List of Excipients in Branded Drug CLEMASTINE FUMARATE

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Generic Drugs Containing CLEMASTINE FUMARATE

Company	Ingredient	NDC	Excipient
Teva Pharmaceuticals USA Inc	clemastine fumarate	0093-0308	LACTOSE
Teva Pharmaceuticals USA Inc	clemastine fumarate	0093-0308	POVIDONE K30
Teva Pharmaceuticals USA Inc	clemastine fumarate	0093-0308	SILICON DIOXIDE
Teva Pharmaceuticals USA Inc	clemastine fumarate	0093-0308	STARCH, CORN

What are the Most Frequently-Used Excipients in CLEMASTINE FUMARATE?

# Of NDCs	Excipient
4	ALCOHOL
2	CELLULOSE, MICROCRYSTALLINE
2	FUMARIC ACID
2	HYPROMELLOSE 2910

Clemastine Fumarate Excipient Strategy and Commercial Opportunities

Last updated: September 16, 2026

Clemastine fumarate is a legacy, low-dose, sedating H1 antihistamine with limited composition-of-matter patent value and a formulation-led commercial opportunity. The strongest product strategies are low-cost immediate-release tablets, pediatric oral liquids, orally disintegrating tablets, chewables, and differentiated allergy products that improve dosing convenience without increasing sedation or anticholinergic burden.

The core technical challenge is dose uniformity. Clemastine fumarate is administered at milligram and sub-milligram strengths, so excipient selection, powder blending, segregation control, dissolution, and analytical sensitivity have greater importance than tablet size or raw-material cost.

What is clemastine fumarate and how is it marketed?

Clemastine fumarate is the fumarate salt of clemastine, a first-generation antihistamine used for allergic rhinitis, hay fever, and urticaria. It is administered orally and has sedating and anticholinergic properties typical of older H1 antihistamines. FDA labeling warns about drowsiness and advises caution with alcohol, sedatives, and activities requiring alertness (DailyMed, 2024a; DailyMed, 2024b).

Attribute	Commercially relevant detail
Active ingredient	Clemastine fumarate
Drug class	First-generation H1 antihistamine
Common strengths	1.34 mg and 2.68 mg tablets; liquid strength commonly 0.67 mg/5 mL
Equivalent clemastine content	Approximately 1 mg and 2 mg per tablet, depending on strength
Dosage forms	Immediate-release tablets and oral liquid
Main indications	Allergic rhinitis, hay fever, urticaria
Key tolerability issue	Sedation and anticholinergic effects
Regulatory category	Small-molecule drug; not a biologic
Main development opportunity	Formulation differentiation and channel expansion

Clemastine fumarate has a low active dose. That creates a high risk of content-uniformity failure if the active pharmaceutical ingredient is poorly dispersed in the excipient matrix. The formulation must control particle-size distribution, blend time, order of addition, and segregation during transfer and compression.

What excipient strategy is best for clemastine fumarate tablets?

The most defensible tablet strategy is a conventional immediate-release formulation using a diluent, disintegrant, binder or dry-granulation aid, glidant, and lubricant. The formulation should prioritize robust dose uniformity and rapid release rather than complex modified-release technology.

Recommended immediate-release excipient platform

Functional role	Candidate excipients	Commercial rationale
Diluent	Microcrystalline cellulose, lactose monohydrate, mannitol, dibasic calcium phosphate	Provides blend volume and improves manufacturability at low drug loading
Dry binder	Microcrystalline cellulose, copovidone, povidone	Supports tablet strength and content uniformity
Disintegrant	Crospovidone, croscarmellose sodium, sodium starch glycolate	Promotes rapid tablet breakup
Glidant	Colloidal silicon dioxide	Improves powder flow and die filling
Lubricant	Magnesium stearate, sodium stearyl fumarate	Controls ejection force and tooling adhesion
Taste-masking aid	Mannitol, flavor, sweetener, polymer coating	Supports chewable and orally disintegrating products
Film coating	Hypromellose, polyethylene glycol, titanium dioxide or approved colorants	Improves swallowability, identity, and moisture handling

Microcrystalline cellulose is a strong starting diluent for direct compression or dry granulation. Lactose can reduce cost and support established tablet technology, but compatibility and moisture behavior must be confirmed. Mannitol is more attractive for chewables and orally disintegrating tablets because it provides a cooling mouthfeel and lower perceived sweetness than sucrose.

