic salts)
• Antiperspirant/deodorant-adjacent drying agents where the primary function is tissue contraction/drying
• Astringent oral rehydration adjuncts and gastrointestinal “drying” adjuncts in some geographies (class-adjacent, not always aligned with strict OTC labeling)

Because the class is mechanistically broad, the patent landscape is also broad. Most enforceable IP tends to map to:

• Dosage form: gel versus solution versus paste versus film-forming composition
• Concentration windows: specific percent ranges of actives and excipients
• Stability and compatibility: chelation, pH windows, oxygen/moisture stability for polyphenols and metal salts
• Combination therapy: pairing an astringent with an anti-inflammatory, local anesthetic, antifungal, antiseptic, or barrier polymer
• Delivery system: mucoadhesive gels, sustained-release films, and spray/foams designed for local contact time

Which active-ingredient archetypes show the most patent activity?

Across jurisdictions, the actives most frequently tied to post-approval IP in this category fall into a small number of families:

1. Metal salts / styptic salts

   • Examples include ferric compounds and other iron-based astringents used for local hemostasis or discharge reduction.
   • Patent value is commonly in formulation stability, particle dispersion, film formation, and dosing regimens.

2. Tannins and polyphenols

   • Botanically derived astringents or purified polyphenols.
   • Patent value is commonly in standardized composition, extraction process, and stabilized formulations to prevent oxidation and color drift.

3. Phenolic derivatives and synthetic astringents

   • Patent value is typically in topical composition platforms and combination products.

4. Barrier-forming “drying” skin protectants

   • Even when the marketing category uses “astringent” language, IP often targets film-forming agents and rheology, not “astringency” as a standalone pharmacologic mechanism.

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How does the market structure for OTC astringents change patent strategy and bargaining power?

Most products in this MeSH class compete in OTC and pharmacy retail channels or through medical device/procedure-adjacent procurement, leading to three market effects:

1. Rapid erosion of branded pricing

   • Even when formulation patents exist, channel incentives (formularies, retailer private label) push substitution once any generic or equivalent appears.
   • Shelf-life and packaging constraints matter; they frequently act as de facto barriers even when legal exclusivity is expired.

2. Lower willingness to fund long exclusivity battles

   • Patent litigation is less common when the product’s revenue ceiling is capped by OTC competition and low absolute spend per patient.
   • Where disputes occur, they often focus on specific combination products or specific dosage forms rather than broad method-of-use claims.

3. More value in reformulation and line extensions

   • Patent strategy shifts toward:
     • stable fixed-dose combinations,
     • improved tolerability,
     • better spreadability or adhesion,
     • and patient-facing formats (spray, squeeze tube gel, prefilled applicator).

Featured snippet answer: What wins in “astringents” patent strategy?

Formulation patents tied to specific dosage forms and fixed combinations usually carry more enforceability and commercial relevance than broad mechanism-of-action method patents in this class.

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What patents protect key astringent drugs, and what is the typical claim scope?

Astringent product patent estates often include four layers.

1) Composition of matter for active or standardized composition

Less common for well-known actives. More common for:

• standardized tannin/polyphenol fractions
• purification processes
• novel derivatives
• specialized combinations

2) Formulation and composition claims

Most common IP layer, including:

• vehicle/excipient selection and proportions
• pH and buffering systems
• viscosity and rheology agents
• chelation and stability-increasing agents
• particle size/distribution for metal salt dispersion

3) Use and method-of-use claims

Common patterns:

• topical application frequency
• duration and treatment intervals
• anatomically targeted use (e.g., hemorrhoidal application schedules)
• combination method claims (astringent + anti-inflammatory)

Litigation risk varies because method claims can be harder to enforce against OTC equivalents unless the labeling or instructions are tied directly to the claim.

4) Process and manufacturing patents

Often “quietly” important for generic barriers:

• mixing and dispersion processes
• controlled crystallization
• sterile or low-contamination production (for certain formulations)

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When does exclusivity end for astringents, and how do different exclusivity types interplay?

Across the MeSH class, the most relevant exclusivity end points are:

• Patent term expiration on formulation/composition IP
• Pediatric exclusivity (where applicable) and other regulatory exclusivity add-ons, usually concentrated in prescription contexts
• OTC switches and regulatory pathways that allow faster “same-ingredient” entry once patents lapse

Typical timing pattern

For many astringents, the practical “generic launch window” aligns less to regulatory exclusivity and more to:

• the expiry of the last formulation/combination patent for the marketed dosage form
• the availability of a bioequivalent-equivalent manufacturing method that avoids infringing process claims

Featured snippet answer: When does market exclusivity really end?

Usually when the last formulation and combination patent for the specific dosage form expires, not when any single “active ingredient” patent expires.

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What generic entry risks exist for astringents, including Paragraph IV challenges?

Paragraph IV filings are most likely when:

• a branded product is tied to a protected formulation or combination and
• the generic applicant can plausibly certify non-infringement or invalidity for those patents.

In OTC-heavy categories, Paragraph IV activity can be lower because many products are not coded in a way that triggers the Orange Book framework the same way as prescription NMEs. Where risk exists, it clusters around:

• fixed combination products (astringent + antiseptic/anti-inflammatory/local anesthetic)
• dosage forms with specific delivery systems

Litigation style in this class

• Fewer high-judgment method-of-use disputes.
• More disputes about composition/formulation infringement and label instructions that imply use of claimed regimens.

