List of Excipients in Branded Drug FELDENE

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Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Pfizer Laboratories Div Pfizer Inc	FELDENE	piroxicam	0069-3220	FD&C BLUE NO. 1
Pfizer Laboratories Div Pfizer Inc	FELDENE	piroxicam	0069-3220	FD&C RED NO. 3
Pfizer Laboratories Div Pfizer Inc	FELDENE	piroxicam	0069-3220	LACTOSE
Pfizer Laboratories Div Pfizer Inc	FELDENE	piroxicam	0069-3220	MAGNESIUM STEARATE

Generic Drugs Containing FELDENE

Company	Ingredient	NDC	Excipient
Keltman Pharmaceuticals Inc	piroxicam	68387-700	COLLOIDAL SILICON DIOXIDE
Keltman Pharmaceuticals Inc	piroxicam	68387-700	D&C YELLOW NO. 10
Keltman Pharmaceuticals Inc	piroxicam	68387-700	FD&C GREEN NO. 3
Keltman Pharmaceuticals Inc	piroxicam	68387-700	GELATIN

What are the Most Frequently-Used Excipients in FELDENE?

# Of NDCs	Excipient
1	COLLOIDAL SILICON DIOXIDE
1	D&C YELLOW NO. 10
1	FD&C GREEN NO. 3
1	GELATIN

Feldene Excipient Strategy and Commercial Opportunities for Piroxicam

Last updated: September 24, 2026

Feldene is the Pfizer brand for piroxicam, a long-acting nonsteroidal anti-inflammatory drug approved for osteoarthritis and rheumatoid arthritis. Its core composition is commercially mature, and broad composition-of-matter exclusivity has expired. The strongest opportunities are therefore in differentiated delivery systems, patient-friendly dosage forms, topical products, and excipient platforms that improve manufacturability or reduce formulation-specific risk.

Piroxicam’s long half-life, dose-related gastrointestinal risk, poor aqueous solubility, and low-dose loading requirement create a practical formulation opportunity. They also limit the value of aggressive absorption enhancement because higher systemic exposure can increase toxicity.

What is Feldene and how is piroxicam regulated?

Feldene contains piroxicam, an oxicam-class NSAID. The U.S. FDA label identifies Feldene capsules as prescription products in 10 mg and 20 mg strengths. The recommended dose is generally 20 mg once daily or 10 mg twice daily, with the lowest effective dose advised for the shortest duration consistent with treatment goals (FDA, 2023).

Piroxicam is regulated as a conventional small-molecule drug, not a biologic. Biosimilar competition is therefore irrelevant. Competitive pressure comes from:

• Generic piroxicam capsules
• Other oral NSAIDs
• Topical NSAIDs
• Selective COX-2 inhibitors
• Fixed-dose analgesic combinations
• Injectable or locally delivered anti-inflammatory products

The main commercial constraint is the safety profile. FDA labeling carries boxed warnings for serious cardiovascular thrombotic events and gastrointestinal bleeding, ulceration, and perforation. Piroxicam also has a relatively long elimination half-life, reported at approximately 50 hours, which supports once-daily dosing but can prolong adverse-event exposure (FDA, 2023).

What excipients are used in Feldene capsules?

The commercial Feldene capsule is a conventional immediate-release hard gelatin dosage form. Public product labeling identifies standard capsule excipients, including diluents, disintegrants, lubricants, surfactants, and capsule-shell materials. Exact excipient composition can differ by market, strength, and manufacturing site.

The formulation objectives are conventional:

Formulation objective	Excipient function	Commercial relevance
Uniform low-dose distribution	Diluent and filler	Important because piroxicam is present at 10 mg or 20 mg
Rapid capsule rupture	Disintegrant	Supports immediate-release performance
Powder flow	Glidant and lubricant	Reduces fill-weight variation
Wetting of poorly soluble piroxicam	Surfactant or wetting agent	Can improve dissolution consistency
Product stability	Moisture and oxygen control	Important for long shelf life
Patient acceptability	Capsule-shell color and size	Supports product identification and adherence

Piroxicam is practically insoluble in water, so dissolution performance is more important than the simple capsule presentation suggests. A generic manufacturer can copy the nominal strength while still needing to manage powder flow, wetting, polymorphic behavior, particle size, dissolution, and content uniformity.

The U.S. product label is the controlling source for the marketed Feldene composition and should be compared with the formulation used in any abbreviated new drug application (FDA, 2023).

Which excipient properties matter most for piroxicam?

