List of Excipients in Branded Drug SILDENAFIL FOR ORAL SUSPENSION

Generic Drugs Containing SILDENAFIL FOR ORAL SUSPENSION

Company	Ingredient	NDC	Excipient
Cipla USA Inc	sildenafil citrate	69097-903	ANHYDROUS CITRIC ACID
Cipla USA Inc	sildenafil citrate	69097-903	SILICON DIOXIDE
Cipla USA Inc	sildenafil citrate	69097-903	SODIUM BENZOATE
Cipla USA Inc	sildenafil citrate	69097-903	SORBITOL
Cipla USA Inc	sildenafil citrate	69097-903	SUCRALOSE
Cipla USA Inc	sildenafil citrate	69097-903	TITANIUM DIOXIDE
Cipla USA Inc	sildenafil citrate	69097-903	TRISODIUM CITRATE DIHYDRATE

What are the Most Frequently-Used Excipients in SILDENAFIL FOR ORAL SUSPENSION?

# Of NDCs	Excipient
2	ANHYDROUS CITRIC ACID
2	SILICON DIOXIDE
2	SODIUM BENZOATE
2	SORBITOL
2	SUCRALOSE
2	TITANIUM DIOXIDE
2	TRISODIUM CITRATE DIHYDRATE

Sildenafil for Oral Suspension: Excipient Strategy, Patent Position, and Commercial Opportunities

Last updated: September 24, 2026

Sildenafil for oral suspension is a differentiated pulmonary arterial hypertension dosage form with limited direct competition relative to sildenafil tablets. The reference product, Revatio 10 mg/mL powder for oral suspension, uses a conventional dry-powder system built around mannitol, hypromellose, xanthan gum, sodium benzoate, sucralose, and silicon dioxide. The largest commercial opportunities are pediatric and dysphagia-friendly delivery, improved reconstitution, longer in-use stability, better palatability, preservative reduction, and device-enabled dosing.

The active ingredient is sildenafil citrate. The product is approved for pulmonary arterial hypertension, including pediatric use in certain patients, and is distinct from sildenafil products marketed for erectile dysfunction. The relevant regulatory pathway is an abbreviated new drug application or 505(b)(2) application, depending on the extent of formulation and clinical bridging work.

What is sildenafil for oral suspension?

Sildenafil for oral suspension is a 10 mg/mL liquid dosage form supplied as a powder that is reconstituted with water before administration. The reference product is Revatio oral suspension, approved by the U.S. Food and Drug Administration for pulmonary arterial hypertension under Pfizer’s Revatio franchise.[1]

Attribute	Reference product profile
Active ingredient	Sildenafil citrate
Strength	10 mg/mL after reconstitution
Therapeutic area	Pulmonary arterial hypertension
Reference brand	Revatio
Dosage form	Powder for oral suspension
U.S. regulatory pathway	NDA
Primary users	Patients requiring pulmonary hypertension therapy who cannot use tablets reliably
Key formulation need	Uniform dose delivery after reconstitution
Commercial distinction	Liquid administration and pediatric suitability

The suspension format is relevant because many pulmonary arterial hypertension patients have swallowing limitations, feeding tubes, complex medication regimens, or a need for weight-based dosing. The product also supports dose measurement at volumes below the 20 mg tablet strength.

What excipients are used in Revatio oral suspension?

The Revatio powder contains excipients selected for bulk formation, viscosity control, suspension stability, microbial protection, taste masking, and powder flow. The FDA prescribing information identifies the following inactive ingredients:[1]

Excipient	Primary formulation function	Commercial relevance
Mannitol	Bulking agent and mouthfeel modifier	Supports powder volume and low-sugar positioning
Hypromellose	Suspending and viscosity-enhancing polymer	Controls sedimentation and redispersibility
Xanthan gum	Suspending agent and rheology modifier	Improves dose uniformity after reconstitution
Sodium benzoate	Preservative	Supports multidose in-use stability
Sucralose	High-intensity sweetener	Masks sildenafil-associated bitterness
Citric acid, anhydrous	pH adjustment and acidulant	Supports taste and preservative performance
Colloidal silicon dioxide	Glidant and powder-flow aid	Supports manufacturing and reconstitution behavior
Titanium dioxide	Opacifier and appearance modifier	Provides a consistent suspension appearance

The formulation does not depend on a proprietary excipient. Its commercial value is created by the combination of excipients, concentration, manufacturing process, reconstitution instructions, packaging, and dosing device.