Croscarmellose sodium and crospovidone are suitable disintegrants for rapid-release products. Crospovidone is often attractive where rapid wicking and low swelling are desired. Sodium starch glycolate can provide strong disintegration but may produce variability if overused or poorly distributed.

Magnesium stearate remains commercially standard, but excessive lubrication can slow wetting and dissolution. Sodium stearyl fumarate is a useful alternative when a less hydrophobic lubricant profile is needed.

How should manufacturers control low-dose content uniformity?

Content uniformity is the principal formulation risk for clemastine fumarate. A tablet may contain only about 1 to 2 mg of clemastine equivalent, while the total tablet weight is substantially higher. Small segregation effects can therefore create meaningful potency variation.

Critical process controls

1. Use a narrow particle-size distribution for clemastine fumarate.
2. Deagglomerate the active ingredient before blending.
3. Apply geometric dilution when the active concentration is low.
4. Use ordered mixing with a preblend of the active and a portion of the diluent.
5. Limit excessive post-blend handling.
6. Validate blend and hold-time uniformity.
7. Control lubricant addition and mixing duration.
8. Test blend uniformity and finished-product content uniformity.
9. Evaluate segregation after hopper discharge and tablet press transfer.
10. Establish dissolution specifications that detect over-lubrication or granulation changes.

Direct compression can reduce processing steps, but it depends heavily on powder flow and segregation control. Roller compaction or dry granulation can improve flow and compressibility while avoiding water exposure. Wet granulation may be appropriate where the selected excipients require granulation to achieve uniformity, but it adds drying and residual-moisture controls.

ICH quality guidance supports a risk-based approach that links formulation attributes and process parameters to critical quality attributes such as assay, content uniformity, dissolution, hardness, friability, and stability (International Council for Harmonisation, 2009).

Which liquid excipients are suitable for clemastine fumarate?

An oral liquid is commercially important because clemastine has an established pediatric and family-use profile. The principal liquid risks are dose uniformity, chemical stability, microbial control, palatability, and accurate measurement at low doses.

Solution versus suspension

A clear solution is preferable if clemastine fumarate can be maintained at the target concentration across the product’s pH and storage conditions. If solubility or precipitation limits prevent a stable solution, a suspension may provide a more robust platform.

A suspension requires:

• A suspending system such as xanthan gum, microcrystalline cellulose with carboxymethylcellulose sodium, or other permitted rheology modifiers.
• Wetting agents to disperse the active.
• A preservative system validated against relevant microorganisms.
• Shake-well labeling.
• A dosing syringe rather than a household teaspoon.
• Redispersibility testing after storage and transport.

A solution may use purified water, glycerin, sorbitol solution, propylene glycol, or a combination of these vehicles. Sweeteners and flavors are important because clemastine can produce an objectionable taste, while high levels of polyols may create gastrointestinal effects.

The product should avoid unnecessary alcohol because clemastine itself can cause drowsiness, and alcohol can intensify central nervous system depression. FDA labeling specifically warns about additive sedative effects with alcohol and other central nervous system depressants (DailyMed, 2024a).

What formulations are protected by clemastine fumarate patents?

The commercial value of clemastine fumarate is primarily formulation-based rather than patent-based. The active ingredient is an established small molecule, and the principal historical product formats are conventional immediate-release tablets and oral liquid.

