List of Excipients in Branded Drug DOLOBID

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Generic Drugs Containing DOLOBID

Company	Ingredient	NDC	Excipient
INA Pharmaceutics Inc	diflunisal	74157-009	CELLULOSE, MICROCRYSTALLINE
INA Pharmaceutics Inc	diflunisal	74157-009	CROSCARMELLOSE SODIUM
INA Pharmaceutics Inc	diflunisal	74157-009	FD&C BLUE NO. 2 ALUMINUM LAKE

What are the Most Frequently-Used Excipients in DOLOBID?

# Of NDCs	Excipient
1	CELLULOSE, MICROCRYSTALLINE
1	CROSCARMELLOSE SODIUM
1	FD&C BLUE NO. 2 ALUMINUM LAKE

DOLOBID (Diflunisal) Excipient Strategy and Commercial Opportunities

Last updated: September 24, 2026

DOLOBID is the former Merck brand for diflunisal, a nonsteroidal anti-inflammatory drug (NSAID) approved in the United States in 1978. Its commercial opportunity is no longer based on primary-molecule exclusivity. The value lies in low-cost generic manufacture, supply reliability, formulation differentiation, and possible 505(b)(2) products. The original immediate-release tablet uses conventional excipients and presents limited technical barriers to generic entry. [1][2]

What is DOLOBID and what is its current FDA status?

DOLOBID contains diflunisal, an orally administered salicylic-acid derivative used for pain and osteoarthritis or rheumatoid arthritis symptoms. The marketed strengths were 250 mg and 500 mg tablets. [1]

Attribute	DOLOBID / diflunisal
Active ingredient	Diflunisal
Drug class	NSAID; salicylate derivative
Original sponsor	Merck Sharp & Dohme
Original U.S. approval	1978
Dosage form	Immediate-release tablet
Historical strengths	250 mg and 500 mg
Current brand position	Legacy product; no meaningful brand exclusivity
Generic status	Generic diflunisal tablets have been marketed
FDA regulatory pathway for standard generic	ANDA under Section 505(j)
Patent barrier	No identified active primary-composition barrier
Main commercial issue	Demand, pricing, supply continuity, and formulation differentiation

The original DOLOBID product is generally treated as a legacy or discontinued brand rather than a current branded growth product. FDA records and current product databases should be used to distinguish a discontinued brand listing from an active approved generic presentation. [2][3]

What excipients were used in DOLOBID tablets?

The historical DOLOBID label identifies conventional tablet excipients, including lactose, corn starch, magnesium stearate, povidone, and sodium lauryl sulfate, although excipient details can vary by strength, manufacturing period, and approved labeling version. [1]

Excipient category	Historical or commonly associated component	Functional role
Diluent	Lactose	Provides tablet mass and improves manufacturability
Binder	Povidone	Supports granule and tablet strength
Disintegrant	Corn starch	Promotes tablet breakup after ingestion
Lubricant	Magnesium stearate	Reduces die-wall friction
Wetting agent	Sodium lauryl sulfate	Improves wetting of hydrophobic drug particles
Coating system	Strength- and supplier-dependent	Supports identification, handling, and swallowability

The excipient system is technically conventional. It does not indicate a protected delivery platform, sustained-release technology, or complex manufacturing process. The inclusion of a wetting agent is commercially relevant because diflunisal has limited aqueous solubility and can require controlled wetting and particle-dispersion behavior for consistent dissolution.

An applicant should not assume that the historical brand excipient formula is the only acceptable composition. An ANDA may use different inactive ingredients if the product meets applicable pharmaceutical equivalence, bioequivalence, quality, labeling, and inactive-ingredient requirements. [4][5]

What formulation characteristics matter for diflunisal?

Diflunisal is a poorly water-soluble, crystalline drug with pH-dependent solubility. Its formulation performance depends on particle size, polymorphic behavior, wetting, granulation, compression, and dissolution control.

The key formulation risks are:

1. Slow wetting of the drug substance.
2. Incomplete dissolution at physiologically relevant pH.
3. Tablet hardness that delays disintegration.
4. Lubricant overuse, especially excessive magnesium stearate.
5. Variability caused by drug-substance particle-size distribution.
6. Potential lactose intolerance or excipient sensitivity in selected patients.
7. Dose-related gastrointestinal tolerability issues that excipient changes cannot eliminate.

For a conventional tablet, the critical quality attributes are assay, content uniformity, disintegration, dissolution, impurities, hardness, friability, and stability. A development program should link excipient levels to dissolution rather than optimize only for mechanical strength.

