List of Excipients in Branded Drug RIMSO-50

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Mylan Institutional LLC	RIMSO-50	dimethyl sulfoxide	67457-177	WATER

RIMSO-50 Excipient Strategy and Commercial Opportunities

Last updated: August 5, 2026

RIMSO-50 is a sterile 50% dimethyl sulfoxide (DMSO) solution for intravesical treatment of interstitial cystitis. Its commercial position depends less on active-ingredient exclusivity than on sterile manufacturing, container compatibility, supply reliability, labeling compliance, and differentiation in bladder-delivery products. The product has limited conventional patent protection, leaving opportunities for improved presentations, ready-to-use packaging, hospital supply contracts, and adjacent urology products. [1]

What is RIMSO-50 and how is it administered?

RIMSO-50 contains DMSO at a concentration of 50% and is administered directly into the bladder. The labeled dose is 50 mL, typically instilled through a catheter and retained for approximately 15 minutes before drainage or urination. It is indicated for the symptomatic relief of interstitial cystitis. [1]

Product attribute	RIMSO-50 profile
Active ingredient	Dimethyl sulfoxide
Strength	50% solution
Route	Intravesical
Dosage form	Sterile solution
Labeled volume	50 mL
Primary indication	Interstitial cystitis
FDA pathway	Approved drug product
Biologic status	Not applicable
Primary commercial constraint	Sterile liquid manufacturing and packaging

DMSO is a small-molecule solvent with high polarity and strong tissue penetration. At the labeled concentration, it is also associated with odor and local tolerability considerations. The formulation therefore requires a balance between chemical stability, patient acceptability, container compatibility, and preservation of the labeled concentration.

What excipients are used in RIMSO-50?

The principal formulation components are DMSO and sterile water. RIMSO-50 is not a conventional multidose, preservative-containing injectable product. The formulation is designed as a concentrated aqueous solution for single-use intravesical administration.

Component	Functional role	Strategic relevance
Dimethyl sulfoxide	Active pharmaceutical ingredient and solvent	Determines concentration, odor, permeability and compatibility profile
Sterile water	Vehicle	Controls concentration, osmolality and fill volume
Container-closure system	Product-contact packaging	Critical for extractables, leachables, adsorption and DMSO permeation
Labeling and administration materials	Use-system controls	Affect catheter compatibility, handling and administration time

The absence of a complex excipient system reduces formulation patent opportunities but increases the importance of manufacturing controls. DMSO can interact with plastics, elastomers, adhesives, inks and other packaging materials. A commercial formulation strategy must evaluate the complete product-contact system rather than only the liquid composition.

How does DMSO affect excipient and packaging selection?

DMSO is a powerful solvent. It can extract low-molecular-weight substances from polymers, soften certain plastics, alter elastomer performance, and transport chemicals through contact surfaces. These properties create a significant container-closure and administration-set risk.

Container-closure considerations

A manufacturer evaluating a RIMSO-50 alternative should assess:

• DMSO loss through permeation or evaporation.
• Extractables and leachables from the primary container.
• Closure swelling, brittleness or dimensional change.
• Compatibility with transfer devices and catheters.
• Label adhesive migration.
• Stability during refrigerated, room-temperature and accelerated storage.
• Integrity after shipping, handling and repeated thermal cycling.

Glass may offer a strong compatibility profile but can increase breakage risk, weight and logistics costs. High-barrier polymer containers may reduce shipping cost but require extensive compatibility testing. Standard flexible intravenous bags, syringes and plastic bottles cannot be assumed to be suitable for concentrated DMSO.

Excipient screening

Potential formulation modifications should be approached conservatively. Buffers, surfactants, tonicity agents and preservatives may create new safety and compatibility issues. A formulation that changes pH, osmolality or viscosity may alter bladder tolerability and administration performance.

The strongest near-term strategy is likely to preserve the active concentration and use the minimum excipient set needed to establish stability. This limits clinical-development requirements and reduces the risk that a reformulation becomes a new safety or efficacy product rather than a pharmaceutical-equivalence product.

What patents protect RIMSO-50?

RIMSO-50 has limited apparent patent-based protection compared with newer specialty pharmaceuticals. DMSO is an established compound, and the labeled use of intravesical DMSO is longstanding. The principal barriers are regulatory approval, sterile production, quality systems and commercial supply rather than composition-of-matter patents.

