List of Excipients in Branded Drug DEXTROMETHORPHAN POLISTIREX EXTENDED-RELEASE

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Generic Drugs Containing DEXTROMETHORPHAN POLISTIREX EXTENDED-RELEASE

Company	Ingredient	NDC	Excipient
Amneal Pharmaceuticals LLC	dextromethorphan polistirex	65162-700	CITRIC ACID MONOHYDRATE
Amneal Pharmaceuticals LLC	dextromethorphan polistirex	65162-700	CORN OIL
Amneal Pharmaceuticals LLC	dextromethorphan polistirex	65162-700	EDETATE DISODIUM
Amneal Pharmaceuticals LLC	dextromethorphan polistirex	65162-700	ETHYLCELLULOSES

What are the Most Frequently-Used Excipients in DEXTROMETHORPHAN POLISTIREX EXTENDED-RELEASE?

# Of NDCs	Excipient
2	CITRIC ACID MONOHYDRATE
2	CORN OIL
1	D&C RED NO. 33
2	EDETATE DISODIUM

Dextromethorphan Polistirex Extended-Release: Excipient Strategy, Patent Position and Commercial Opportunities

Last updated: October 14, 2026

Dextromethorphan polistirex extended-release is an established 12-hour cough-suppressant platform based on an ion-exchange resin complex. Its commercial value is concentrated in formulation execution rather than active-ingredient exclusivity. The main opportunities are sugar-free pediatric products, improved taste masking, lower-viscosity suspensions, private-label products, and differentiated delivery formats.

The U.S. reference product, Delsym 12 Hour Cough Relief, contains dextromethorphan polistirex equivalent to 30 mg dextromethorphan hydrobromide per 5 mL. It is marketed as an over-the-counter cough suppressant and is regulated under the FDA’s OTC cough-and-cold framework rather than through a conventional prescription-drug approval and Orange Book strategy.[1,2]

What is dextromethorphan polistirex extended-release?

Dextromethorphan polistirex is a complex of dextromethorphan with a sulfonated polystyrene-divinylbenzene ion-exchange resin. The resin limits immediate dissolution of the active ingredient and produces extended release after oral administration.

Attribute	Commercial profile
Active ingredient	Dextromethorphan polistirex
Pharmacologic category	Antitussive
Reference dose	Equivalent to 30 mg dextromethorphan hydrobromide per 5 mL
Typical dosing interval	Every 12 hours
Dosage form	Oral suspension
Principal brand	Delsym 12 Hour Cough Relief
Regulatory route	OTC monograph framework
Primary technical barrier	Resin complexation, release control, suspension stability and taste
Primary commercial barrier	Consumer acceptance, retail distribution and established brand recognition

The polistirex approach creates a differentiated product relative to immediate-release dextromethorphan syrups. The commercial claim is convenience: two doses per day instead of more frequent dosing. The formulation must maintain dose uniformity because the resin complex is suspended rather than fully dissolved.

Which excipients are used in dextromethorphan polistirex suspension?

A representative U.S. Delsym formulation uses excipients for suspension control, viscosity, preservation, pH adjustment, sweetness, flavor and product stability. Exact excipients vary by strength, flavor, sugar content and market.

Excipient category	Representative materials	Formulation function
Suspending agent	Xanthan gum	Limits settling and supports redispersion
Sweetener and vehicle	Sucrose, high-fructose corn syrup or other carbohydrate vehicle	Palatability, viscosity and bulk
Chelating agent	Edetate disodium	Binds trace metals and can support stability
pH adjuster/buffer	Sodium citrate	Controls pH and improves stability
Preservative	Methylparaben	Microbial control in multidose liquid
Film or matrix aid	Ethylcellulose	May support particle coating or release control
Solvent or cosolvent	Propylene glycol, where used	Solubilization and processing support
Colorant	Approved color additive	Product identification and consumer acceptance
Flavor	Citrus, berry or other flavor system	Taste masking and brand differentiation

The key excipient is not a conventional release polymer dispersed throughout a matrix. Release is primarily governed by the resin complex and its interaction with the gastrointestinal environment. The surrounding liquid system controls whether the particles remain uniformly distributed, whether the dose can be measured accurately and whether the product remains acceptable during storage.

What is the role of the ion-exchange resin?

The resin is the core release-control component. It binds the cationic form of dextromethorphan and releases the drug through ion exchange in gastrointestinal fluids. Resin particle size, crosslink density, loading ratio, washing procedure and residual ionic content can materially affect release.

Manufacturers must control:

• Drug-to-resin loading ratio
• Resin particle-size distribution
• Resin swelling and hydration
• Residual salts and process impurities
• Complexation efficiency
• Release profile across relevant pH conditions
• Suspension sedimentation and redispersion
• Dose uniformity after storage and patient handling

The resin is also part of the intellectual-property and manufacturing barrier. A competitor can use the same active ingredient but still need to develop a reproducible complexation process that matches the intended 12-hour release profile.