Immediate-release tablet strategy

A low-risk generic formulation would normally use:

• A direct-compression or wet-granulation platform.
• Microcrystalline cellulose or lactose as a diluent.
• Povidone or a comparable binder.
• Crospovidone, croscarmellose sodium, or sodium starch glycolate as a modern disintegrant option.
• Magnesium stearate at a controlled concentration.
• Colloidal silicon dioxide where needed to improve flow.
• A film coat for identification and swallowability.

A formulation that replaces corn starch with a more efficient superdisintegrant could reduce disintegration time and improve process robustness. The substitution would still require comparative dissolution and bioequivalence support.

Wetting and solubilization strategy

Sodium lauryl sulfate or another surfactant may improve wetting, but the amount must be controlled. Excess surfactant can alter dissolution, create processing problems, affect tablet strength, or complicate tolerability assessments.

Alternative approaches include:

• Micronized diflunisal.
• Drug-excipient co-processing.
• Spray-dried dispersions.
• pH-modifying excipients.
• Surfactant-assisted granulation.
• Amorphous solid dispersion technology.

These approaches can improve dissolution, but they also raise cost, scale-up, stability, and regulatory-complexity risks. For a mature low-price NSAID, a sophisticated dispersion platform is commercially justified only if it enables a meaningful product distinction, such as lower dose, faster onset, improved absorption, or a new route of administration.

What formulation patents protect DOLOBID?

No currently material patent estate appears to protect the original diflunisal immediate-release tablet as a commercial barrier. The active ingredient and the conventional tablet concept are long out of exclusivity.

IP category	Commercial assessment
Diflunisal compound patent	Historical protection; expired
Original immediate-release tablet	Historical protection; expired or no longer commercially relevant
Standard excipient combination	Generally difficult to protect broadly
Specific dissolution-enhancing formulation	Potentially patentable if novel and non-obvious
Modified-release diflunisal	Potential 505(b)(2) and patent opportunity
Combination product	Potentially protectable, subject to clinical and regulatory requirements
Manufacturing process	Potential trade-secret value; limited broad exclusionary power
Method of use	Possible only for a genuinely differentiated indication or dosing regimen

A new formulation patent would need more than a list of common excipients. The strongest claims would typically require a defined drug-excipient ratio, particle-size distribution, solid-state form, dissolution profile, pharmacokinetic result, or manufacturing parameter tied to an unexpected technical effect.

When did DOLOBID lose exclusivity?

DOLOBID lost meaningful market exclusivity decades ago. The original 1978 approval predates the modern generic competition environment, and any original compound or product patents have expired. No current exclusivity period comparable to new chemical entity exclusivity, orphan exclusivity, pediatric exclusivity, or a first-generic 180-day period should be assumed for the legacy brand. [2][3]

Exclusivity type	Status
New chemical entity exclusivity	Expired
Original product patent protection	Expired
Orphan exclusivity	Not identified
Pediatric exclusivity	Not commercially relevant
Current brand exclusivity	None identified
Generic first-filer exclusivity	Product-specific and not a barrier to the overall market

The practical result is an open-entry market, subject to ANDA approval, supply economics, and any product-specific FDA listing status.

What is the Orange Book status of DOLOBID?

The Orange Book is relevant for identifying approved drug products, patent listings, and exclusivity information. For an old diflunisal product, the key commercial question is whether a specific NDA remains active, whether the brand product is listed as marketed or discontinued, and whether any patents or exclusivity codes remain listed. [3]

The expected Orange Book profile is:

• No meaningful unexpired patent claim blocking standard diflunisal tablets.
• No current branded exclusivity supporting premium pricing.
• Generic products evaluated against the relevant reference-listed drug.
• Potential variation in active manufacturer and market availability.

An Orange Book entry alone does not establish that the historical brand remains commercially available. Marketing status must be reviewed alongside FDA approval records and current labeling.

Are Paragraph IV challenges relevant to diflunisal?

Paragraph IV litigation is unlikely to be a significant current issue for conventional diflunisal tablets because the core product is old and generic competition has already existed. Paragraph IV certification matters when an ANDA applicant challenges a listed patent. If no relevant unexpired patent remains listed, the applicant’s pathway is more likely to involve Paragraph III, a patent-free certification, or another applicable certification rather than a high-value Paragraph IV dispute. [3][6]

For a newly developed diflunisal formulation, the situation changes. A sponsor could list formulation or method-of-use patents in the Orange Book if they satisfy statutory listing requirements. Later ANDA applicants could then challenge those patents, creating conventional Paragraph IV exposure.