Which excipients create the greatest technical risk?

The highest technical risks are sedimentation, caking, incomplete redispersion, viscosity drift, microbial growth, and bitterness. A formulation that passes initial release testing can still fail during the in-use period if the suspension forms a compact sediment or the dose concentration changes between the first and last administration.

Hypromellose and xanthan gum require careful optimization. Excessive polymer concentration can make the product difficult to pour or withdraw through an oral syringe. Insufficient polymer concentration can produce rapid settling and nonuniform dosing.

Sodium benzoate introduces a preservative-related development constraint. Its performance depends on pH, preservative concentration, microbial challenge results, packaging, and the product’s storage conditions. A preservative-free formulation could have commercial value but would require a robust single-dose or unit-dose presentation and a revised stability strategy.

What excipient strategies can improve sildenafil oral suspension?

The strongest opportunities are incremental formulation improvements that preserve the active ingredient and target an identified administration problem.

1. Improve redispersibility

A next-generation suspension can use a different polymer system, such as a xanthan-gum and cellulose-derivative combination, to reduce sedimentation and eliminate hard cake formation. The objective is a product that redistributes with limited shaking and remains homogeneous long enough to withdraw the prescribed dose.

Relevant development measurements include:

• Sedimentation volume
• Redispersion time
• Particle-size distribution
• Viscosity across shear rates
• Dose uniformity from beginning, middle, and end of container use
• Delivered dose through the intended oral syringe
• Stability after repeated opening and shaking

A formulation with lower viscosity but equivalent dose uniformity could improve caregiver handling and reduce administration errors.

2. Replace or reduce sodium benzoate

A preservative-reduced formulation could target patients with excipient sensitivity, institutional formulary preferences, or long-term pediatric use. Potential approaches include:

• Unit-dose oral suspension
• Smaller multidose containers
• A dual-chamber package
• A dry powder with on-demand reconstitution
• Alternative preservative systems
• Improved container-closure protection

The commercial tradeoff is important. A preservative-free liquid may increase packaging and distribution costs. It may also reduce the usable in-use period unless the product is supplied in single-dose units.

3. Improve palatability

Sildenafil has a known bitterness challenge. Sucralose provides sweetness but does not necessarily remove the active’s bitter aftertaste. An improved system could combine:

• Sucralose with a flavor system
• pH optimization
• Polymer-based taste masking
• Ion-exchange resin complexes
• Microparticles or coated sildenafil citrate
• Lipid or emulsion-based taste-masking systems

Taste-masking patents could create a stronger formulation position than a simple excipient substitution, particularly if the formulation improves pediatric adherence without materially increasing dose volume.

4. Reduce dose volume

A more concentrated suspension could reduce administration volume, but concentration increases may create problems with viscosity, sedimentation, taste intensity, and dose measurement. A 20 mg/mL product would need to demonstrate accurate delivery through an oral syringe and adequate stability after reconstitution.

A high-concentration product could be commercially attractive for patients receiving larger weight-based doses. It would also create a risk of medication error if the concentration is confused with the 10 mg/mL reference product. Distinct labeling, syringe markings, and packaging would be necessary.

5. Develop a ready-to-use suspension

A ready-to-use product would eliminate reconstitution errors and improve pharmacy workflow. Its principal barriers are chemical stability, microbial control, shipping weight, container compatibility, and shelf-life requirements.

The product could use a preservative system, aseptic processing, or a sterile single-dose package. The strongest commercial use case is a hospital or specialty-pharmacy product where reconstitution labor and dosing errors have measurable operational costs.