Solubility enhancement

Piroxicam’s low water solubility makes wetting and dissolution the primary excipient issues. Candidate approaches include:

• Sodium lauryl sulfate or other surfactants
• Poloxamers
• Crospovidone and croscarmellose sodium
• Amorphous solid dispersions
• Cyclodextrin complexes
• Lipid-based self-emulsifying systems
• Co-crystals or salt-related solid-state approaches
• Nanocrystalline piroxicam

Surfactants can improve dissolution but may create tolerability, content-uniformity, or regulatory comparability issues. A high-surfactant formulation also has limited value if it improves in vitro dissolution without improving in vivo performance.

Solid-state control

Piroxicam can exist in different solid-state forms, including polymorphic and hydrate-related forms reported in the pharmaceutical literature. Solid-state selection affects dissolution, stability, and bioavailability. A formulation developer should control:

• Polymorphic form
• Crystallinity
• Residual solvent
• Water activity
• Particle-size distribution
• Milling-induced transformation
• Storage-related recrystallization

Solid-state control can create a stronger technical position than a simple excipient substitution, particularly if the resulting product has a measurable dissolution or stability advantage.

Content uniformity

The active load is relatively low compared with the capsule fill weight. Direct blending may create segregation risk, especially with high-density excipients or broad particle-size distributions. Granulation, ordered mixing, spray drying, or drug layering can improve uniformity.

A robust platform should demonstrate acceptable blend uniformity after scale-up, transport, and hopper residence. These manufacturing controls can support regulatory approval but do not automatically create enforceable patent protection.

Moisture management

Moisture-sensitive excipients and gelatin shells can affect capsule stability. Commercial development should evaluate:

• Water activity
• Shell moisture migration
• Disintegration after storage
• Interaction between surfactants and gelatin
• Packaging in high-barrier blister or bottle systems
• Desiccant requirements

A moisture-control strategy can reduce batch failures and extend shelf life, although it is usually easier to protect through manufacturing know-how than through a broad composition patent.

What formulation patents could protect Feldene alternatives?

The original Feldene product and piroxicam active ingredient are long-established. New commercial protection is more likely to arise from a specific formulation, dosage form, manufacturing process, or method of use.

Potential patent categories include:

Patent category	Potential claim subject	Relative commercial value
Solid-state patent	Specific polymorph, hydrate, co-crystal, or amorphous form	High if the form is necessary for the product
Composition patent	Piroxicam with a defined excipient system	Moderate to high if narrowly linked to performance
Delivery-system patent	Nanoparticles, lipid system, mucoadhesive system, or depot	High if clinical benefit is demonstrated
Dosage-form patent	Orally disintegrating tablet, granule, sachet, or modified-release product	Moderate
Process patent	Spray drying, hot-melt extrusion, wet granulation, or continuous manufacturing	Moderate
Method-of-use patent	Lower-dose regimen, defined patient population, or new indication	High only if clinically meaningful
Packaging patent	Moisture-barrier system or unit-dose presentation	Usually low to moderate

A patent based only on replacing one conventional filler with another is vulnerable to obviousness and lack of unexpected results. A stronger case requires evidence such as faster dissolution, reduced food effect, improved stability, lower variability, or a clinically relevant reduction in dose.

What patent barriers exist for generic piroxicam?

Generic piroxicam products generally face a mature patent landscape. The key regulatory barrier is likely bioequivalence and product quality rather than an active composition-of-matter patent. For a standard immediate-release capsule, an ANDA applicant would typically assess:

• Orange Book patent listings
• Reference-listed-drug status
• Paragraph I, II, III, or IV certification
• Bioequivalence requirements
• Dissolution profile
• Labeling restrictions
• Any listed method-of-use patents

The FDA Orange Book should be checked for the current listing status of Feldene and any listed patents at the time of filing. Historical patent expiration cannot be treated as a substitute for a current Orange Book review (FDA, 2024a).

When did Feldene lose exclusivity?

Feldene’s core commercial exclusivity has expired. Piroxicam was approved in the United States decades ago, and generic piroxicam products have been marketed for many years. The original active-ingredient and early product patents are not a current barrier to ordinary generic capsule entry.

There is no practical biosimilar-style exclusivity period because Feldene is a small-molecule drug. Any remaining exclusivity would need to arise from a specific later approval, pediatric study, orphan designation, or newly patented formulation. No such exclusivity should be assumed without a current FDA database review.

What is the Orange Book status of Feldene?

Feldene is an FDA-approved prescription small-molecule product. Orange Book analysis should distinguish among:

1. The reference-listed drug.
2. Approved generic piroxicam products.
3. Any active patents listed against the reference product.
4. Therapeutic-equivalence codes for generic capsules.
5. Marketed versus discontinued presentations.