Patent and exclusivity profile

Issue	Assessment
New chemical entity exclusivity	Expired
Composition-of-matter patent opportunity	Limited for a legacy active ingredient
Biosimilar pathway	Not applicable
Generic pathway	ANDA pathway for therapeutically equivalent products
Formulation patent opportunity	Possible for novel ODT, chewable, taste-masked, or stability-enhanced products
Method-of-use patent opportunity	Narrow and dependent on a genuinely differentiated clinical use
Orange Book relevance	FDA Orange Book listings and current patent certifications control for an active NDA
Paragraph IV exposure	Potentially limited unless an active listed patent covers a marketed NDA product
Commercial moat	Brand, channel access, formulation quality, and regulatory execution

A developer should not assume that a new excipient combination creates enforceable patent protection. A formulation patent requires novelty, non-obviousness, written description, enablement, and commercially relevant claim scope. A claim covering a specific clemastine concentration, disintegrant ratio, particle-size distribution, dissolution profile, or stability result may be stronger than a generic claim to “a pharmaceutical composition comprising clemastine.”

Current Orange Book records should be used to determine whether any active listed patent is associated with a marketed clemastine fumarate NDA. FDA describes the Orange Book as the source for approved drug products and listed patent and exclusivity information (U.S. Food and Drug Administration, 2024a).

When does clemastine fumarate lose exclusivity?

Clemastine fumarate has long passed the exclusivity period associated with its original approval. The relevant commercial question is therefore not loss of basic exclusivity but whether a new product can obtain regulatory protection through a differentiated formulation, method of use, or delivery system.

Potential protection mechanisms include:

• A 505(b)(2) application for a materially different dosage form or route.
• A new formulation with a clinically relevant performance advantage.
• A new indication supported by adequate clinical evidence.
• Pediatric labeling supported through an applicable regulatory pathway.
• Orphan-drug exclusivity only if the product qualifies for a rare disease indication.
• Patent protection for a novel composition, manufacturing process, or use.

A conventional generic tablet is unlikely to obtain meaningful market exclusivity. A 505(b)(2) product may have a more differentiated regulatory position, but the development burden is higher and the product must demonstrate that the new formulation or use is clinically and commercially meaningful.

What generic entry risks exist for clemastine fumarate?

Generic entry risk is structurally high because the drug is old, orally administered, and available in conventional dosage forms. An ANDA applicant can target the reference product using an immediate-release tablet or oral-liquid formulation if the applicant meets applicable pharmaceutical equivalence, bioequivalence, quality, and labeling requirements.

Paragraph IV challenges

A Paragraph IV certification becomes relevant when an ANDA applicant asserts that a listed patent is invalid, unenforceable, or will not be infringed. For a legacy clemastine product, the risk is likely to arise from any remaining formulation or method-of-use patents rather than from the active ingredient itself.

A generic developer may pursue:

• A Paragraph III certification with a delayed launch date.
• A Paragraph IV certification with potential litigation and a 30-month stay.
• A section viii statement carving out a patented method of use.
• A direct ANDA route where no relevant listed patent blocks approval.

The commercial significance of a Paragraph IV challenge depends on whether the listed patent covers the principal revenue-generating indication and dosage form. A narrow patent covering a discontinued presentation may have limited blocking value.

What FDA regulatory status applies to clemastine fumarate?

Clemastine fumarate is regulated as a small-molecule drug. It is not subject to the biosimilar pathway used for monoclonal antibodies, insulin products historically approved as biologics, or other biologic medicines.

The relevant U.S. routes are:

Development objective	Likely pathway
Copy of an approved tablet or liquid	ANDA
New dosage form or formulation	505(b)(2), depending on the product
New indication	505(b)(2) or traditional NDA route
Novel combination product	NDA or 505(b)(2), depending on reliance and changes
Product with no reference for the intended presentation	NDA or 505(b)(2)

FDA’s Inactive Ingredient Database can support excipient selection by identifying inactive ingredients used in approved products, but database precedent does not eliminate the need to justify maximum daily exposure, route-specific safety, functionality, and product quality (U.S. Food and Drug Administration, 2024b).

What commercial opportunities exist for clemastine fumarate?