What patents protect sildenafil oral suspension?

The core sildenafil compound and early pulmonary hypertension use patents are no longer the principal source of exclusivity for a new oral suspension product. The commercial opportunity is therefore more likely to depend on formulation, manufacturing, device, and method-of-use claims.

Patent category	Strategic importance	Current commercial implication
Sildenafil compound patents	Historically high	Expired or no longer a practical barrier to routine generic development
Pulmonary hypertension method patents	Historically important for Revatio	Limited ability to block a conventional sildenafil product
Suspension formulation patents	Potentially high	Can protect polymer systems, taste masking, stability, or concentration
Reconstitution process patents	Moderate	May protect specific powder-to-liquid conversion methods
Packaging and device patents	Moderate	Can support proprietary dosing systems
Pediatric method-of-use patents	Variable	May affect labeling and carve-out strategy
Manufacturing process patents	Moderate to high	Can raise technical barriers if difficult to design around

The principal historical U.S. patent associated with sildenafil’s pulmonary hypertension use is U.S. Patent No. 6,469,012, assigned to Pfizer-related entities. Its term has expired, and it does not create a current compound-level barrier to sildenafil development.[2]

A developer seeking durable protection should focus on claims directed to a specific technical result, such as improved redispersion after storage, reduced bitterness, preservative-free stability, or accurate dosing through a defined delivery device. Broad claims covering a suspension of sildenafil alone would face substantial validity and obviousness pressure.

What is the Orange Book status of sildenafil oral suspension?

The Orange Book identifies FDA-approved drug products and applicable patent and exclusivity information. Revatio oral suspension is an NDA product, while generic sildenafil products have historically concentrated on tablets and other dosage forms.[3]

A generic oral suspension developer would need to assess:

• Whether an approved reference product is available for ANDA reference
• Whether the proposed product can match the reference concentration and dosage form
• Whether listed patents remain active against the relevant NDA
• Whether a Paragraph IV certification is required
• Whether labeling can be identical or requires a carve-out
• Whether the applicant must use a 505(b)(2) pathway because of formulation differences

The absence of a live compound patent does not guarantee rapid approval. Suspension-specific bioequivalence, in vitro performance, stability, preservative effectiveness, and device compatibility can create meaningful development work.

When does sildenafil lose exclusivity?

Sildenafil’s primary small-molecule and pulmonary hypertension exclusivity periods have expired. Revatio therefore faces generic competition in tablet presentations, while the oral suspension segment remains more formulation-sensitive.

Exclusivity type	Status
Sildenafil compound exclusivity	Expired
Original Revatio regulatory exclusivity	Expired
Historical pediatric extension	Expired
Core pulmonary hypertension patent protection	Expired
Formulation-specific protection	Must be assessed patent by patent
Biosimilar exclusivity	Not applicable

Sildenafil is a synthetic small molecule, not a biologic. Biosimilar risk does not apply. The relevant competitive threat is from generic oral products, compounded suspensions, and new branded formulations.

Which companies are challenging sildenafil exclusivity?

Generic competition has included major pharmaceutical manufacturers and specialty-generic companies supplying sildenafil tablets. The commercial challenge to the oral suspension is less direct because tablet approval does not automatically deliver a liquid dosage form.

The likely competitor groups are:

1. Generic manufacturers with existing sildenafil API and tablet infrastructure.
2. Contract development and manufacturing organizations with powder-for-suspension capabilities.
3. Specialty pharmaceutical companies focused on pediatric and rare-disease delivery systems.
4. Compounding pharmacies supplying extemporaneous sildenafil suspensions where permitted.
5. Device companies offering oral syringes, unit-dose packaging, or tube-compatible delivery systems.

The most credible oral suspension entrant is likely to be a company that already manufactures pediatric liquids or specialty hospital products. A tablet-focused generic manufacturer would need additional formulation, packaging, and stability capabilities.

