List of Excipients in Branded Drug ZIPSOR

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Assertio Therapeutics Inc	ZIPSOR	diclofenac potassium	13913-008	GELATIN
Assertio Therapeutics Inc	ZIPSOR	diclofenac potassium	13913-008	GLYCERIN
Assertio Therapeutics Inc	ZIPSOR	diclofenac potassium	13913-008	HYDROCHLORIC ACID

Zipsor is a 25 mg diclofenac potassium liquid-filled softgel whose commercial differentiation depends on formulation and delivery, not on a novel active ingredient. The principal opportunity is to develop lower-cost or differentiated diclofenac products that reproduce the liquid-filled capsule’s release, absorption, tolerability, and manufacturing profile. Zipsor’s market position is exposed to generic competition, but softgel manufacturing, formulation equivalence, and any remaining listed patents can raise entry costs.

Last updated: August 8, 2026

Zipsor Excipient Strategy and Commercial Opportunities

What is Zipsor and how is it formulated?

Zipsor is an oral prescription nonsteroidal anti-inflammatory drug containing 25 mg of diclofenac potassium in a liquid-filled soft gelatin capsule. The product is indicated for the relief of mild to moderate acute pain in adults. Its formulation differs from conventional immediate-release diclofenac tablets because the active ingredient is delivered in a liquid-filled capsule rather than a compressed solid dosage form.[1]

The product’s excipient strategy has four commercial functions:

1. Maintain diclofenac potassium in a physically and chemically stable liquid vehicle.
2. Support rapid release from the softgel shell.
3. Improve manufacturability and dose uniformity.
4. Create a formulation barrier against simple tablet or capsule substitution.

Public labeling identifies inactive ingredients associated with the softgel shell and liquid fill, including gelatin, glycerin, sorbitol, propylene glycol, mineral oil, lecithin, titanium dioxide and capsule colorants, although the exact role and concentration of each excipient are not generally disclosed in the prescribing information.[1,2]

Product attribute	Zipsor position
Active ingredient	Diclofenac potassium
Strength	25 mg
Dosage form	Liquid-filled soft gelatin capsule
Route	Oral
Indication	Mild to moderate acute pain
Regulatory pathway	FDA-approved NDA product
Primary formulation differentiator	Liquid-filled diclofenac potassium softgel
Core commercial barrier	Reproduction of the formulation, shell, release and bioequivalence profile

What excipients are used in Zipsor?

The Zipsor label identifies excipients used in the gelatin capsule and liquid formulation. The formulation includes materials associated with shell elasticity, moisture control, solubilization, dispersion, viscosity control, and appearance.

Liquid-fill excipient functions

Excipient category	Likely formulation role
Propylene glycol	Cosolvent and vehicle component
Mineral oil	Hydrophobic vehicle and viscosity modifier
Lecithin	Wetting, dispersion or emulsification support
Glycerin	Plasticizer and moisture-control component, primarily associated with the shell
Sorbitol	Plasticizer, humectant and shell-property modifier
Gelatin	Softgel shell-forming polymer
Titanium dioxide	Opacifier and light-protection component
Colorants	Product identification and brand differentiation

The formulation is commercially important because diclofenac potassium must remain adequately dispersed or dissolved in the fill material while avoiding precipitation, leakage, shell brittleness, cross-linking, and unacceptable dissolution variability.

The product’s use of a softgel shell also introduces manufacturing variables that are absent or less pronounced in conventional tablets. These include gelatin bloom strength, shell moisture, fill temperature, seam integrity, encapsulation speed, drying conditions and interaction between the fill and shell.

Why does the Zipsor excipient strategy matter commercially?

The excipients are not likely to provide independent therapeutic activity. Their value is in the delivery system. A liquid-filled softgel can provide a differentiated product profile while making generic development more complex.

The principal technical advantages are:

• A liquid vehicle can improve wetting and dispersion of diclofenac potassium.
• The softgel may provide faster disintegration than some compressed tablets.
• The dosage form can support dose uniformity for a low-strength product.
• The capsule can improve swallowability compared with larger tablets.
• The shell and fill can create a distinct product identity for specialty prescribing.

The commercial limitation is cost. Softgels require specialized encapsulation equipment, controlled shell drying, higher process monitoring and packaging that protects against moisture and mechanical damage. A generic manufacturer must determine whether the incremental development and manufacturing cost is justified by expected market share.

