List of Excipients in Branded Drug CELESTONE SOLUSPAN

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Merck Sharp & Dohme Corp	CELESTONE SOLUSPAN	betamethasone acetate and betamethasone sodium phosphate	0085-0566	BENZALKONIUM CHLORIDE
Merck Sharp & Dohme Corp	CELESTONE SOLUSPAN	betamethasone acetate and betamethasone sodium phosphate	0085-0566	EDETATE DISODIUM
Merck Sharp & Dohme Corp	CELESTONE SOLUSPAN	betamethasone acetate and betamethasone sodium phosphate	0085-0566	SODIUM PHOSPHATE, DIBASIC, ANHYDROUS
Merck Sharp & Dohme Corp	CELESTONE SOLUSPAN	betamethasone acetate and betamethasone sodium phosphate	0085-0566	SODIUM PHOSPHATE, MONOBASIC, MONOHYDRATE
Organon LLC	CELESTONE SOLUSPAN	betamethasone acetate and betamethasone sodium phosphate	78206-118	BENZALKONIUM CHLORIDE
Organon LLC	CELESTONE SOLUSPAN	betamethasone acetate and betamethasone sodium phosphate	78206-118	EDETATE DISODIUM

CELESTONE SOLUSPAN Excipient Strategy, Formulation Patents, and Commercial Opportunities

Last updated: August 28, 2026

Celestone Soluspan is a dual-depot betamethasone injectable suspension containing betamethasone sodium phosphate and betamethasone acetate. Its commercial differentiation depends on suspension stability, predictable redispersion, injection performance, preservative control, and regulatory equivalence rather than on active-ingredient exclusivity. The strongest opportunities are generic or differentiated injectable products using the same pharmacologic concept with improved excipient systems, preservative-free presentations, optimized syringes, and better manufacturing controls.

What is Celestone Soluspan and how does its formulation work?

Celestone Soluspan combines an immediately available corticosteroid salt with a poorly soluble corticosteroid ester.

Component	Function
Betamethasone sodium phosphate	Water-soluble fraction intended to provide rapid systemic corticosteroid availability
Betamethasone acetate	Low-solubility depot fraction intended to provide prolonged local or systemic exposure
Aqueous vehicle	Dispersion medium for the injectable suspension
Buffering agents	pH control and chemical stability
Tonicity agents	Control of osmolality and injection tolerability
Suspending and wetting system	Particle dispersion, redispersion, and dose uniformity
Preservative system	Multidose-container microbial protection, where applicable

The labeled strength is generally expressed as 6 mg/mL total betamethasone, consisting of 3 mg/mL betamethasone sodium phosphate and 3 mg/mL betamethasone acetate. The product is administered by intramuscular, intra-articular, intrabursal, intradermal, and other routes identified in the labeling, but it is not intended for intravenous administration because of the depot suspension component. [1]

The formulation challenge is the coexistence of two active forms with different solubility profiles. The phosphate fraction remains dissolved, while the acetate fraction must remain uniformly suspended. The product therefore requires control over particle size, wetting, sedimentation, flocculation, viscosity, syringeability, and dose withdrawal.

What excipients are protected by the Celestone Soluspan formulation?

The commercial product’s exact excipient system should be determined from the current approved labeling and regulatory filing. Public labeling identifies the product as an aqueous injectable suspension with inactive ingredients used for pH adjustment, tonicity, stability, and preservation. [1]

The formulation-relevant excipient categories are more important commercially than any single inactive ingredient:

Buffer and pH-control excipients

Phosphate buffering can support chemical stability and maintain an injectable pH range. Excessive buffer concentration can affect ionic strength, particle interactions, and precipitation behavior. A generic developer must demonstrate that pH remains controlled during storage without changing the physical state of betamethasone acetate.

Tonicity agents

Sodium chloride or another tonicity modifier can improve injection tolerability. Tonicity changes can also alter zeta potential, sedimentation behavior, and the interaction between suspended particles and container surfaces.