For a conventional generic capsule, an applicant would normally pursue an ANDA referencing the approved piroxicam product. A Paragraph IV challenge would be commercially relevant only if the Orange Book contains an unexpired patent that could block approval or launch.

Because Feldene is an older product with established generic competition, the probability of a commercially meaningful Paragraph IV event is lower than for a recently approved reformulation. The greater risk is a formulation developer obtaining a later patent on an improved piroxicam product and asserting that patent against a competing differentiated formulation.

Which companies are challenging Feldene exclusivity?

Generic competition has already challenged the commercial exclusivity of the Feldene brand through approved piroxicam products. The relevant competitive group includes manufacturers of generic piroxicam capsules and distributors that sell products under private-label arrangements.

A complete current company-by-company Paragraph IV list cannot be stated reliably without a live litigation and Orange Book search. Older ANDA approvals do not necessarily indicate current commercial marketing, and patent litigation databases may list cases after the product has exited the market.

The commercially important distinction is between:

• Ordinary generic capsule competition, which is mature.
• A new piroxicam formulation, which may have separate patent protection.
• A topical or locally delivered product, which may compete under a different regulatory and patent strategy.

What are the best commercial excipient opportunities for Feldene?

Orally disintegrating piroxicam

An orally disintegrating tablet could address patients with dysphagia or difficulty swallowing capsules. The main technical requirements are:

• Low tablet weight
• Adequate mechanical strength
• Rapid disintegration
• Taste masking
• Piroxicam content uniformity
• Acceptable mouthfeel
• Moisture protection

Mannitol, crospovidone, silicified microcrystalline cellulose, co-processed excipients, and taste-masking polymers are potential platform components. The product would need to show that rapid disintegration does not create unacceptable local irritation or excessive early exposure.

Granules or sprinkle formulation

A sachet or sprinkle product could improve administration for patients who cannot swallow capsules. Multiparticulates also allow taste masking and particle coating. Commercial value would depend on whether the product can be administered with food without compromising bioequivalence.

Topical piroxicam

Topical piroxicam is a more significant product opportunity outside the U.S. Several markets have topical piroxicam products, including gels and other semisolid presentations. Excipient strategies include:

• Alcohol-water solvent systems
• Propylene glycol or polyethylene glycol
• Carbomer or cellulose-based gels
• Penetration enhancers
• Liposomes
• Nanoemulsions
• Adhesive or film-forming polymers

Topical delivery could reduce systemic exposure, but it does not eliminate systemic NSAID risks. A commercially credible product needs evidence of local efficacy, acceptable skin tolerability, consistent dose delivery, and controlled permeation.

Long-acting local delivery

Intra-articular, periarticular, or implantable piroxicam systems may have technical appeal, but they face a higher regulatory burden. The formulation must control burst release, local tolerability, sterility, and dose recovery. These products are more suitable for a specialty development program than for a low-cost generic strategy.

Amorphous solid dispersion or nanocrystal capsule

A dissolution-enhanced oral capsule could use spray drying, hot-melt extrusion, or nanocrystal technology. The commercial proposition is strongest if the developer can show:

• Faster and more reproducible dissolution
• Lower intersubject variability
• Reduced food effect
• Lower effective dose
• Improved exposure consistency

The main risks are physical instability, scale-up complexity, excipient load, and the possibility that greater bioavailability increases toxicity without improving clinical outcomes.

How does Feldene compare with competing NSAIDs?

Product	Active ingredient	Typical formulation opportunity	Key competitive issue
Feldene	Piroxicam	ODT, topical gel, dissolution-enhanced capsule	Long half-life and safety warnings
Celebrex	Celecoxib	Capsules, solid-state and solubility strategies	COX-2 positioning and generic competition
Mobic	Meloxicam	Tablets, oral suspension, ODT	Broad generic availability
Voltaren	Diclofenac	Topical gel, tablets, patches	Strong topical brand recognition
Naprosyn	Naproxen	Tablets, suspension, delayed-release forms	Low-cost generic competition
Motrin	Ibuprofen	Tablets, liquids, softgels, chewables	High-volume commodity market

Piroxicam has a dosing-convenience advantage because of its long half-life. It has a weaker safety and lifecycle position than products supported by topical delivery, pediatric formulations, or large consumer-health channels.

What generic launch risks exist for piroxicam?

A standard capsule launch has relatively low intellectual-property risk but meaningful commercial risk. Key factors include:

• Low pricing after multiple generic entrants
• Limited brand loyalty
• Restricted use because of NSAID safety concerns
• Competition from meloxicam, naproxen, diclofenac, and celecoxib
• Potential manufacturing costs associated with dissolution control
• FDA scrutiny of bioequivalence and product quality
• Limited reimbursement differentiation

A differentiated formulation can improve pricing power, but it also increases clinical, regulatory, and manufacturing costs. The best near-term opportunity is usually a low-complexity dosage form with a clear patient-use advantage rather than a highly engineered delivery system without clinical differentiation.