What patents protect Zipsor?

Zipsor’s protection is likely divided between product patents, formulation patents, manufacturing technology and regulatory exclusivity. The relevant patent estate should be evaluated through the FDA Orange Book, USPTO Patent Center, Patent Examination Data System records and district-court litigation databases.[3-5]

Public FDA sources should be treated as controlling for Orange Book-listed patents. A patent that covers a formulation or method of use can affect an ANDA applicant even when the active ingredient itself is long established. The commercially relevant claims may include:

• Liquid diclofenac formulations.
• Specific solvent or vehicle systems.
• Softgel dosage forms.
• Release or absorption characteristics.
• Treatment of acute pain with a particular dose regimen.
• Manufacturing processes for encapsulation or stabilization.

A definitive current patent-expiration table cannot be stated without a verified, current Orange Book and USPTO review. Patent term adjustments, terminal disclaimers, pediatric extensions, ownership changes and delisting activity can change the effective analysis.

Protection category	Relevance to Zipsor
Active-ingredient patent	Limited because diclofenac is an established NSAID
Formulation patent	Potentially significant
Softgel or delivery patent	Potentially significant
Method-of-use patent	May affect labeling and Paragraph IV strategy
FDA exclusivity	Depends on the approved NDA and any later qualified exclusivity
Trade secret protection	Relevant to exact fill composition and manufacturing process

When does Zipsor lose exclusivity?

Zipsor’s active ingredient has no meaningful new-molecule exclusivity because diclofenac has been marketed for decades. The product’s remaining commercial protection depends on FDA-listed patents, regulatory exclusivity and the difficulty of demonstrating pharmaceutical equivalence and bioequivalence.

For an ANDA applicant, the main timing pathways are:

ANDA certification	Effect
Paragraph I	No relevant patent information is listed
Paragraph II	All listed patents have expired
Paragraph III	Applicant agrees to wait until patent expiration
Paragraph IV	Applicant asserts that listed patents are invalid, unenforceable or not infringed

A first substantially complete Paragraph IV challenge can create a 180-day generic exclusivity period if statutory requirements are met. Patent litigation may trigger a 30-month stay of FDA approval under the Hatch-Waxman framework, subject to statutory exceptions and court developments.[6]

The practical launch date is therefore not necessarily the earliest listed patent expiration. It can depend on:

• Whether the innovator sues within the statutory period.
• Whether a court grants an injunction.
• Whether the patent is invalidated or avoided.
• Whether the ANDA applicant receives first-filer status.
• Whether the generic satisfies the reference-listed-drug requirements.
• Whether a settlement permits an agreed entry date.

What generic entry risks exist for Zipsor?

Zipsor presents a moderate formulation-development challenge but not an insurmountable barrier. Diclofenac potassium is widely available, and the target dose is established. The more difficult work involves demonstrating equivalence to a liquid-filled softgel.

A generic developer may choose among three strategies:

Softgel generic

A softgel generic would most directly compete with Zipsor. It would need to match the active ingredient, strength, dosage form, route and relevant pharmaceutical characteristics. The developer would also need to establish bioequivalence under FDA requirements.

The key risks are fill precipitation, shell interaction, dissolution variability and scale-up failure. A formulation that works in a laboratory batch may fail during commercial encapsulation or accelerated stability testing.

Alternative immediate-release dosage form

A tablet or hard capsule may be cheaper to manufacture, but it may not qualify as therapeutically or pharmaceutically equivalent to a softgel reference product. The applicant could face a different regulatory pathway or a requirement to support the product with clinical or pharmacokinetic evidence.

505(b)(2) product

A reformulated diclofenac product could use the Zipsor or another diclofenac product as a reference while pursuing differentiated claims. Possible features include a lower-cost softgel, a smaller capsule, a liquid oral formulation, modified flavor, improved stability or a new packaging system.

A 505(b)(2) strategy may be commercially attractive when the sponsor wants product differentiation but cannot justify the cost and risk of a fully independent NDA.

What formulation opportunities exist around Zipsor?

The strongest opportunities involve delivery and patient-use improvements rather than new diclofenac pharmacology.

Lower-cost softgel

A manufacturer could reduce cost through:

• A simpler fill system.
• Lower-cost gelatin or non-gelatin shell materials.
• Improved encapsulation throughput.
• More efficient drying cycles.
• Reduced overage.
• Standardized color and opacifier systems.
• High-barrier blister packaging rather than premium bottle packaging.

