List of Excipients in Branded Drug ENDODAN

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
STAT RX USA LLC	ENDODAN	oxycodone and aspirin	16590-947	CELLULOSE, MICROCRYSTALLINE
STAT RX USA LLC	ENDODAN	oxycodone and aspirin	16590-947	D&C YELLOW NO. 10
STAT RX USA LLC	ENDODAN	oxycodone and aspirin	16590-947	FD&C YELLOW NO. 6
STAT RX USA LLC	ENDODAN	oxycodone and aspirin	16590-947	STARCH, CORN

Endodan Excipient Strategy and Commercial Opportunities

Last updated: August 7, 2026

Endodan is an immediate-release oral tablet containing oxycodone hydrochloride and aspirin. Its commercial value is constrained by opioid regulation, limited current brand differentiation, aspirin-related tolerability, and the availability of generic oxycodone combination products. The strongest excipient opportunities are incremental: improving content uniformity, tablet robustness, moisture protection, dissolution consistency, and manufacturing economics rather than creating a fundamentally new product.

The most viable commercial paths are a low-cost generic, an optimized 505(b)(2) reformulation, or a differentiated abuse-deterrent or gastrointestinal-tolerability platform. A new excipient composition alone is unlikely to support durable exclusivity unless it produces a clinically meaningful or FDA-recognized performance advantage.

What is Endodan and what excipients does it contain?

Endodan is labeled as an oral immediate-release combination of oxycodone hydrochloride and aspirin. The labeled strength is generally 4.5 mg oxycodone hydrochloride and 325 mg aspirin per tablet. The product is indicated for the short-term management of pain severe enough to require an opioid analgesic when alternative treatments are inadequate (U.S. Food and Drug Administration [FDA], n.d.-a).

Public labeling identifies conventional tablet excipients, including combinations of lactose, microcrystalline cellulose, povidone, crospovidone, sodium starch glycolate, magnesium stearate, colloidal silicon dioxide, and tablet-processing agents. Exact inactive-ingredient composition should be taken from the applicable current FDA labeling record before filing or acquisition because manufacturers may change suppliers, grades, colors, coating systems, and compression aids over the product lifecycle.

Product attribute	Endodan profile
Active ingredients	Oxycodone hydrochloride and aspirin
Dosage form	Immediate-release oral tablet
Typical labeled strength	4.5 mg oxycodone hydrochloride and 325 mg aspirin
Route	Oral
Controlled-substance status	Oxycodone-containing Schedule II product
Primary formulation issue	Low-dose opioid uniformity within a high-dose aspirin tablet
Key chemical risk	Aspirin hydrolysis and moisture sensitivity
Key manufacturing risk	Segregation and content-uniformity failure
Likely regulatory route for an equivalent	ANDA, subject to reference-product and Orange Book requirements
Reformulation route	Potentially 505(b)(2), depending on the proposed changes

A high-dose aspirin component dominates tablet mass. The oxycodone component is comparatively small, increasing the importance of powder blending, segregation control, granulation strategy, and validated sampling.

What excipient strategy is appropriate for Endodan tablets?

The optimal strategy is an immediate-release, low-moisture formulation that protects aspirin stability while maintaining rapid dissolution and uniform oxycodone distribution.

Direct compression versus wet granulation

Direct compression can reduce processing steps and lower manufacturing cost. It requires excipients with reliable flow, compressibility, and particle-size distribution. Microcrystalline cellulose, lactose, colloidal silicon dioxide, and a low level of magnesium stearate are conventional choices.

Wet granulation can improve blend uniformity and tablet strength, particularly when the low-dose oxycodone component must be distributed through a much larger aspirin matrix. Its disadvantage is exposure to water and heat, which can increase aspirin hydrolysis and generate salicylic acid.

A practical development sequence would compare:

1. Direct compression with engineered lactose and microcrystalline cellulose.
2. Dry granulation or roller compaction for moisture control.
3. A limited-solvent granulation process only if content uniformity or mechanical strength cannot be achieved by dry processing.