What generic entry risks exist for sildenafil oral suspension?

The principal generic entry risks are technical rather than patent-driven.

ANDA risk

A proposed generic must demonstrate pharmaceutical equivalence and bioequivalence to the reference product. Differences in excipients may be acceptable, but they cannot alter safety, efficacy, dose delivery, stability, or labeling requirements.

505(b)(2) risk

A materially different concentration, taste-masking technology, preservative system, or delivery device may be better suited to a 505(b)(2) application. That pathway can support product differentiation but may trigger additional clinical or bridging requirements.

Compounding risk

Compounded sildenafil suspensions can compete on local availability and customization. They generally lack the manufacturing scale, validated shelf life, and standardized commercial packaging of an FDA-approved product. Their presence can still limit pricing in hospital and specialty-pharmacy channels.

Labeling risk

Pulmonary arterial hypertension products require precise dosing and administration instructions. A concentration change can increase dosing errors, particularly when caregivers use a syringe calibrated for a different strength.

What formulation patents could create commercial value?

The strongest patent candidates are formulation claims tied to measurable performance. Examples include:

• A sildenafil suspension with a defined particle-size distribution and redispersion time.
• A polymer system that maintains dose uniformity over a specified in-use period.
• A taste-masked sildenafil particle or coated particle.
• A preservative-free unit-dose suspension with defined microbial limits.
• A high-concentration suspension with controlled viscosity.
• A suspension compatible with enteral feeding tubes.
• A package and dosing syringe combination that reduces dose error.
• A dry powder that reconstitutes with a specified water volume and remains stable for a defined period.

Method-of-use claims may protect administration to pediatric patients, patients with dysphagia, or patients receiving enteral nutrition. Such claims must be evaluated against prior art and the existing Revatio labeling.

How strong is the patent estate for a new sildenafil suspension?

A conventional 10 mg/mL suspension using publicly known excipients would have a weak standalone patent position. A stronger estate would combine several claim layers:

Claim layer	Expected strength
Broad sildenafil suspension claim	Weak
Specific polymer ratio and rheology profile	Moderate
Taste-masked particle technology	Moderate to strong
Preservative-free unit-dose system	Moderate
Validated enteral-tube delivery system	Moderate
Manufacturing process producing a distinctive particle profile	Moderate
Package-device combination	Moderate
Clinical method claim based only on known sildenafil use	Weak to moderate

Patent strength will depend on unexpected results. Demonstrating superior taste, improved dose uniformity, longer in-use stability, or reduced administration error would support inventive-step arguments more effectively than merely substituting one common excipient for another.

What licensing deals could support a sildenafil suspension?

The most relevant licensing targets are not likely to be sildenafil molecule licensors. Sildenafil is widely available from API suppliers. Commercial partnerships would more likely involve:

• Taste-masking technology providers
• Pediatric liquid formulation companies
• Oral syringe and dosing-device manufacturers
• Specialty-pharmacy distribution networks
• Enteral-delivery device companies
• CDMOs with powder-for-suspension manufacturing lines
• Preservative-free packaging specialists

A license structured around a proprietary taste-masking platform or unit-dose suspension package could create differentiation without requiring ownership of the active ingredient. Royalty economics would need to be balanced against sildenafil’s generic pricing environment.

How does sildenafil suspension compare with sildenafil tablets?

Factor	Oral suspension	Tablets
Pediatric flexibility	Higher	Lower
Swallowing burden	Lower	Higher
Weight-based dosing	More flexible	Less flexible
Manufacturing complexity	Higher	Lower
Packaging cost	Higher	Lower
Stability burden	Higher after reconstitution	Lower
Dose-volume risk	Present	Limited
Taste challenge	Significant	Limited after swallowing
Direct generic competition	More limited	Extensive
Differentiation potential	Higher	Lower

The suspension has a stronger value proposition in patients who cannot reliably swallow tablets. Tablets remain more attractive for adult patients because of lower cost, simpler logistics, and longer shelf stability.

