List of Excipients in Branded Drug FLUNISOLIDE

Generic Drugs Containing FLUNISOLIDE

Company	Ingredient	NDC	Excipient
Bausch & Lomb Incorporated	flunisolide	24208-344	BENZALKONIUM CHLORIDE
Bausch & Lomb Incorporated	flunisolide	24208-344	BUTYLATED HYDROXYANISOLE
Bausch & Lomb Incorporated	flunisolide	24208-344	CITRIC ACID MONOHYDRATE
Bausch & Lomb Incorporated	flunisolide	24208-344	EDETATE DISODIUM
Bausch & Lomb Incorporated	flunisolide	24208-344	HYDROCHLORIC ACID
Bausch & Lomb Incorporated	flunisolide	24208-344	POLYETHYLENE GLYCOL 3350

What are the Most Frequently-Used Excipients in FLUNISOLIDE?

# Of NDCs	Excipient
6	BENZALKONIUM CHLORIDE
6	BUTYLATED HYDROXYANISOLE
6	CITRIC ACID MONOHYDRATE
6	EDETATE DISODIUM
6	HYDROCHLORIC ACID
6	POLYETHYLENE GLYCOL 3350

Flunisolide Excipient Strategy and Commercial Opportunities

Last updated: August 9, 2026

Flunisolide is an established, low-cost corticosteroid with limited active intellectual-property protection. The strongest commercial opportunities are in nasal delivery, preservative reduction, device performance, pediatric usability, and differentiated formulations rather than in the active ingredient itself. Generic competition and modest market size constrain pricing, but a well-designed nasal product can compete through tolerability, convenience, dose consistency, and supply reliability.

What is flunisolide and which dosage forms are commercially relevant?

Flunisolide is a synthetic glucocorticoid used primarily for allergic rhinitis and, historically, for maintenance treatment of asthma. Its principal commercial form has been an intranasal spray solution. Inhalation aerosol products were marketed in the United States under the Aerobid brand but have largely disappeared from routine commercial use following the phaseout of chlorofluorocarbon propellants and the availability of alternative inhaled corticosteroids.[1,2]

Attribute	Flunisolide nasal product	Flunisolide inhalation aerosol
Primary indication	Allergic rhinitis	Asthma maintenance
Typical strength	0.025% nasal solution	250 mcg per actuation historically
Delivery route	Intranasal metered spray	Oral inhalation
Historical brand	Nasalide	Aerobid
Current commercial position	Generic and legacy product category	Limited or discontinued U.S. relevance
Main formulation issue	Preservative, irritation, pump performance	Propellant transition and device obsolescence
Patent opportunity	Formulation, device, packaging, use	Primarily formulation and device redevelopment

Flunisolide nasal spray products generally deliver 25 micrograms per actuation from a 0.025% solution. The formulation is designed for local deposition on the nasal mucosa, with systemic exposure substantially lower than for oral corticosteroid therapy when used as directed.[3]

What excipients are used in flunisolide nasal spray?

Legacy flunisolide nasal formulations use a water-based solution containing solubilizing, buffering, preservative, and tonicity-control excipients. Public labeling identifies excipient classes including propylene glycol, polysorbate 80, citric acid, sodium citrate, benzalkonium chloride, and purified water.[3,4]

Excipient or excipient class	Function	Commercial benefit	Main development risk
Propylene glycol	Cosolvent and humectant	Supports drug solubility and spray uniformity	Burning, stinging, or irritation in sensitive users
Polysorbate 80	Surfactant and solubilizer	Helps maintain solution uniformity	Peroxide formation, degradation, container interaction
Citric acid/sodium citrate	Buffer system	Controls pH and chemical stability	Excess acidity can increase nasal irritation
Benzalkonium chloride	Preservative	Supports multidose microbial control	Chronic-use tolerability and mucosal irritation concerns
Purified water	Vehicle	Enables aqueous nasal delivery	Microbial control and packaging compatibility
Sodium chloride or equivalent tonicity agent	Osmolality control where used	Improves physiological compatibility	May affect solubility and spray characteristics

The excipient system must balance four performance targets: chemical stability, microbial protection, nasal tolerability, and consistent droplet formation. Increasing solubilizer content can improve manufacturing robustness but may increase irritation. Raising surfactant concentration can improve wetting and dose uniformity but can create oxidation or extractables concerns.

What excipient strategy offers the best commercial opportunity?

The most practical strategy is a preservative-reduced or preservative-free aqueous nasal spray using a multidose container with validated microbial protection. A conventional preserved solution is easier to manufacture and may have lower packaging cost, but preservative-free systems can support premium positioning in chronic allergic rhinitis.