Any excipient substitution would require evaluation of dissolution, stability, shell integrity, impurities, extractables and leachables.

Non-gelatin softgel

A vegetarian or non-animal shell could target patients, institutions or markets that restrict bovine or porcine gelatin. Hydroxypropyl starch, modified starch and carrageenan systems may provide alternatives, but they can change moisture transmission, mechanical strength and dissolution.

Pediatric or geriatric presentation

Zipsor is indicated for adults. A smaller capsule, sprinkle formulation, oral liquid or dose-flexible product could target patients who cannot swallow softgels. Such products would require careful evaluation of dosing accuracy, palatability, NSAID safety and regulatory labeling.

Unit-dose packaging

Acute pain treatment is well suited to portable unit-dose packaging. Blister packs could improve adherence, reduce exposure to moisture and support pharmacy, urgent-care and hospital distribution. Packaging also can distinguish a product in a generic market without materially changing the active formulation.

Combination products

A diclofenac product combined with acetaminophen or another analgesic could target multimodal pain management. The regulatory and safety burden would be higher, particularly because combined NSAID use can increase gastrointestinal, renal and cardiovascular risk. A combination product would require a clear clinical and labeling rationale.

How does Zipsor compare with other diclofenac products?

Zipsor competes within a broad diclofenac market that includes tablets, capsules, topical gels, ophthalmic products, injections, oral powders and other specialized formulations.

Product type	Primary differentiation	Commercial implication
Zipsor softgel	Liquid-filled diclofenac potassium	Formulation and dosage-form differentiation
Generic diclofenac potassium tablet	Low manufacturing cost	Strong price competition
Voltaren topical gel	Local delivery	Lower systemic exposure positioning
Cambia oral solution	Rapid-use oral powder solution	Different acute migraine positioning
Dyloject injection	Parenteral administration	Hospital and procedural use
Diclofenac sodium delayed-release tablet	Delayed oral release	Different release and salt profile

Zipsor’s opportunity is strongest where prescribers value an oral liquid-filled dosage form for acute pain. Its weakness is the availability of lower-cost diclofenac products with established prescribing familiarity.

What is the FDA regulatory status of Zipsor?

Zipsor is an FDA-approved prescription product. The FDA-approved labeling identifies diclofenac potassium as the active ingredient and specifies the 25 mg liquid-filled softgel dosage form.[1]

The regulatory review should focus on:

• NDA approval and supplements.
• Current labeling.
• Orange Book therapeutic-equivalence listings.
• Listed patents and exclusivity.
• Approved manufacturing sites.
• Drug shortages or supply constraints.
• Postmarketing safety information.

The product carries the class-wide NSAID risks associated with cardiovascular thrombotic events, gastrointestinal bleeding and ulceration. These risks constrain expansion into chronic-use markets and make label-compliant acute-pain positioning commercially important.

Which companies are challenging Zipsor?

A definitive list of current ANDA applicants, Paragraph IV challengers and litigation parties requires a current FDA Orange Book review and federal court docket search. Generic diclofenac manufacturers are the natural competitive pool, but not every diclofenac manufacturer necessarily has an ANDA directed to Zipsor’s liquid-filled softgel.

Potential competitors include:

• Established generic pharmaceutical companies with softgel capacity.
• Contract development and manufacturing organizations.
• Specialty pharmaceutical companies using 505(b)(2) strategies.
• Branded NSAID companies with acute-pain portfolios.
• International manufacturers seeking U.S. entry.

The most credible challengers will have softgel manufacturing capability, regulatory experience with complex dosage forms and access to bioequivalence testing.

How strong is the Zipsor patent estate?

The estate should be rated as formulation-dependent rather than molecule-dependent.

Factor	Assessment
Active ingredient protection	Weak or expired because diclofenac is old
Formulation differentiation	Meaningful
Manufacturing complexity	Moderate
Bioequivalence burden	Higher than a conventional tablet
Substitution risk	High if a low-cost equivalent is approved
Clinical differentiation	Limited
Brand durability	Dependent on prescribing and distribution

Formulation claims can be valuable when they cover a narrow but commercially necessary vehicle or dosage form. Their weakness is design-around risk. A generic sponsor may avoid infringement by changing solvent ratios, surfactants, shell composition or manufacturing conditions while maintaining equivalent performance.