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What is the Orange Book status of “astringents,” and why does it differ across products?

Orange Book listing is product-specific, not MeSH-class-specific. “Astringents” includes actives and products that may be:

• not prescription-based
• or marketed through routes that do not map cleanly to Orange Book listing conventions

When Orange Book entries exist, the listing pattern typically shows:

• multiple patents for a single NDA/ANDA tied to formulation and method.
• the most recent patents often correspond to line extensions.

Featured snippet answer: How to interpret Orange Book for this class?

Treat Orange Book as a mapping tool for particular branded products in the category, not as a proxy for “astringents” as a whole.

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How does patent strength for astringents compare with other dermatology and gastrointestinal categories?

Astringents typically show:

• lower breadth of enforceable claims at the active-ingredient level
• higher density of claims at the formulation layer
• comparatively shorter economic duration of exclusivity because OTC competition reduces dwell time

In contrast:

• immunology, oncology, and some CNS categories often feature broad, activity-defining patents on the active with strong commercial protection and heavier litigation.

Commercial consequence

Investors and licensors generally underwrite:

• shorter monetization horizons per patent family
• higher likelihood of design-around for composition claims
• greater importance of manufacturing know-how and stability data

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What formulation patents are most commonly litigated in topical and mucosal astringent products?

For topical and mucosal astringent products, infringement allegations frequently address:

• concentration ranges of the astringent active
• excipient selection (gelling agents, film formers, penetration enhancers)
• pH ranges and buffering
• stabilization (antioxidants, oxygen scavengers, chelators)
• viscosity and spread profile

Manufacturing barriers that matter

Even when composition patents are narrow, process patents can block:

• mixing order and time
• milling/dispersing steps
• controlled crystallization steps for metal salts
• packaging compatibility tests

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Which companies dominate astringents innovation and which companies drive generic competition?

The class is fragmented. Innovation tends to be led by:

• established OTC dermatology/pharmacy manufacturers for skin and mucosal use
• ingredient suppliers and formulators that license standardized actives
• niche companies with standardized botanicals or specialized metal-salt formulations

Generic competition tends to be driven by:

• OTC and dermatology generic houses
• contract manufacturers capable of stable, scale-ready formulations

Commercial battleground

In practice, the battleground is narrow:

• the specific dosage form that sells
• the combination product that differentiates
• the stability and packaging format that ensures shelf-life

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What regulatory pathways shape patent strategy for astringents?

The regulatory route affects how quickly generics can enter and what claim types matter.

Prescription products

If astringents are marketed as prescription:

• patent term plays a larger role via regulatory exclusivity and Orange Book listing
• method-of-use claims can be more relevant because labeling and physician usage can track claimed regimens

OTC products

For OTC products:

• competition accelerates once patents lapse
• labeling alignment becomes central to enforcement
• process and formulation patents can still matter, but infringement proofs shift toward formulation equivalence and stability.

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How should licensors and generic developers map an astringents patent estate?

A practical estate map for this class should be built to answer these determinate questions:

1. What is the marketed dosage form?
   Formulation claims are usually form-specific.

2. What is the active archetype?
   Metal-salt versus tannin versus synthetic phenolic patterns often dictate different stability and excipient families.

3. What are the combination partners?
   Fixed combinations are where patent differentiation often lives.

4. What is the expiry schedule across jurisdictions?
   Patent families can stagger due to differing filing and grant dates.

5. Are manufacturing steps claimed?
   Process claims are a common “design-around wall.”

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Key takeaways

• The MeSH “Astringents” class is too broad for an actives-only patent view; value concentrates in product-specific formulation, combination, and manufacturing IP.
• Market dynamics favor OTC competition and rapid substitution, making line extensions and dosage-form differentiation the dominant monetization levers.
• Patent disputes, when they occur, more often target formulation equivalence and combination composition than core active pharmacology.
• For enforcement and FTO work, focus on the last-to-expire formulation and combination patents tied to the exact marketed dosage form and labeling.

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FAQs

1) What patent claim types most frequently block generic entry for topical astringent gels?

Formulation composition claims tied to concentration windows and excipient systems, followed by manufacturing/process claims and stabilization-related claims.

2) Do astringent products typically have Orange Book listings tied to multiple patents?

Some branded prescription or combination products do; OTC-only products commonly show limited Orange Book relevance. The listing is product-specific, not MeSH-class universal.

3) Are Paragraph IV challenges common for astringents?

They are less frequent than in blockbuster categories and tend to cluster around branded prescription/combination products where formulation patents can be certified.

4) How do device-like delivery systems affect astringents patentability?

Film-forming, mucoadhesive, and sustained-contact delivery systems can shift IP value from actives to excipient matrices and performance-defined formulation claims.

5) What is the fastest practical generic “design-around” route for astringents?

Reformulating concentrations and excipients to exit claimed ranges while meeting stability and shelf-life requirements, with attention to any process patent constraints.

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References

1. National Library of Medicine. MeSH Browser. “Astringents.” (Accessed 2026-07-29).
2. U.S. Food and Drug Administration. Orange Book: Approved Drug Products with Therapeutapeutic Equivalence Evaluations. (Accessed 2026-07-29).
3. FDA. Paragraph IV Certifications and Notice of Certifications. (Accessed 2026-07-29).