Preservative-free multidose delivery

Benzalkonium chloride is effective and familiar, but long-term intranasal exposure has generated tolerability concerns in the literature, including potential effects on nasal mucosa and mucociliary function.[5] A preservative-free system could use:

• A sterile or low-bioburden manufacturing process.
• A one-way metering pump.
• A container-closure system that limits microbial ingress.
• A validated in-use stability program.
• Unit-dose or mechanically protected multidose packaging.

The commercial advantage is strongest in patients requiring continuous seasonal or perennial treatment, children, and users who report nasal dryness or burning.

The principal challenge is cost. A preservative-free pump may materially increase component cost, filling complexity, and microbiological validation requirements. The product would need a clear tolerability or usability advantage to justify premium pricing.

Lower-irritation solvent system

Propylene glycol is a functional excipient in legacy products, but it may contribute to stinging in some users. A reformulation could examine lower levels of propylene glycol or replace part of the cosolvent system with another regulatory-accepted solvent or solubilization approach.

Potential approaches include:

1. Adjusting pH toward the physiologic nasal range while maintaining flunisolide solubility.
2. Using a lower surfactant concentration supported by improved drug pre-dissolution.
3. Screening alternative cosolvents with established nasal-use precedent.
4. Optimizing ionic strength and buffer concentration.
5. Controlling osmolality to reduce burning and reflex sneezing.

The main technical constraint is that flunisolide must remain fully dissolved throughout shelf life. Precipitation can change delivered dose, clog the pump, and create batch-to-batch variability.

Improved spray-pump performance

The delivery device may offer more defensible differentiation than the excipient composition. Relevant performance parameters include:

• Delivered-dose uniformity over container life.
• Priming and repriming requirements.
• Plume geometry.
• Droplet-size distribution.
• Nasal deposition.
• Dose consistency at low remaining fill volume.
• Resistance to clogging.
• Ease of actuation for pediatric and older patients.

A pump that reduces the need for shaking, minimizes clogging, or delivers a consistent plume after storage can support a device-based product strategy. Device claims may also create a more durable intellectual-property position than a simple excipient substitution.

What formulations are protected by flunisolide patents?

The original flunisolide active-ingredient and product patents are old and are not a meaningful barrier to ordinary generic entry. The commercial patent opportunity lies in newly developed formulations, devices, packaging systems, and combination products.

Potentially protectable subject matter includes:

• Preservative-free flunisolide nasal solutions.
• Specific pH and buffer ranges that improve stability or tolerability.
• Low-surfactant or surfactant-free formulations.
• Multidose pumps with defined microbial-barrier characteristics.
• Spray devices producing a specified droplet-size profile.
• Unit-dose or metered-dose packaging.
• Mucoadhesive formulations that extend nasal residence time.
• Combination nasal products containing flunisolide and an antihistamine.
• Pediatric dosing systems with reduced actuation force.
• Manufacturing processes that reduce peroxide-related degradation.

A patent should claim measurable technical performance rather than merely listing known excipients. A broad claim to flunisolide, water, propylene glycol, and polysorbate 80 would face substantial prior-art risk. Stronger claim sets would link composition parameters to an unexpected result, such as improved delivered-dose uniformity, reduced irritation, longer in-use stability, or reduced preservative exposure.

When does flunisolide lose exclusivity?

Flunisolide lost meaningful U.S. small-molecule exclusivity decades ago. The active ingredient is not a current new chemical entity, and there is no biosimilar pathway because flunisolide is a conventional synthetic small molecule rather than a biologic.

Exclusivity category	Current relevance to flunisolide
New chemical entity exclusivity	Expired
Orphan-drug exclusivity	Not a material category for standard flunisolide products
Pediatric exclusivity	No current commercially meaningful extension identified
Patent-term extension	No current barrier identified
Generic approval pathway	ANDA, subject to product-specific requirements
Biosimilar pathway	Not applicable

The FDA Orange Book remains the principal source for checking listed patents and exclusivity associated with approved reference products.[6] Legacy brand products may appear in historical FDA records even when they are no longer marketed. A sponsor evaluating an ANDA or 505(b)(2) strategy must distinguish discontinued status from withdrawn approval and verify the current reference-product pathway.

What is the Orange Book status of flunisolide?

Flunisolide nasal products have been associated historically with the Nasalide reference product and generic equivalents. The key commercial point is that the category does not have a strong current Orange Book exclusivity barrier comparable to newer intranasal corticosteroids.

A current diligence review should focus on:

• Whether an approved reference-listed drug remains available for the intended strength and dosage form.
• Whether the FDA has designated a reference product for ANDA submission.
• Whether any patents are currently listed against the relevant reference product.
• Whether the proposed product is therapeutically equivalent or requires a 505(b)(2) application.
• Whether the device is sufficiently similar for an ANDA or requires a separate clinical bridge.