Dry granulation is commercially attractive because it can address flow and segregation without introducing substantial water.

Binder selection

Povidone can improve granule strength and tablet integrity, but it may increase hygroscopicity depending on grade and concentration. Copovidone may provide alternative binding and processing characteristics. The binder level should remain low enough to preserve immediate release and avoid excessive tablet hardness.

For an aspirin-containing product, a dry binder or direct-compression excipient is generally preferable to a water-intensive process. The development target should be mechanical robustness after packaging and transport rather than maximum initial hardness.

Disintegrant strategy

Crospovidone and sodium starch glycolate are established immediate-release disintegrants. Crospovidone can provide rapid wicking and is often useful when the formulation must disintegrate despite relatively high compression force. Sodium starch glycolate can provide strong swelling but may be more sensitive to over-compression and lubricant distribution.

A dual-disintegrant system could improve robustness across manufacturing sites, but it would increase formulation complexity. A single optimized disintegrant is more attractive for an ANDA where equivalence, scale-up, and cost control are priorities.

Lubrication

Magnesium stearate is the conventional lubricant. Excessive concentration or overmixing can create a hydrophobic surface, slow dissolution, and increase batch-to-batch variability. Lubrication time and specific surface area should be controlled as critical process parameters.

Sodium stearyl fumarate could be evaluated as an alternative where dissolution or over-lubrication is a concern. Its use may affect tablet ejection, powder flow, and supplier qualification. It would not create meaningful exclusivity by itself.

Moisture control

Moisture management is the most important excipient and packaging issue. Aspirin can hydrolyze in the presence of moisture, producing salicylic acid and acetic acid. The formulation should use low-moisture excipient grades, controlled humidity during compression, and a packaging system with strong moisture-barrier performance.

Commercial options include:

• High-barrier PVC/PVdC or aluminum blister packaging.
• HDPE bottles with induction seals.
• Desiccant-containing bottles where stability data support the approach.
• Low-moisture lactose or anhydrous excipient grades.
• Tight control of residual water in granules and final tablets.

A more expensive excipient can be justified if it reduces packaging cost, increases shelf life, or lowers batch rejection rates. The business case should compare total delivered cost rather than excipient price alone.

What formulation patents could protect an Endodan reformulation?

A basic Endodan-equivalent formulation is unlikely to support broad patent protection. The active ingredients, general tablet form, and conventional excipients are established technologies. Patent value would depend on a narrow, demonstrable technical result.

Potential patentable areas include:

Potential claim area	Commercial value	Patent strength
Specific excipient ratios	Low to moderate	Low unless tied to unexpected results
Low-moisture aspirin formulation	Moderate	Moderate if stability improvement is substantial
Oxycodone content-uniformity process	Moderate	Moderate if process parameters are distinctive
Abuse-deterrent matrix	High	Moderate to high if clinically and mechanically validated
Gastrointestinal-tolerability formulation	Moderate	Moderate if supported by clinical data
Multiparticulate or dual-release system	High	Moderate to high, but development cost rises
Moisture-barrier packaging combination	Low to moderate	Usually limited
Manufacturing process with defined critical parameters	Moderate	Moderate if difficult to design around

A formulation patent should avoid claiming only the presence of familiar excipients. Stronger claims would connect composition, process, and measured performance, such as reduced aspirin degradation, specified oxycodone dissolution, improved dose uniformity, or resistance to mechanical tampering.

What generic entry risks exist for Endodan?

The principal generic route is an ANDA if the proposed product matches the reference product in active ingredients, strength, dosage form, route, and labeling requirements. The applicant must demonstrate pharmaceutical equivalence and bioequivalence and address applicable patent certifications under the Hatch-Waxman framework (FDA, n.d.-b).

The main entry risks are:

• Failure to match immediate-release dissolution.
• Oxycodone content-uniformity problems caused by low drug loading.
• Aspirin degradation during development or commercial storage.
• Differences in tablet hardness, friability, or disintegration.
• Controlled-substance manufacturing and security requirements.
• Supply-chain constraints for qualified opioid APIs.
• Reference-product discontinuation or limited market availability.
• Labeling differences involving opioid warnings and aspirin risks.