How strong is the Feldene patent estate?

The legacy Feldene patent estate is weak as a barrier to ordinary generic entry because piroxicam has been marketed for decades and generic products are established. A new patent estate could still be strong if it protects a necessary and non-obvious formulation attribute.

Patent strength should be assessed against five criteria:

1. Whether the claim covers the active product rather than an optional excipient.
2. Whether the formulation produces unexpected dissolution, stability, or clinical results.
3. Whether competitors can design around the excipient ratio or process.
4. Whether the claims survive obviousness and enablement challenges.
5. Whether the product receives a relevant Orange Book listing or only standalone patent protection.

A formulation patent with narrow excipient percentages and no clinical or performance advantage is generally less durable than a patent covering a defined solid-state form, controlled-release profile, or clinically differentiated delivery system.

What licensing opportunities exist around piroxicam excipients?

Licensing opportunities are more likely to involve enabling technologies than Feldene-specific rights. Relevant technologies include:

• Spray-dried dispersion platforms
• Nanocrystal manufacturing
• Liposomal or nanoemulsion systems
• Taste-masking coatings
• Mucoadhesive topical gels
• Co-processed direct-compression excipients
• Continuous manufacturing and real-time blend control

A licensee should evaluate whether the excipient or delivery technology has prior use with NSAIDs, whether it creates new safety concerns, and whether the supplier can support pharmaceutical-grade scale-up. Freedom-to-operate analysis should cover the active ingredient, solid-state form, dosage form, manufacturing process, and delivery platform separately.

Key Takeaways

• Feldene is piroxicam, an old small-molecule NSAID with expired core exclusivity and established generic competition.
• The conventional immediate-release capsule has limited standalone commercial differentiation.
• Piroxicam’s main formulation challenges are poor aqueous solubility, content uniformity, solid-state control, and moisture management.
• ODT, sprinkle, topical, nanocrystal, and amorphous-dispersion products offer the clearest lifecycle opportunities.
• Excipient substitution alone is unlikely to support strong patent protection without unexpected performance data.
• Topical piroxicam has greater commercial differentiation potential than another standard oral capsule.
• Generic entry risk is high for ordinary capsules and lower only where a differentiated, patent-protected formulation has regulatory and clinical support.
• The FDA Orange Book and current FDA approval records control the final assessment of listed patents, reference-product status, and Paragraph IV exposure.

FAQs

Is piroxicam still patent protected?

The original piroxicam and Feldene exclusivity periods have expired. New patents may protect later formulations, solid-state forms, delivery systems, or methods of use.

Can excipients reduce piroxicam gastrointestinal toxicity?

Excipients can alter dissolution and absorption but cannot be assumed to reduce NSAID-related gastrointestinal risk. A safety claim requires clinical evidence and appropriate regulatory support.

Is topical piroxicam a stronger commercial opportunity than oral Feldene?

Topical piroxicam generally offers more product differentiation than another immediate-release capsule, but success depends on local efficacy, skin tolerability, permeation control, and market-specific regulatory requirements.

Does piroxicam require a Paragraph IV challenge for generic entry?

Only if an unexpired patent is listed for the relevant reference product. Established generic piroxicam capsules indicate that ordinary entry is not dependent on challenging the original Feldene exclusivity.

Which excipient platform is most suitable for piroxicam?

The best platform depends on the product objective. Wetting and disintegrant systems suit a conventional oral product, amorphous dispersions or nanocrystals suit dissolution enhancement, and carbomer, solvent, lipid, or film-forming systems suit topical delivery.

References

1. U.S. Food and Drug Administration. (2023). Feldene (piroxicam) capsules prescribing information. Pfizer Laboratories.

2. U.S. Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book-data-files

3. U.S. Food and Drug Administration. (2024b). Drugs@FDA: FDA-approved drugs database. https://www.accessdata.fda.gov/scripts/cder/daf/

4. U.S. Food and Drug Administration. (2024c). Inactive ingredient database. https://www.accessdata.fda.gov/scripts/cder/iig/index.cfm

5. U.S. Food and Drug Administration. (2016). Guidance for industry: Waiver of in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms based on a biopharmaceutics classification system. https://www.fda.gov/media/70958/download

6. European Medicines Agency. (2006). Assessment report for piroxicam-containing medicinal products. European Medicines Agency.