What FDA regulatory issues affect commercial launch?

A launch plan should address the FDA’s expectations for:

• Product quality and content uniformity
• Reconstitution instructions
• In-use stability
• Preservative effectiveness
• Container-closure integrity
• Dose delivery through the supplied syringe
• Compatibility with enteral feeding tubes
• Labeling for pediatric administration
• Drug-drug and food-related administration instructions
• Manufacturing controls for powder flow and blend uniformity

A product with an alternative concentration or a materially different excipient system may not qualify as a straightforward generic equivalent. The regulatory strategy should be selected early because it determines clinical, bioequivalence, labeling, and patent-certification requirements.

What are the main commercial opportunities?

The most attractive opportunities are:

1. A lower-viscosity formulation with faster redispersion.
2. A better-tasting pediatric product.
3. A preservative-free unit-dose suspension.
4. A high-concentration product that reduces dose volume.
5. A feeding-tube-compatible formulation.
6. A ready-to-use product for hospitals and specialty pharmacies.
7. A formulation-device combination that reduces caregiver dosing errors.
8. A private-label or licensed product for international markets where pediatric pulmonary hypertension treatment is underserved.

Revenue exposure is difficult to quantify because public filings generally do not disclose Revatio oral suspension sales separately from broader sildenafil or pulmonary hypertension revenue. The market is likely smaller than the sildenafil tablet market but can support premium pricing where administration, adherence, and specialty distribution create measurable value.

Key Takeaways

• Revatio oral suspension is a 10 mg/mL sildenafil citrate product for pulmonary arterial hypertension.
• Its excipient system uses mannitol, hypromellose, xanthan gum, sodium benzoate, sucralose, citric acid, colloidal silicon dioxide, and titanium dioxide.
• Sildenafil’s core composition and historical pulmonary hypertension patent protection no longer provide a meaningful barrier to conventional generic development.
• The strongest new IP opportunities involve taste masking, redispersion, preservative-free stability, concentration, enteral compatibility, manufacturing, and dosing devices.
• Biosimilar risk does not apply because sildenafil is a synthetic small molecule.
• The oral suspension market has less direct competition than sildenafil tablets but carries greater technical and regulatory complexity.
• Commercial differentiation is most credible in pediatric, dysphagia, feeding-tube, hospital, and specialty-pharmacy settings.
• A conventional copy using known excipients would have limited patent strength unless supported by unexpected technical performance.

FAQs

Is sildenafil oral suspension the same as Viagra liquid?

No. Revatio oral suspension is associated with pulmonary arterial hypertension, while Viagra is approved for erectile dysfunction. Both contain sildenafil, but their approved indications, labeling, strengths, and commercial positioning differ.

Can sildenafil oral suspension be administered through a feeding tube?

Administration may be technically feasible, but tube compatibility should be established for the specific formulation, tube material, flushing procedure, and dose volume. A product with validated enteral-tube performance could support a differentiated method-of-use and device strategy.

Is a preservative-free sildenafil suspension commercially viable?

Yes, particularly as a unit-dose or short-use product. The main tradeoffs are packaging cost, microbial control, in-use stability, and distribution complexity.

What is the best excipient for sildenafil taste masking?

No single excipient is sufficient in all formulations. Sucralose can reduce perceived bitterness, but stronger performance may require pH control, flavor pairing, polymer coating, ion-exchange technology, or coated sildenafil particles.

Could a new sildenafil suspension receive patent protection?

Yes, but a patent would be more defensible when directed to a specific composition, manufacturing process, packaging system, or measurable performance advantage rather than to a conventional suspension containing sildenafil and known excipients.

References

1. U.S. Food and Drug Administration. (2023). Revatio (sildenafil citrate) for oral suspension: Prescribing information. Pfizer Laboratories.

2. U.S. Patent and Trademark Office. (2002). U.S. Patent No. 6,469,012: Use of sildenafil in the treatment of pulmonary hypertension. Pfizer Inc.

3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.