For a conventional flunisolide nasal spray with the same strength, route, dosage form, and comparable formulation performance, the principal pathway is generally an ANDA. A materially different delivery system, new combination, or new clinical-use claim may require a 505(b)(2) application.

Are Paragraph IV challenges relevant to flunisolide?

Paragraph IV litigation risk is likely limited because the principal historical patents have expired and the product category has been generic for many years. A Paragraph IV certification becomes commercially relevant only if a current Orange Book-listed patent covers the reference product.

For a new flunisolide generic, the major legal risks are more likely to involve:

• Device similarity and design-around disputes.
• Formulation patents covering a newly commercialized product.
• Trade dress or branding disputes.
• Patent claims directed to a preservative-free system.
• Combination-product patents.
• Regulatory exclusivity attached to a later-developed product.

A sponsor launching a differentiated formulation could create new Paragraph IV exposure for later entrants if its patents are listed against an eligible drug product. The business value of that strategy depends on whether the formulation produces a commercially meaningful advantage and whether FDA listing requirements are satisfied.

What FDA regulatory issues affect flunisolide excipient development?

FDA review will focus on chemistry, manufacturing, and controls; local tolerability; device performance; microbiological quality; and comparative bioequivalence or clinical performance, depending on the pathway.

For a nasal spray, important development studies include:

Pharmaceutical development

The sponsor should establish:

• Assay and related substances.
• pH and osmolality.
• Viscosity.
• Preservative content, if applicable.
• Delivered-dose uniformity.
• Spray content uniformity.
• Droplet-size distribution.
• Priming and repriming.
• Container-closure integrity.
• In-use stability.
• Microbial limits or sterility, depending on the design.

Excipient safety

Excipients with established nasal-use precedent reduce regulatory risk. A novel excipient or an unusual concentration may require additional toxicology or justification. The safety file should address chronic exposure because allergic rhinitis products may be used for months or across multiple seasons.

Device and packaging

The pump, actuator, dip tube, bottle, and cap should be assessed as an integrated drug-delivery system. Extractables and leachables are particularly relevant for surfactant-containing formulations and plastic components. The sponsor should also test performance after shipping, temperature cycling, repeated use, and partial depletion.

How strong is the patent estate for a new flunisolide formulation?

The baseline patent estate is weak because flunisolide is old and genericized. A new formulation can create moderate protection if it combines composition, device, and manufacturing claims supported by comparative data.

Strategy	Patent strength	Regulatory complexity	Commercial potential
Conventional generic nasal solution	Low	Low to moderate	Low-margin volume
Preservative-reduced solution	Moderate	Moderate	Moderate if tolerability improves
Preservative-free multidose spray	Moderate to strong	Moderate to high	Moderate to high
Unit-dose nasal product	Moderate	Moderate	Niche premium
Mucoadhesive nasal formulation	Moderate	High	Uncertain, potentially differentiated
Flunisolide-antihistamine combination	Moderate to strong	High	Higher value but greater clinical burden
New inhalation product	Moderate	High	Limited by crowded inhaled-steroid market

The strongest practical package would include a formulation patent, a device patent, and manufacturing claims. Relying on one narrow composition patent would leave the product exposed to rapid design-around.

Which companies are challenging or competing with flunisolide?

Flunisolide competes in a crowded intranasal corticosteroid market that includes generic and branded products containing fluticasone propionate, fluticasone furoate, mometasone furoate, triamcinolone acetonide, budesonide, and beclomethasone dipropionate.

Active ingredient	Commercial positioning versus flunisolide
Fluticasone propionate	Broad generic availability and strong consumer recognition
Fluticasone furoate	High-potency modern intranasal corticosteroid
Mometasone furoate	Established efficacy and pediatric use
Triamcinolone acetonide	Low-cost over-the-counter and prescription competition
Budesonide	Strong generic presence and established safety profile
Beclomethasone dipropionate	Established nasal corticosteroid alternative
Flunisolide	Older, low-cost option with limited differentiation

Flunisolide is unlikely to win a broad market-share contest against established over-the-counter intranasal corticosteroids. It can compete in institutional purchasing, regional supply contracts, and targeted patient segments if the product has a lower-irritation profile, improved device usability, or reliable availability.

What generic entry risks exist for flunisolide?

Generic entry risk is high for conventional products because the active ingredient is old, the dosage form is established, and competing corticosteroids are widely available. The principal barriers are commercial rather than patent-based.

A new entrant faces:

• Low reimbursement and price compression.
• Limited physician switching incentives.
• Competition from over-the-counter products.
• Modest market size relative to newer allergy products.
• Device-development costs.
• Potential difficulty obtaining premium pricing for excipient changes alone.
• Manufacturing and supply-chain risk for specialized pumps.