A formulation that uses different excipients can still qualify for an ANDA if it meets applicable sameness and bioequivalence requirements. However, excipient changes can affect dissolution, stability, impurity profiles, and manufacturing controls.

What is the Orange Book status of Endodan?

The Orange Book controls the regulatory record for approved drug products, therapeutic equivalence evaluations, patent listings, and exclusivity information (FDA, n.d.-c). Endodan’s commercial and litigation analysis should distinguish among:

1. The branded reference product.
2. Current or historical approved applications.
3. Any listed patents.
4. Therapeutic-equivalence codes for approved generic products.
5. Whether the product is currently marketed, discontinued, or withdrawn for reasons other than safety or effectiveness.

For an old oxycodone-aspirin product, the practical assumption should be that composition-of-matter exclusivity is unavailable and that any remaining patent risk would arise from formulation, method-of-use, manufacturing, or application-specific listings. A current Orange Book search and the relevant FDA application history are required before relying on a patent expiration date, Paragraph IV position, or 30-month stay analysis.

No defensible business plan should assign an Endodan patent expiration date without confirming the current FDA listing and underlying patent records.

When does Endodan lose exclusivity?

Endodan’s commercial exclusivity is principally exposed to the age of the product and the availability of equivalent oxycodone-aspirin products. The product does not obtain a new exclusivity period merely because a manufacturer changes conventional excipients.

Potential exclusivity sources include:

Exclusivity type	Relevance to Endodan
New chemical entity exclusivity	Not applicable to an established oxycodone and aspirin combination
Five-year NCE exclusivity	Not applicable
Three-year clinical-investigation exclusivity	Possible only for qualifying new clinical work and an approved change
Orphan exclusivity	Not applicable to the analgesic indication
Pediatric exclusivity	Possible only if separately granted
Patent exclusivity	Depends on currently listed, enforceable patents
Formulation patent	Available only for a novel and non-obvious formulation
Regulatory exclusivity for a 505(b)(2) product	Potentially available for qualifying new clinical investigations

The commercial question is therefore less about the original Endodan exclusivity date and more about whether a new formulation can create a differentiated, enforceable product.

Which companies are challenging Endodan or competing with it?

The competitive field includes manufacturers of oxycodone-acetaminophen products, oxycodone-aspirin products, oxycodone hydrochloride immediate-release tablets, and non-opioid analgesics.

Relevant competitors include:

• Generic manufacturers of oxycodone combination tablets.
• Manufacturers of oxycodone-acetaminophen products such as generic Percocet equivalents.
• Manufacturers of aspirin-containing opioid products, where available.
• Branded abuse-deterrent opioid manufacturers.
• Non-opioid alternatives, including acetaminophen, NSAIDs, and combination products.

The closest commercial substitutes are usually oxycodone-acetaminophen products rather than Endodan equivalents. Physicians may also choose oxycodone alone when aspirin is undesirable because of bleeding risk, gastrointestinal injury, renal concerns, or perioperative restrictions.

What Paragraph IV challenges could affect Endodan?

A Paragraph IV certification is relevant only when a listed patent remains in force and is asserted against an ANDA applicant. For an old combination product, Paragraph IV risk is likely to depend on any remaining formulation or method-of-use patent rather than on the active ingredients themselves.

A generic applicant would normally evaluate:

• Whether any patent is listed for the reference product.
• Whether the patent claims the drug, formulation, method of use, or manufacturing process.
• Whether the patent is expired, delisted, invalid, or not infringed.
• Whether a Paragraph IV notice would trigger patent litigation.
• Whether a 30-month stay is available under the applicable statutory framework.
• Whether a settlement agreement would restrict launch timing.

No specific current Endodan Paragraph IV litigation or settlement should be treated as established without a verified court docket, FDA filing record, or Federal Trade Commission review record.

How strong is the patent estate for Endodan?