Chelating agents

A chelator such as edetate may reduce degradation catalyzed by trace metals. The commercial value of a chelator is usually indirect. It can improve stability and support a longer shelf life, but it also creates compatibility and regulatory comparability questions.

Preservatives

A multidose injectable may require an antimicrobial preservative. Benzalkonium chloride and related preservatives can create safety, tolerability, container-compatibility, and particulate concerns. A preservative-free single-dose product could command a premium in settings where repeated exposure or local injection tolerability is a concern.

Wetting and suspension-control excipients

The acetate fraction requires an excipient system that prevents hard caking and supports rapid redispersion. A formulation that settles slowly but forms a compact sediment may perform worse than a faster-settling, easily redispersible suspension.

Potential excipient strategies include:

• Nonionic surfactants to improve particle wetting.
• Polymeric suspending agents to control sedimentation.
• Controlled ionic strength to manage particle-particle interactions.
• Optimized buffer concentration to reduce precipitation risk.
• Low-viscosity systems that preserve syringeability.
• Excipient combinations that reduce aggregation after agitation and temperature cycling.

Any change must be evaluated against injectable safety, particulate limits, extractables and leachables, sterilization compatibility, and route-specific tolerability.

What formulation patents could protect a Celestone Soluspan generic?

A new patent would likely need to claim a technical improvement rather than the basic combination of betamethasone sodium phosphate and betamethasone acetate. The active ingredients and the general depot concept are old.

Potential claim areas include:

Patent area	Potential claim subject	Commercial value
Excipient composition	Defined buffer, tonicity, surfactant, and suspension system	Moderate if linked to measurable performance
Particle engineering	Specific acetate particle-size distribution or morphology	High if it improves dose uniformity or release
Redispersion	Formulation that meets a defined agitation or redispersion endpoint	Moderate to high
Injection performance	Reduced needle force, reduced clogging, improved syringeability	Moderate
Preservative-free product	Single-dose suspension with improved stability	High in selected clinical channels
Container closure	Prefilled syringe, dual-chamber device, or specialized vial	Moderate to high
Manufacturing process	Wet milling, homogenization, sterile processing, or aseptic blending	High if difficult to design around
Stability	Long-term stability under defined temperature and agitation conditions	Moderate
Local delivery	Formulation optimized for intra-articular or intrabursal administration	Potentially high, subject to clinical support

A strong formulation patent should connect the excipient choices to objective results. Examples include reduced particle growth, improved redispersion after storage, lower injection force, reduced sedimentation variability, or a defined in-vitro release profile.

A claim that simply lists common excipients at conventional concentrations would face greater validity and freedom-to-operate risks. The strongest claims would use narrow concentration ranges, particle-size limits, manufacturing parameters, and performance tests that are difficult to reproduce with alternative systems.

How strong is the patent estate for Celestone Soluspan?

The original Celestone Soluspan patent estate is unlikely to provide meaningful current exclusivity because the product and its active ingredients have been marketed for decades. The key commercial barriers are regulatory, manufacturing, and clinical rather than basic composition patents.

The relevant patent categories are:

1. Original composition patents. These are expected to be expired or commercially irrelevant because of the product’s age.
2. Formulation patents. Any later patents would need to cover a specific improved suspension, excipient combination, container, or process.
3. Method-of-use patents. Older corticosteroid indications are generally vulnerable to expiration and cannot be assumed to block generic use.
4. Device patents. Prefilled syringe or specialty delivery patents may still matter if a later presentation was developed.
5. Manufacturing patents. Process patents may affect freedom to operate even when the drug product itself is no longer protected.

The decisive diligence issue is not whether the historical product had patents. It is whether any unexpired U.S. patent is currently listed in the FDA Orange Book or asserted against a proposed abbreviated new drug application. The Orange Book identifies patents and exclusivity for approved drug products when listing requirements are met. [2]

What is the Orange Book status of Celestone Soluspan?

Celestone Soluspan should be assessed at the specific product, strength, dosage form, and marketing-application level. The Orange Book does not treat every historical brand product uniformly, and a product may have different status depending on whether its application remains active, discontinued, or transferred.