What commercial opportunities exist for diflunisal excipient innovation?

1. Cost-optimized generic tablets

This is the lowest-risk opportunity. The product can be positioned around:

• Reliable supply.
• Competitive contract manufacturing.
• Dual sourcing of lactose, binder, and lubricant materials.
• Robust dissolution across manufacturing sites.
• Packaging optimized for moisture and shelf-life control.

The commercial ceiling is limited because diflunisal is a mature NSAID with therapeutic substitutes, including ibuprofen, naproxen, diclofenac, and generic aspirin-related products.

2. Dye-free or allergen-conscious tablets

A formulation that removes unnecessary colorants, minimizes excipient complexity, or uses lactose-free materials could target hospitals, institutional purchasers, and patients with specific excipient preferences. This opportunity is commercially narrower than a standard generic strategy but may support formulary differentiation.

3. Orally disintegrating tablets

An orally disintegrating diflunisal tablet could target patients with swallowing difficulty. The principal technical problems are the relatively high dose, taste, mouthfeel, tablet friability, and the need to maintain rapid disintegration without compromising stability.

A successful product would require:

• Taste masking.
• A high-load ODT platform.
• Low friability.
• Acceptable mouthfeel.
• Demonstrated equivalence or an appropriate 505(b)(2) strategy.

4. Oral suspension or granules

A liquid or sprinkle product could address dysphagia and pediatric or geriatric administration. Diflunisal’s poor water solubility creates formulation challenges, including sedimentation, redispersibility, dose uniformity, palatability, and preservative compatibility.

A suspension would have stronger commercial differentiation than a conventional tablet but also higher development and lifecycle-management costs.

5. Modified-release products

Modified release could reduce dosing frequency or smooth plasma exposure. It would require a clinical rationale because the product is used for analgesic and anti-inflammatory treatment, where onset and predictable exposure are important.

This route would likely require a 505(b)(2) application rather than a simple ANDA if the dosage form or pharmacokinetic profile differs materially from the reference product. The opportunity is technically possible but commercially uncertain.

6. Combination products

A diflunisal combination with another analgesic, gastroprotective agent, or adherence-supporting component could create a new product concept. Combination products bring clinical, safety, labeling, and intellectual-property requirements. The NSAID class’s gastrointestinal, renal, cardiovascular, and bleeding risks would remain central to regulatory review.

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

The legacy estate is weak because the molecule and conventional tablet platform are old. A new estate could be moderately strong if it protects a narrowly defined formulation with measurable performance advantages.

Patent strategy	Relative strength	Main weakness
Broad excipient list	Low	Easy design-around; weak inventive step
Specific excipient ratio	Low to moderate	Competitors may alter ratios
Defined dissolution profile	Moderate	Requires credible technical support
Particle-size and solid-state claims	Moderate to strong	Depends on enforceability and reproducibility
Modified-release system	Moderate	Clinical and regulatory burden
New indication	Variable	Requires meaningful clinical differentiation
Manufacturing process	Moderate as trade secret	Difficult to enforce against independent processes

The strongest commercial protection would combine composition claims, process claims, and method-of-use claims. A sponsor should avoid relying on a single formulation patent with narrow excipient language.

Which companies are likely to challenge or compete with DOLOBID?

Competition is more likely to come from generic manufacturers than from branded innovators. Potential competitors include companies with established oral-solid-dose manufacturing and ANDA capabilities, such as large generic suppliers, contract manufacturers, and regional pharmaceutical companies.

The broader competitive set includes:

• Generic diflunisal tablet suppliers.
• Generic naproxen manufacturers.
• Generic ibuprofen manufacturers.
• Diclofenac product manufacturers.
• Aspirin and other salicylate suppliers.
• Specialty companies pursuing reformulated analgesics.

The main competitive threat is substitution within the NSAID class. Diflunisal must demonstrate a practical benefit, such as supply reliability, lower acquisition cost, improved administration, or a differentiated formulation.

What FDA pathway applies to new DOLOBID products?