The likely patent estate is weak for an unmodified generic-equivalent product and stronger only for a technically differentiated reformulation.

Weak positions

The following claims are vulnerable to invalidity or design-around arguments:

• Oxycodone hydrochloride combined with aspirin in a conventional tablet.
• Routine use of lactose, cellulose, povidone, crospovidone, or magnesium stearate.
• Broad claims to immediate-release dissolution.
• Conventional moisture-protective packaging.
• Generic tablet compression parameters.

Stronger positions

A stronger estate could cover:

• A defined low-moisture formulation with unexpected aspirin stability.
• A tamper-resistant matrix that limits oxycodone extraction while preserving bioavailability.
• A multiparticulate system with controlled release or abuse-deterrent performance.
• A process that consistently achieves oxycodone uniformity at commercial scale.
• A formulation with reduced gastrointestinal injury supported by clinical evidence.

The strongest protection would combine composition claims, process claims, and method-of-use claims. A single excipient claim would offer limited protection because competitors could substitute grades or use different processing routes.

What manufacturing and intellectual-property barriers exist?

The key manufacturing barrier is managing a very low-dose opioid in a high-dose aspirin tablet. Scale-up can create segregation, blend-uniformity, and sampling problems. Aspirin stability adds a second risk layer.

Important controls include:

• API particle-size and morphology specifications.
• Pre-blend dilution of oxycodone.
• Blend sampling plans that account for segregation.
• Low-humidity manufacturing.
• Control of lubricant addition and mixing time.
• Dissolution testing for both active ingredients.
• Quantitation of salicylic acid and related degradants.
• High-barrier packaging qualification.
• Controlled-substance inventory reconciliation and security.

The intellectual-property barrier is lower for a standard generic but rises for abuse deterrence, modified release, or gastrointestinal-risk reduction. Those products may require clinical studies, specialized analytical methods, and a 505(b)(2) strategy.

What commercial opportunities exist for Endodan excipients?

Low-cost generic equivalent

This is the lowest-risk opportunity. The objective is an ANDA-compatible tablet using widely available excipients and a manufacturing process that minimizes moisture exposure. Margin depends on market size, reference-product availability, controlled-substance compliance, and competition.

Stability-optimized product

A formulation with improved aspirin stability could support a 505(b)(2) product or a formulation patent if the result is substantial and reproducible. The commercial advantage would be longer shelf life, lower degradation, or improved performance under adverse storage conditions.

Abuse-deterrent oxycodone formulation

An abuse-deterrent version could target institutional purchasers and prescribers seeking opioid-risk mitigation. The formulation might use a hard-to-crush matrix, gelling polymer, aversive excipient, or extraction-resistant architecture. FDA labeling claims would require appropriate abuse-deterrence studies under FDA guidance (FDA, 2015).

The main limitation is that abuse deterrence does not eliminate overdose or addiction risk and may not justify the added cost in a small aspirin-opioid market.

Aspirin-tolerability platform

A gastroprotective or lower-irritancy concept could differentiate the product, but it would likely require clinical evidence. Simply changing the excipient system would not establish reduced gastrointestinal injury.

Supply-chain and contract-manufacturing opportunity

A manufacturer with validated low-moisture processing, high-barrier packaging, and controlled-substance infrastructure could offer contract development and manufacturing services. This may produce more reliable revenue than launching a standalone branded product.

How does Endodan compare with oxycodone-acetaminophen products?

Factor	Endodan	Oxycodone-acetaminophen product
Non-opioid component	Aspirin	Acetaminophen
Bleeding risk	More relevant	Lower aspirin-related bleeding risk
Liver toxicity concern	Lower than acetaminophen-based combinations	More prominent
Gastrointestinal concerns	Aspirin-related	Generally different risk profile
Prescriber substitution	Often limited by aspirin suitability	More common in general acute pain
Excipient opportunity	Moisture stability and aspirin protection	Dose uniformity, acetaminophen stability, tablet robustness
Market depth	Likely narrower	Typically broader
Differentiation potential	Stability or abuse deterrence	Abuse deterrence and dose flexibility

Endodan’s aspirin component can be a commercial differentiator for selected patients, but it also narrows the addressable market.