The core regulatory questions are:

• Is there an active reference listed drug for the injectable suspension?
• Is the specific 6 mg/mL presentation listed as a reference product?
• Are any patents listed under the relevant application number?
• Is the product eligible for an ANDA pathway?
• Does the reference product have a therapeutic-equivalence code?
• Are there active exclusivity periods attached to the reference application?

FDA’s Drugs@FDA database and the Orange Book are the controlling public sources for application history, labeling, approval status, and listed patents. [2,3]

Because Celestone Soluspan is an old small-molecule injectable, a conventional ANDA strategy is generally more relevant than a 505(b)(2) strategy, assuming the proposed product can demonstrate pharmaceutical equivalence and bioequivalence or otherwise satisfy FDA’s requirements for the suspension product. A 505(b)(2) approach may be commercially useful for a materially different presentation, route, device, preservative-free formulation, or differentiated clinical use. [4]

When does Celestone Soluspan lose exclusivity?

The principal compound and product exclusivity for Celestone Soluspan are long expired or no longer expected to be the primary market barrier. The relevant dates are historical approval dates, patent expiration dates, and any current Orange Book listings rather than a future brand exclusivity cliff.

Exclusivity category	Likely commercial position
New chemical entity exclusivity	Expired
Original formulation patents	Expected to be expired because of product age
Pediatric exclusivity	No current commercial significance identified
Orphan exclusivity	Not the central product strategy
Later formulation patents	Must be checked individually
Method-of-use patents	Must be checked by indication and claim scope
Regulatory exclusivity for a new presentation	Possible only for a qualifying new application

A generic entrant should not assume that the absence of basic active-ingredient patents eliminates all risk. Unexpired patents can arise from later devices, delivery systems, manufacturing methods, or differentiated formulations.

What generic entry risks exist for Celestone Soluspan?

Generic entry risk is substantial at the active-ingredient level but more complex at the product level. Injectable suspensions create more regulatory and manufacturing risk than simple immediate-release solutions.

Regulatory equivalence risk

The applicant must control:

• Identity and strength of both betamethasone forms.
• Particle-size distribution of betamethasone acetate.
• Dissolved versus suspended drug fraction.
• pH and osmolality.
• Sterility and bacterial endotoxin levels.
• Particulate matter.
• Delivered dose after shaking and withdrawal.
• Stability after storage and temperature excursions.
• Container-closure integrity.

FDA guidance treats injectable suspensions as products requiring careful assessment of physical attributes and performance. [5]

Manufacturing risk

The acetate fraction can create scale-up problems. Laboratory mixing may produce a uniform suspension that fails during commercial manufacture because of differences in shear, milling energy, hold time, vessel geometry, or filling speed.

Critical process parameters may include:

• Milling or homogenization conditions.
• Order of excipient addition.
• Temperature during dispersion.
• Bulk hold time before filling.
• Mixing speed during filling.
• Sterilization or aseptic-processing conditions.
• Container orientation during storage.
• Agitation instructions before administration.

Litigation risk

A Paragraph IV challenge would be relevant only if the Orange Book contains an unexpired patent covering the reference product. If no relevant patent is listed, an ANDA applicant would face ordinary regulatory and commercial competition rather than a patent certification dispute. [2,6]

Potential litigation could involve:

• Formulation claims.
• Particle-size claims.
• Device or prefilled-syringe claims.
• Manufacturing-process claims.
• Method-of-use claims.
• Trade-secret allegations involving suspension processing.

A later entrant could reduce litigation exposure by using a distinct excipient system, a different particle-engineering method, and a non-infringing presentation.

What formulation and excipient opportunities exist?

Preservative-free single-dose suspension

A preservative-free vial or prefilled syringe could target hospitals, ambulatory surgery centers, pain clinics, and clinicians concerned about repeated preservative exposure. The trade-off is higher packaging cost and potentially lower flexibility for multidose use.

Commercial requirements include:

• Demonstrated sterility through shelf life.
• Single-dose labeling.
• Acceptable syringeability.
• Low particulate burden.
• Stable suspension after shipping.
• Clear instructions for resuspension.