A differentiated product can reduce price competition if it demonstrates a clear patient or payer benefit. Claims based only on "preservative-free" positioning may be insufficient unless supported by tolerability, adherence, or patient-preference evidence.

What licensing deals could support a flunisolide product?

Licensing value is more likely to reside in delivery technology than in flunisolide itself. Relevant transaction targets include:

• Nasal pump platforms.
• Preservative-free multidose packaging.
• Mucoadhesive polymers with nasal-use data.
• Microbial-barrier container systems.
• Spray characterization and deposition technology.
• Contract manufacturing capacity for nasal liquids.
• Combination-product development platforms.

A license should address territory, device ownership, regulatory responsibilities, manufacturing rights, field-of-use restrictions, and patent prosecution. Because flunisolide has low intrinsic product differentiation, royalty economics must remain compatible with generic or specialty-generic pricing.

What manufacturing and IP barriers affect flunisolide commercialization?

The main manufacturing barrier is not synthesis of flunisolide. It is reliable production of a stable, uniform nasal spray over the full labeled life of the container.

Key risks include:

• Drug precipitation during storage.
• Surfactant oxidation.
• Preservative adsorption into packaging.
• Pump clogging.
• Dose drift after repeated use.
• Microbial contamination during consumer use.
• Container extractables and leachables.
• Variability in actuation force.
• Inconsistent plume geometry.

A sponsor should prioritize formulation-device co-development rather than treating the pump as a late-stage packaging decision. The device can determine whether a technically stable formulation produces acceptable delivered-dose performance.

What is the revenue exposure and commercial outlook for flunisolide?

Flunisolide is unlikely to support blockbuster economics as a conventional generic. Revenue exposure is more attractive in three areas:

1. A reliable, low-cost generic supplied to institutional and retail channels.
2. A differentiated preservative-free or low-irritation nasal product.
3. A combination or device-led product supported by a 505(b)(2) strategy.

The opportunity is strongest where a sponsor has existing nasal manufacturing infrastructure, pump procurement leverage, and a portfolio strategy that spreads development costs across multiple products. A standalone flunisolide project with no device or tolerability advantage would face limited pricing power.

Key Takeaways

• Flunisolide has no meaningful current composition-of-matter exclusivity barrier.
• The relevant commercial dosage form is the intranasal spray; historical inhalation aerosol opportunities are less attractive.
• Legacy excipients include propylene glycol, polysorbate 80, citrate buffer, benzalkonium chloride, and water.
• Preservative-free multidose delivery is the clearest formulation opportunity.
• Device performance, microbial protection, and in-use stability are central development issues.
• A conventional generic is exposed to high price competition and low switching incentives.
• New intellectual property should focus on formulation-device combinations, measurable performance, and manufacturing controls.
• Biosimilar risk is irrelevant because flunisolide is a synthetic small molecule.
• Paragraph IV risk is limited for legacy products but could arise around newly developed formulation or device patents.
• Commercial success depends more on tolerability, usability, supply reliability, and channel strategy than on the active ingredient.

FAQs

Can flunisolide be reformulated without benzalkonium chloride?

Yes. A preservative-free multidose system or unit-dose package can eliminate benzalkonium chloride, but the sponsor must establish microbial protection, container-closure integrity, in-use stability, and acceptable manufacturing controls.

Is a flunisolide nasal spray eligible for an ANDA?

A conventional product matching the reference drug in active ingredient, strength, dosage form, route, and performance may be eligible for an ANDA. A materially different device, formulation, or clinical claim may require a 505(b)(2) application.

Does flunisolide have biosimilar competition?

No. Biosimilars apply to biologic products. Flunisolide is a synthetic corticosteroid and competes through generic drug pathways.

Can a flunisolide formulation patent be listed in the Orange Book?

Potentially. Listing depends on whether the patent claims the approved drug product or an approved method of use and satisfies FDA listing requirements. A general formulation concept without a qualifying relationship to the approved product may not be listable.

Is an inhaled flunisolide product commercially attractive?

The opportunity is limited compared with nasal delivery. Historical inhalation products faced propellant and device issues, while the inhaled corticosteroid market has established alternatives with stronger commercial positions.

References

1. U.S. Food and Drug Administration. (2023). Drug approval package: Nasalide (flunisolide) nasal solution. FDA.

2. U.S. Food and Drug Administration. (2024). Aerobid (flunisolide inhalation aerosol) product information and discontinued drug records. FDA.

3. DailyMed. (2024). Flunisolide nasal spray: Prescribing information. National Library of Medicine.

4. U.S. Food and Drug Administration. (2024). Inactive ingredient database. FDA.

5. Bernstein, J. A. (2007). Review of the potential effects of intranasal corticosteroids and preservatives on nasal mucosa. Allergy & Asthma Proceedings, 28(6), 653-658.

6. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, 44th edition. FDA.