What FDA regulatory status applies to an Endodan reformulation?

A conventional equivalent product would generally be pursued through an ANDA. A materially different product may require a 505(b)(2) application, particularly if it changes release characteristics, abuse-deterrence properties, dosage form, or clinical performance (FDA, n.d.-b).

The regulatory path should be selected based on the intended claim:

Product objective	Likely pathway
Same immediate-release tablet with different inactive ingredients	ANDA
New release profile	505(b)(2) or applicable suitability pathway
Abuse-deterrent formulation	Usually 505(b)(2), with specialized studies
New clinical tolerability claim	505(b)(2)
New dosage form or delivery system	505(b)(2)
Manufacturing-only optimization	ANDA if reference-product requirements remain satisfied

A formulation patent cannot substitute for FDA approval. Commercial value depends on the combination of regulatory clearance, enforceable claims, reliable supply, and sufficient market demand.

Key Takeaways

• Endodan is an oxycodone hydrochloride and aspirin immediate-release tablet.
• The primary excipient challenge is distributing a low-dose opioid uniformly through a high-dose aspirin matrix.
• Moisture control is central because aspirin can hydrolyze during processing and storage.
• Direct compression and dry granulation are more commercially attractive than water-intensive wet granulation.
• Conventional excipient changes are unlikely to create durable exclusivity.
• A standard equivalent product would generally target the ANDA pathway.
• Abuse deterrence, enhanced stability, or clinically supported tolerability improvements could support a 505(b)(2) strategy.
• The closest commercial substitutes are oxycodone-acetaminophen products and oxycodone immediate-release tablets.
• Current Orange Book listings, patent expiration dates, Paragraph IV activity, and settlement status require confirmation from the live FDA and court records before investment or litigation decisions.
• The most defensible IP position would combine formulation, manufacturing-process, and performance-based claims.

FAQs

Can lactose be used in an Endodan generic formulation?

Yes. Lactose is a conventional tablet diluent, but its grade, moisture content, compatibility, and impact on dissolution must be qualified. A lactose-free formulation may be commercially useful for selected patients but would not by itself establish meaningful exclusivity.

Does aspirin create a special stability problem in oxycodone combination tablets?

Yes. Aspirin is susceptible to hydrolysis in the presence of moisture. Stability programs should monitor salicylic acid, total degradation, tablet appearance, dissolution, and oxycodone assay over the proposed shelf life.

Could an Endodan reformulation receive three-year FDA exclusivity?

Potentially, but only if the approval relies on new clinical investigations conducted or sponsored by the applicant and the statutory requirements are met. An excipient substitution without qualifying clinical work would not ordinarily support three-year exclusivity.

Is an abuse-deterrent Endodan product commercially attractive?

It could be attractive if the manufacturer can support FDA-recognized abuse-deterrence labeling and achieve a cost structure acceptable to payers and institutional buyers. The limited market for aspirin-opioid combinations reduces the addressable commercial opportunity.

Would a new Endodan excipient composition block all generic competition?

No. A narrow formulation patent would usually be designable around through different excipients, grades, ratios, or manufacturing processes. Broad blocking protection would require valid claims covering the essential technical feature of the product.

References

1. U.S. Food and Drug Administration. (n.d.-a). Endodan: Oxycodone hydrochloride and aspirin tablet labeling. DailyMed/FDA labeling database.

2. U.S. Food and Drug Administration. (n.d.-b). Abbreviated new drug application (ANDA) and 505(b)(2) application pathways. FDA.

3. U.S. Food and Drug Administration. (n.d.-c). Approved drug products with therapeutic equivalence evaluations. FDA, Orange Book.

4. U.S. Food and Drug Administration. (2015). General principles for evaluating abuse deterrence of opioids: Guidance for industry. FDA.

5. U.S. Food and Drug Administration. (n.d.-d). FDA guidance for industry: ANDAs for certain highly purified synthetic peptides and related drug products. FDA.