Which excipients create the greatest commercial opportunity?

The most attractive opportunities are excipient-led improvements that preserve the monograph-compliant active ingredient while solving consumer or manufacturing problems.

Sugar-free and diabetic-friendly suspensions

Sugar-free products can expand use among consumers avoiding sucrose or high-fructose corn syrup. Removing carbohydrate solids changes viscosity, mouthfeel, density and microbial risk. Candidate systems may use sorbitol, glycerin, maltitol, xylitol or combinations of polyols with high-intensity sweeteners.

The formulation risks are significant:

• Polyols can produce gastrointestinal intolerance at higher exposure.
• Sweetener systems can leave bitterness or cooling effects.
• Sugar-free vehicles may require new preservative strategies.
• Density changes can affect dose measurement and sedimentation.
• Flavor intensity may need adjustment because dextromethorphan has a strong bitter taste.

A sugar-free product should be evaluated as a new suspension system rather than a simple substitution of sucrose with a sweetener.

Pediatric taste masking

Pediatric use creates a high-value formulation opportunity, but dextromethorphan products must be positioned carefully because FDA labeling includes age restrictions and warnings. Taste masking can combine resin entrapment, flavor systems, sweeteners and mouthfeel modifiers.

Commercially relevant targets include:

• Lower bitterness after swallowing
• Reduced aftertaste
• Less throat coating
• Better acceptance at the labeled dose
• Stable flavor over shelf life
• Lower color migration and flavor interaction

Taste masking should not accelerate drug release or increase the risk of dose dumping. Flavors and sweeteners should be screened against the resin complex, preservatives and packaging materials.

Lower-viscosity suspensions

Many extended-release cough suspensions use moderate-to-high viscosity to keep resin particles suspended. A lower-viscosity product could improve pouring, dosing through oral syringes and consumer perception. The tradeoff is greater sedimentation risk.

Potential approaches include:

• Narrower resin particle-size distribution
• Controlled flocculation
• Structured vehicles with lower apparent viscosity during pouring
• Optimized xanthan or cellulose-polymer blends
• Density matching between the resin complex and liquid vehicle
• Improved bottle and dosing-device design

The strongest product concept may combine a low-pour-force suspension with rapid redispersion after modest shaking.

Preservative and clean-label positioning

Methylparaben and related preservatives are common in multidose oral liquids, but some consumers and retailers prefer products described as preservative-free. A preservative-free product would require a different risk-control strategy, such as:

• Single-dose packaging
• Unit-dose stick packs
• Aseptic processing
• Lower water activity
• Alternative antimicrobial systems
• Improved closure integrity
• Packaging that limits repeated contamination

Preservative-free positioning creates packaging and cost challenges. It is more commercially plausible for premium or travel-oriented products than for low-cost mass-market syrups.

What formulation patents protect dextromethorphan polistirex?

The principal protection historically associated with this product category concerns the resin-drug complex, sustained-release behavior and liquid suspension formulation. The active ingredient itself is old and does not provide meaningful composition-of-matter exclusivity.

Protection layer	Likely commercial relevance
Dextromethorphan active ingredient	Minimal current exclusivity value
Dextromethorphan-resin complex	Historically important; foundational claims are likely expired
Controlled-release profile	May support formulation differentiation if claims remain enforceable
Suspension vehicle	Potentially useful for later-generation products
Taste-masking system	Potentially protectable if technically specific
Sugar-free formulation	Potentially protectable through composition and performance claims
Packaging and dosing system	Can create narrower product-specific protection
Manufacturing process	May be difficult to detect and enforce but can create supply barriers

Because the product is generally marketed under the OTC monograph pathway, it does not have the same Orange Book patent-listing structure as a newly approved prescription product. A company developing a competing OTC product should evaluate historical patents, current formulation patents, trademarks, trade secrets and regulatory exclusivity separately.

How strong is the patent estate for dextromethorphan polistirex?

The estate is stronger as a technical know-how and manufacturing platform than as a basic active-ingredient patent estate. Foundational resin-complex and extended-release concepts date back decades, making ordinary 20-year patent terms a limited source of present-day exclusivity.[3]

The strongest residual barriers are likely to be:

1. Proprietary resin loading and washing conditions.
2. Particle engineering that improves release consistency.
3. A suspension system with superior redispersion.
4. A sugar-free or low-viscosity composition with validated stability.
5. Process controls that competitors cannot easily infer from the finished product.

Trade-secret protection may be more important than patent protection for resin preparation, in-process testing and scale-up parameters.

When does dextromethorphan polistirex lose exclusivity?