Orally disintegrating tablets

An ODT could target adults and adolescents who have difficulty swallowing conventional tablets. Mannitol, crospovidone, low-substitution hydroxypropyl cellulose, and flavor systems are potential platform components.

The commercial limitation is that an ODT does not remove clemastine’s sedation. Marketing should focus on convenience and administration, not on claims of superior alertness or non-sedating allergy relief.

Chewable tablets

A chewable product could target pediatric and family allergy use. The main development risks are taste masking, dose uniformity, friability, and accidental overconsumption. A child-resistant package and calibrated dosing information would be important.

Dosing-syringe oral liquid

A ready-to-use liquid with a calibrated oral syringe could improve dose accuracy compared with household spoons. The product could compete through palatability, preservative strategy, sugar-free positioning, and packaging convenience.

Sugar-free and alcohol-free formulations

Sugar-free products using sorbitol, glycerin, sucralose, or other permitted excipients could target diabetic or calorie-conscious consumers. Alcohol-free positioning is commercially relevant because of clemastine’s sedative profile and the need to avoid additive central nervous system depression.

Hospital and institutional supply

Hospitals, long-term-care facilities, and pharmacies may value reliable generic supply, standardized oral-liquid concentrations, tamper-evident packaging, and unit-dose formats. The opportunity is operational rather than premium-priced.

Combination allergy products

A combination with a decongestant or another allergy ingredient could provide a differentiated product, but it would increase regulatory, safety, and labeling complexity. Combining a sedating antihistamine with a stimulant decongestant may create a less attractive risk-benefit profile and should not be treated as a simple line extension.

How strong is the clemastine fumarate patent estate?

The patent estate is weak for a conventional product and potentially moderate for a genuinely differentiated delivery system.

Product concept	Patent strength	Regulatory difficulty	Commercial outlook
Standard immediate-release tablet	Low	Low	Commodity
Standard oral liquid	Low	Low to moderate	Moderate if supply is reliable
Sugar-free liquid	Low to moderate	Moderate	Niche opportunity
Orally disintegrating tablet	Moderate if technically differentiated	Moderate	Potentially attractive
Chewable tablet	Moderate if taste masking is novel	Moderate	Pediatric and retail opportunity
Novel sustained-release product	Moderate to high	High	Uncertain due to sedating pharmacology
New indication	Potentially high	High	Dependent on clinical evidence
Combination product	Moderate	High	Safety and labeling constrained

A stronger patent position would require data showing that the formulation solves a specific technical problem. Useful claim-supporting data could include improved content uniformity, reduced dissolution variability, superior stability under accelerated conditions, reduced bitterness, improved redispersibility, or a measurable administration advantage.

What manufacturing and intellectual-property barriers matter most?

Manufacturing barriers are more significant than active-ingredient supply barriers. Key risks include low-dose blending, API particle-size variability, salt-form consistency, powder segregation, liquid precipitation, preservative effectiveness, and packaging interaction.

Potentially protectable manufacturing innovations include:

• Controlled particle-size clemastine fumarate.
• Ordered dilution and preblend processes.
• Segregation-resistant granulation.
• Low-shear blending methods.
• Improved liquid solubilization or suspension systems.
• Moisture-protective packaging.
• Unit-dose liquid packaging with enhanced dose accuracy.

The most practical intellectual-property strategy is a layered portfolio. One patent family could cover the composition, another the manufacturing process, and another the dosage form or delivery system. Trade secrets may protect blend order, granulation endpoints, coating parameters, and scale-up conditions even where patent claims are difficult to obtain.

How does clemastine fumarate compare with competing antihistamines?

Clemastine competes with both first-generation and second-generation antihistamines.