Prefilled syringe

A prefilled syringe could reduce preparation time, drug wastage, and dosing errors. It also creates opportunities for differentiated intellectual property around suspension homogeneity, agitation, needle geometry, plunger force, and container compatibility.

A conventional prefilled syringe may be unsuitable if the product requires vigorous agitation or if the suspension settles during storage. Device development must therefore test dose uniformity at multiple positions within the syringe.

Lower-sedimentation formulation

Reducing sedimentation can improve usability but may require greater viscosity. Excess viscosity increases injection force and may limit needle gauge. The optimal product balances sedimentation rate, redispersion energy, and injection force rather than maximizing any single variable.

Route-specific presentation

The same corticosteroid suspension is used across several administration routes. A developer could pursue differentiated presentations for:

• Intra-articular injection.
• Intrabursal injection.
• Intramuscular injection.
• Intradermal use.
• Soft-tissue injection.

Route-specific claims would require clinical and regulatory support. A formulation optimized for intra-articular injection may not be appropriate for intramuscular use because of differences in tissue tolerance, injection volume, and release requirements.

Reduced-volume or higher-concentration product

A higher-concentration presentation could reduce injection volume but would require assessment of local tolerability, particle loading, suspension stability, and delivery force. It may create a new product opportunity under a 505(b)(2) pathway if the formulation is clinically and regulatorily differentiated.

How does Celestone Soluspan compare with competing corticosteroid injections?

Product type	Principal depot component	Formulation profile	Competitive implication
Celestone Soluspan	Betamethasone acetate plus betamethasone sodium phosphate	Dual-fraction suspension	Rapid and depot corticosteroid concept
Triamcinolone acetonide suspension	Low-solubility corticosteroid ester	Depot suspension	Strong established competition in joint and soft-tissue use
Methylprednisolone acetate suspension	Low-solubility corticosteroid ester	Depot suspension	Broad clinical familiarity and generic availability
Dexamethasone sodium phosphate solution	Soluble corticosteroid salt	Clear solution	Easier manufacturing, no depot fraction
Betamethasone sodium phosphate solution	Soluble corticosteroid salt	Clear solution	Different duration and delivery profile

Celestone Soluspan’s differentiator is the combination of rapid-release and depot fractions. Its disadvantages for a generic developer are the physical complexity of a two-phase injectable suspension and the need to demonstrate consistent dose delivery after settling.

Which companies are challenging Celestone Soluspan?

The likely competitive field includes manufacturers of generic betamethasone injectable products, corticosteroid suspension suppliers, contract developers, and companies producing prefilled injectable devices. Exact applicant identities and Paragraph IV challengers must be verified through FDA application records, Orange Book patent certifications, court dockets, and Abbreviated New Drug Application litigation filings.

The competitive landscape is more likely to develop around:

• Generic betamethasone injectable suspension.
• Preservative-free corticosteroid presentations.
• Prefilled syringes.
• Hospital-use ready-to-administer products.
• Specialty orthopedic and pain-clinic distribution.
• Alternative corticosteroid suspensions with established generic supply.

What licensing deals could create commercial value?

Licensing opportunities would be strongest in four areas:

1. Suspension technology. A developer with sterile particle engineering, controlled flocculation, or long-term redispersion technology could license the formulation platform.
2. Prefilled delivery systems. A device company could license a syringe or cartridge system designed for suspensions.
3. Contract manufacturing. Injectable manufacturers with aseptic filling and suspension scale-up capabilities could support a sponsor without internal sterile infrastructure.
4. Regional commercialization. Local partners could provide hospital access, tender participation, and regulatory registrations in markets where Celestone Soluspan or equivalent products remain clinically established.

A licensing agreement should address ownership of formulation improvements, manufacturing know-how, process validation data, regulatory responsibility, minimum purchase commitments, device rights, and geographic exclusivity.

What is the revenue exposure and commercial opportunity?

Celestone Soluspan revenue is exposed to substitution by generic betamethasone products and competing corticosteroid injections. The brand’s economic value is likely concentrated in prescriber familiarity, supply reliability, route flexibility, and institutional purchasing relationships rather than patent protection.