A standard diflunisal tablet that is pharmaceutically equivalent and bioequivalent to the reference product can generally use the ANDA pathway. [4]

A product with a different dosage form, route, release profile, indication, or clinical performance may require a 505(b)(2) application. That pathway can support reliance on FDA findings for diflunisal while requiring additional bridging or clinical evidence for the change. [7]

Product concept	Likely pathway
Conventional 250 mg or 500 mg tablet	ANDA
Different excipients with same dosage form and performance	ANDA, subject to requirements
Oral suspension	Potentially 505(b)(2)
ODT with materially different performance	ANDA or 505(b)(2), depending on equivalence
Modified-release tablet	Usually 505(b)(2)
New indication	505(b)(2) or full NDA strategy
Combination product	505(b)(2) or NDA, depending on composition and claims

What revenue exposure and launch scenarios exist?

Public revenue data for the discontinued DOLOBID brand are not a reliable basis for forecasting. The market should be modeled as a mature generic opportunity rather than a branded revenue-recapture opportunity.

Base-case generic launch

A manufacturer launches a conventional tablet with low development cost and competes on price and supply. Expected returns depend on market size, number of active suppliers, reimbursement, and procurement contracts.

Premium differentiated launch

A manufacturer launches a lactose-free, dye-free, fast-disintegrating, or otherwise differentiated tablet. This may support a modest premium if the product addresses a defined institutional or patient need.

505(b)(2) launch

A sponsor develops an ODT, suspension, or modified-release formulation. The potential price and IP protection are higher, but development cost, regulatory duration, and clinical risk rise sharply.

Supply-continuity strategy

A company acquires or develops a diflunisal product mainly to secure a niche hospital or institutional supply position. This strategy can work without major formulation innovation if competitors have unreliable manufacturing or intermittent shortages.

What manufacturing and IP barriers remain?

The manufacturing barrier is low for standard tablets and higher for differentiated formulations.

For conventional tablets, the principal barriers are:

• Consistent diflunisal particle properties.
• Reliable granulation and compression.
• Dissolution control.
• API sourcing and quality agreements.
• Stability in commercial packaging.
• Batch-to-batch excipient performance.

For advanced formulations, barriers include:

• Taste masking at high dose.
• Physical stability of amorphous material.
• Suspension uniformity.
• Modified-release reproducibility.
• Scale-up of specialized processing.
• Clinical bridging.
• Formulation patent drafting and enforcement.

Key Takeaways

• DOLOBID is a legacy diflunisal brand with no identified meaningful current exclusivity barrier.
• Standard diflunisal tablets are technically straightforward and generally suitable for an ANDA strategy.
• Historical excipients include lactose, corn starch, magnesium stearate, povidone, and sodium lauryl sulfate, subject to product-specific labeling verification.
• The strongest formulation opportunity is not a conventional excipient substitution alone. It is a product with a measurable benefit in dissolution, administration, tolerability, or dosing convenience.
• ODT, suspension, and modified-release products may support 505(b)(2) development and new formulation patents.
• Paragraph IV risk is limited for the legacy tablet but could arise against patents covering a new formulation.
• Commercial returns are likely to depend more on supply reliability and market concentration than on brand recovery.
• Generic NSAID substitution is the principal competitive threat.

FAQs

Is diflunisal still commercially available?

Generic diflunisal tablets may be available even though the DOLOBID brand is a legacy or discontinued product. Availability depends on active manufacturers and current distribution.

Can a company file an ANDA for diflunisal tablets?

Yes. A conventional tablet that meets FDA requirements for pharmaceutical equivalence and bioequivalence can generally be developed through the ANDA pathway.

Does DOLOBID have an active patent?

No meaningful active patent barrier is identified for the original diflunisal immediate-release tablet. New patents could cover a later formulation, process, or method of use.

Is diflunisal suitable for an orally disintegrating tablet?

It is technically possible, but the 250 mg and 500 mg strengths create high drug-loading, taste-masking, friability, and mouthfeel challenges.

What is the best excipient opportunity for a diflunisal generic?

The most practical opportunity is a robust immediate-release tablet with optimized wetting, rapid disintegration, controlled lubrication, and a differentiated excipient profile such as lactose-free or dye-free composition.

References

1. Merck Sharp & Dohme. (n.d.). DOLOBID (diflunisal) tablets prescribing information. U.S. Food and Drug Administration labeling archive.

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

3. U.S. Food and Drug Administration. (n.d.). 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

4. U.S. Food and Drug Administration. (2023). ANDA submissions: Content and format. FDA.

5. U.S. Food and Drug Administration. (2019). Inactive ingredient database. FDA.

6. U.S. Food and Drug Administration. (n.d.). Hatch-Waxman amendments and abbreviated new drug applications. FDA.

7. U.S. Food and Drug Administration. (2024). Applications covered by Section 505(b)(2). FDA.