Dextromethorphan polistirex has no meaningful new-molecular-entity exclusivity in the United States. The active ingredient has been used for decades, and OTC monograph status allows compliant competitors to enter without waiting for expiration of a prescription-drug exclusivity period.

The practical exclusivity timeline is:

Exclusivity component	Current relevance
New chemical entity exclusivity	None
Prescription-drug regulatory exclusivity	None for the standard OTC product
Foundational active-ingredient patents	Expired or commercially obsolete
Historical formulation patents	Mostly age-limited; claim-by-claim review required
Orange Book-listed patents	Generally not the principal barrier for the OTC monograph product
Brand and trade dress	Ongoing protection if properly maintained
Manufacturing know-how	Potentially ongoing and difficult to assess publicly

What is the FDA regulatory status of dextromethorphan polistirex?

Dextromethorphan is recognized as an OTC antitussive active ingredient under the FDA cough-and-cold monograph framework. The relevant regulatory requirements include permitted dosage, labeling, warnings, directions and product quality standards.[1]

The commercial implications are material:

• A compliant OTC product may avoid the cost and timing of a full new-drug application.
• The sponsor must meet monograph conditions and general OTC requirements.
• Product-specific formulation changes still require quality, stability, safety and labeling support.
• A novel delivery system or materially different claim may fall outside the monograph and require an FDA application.
• Pediatric labeling requires particular attention because cough-and-cold products have age-related restrictions and warnings.

What is the Orange Book status of dextromethorphan polistirex?

The standard Delsym-type OTC product is not principally protected through Orange Book listings. Orange Book patent certifications, including Paragraph IV certifications, are associated with abbreviated new drug applications for approved prescription products and certain other FDA-approved products.[4]

Are Paragraph IV challenges relevant?

Usually not for a conventional OTC monograph product. A competitor entering under the OTC monograph framework generally does not file an ANDA Paragraph IV challenge against the brand in the same manner as a generic prescription drug.

A Paragraph IV issue could become relevant if a sponsor pursued an FDA-approved product outside the monograph, such as:

• A novel formulation requiring an NDA
• A new route of administration
• A new indication
• A prescription product with distinct clinical claims
• A 505(b)(2) application relying partly on an existing product

That pathway would create a different patent and regulatory analysis.

Which companies are challenging the Delsym market?

The competitive field includes branded cough products, store brands, private-label manufacturers and combination products containing dextromethorphan in immediate-release or extended-release forms. The principal competitive distinction is not only the active ingredient. It is the dosing interval, sensory profile, dosage form, price and distribution channel.

Competitor type	Competitive strategy
Branded extended-release product	Brand recognition and 12-hour dosing
Private-label extended-release suspension	Price competition
Immediate-release syrup	Lower manufacturing complexity and broad availability
Capsules or liquid-filled dosage forms	Portability and lower excipient burden
Combination cough-and-cold products	Multiple symptoms in one product
Sugar-free products	Dietary and consumer-preference differentiation
Natural or non-drug products	Alternative positioning, though not direct substitutes

The most direct threat to Delsym is a well-priced, monograph-compliant extended-release suspension with comparable taste, dose uniformity and shelf stability.

What generic launch scenarios exist?

Scenario 1: Standard OTC suspension

This is the lowest regulatory-risk entry. The sponsor uses dextromethorphan polistirex, follows the monograph, matches the labeled strength and competes through price and distribution.

Commercial risk is highest because the product can become a commodity. Retail placement and manufacturing cost determine success.

Scenario 2: Sugar-free premium suspension

This product targets adults avoiding sucrose and selected pediatric-caregiver segments. It can command a modest premium if taste and tolerability are materially better.

The main development challenge is microbial control and maintaining a stable suspension without the viscosity and solids contribution of sugar.

Scenario 3: Unit-dose or stick-pack format

Unit-dose packaging can improve portability, reduce repeated bottle contamination and support preservative-free positioning. It increases packaging cost and may require more complex filling operations.

This format is suitable for travel, convenience stores and e-commerce multipacks.

Scenario 4: Extended-release capsule or multiparticulate product

A capsule or sachet can avoid some suspension problems, but the product must preserve the intended 12-hour release profile and provide an acceptable dose for the target population. It may be less suitable for young children and can lose the familiar liquid-product advantage.

Scenario 5: Pediatric-focused taste-masked product

A differentiated flavor and lower-bitterness product could support premium positioning. Regulatory and safety controls are critical because cough-and-cold products have age-specific restrictions.

What manufacturing and IP barriers affect commercial entry?

The main barriers are technical rather than regulatory exclusivity barriers.

Resin complex manufacturing

The sponsor must achieve consistent drug loading and release performance at commercial scale. Critical variables include resin grade, particle size, mixing energy, contact time, pH, temperature and washing.