The most attractive commercial segments are:

• Hospitals seeking reliable injectable corticosteroid supply.
• Ambulatory surgery centers using ready-to-administer products.
• Orthopedic, rheumatology, pain, and sports-medicine clinics.
• Markets with limited access to dual-fraction betamethasone products.
• Healthcare systems that value reduced preparation and wastage.
• Specialty distributors serving office-based injection practices.

A differentiated entrant could pursue a premium only if it provides a measurable operational benefit, such as lower preparation time, improved dose uniformity, reduced wastage, preservative-free packaging, or better supply continuity. A standard vial with no meaningful manufacturing or presentation advantage would face commodity pricing.

What geographic patent and regulatory coverage matters?

The United States requires review of FDA reference-product status, Orange Book listings, ANDA eligibility, and injectable manufacturing requirements. Europe and other jurisdictions rely on national or regional regulatory systems, and patent protection may differ substantially by country.

The relevant geographic workstreams are:

• U.S. Orange Book and FDA application history.
• European marketing authorizations and national product registrations.
• Patent-family status in major markets.
• Local formulation and process patents.
• Manufacturing-site approvals.
• Import, serialization, and cold-chain requirements.
• Local tender and reimbursement rules.

Because the original product is old, geographic commercial barriers may be more significant than remaining composition patents. Local manufacturing capacity, sterile-filling compliance, and procurement access can determine market entry.

Key Takeaways

• Celestone Soluspan is a dual-fraction betamethasone injectable suspension containing betamethasone sodium phosphate and betamethasone acetate.
• The main formulation challenge is maintaining a uniform, sterile, readily redispersible acetate suspension while preserving the dissolved phosphate fraction.
• Original active-ingredient and early product exclusivity are not expected to be the main current barrier.
• The strongest patent opportunities concern particle engineering, excipient combinations, manufacturing processes, preservative-free products, and prefilled delivery systems.
• Generic entry is technically more difficult than entry for a simple corticosteroid solution.
• Preservative-free single-dose products and prefilled syringes offer the clearest differentiated commercial opportunities.
• Orange Book status, active application status, and any unexpired formulation or device patents must control the final U.S. freedom-to-operate analysis.
• Commercial success depends on sterile manufacturing, suspension robustness, supply reliability, and access to institutional and specialty-clinic channels.

FAQs

Is Celestone Soluspan a solution or a suspension?

It is an injectable suspension containing a soluble betamethasone phosphate fraction and a suspended betamethasone acetate fraction.

Can a generic manufacturer use the same excipients as Celestone Soluspan?

A manufacturer can generally use the same inactive ingredients if the formulation satisfies FDA requirements and does not infringe an unexpired patent. The developer must establish pharmaceutical equivalence, quality, sterility, stability, and performance.

Does a preservative-free Celestone Soluspan product require a new regulatory strategy?

Not necessarily. A preservative-free version may qualify for an ANDA if it meets applicable equivalence requirements, but a materially different formulation or presentation may support a 505(b)(2) strategy.

Which excipient is most important for Celestone Soluspan performance?

No single excipient determines performance. The critical factor is the integrated suspension system, including particle size, wetting, ionic strength, viscosity, buffering, and container compatibility.

Can a prefilled syringe create patent protection for a betamethasone suspension?

Yes, if the claims cover a patentable device, suspension configuration, filling process, dose-uniformity method, or combination that is novel and non-obvious. A generic prefilled syringe without a technical distinction is less likely to provide durable patent protection.

References

1. U.S. Food and Drug Administration. (n.d.). Celestone Soluspan injectable suspension: Prescribing information. FDA-approved labeling.

2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

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

4. U.S. Food and Drug Administration. (2023). Applications covered by section 505(b)(2). FDA guidance and regulatory materials.

5. U.S. Food and Drug Administration. (1999). Guidance for industry: ANDAs for certain highly purified synthetic peptides. FDA.

6. U.S. Food and Drug Administration. (2024). Hatch-Waxman amendments and abbreviated new drug applications. FDA regulatory materials.