Product class	Examples	Sedation profile	Excipient opportunity
First-generation antihistamine	Clemastine, diphenhydramine, chlorpheniramine	Generally higher	Taste masking, liquid dosing, ODT convenience
Second-generation antihistamine	Loratadine, cetirizine, fexofenadine	Generally lower, though not uniform across products	ODT, chewable, combination, pediatric formats
Intranasal antihistamine	Azelastine and others	Local delivery	Device and formulation differentiation

Clemastine’s main disadvantage is sedation. Its commercial advantage is established clinical familiarity, low API cost, and the ability to support multiple conventional dosage forms. A new product is more likely to win through price, availability, pediatric usability, or administration convenience than through a claim of superior allergy efficacy.

What revenue exposure and launch scenarios are realistic?

Standalone clemastine revenue is not typically disclosed by major manufacturers, so product-level revenue estimates should be built from prescription volume, retail distribution, reimbursement, and dosage-form demand rather than corporate reporting.

Generic launch scenarios

Scenario	Expected market position
Lowest-cost tablet generic	High volume potential, low margin
Reliable oral-liquid supplier	Moderate opportunity due to supply shortages and pharmacy demand
Premium ODT	Lower volume, higher price potential
Pediatric chewable	Niche opportunity with stronger branding potential
505(b)(2) formulation	Higher development cost and longer commercialization cycle
Novel indication	Highest uncertainty and evidence burden

The most attractive near-term opportunity is a differentiated oral liquid or ODT with strong content-uniformity data, stable supply, child-resistant packaging, and clear sedation labeling. A conventional tablet can be commercially viable but is likely to face price competition and limited defensible differentiation.

Key Takeaways

• Clemastine fumarate is a legacy small-molecule antihistamine with expired basic exclusivity.
• The principal formulation risk is low-dose content uniformity.
• Microcrystalline cellulose, mannitol, crospovidone, croscarmellose sodium, colloidal silicon dioxide, and controlled lubrication are practical starting points for tablet development.
• Oral liquids require careful control of solubility, suspension stability, taste, preservatives, microbial quality, and dosing accuracy.
• ODT, chewable, sugar-free liquid, and unit-dose formats offer the clearest commercial differentiation.
• Biosimilar competition is not relevant because clemastine fumarate is not a biologic.
• Paragraph IV exposure depends on any currently listed formulation or method-of-use patent, not on the old active ingredient.
• Patent value will depend on demonstrated technical performance, not merely on the use of a new excipient.
• The strongest commercial model combines reliable generic supply with a patient-centered dosage form and defensible manufacturing know-how.

FAQs About Clemastine Fumarate Excipients and Commercial Development

Can clemastine fumarate be formulated as an orally disintegrating tablet?

Yes. Mannitol, crospovidone, microcrystalline cellulose, sweeteners, flavors, and a suitable lubricant can support an ODT platform. Dose uniformity and bitterness control require dedicated development work.

Is clemastine fumarate suitable for a pediatric oral suspension?

Yes, provided the suspension has acceptable potency uniformity, redispersibility, microbial control, palatability, and dosing accuracy. An oral syringe should accompany the product.

Does clemastine fumarate have biosimilar competition?

No. Clemastine fumarate is a small-molecule drug. Competition proceeds through generic or, for differentiated products, 505(b)(2) pathways.

Can a new clemastine formulation receive patent protection?

Yes, if the formulation or manufacturing process is novel, non-obvious, enabled, and supported by meaningful technical data. A routine excipient substitution is unlikely to provide strong patent protection.

What is the best commercial dosage form for a new clemastine product?

A calibrated, alcohol-free oral liquid or a taste-masked ODT offers the clearest differentiation. A standard immediate-release tablet is easier to develop but faces greater commodity pricing pressure.

References

DailyMed. (2024a). Clemastine fumarate tablet: Prescribing information. U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/

DailyMed. (2024b). Clemastine fumarate oral solution or syrup: Prescribing information. U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/

International Council for Harmonisation. (2009). ICH Q8(R2): Pharmaceutical development. https://www.ich.org/

U.S. Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

U.S. Food and Drug Administration. (2024b). Inactive Ingredient Database. https://www.accessdata.fda.gov/scripts/cder/iig/