Suspension scale-up

Laboratory viscosity data do not fully predict commercial behavior. High-shear processing can alter polymer hydration, entrain air or damage particle structure. The finished product must remain uniform during filling and consumer use.

Analytical testing

A robust control strategy should include:

• Assay and impurities
• Resin-bound and free dextromethorphan
• Particle-size distribution
• In vitro release
• Sedimentation and redispersion
• Viscosity across shear rates
• Microbial limits
• Preservative effectiveness
• Container-closure compatibility
• Stability under temperature cycling

Geographic coverage

The U.S. OTC monograph does not automatically establish market access in Europe, Canada, Japan or other jurisdictions. Each market may classify dextromethorphan products differently, require local labeling and impose different rules on excipients, preservatives, pediatric use and combination products.

A global strategy should treat the U.S. formulation as a platform, not as a universal regulatory template.

What licensing deals and litigation affect the opportunity?

Delsym is a branded OTC product, and commercial rights may involve brand ownership, manufacturing arrangements, distribution agreements and private-label supply contracts. Publicly available FDA labeling does not establish the full scope of private commercial agreements.

No current Orange Book patent dispute is central to the standard OTC monograph product. The more relevant legal risks are:

• Trademark and trade-dress disputes
• False or unsupported “12-hour” or “long-lasting” claims
• Product-liability claims involving dosing or age restrictions
• Manufacturing quality failures
• Confidential-information or trade-secret disputes
• Contract disputes involving private-label supply

A new entrant should conduct a separate freedom-to-operate review for resin-complex claims, release-profile claims, excipient combinations, flavor systems, packaging and trademarks before launch.

How does dextromethorphan polistirex compare with immediate-release dextromethorphan?

Factor	Dextromethorphan polistirex ER	Immediate-release dextromethorphan
Dosing interval	Typically 12 hours	More frequent dosing
Main technical issue	Complex release and suspension uniformity	Solubility, taste and liquid stability
Manufacturing complexity	Higher	Lower
Consumer benefit	Convenience and reduced dosing frequency	Simpler, often lower-cost product
Excipient burden	Resin plus suspension system	Conventional syrup or solid dosage excipients
Patent value	Formulation and process history	Limited active-ingredient protection
Premium potential	Higher if sensory performance is strong	More price-sensitive
Best differentiation	Sugar-free, low-viscosity, taste-masked and portable formats	Flavor, price and combination therapy

Key Takeaways

• Dextromethorphan polistirex is an extended-release ion-exchange resin complex, not a newly protected active ingredient.
• The main formulation challenges are dose uniformity, resin release control, sedimentation, redispersion and taste.
• The strongest commercial opportunities are sugar-free suspensions, pediatric taste masking, low-viscosity vehicles and unit-dose packaging.
• OTC monograph status reduces the importance of Paragraph IV litigation and Orange Book patents for conventional products.
• Manufacturing know-how, resin processing and suspension control may create stronger practical barriers than legacy formulation patents.
• A competing product can enter through the OTC pathway if it satisfies applicable monograph and general FDA requirements.
• Premium positioning depends on measurable consumer benefits rather than the presence of dextromethorphan alone.

FAQs

Is dextromethorphan polistirex the same as dextromethorphan hydrobromide?

No. Dextromethorphan polistirex is a resin complex that delivers an amount equivalent to a specified dose of dextromethorphan hydrobromide. The polistirex form is used to extend release.

Can a company sell a generic Delsym product without an ANDA?

A monograph-compliant OTC product may generally enter without the conventional ANDA pathway used for prescription generics. The sponsor must meet the applicable FDA monograph, labeling, manufacturing and quality requirements.

Which excipient is most important for extending release?

The ion-exchange resin is the principal release-control component. Xanthan gum and other suspension excipients mainly control physical stability and dose uniformity in the liquid product.

Is a sugar-free dextromethorphan polistirex product patentable?

A sugar-free formulation may support patent protection if it contains a novel and non-obvious excipient system, manufacturing process or performance profile. Removing sugar alone is unlikely to provide strong protection.

What is the most defensible commercial differentiation strategy?

A combination of improved taste, reliable 12-hour release, low-pour-force suspension behavior, sugar-free positioning and convenient packaging is more defensible than a price-only launch.

References

1. U.S. Food and Drug Administration. (2024). OTC monograph M012: Cough and cold, oral liquid, immediate-release and extended-release dosage forms. https://www.accessdata.fda.gov/

2. DailyMed. (2024). Delsym 12 hour cough relief: Dextromethorphan polistirex oral suspension, extended release. U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/

3. U.S. Patent and Trademark Office. (2024). Patent term adjustment and patent term expiration resources. https://www.uspto.gov/patents/laws/patent-term-calculator

4. 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