What licensing and manufacturing opportunities exist?

The most practical licensing opportunities involve technology rather than the Zipsor brand itself.

Formulation licensing

A sponsor with a stable liquid-fill platform could license:

• Diclofenac potassium softgel technology.
• Non-gelatin shell technology.
• Rapid-release liquid-fill systems.
• High-throughput encapsulation processes.
• Moisture-protective packaging.

Regional commercialization

Zipsor-like products may have value in markets where acute oral analgesics command premium pricing or where softgel dosage forms are preferred. Geographic expansion would require local approval, trademark review, patent clearance and assessment of diclofenac safety restrictions.

Contract manufacturing

Softgel manufacturers can supply generic or private-label versions, but manufacturing agreements should address:

• Control of formulation know-how.
• Ownership of process improvements.
• Change-control obligations.
• Batch-release testing.
• Supply continuity.
• Regulatory inspection risk.
• Minimum purchase commitments.
• Technology-transfer rights.

What revenue exposure does generic entry create?

Zipsor revenue is vulnerable to rapid erosion once an equivalent generic receives approval and gains pharmacy substitution. The size of the exposure depends on the product’s net price, payer coverage, prescribing concentration and the number of approved competitors.

Entry scenario	Likely commercial effect
No approved equivalent	Brand retains pricing power, subject to payer controls
One softgel generic	Price pressure begins; substitution may remain limited
Multiple softgel generics	Significant price erosion and share loss
Tablet-only competition	Partial pressure if dosage-form substitution is limited
Authorized generic	Faster price competition with controlled supply
505(b)(2) competitor	Potential premium-price segmentation

A branded strategy could preserve value through reliable supply, targeted acute-pain promotion, pharmacy access, packaging differentiation and contracting. Those measures cannot fully offset broad generic substitution if an FDA-equivalent softgel becomes available.

Key Takeaways

• Zipsor is a 25 mg diclofenac potassium liquid-filled softgel for acute pain.
• Its excipient strategy supports solubilization, dispersion, shell integrity, release and product stability.
• The principal intellectual-property value lies in formulation and delivery claims, not diclofenac itself.
• A softgel generic faces more development risk than a conventional diclofenac tablet but remains technically feasible.
• The best commercial opportunities are lower-cost softgels, non-gelatin capsules, unit-dose packaging, pediatric or geriatric presentations and 505(b)(2) reformulations.
• Current patent expirations, Orange Book listings and Paragraph IV activity require a live FDA and USPTO review before investment or litigation decisions.
• Generic entry could produce rapid revenue erosion if one or more therapeutically equivalent softgels obtain approval.

FAQs About Zipsor Excipient and Commercial Strategy

Can Zipsor be reformulated without gelatin?

Yes. A non-gelatin softgel or alternative oral dosage form could be developed, but the sponsor would need to address shell strength, moisture transmission, dissolution, stability and bioequivalence.

Is Zipsor’s liquid formulation protected by trade secrets?

The exact quantitative composition, processing conditions and manufacturing controls may be protected as confidential know-how even when broad formulation concepts are disclosed in patents or regulatory documents.

Would a diclofenac tablet automatically substitute for Zipsor?

No. A tablet must satisfy FDA requirements for pharmaceutical equivalence and therapeutic equivalence. A different dosage form may not qualify as an automatic substitute for a liquid-filled softgel.

Can a Zipsor generic use different excipients?

Yes, subject to applicable regulatory requirements. The alternative formulation must demonstrate that excipient differences do not alter safety, performance, dissolution, stability or bioequivalence.

Is Zipsor suitable for chronic pain commercialization?

Its approved positioning is acute pain, and diclofenac carries NSAID-related cardiovascular and gastrointestinal risks. Expansion into chronic-use markets would require a strong clinical and regulatory basis.

References

1. U.S. Food and Drug Administration. (2023). Zipsor (diclofenac potassium) liquid filled capsule: Prescribing information. FDA.

2. National Library of Medicine. (2024). Zipsor- diclofenac potassium capsule, liquid filled. DailyMed.

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

4. United States Patent and Trademark Office. (2024). Patent Center. USPTO.

5. U.S. Courts. (2024). PACER case locator. Administrative Office of the U.S. Courts.

6. U.S. Food and Drug Administration. (2024). ANDA submissions: Amendments and requests for final approval to tentatively approved ANDAs. FDA.