Protection category	RIMSO-50 position	Commercial impact
Composition-of-matter patent	Not commercially relevant for DMSO	Does not block competing formulations
Intravesical use patent	Legacy concepts may exist, but broad blocking protection is unlikely	Limited barrier to alternative products
Formulation patent	Narrow opportunity unless a new stability, tolerability or delivery advantage is demonstrated	Potential for differentiated products
Container-closure patent	Possible for a specific compatible package or administration system	May support narrower product differentiation
Manufacturing patent	Possible for sterile filling, low-particulate control or packaging	Usually protects process execution rather than market broadly
Trademark protection	Product and brand identifiers may remain protectable	Supports commercial positioning

The Orange Book should be reviewed for the current RIMSO-50 listing and any patent certifications associated with an abbreviated new drug application. Publicly available product information identifies RIMSO-50 as an approved drug product but does not indicate the type of active biologic exclusivity associated with newer therapies. [1,2]

When does RIMSO-50 lose exclusivity?

RIMSO-50 does not have a practical biologic exclusivity date because DMSO is a small molecule. The product’s commercial protection is better analyzed through regulatory status and market access than through a single patent-expiration date.

Exclusivity issue	Assessment
New chemical entity exclusivity	Not applicable to this legacy DMSO product
Orphan-drug exclusivity	No current basis identified for RIMSO-50
Pediatric exclusivity	No publicly identified period
Patent term	No commercially material composition patent identified
Generic competition	Possible through an ANDA or other applicable pathway
Compounded competition	Present in some markets, subject to applicable federal and state rules
Biosimilar exposure	Not applicable

A competing manufacturer could pursue an ANDA if the reference product is eligible for an abbreviated pathway and the applicant can demonstrate pharmaceutical equivalence, bioequivalence where applicable, and adequate chemistry, manufacturing and controls data. The intravesical route and concentrated DMSO formulation make product sameness and packaging compatibility important parts of the development program.

What FDA regulatory status does RIMSO-50 have?

RIMSO-50 is an FDA-approved prescription drug product for intravesical use in interstitial cystitis. The FDA labeling identifies the active ingredient, strength, route, dosage instructions, warnings and storage information. [1]

The development route for a competitor depends on the regulatory status of the reference product and FDA’s determination of the appropriate abbreviated or full application pathway. Potential routes include:

1. An ANDA for a pharmaceutically equivalent product.
2. A 505(b)(2) application for a reformulated or differently presented product.
3. A full NDA if the proposed product has material clinical or formulation differences that cannot rely on existing findings.

A 505(b)(2) strategy may be commercially attractive for a ready-to-use device, modified container, altered concentration, or new formulation intended to improve tolerability. It carries greater development cost than a straightforward equivalent but can support stronger differentiation and potentially broader claims.

What formulation patents could protect a RIMSO-50 competitor?

The most defensible patent opportunities are likely to involve measurable technical improvements rather than the basic DMSO-water composition.

Reduced-odor formulations

DMSO has a characteristic odor associated with dimethyl sulfide metabolites and patient handling. A formulation that reduces perceived odor without compromising DMSO concentration, sterility or bladder tolerability could support a patent if the effect is unexpected and reproducible.

Potential claims could cover:

• A defined impurity profile.
• Controlled oxidation or reduction of odor-forming species.
• A specific packaging system that limits odor release.
• A formulation with a defined volatile-organic profile.
• A treatment method using a preconditioned or closed administration system.

Improved tolerability

Claims could target a defined pH or osmolality range, provided clinical or technical data show improved tolerability. The patent must avoid claiming only routine optimization. Useful evidence would include reduced pain, urgency, spasm or premature expulsion while maintaining therapeutic exposure.

Ready-to-use administration systems

A prefilled, sterile, single-use presentation could create value through:

• Reduced preparation time.
• Lower contamination risk.
• Lower pharmacy labor.
• Integrated catheter or transfer connector.
• Closed-system administration.
• Unit-dose labeling and traceability.

Device claims may provide stronger protection than a basic solution claim, especially where the package prevents DMSO interaction with the delivery system.

Stability and low-temperature protection

A formulation or package that maintains concentration, clarity, sterility and container integrity over a commercially useful shelf life could support patent claims. The strongest position would link the formulation composition to a specific stability result and defined packaging structure.

How many patents cover RIMSO-50?

No large, clearly defined active patent estate is apparent for the marketed RIMSO-50 formulation. The relevant protection categories are likely to be legacy DMSO use concepts, product trademarks, manufacturing know-how and any narrow package or delivery-system patents.

The lack of a broad patent estate changes the competitive model. A generic or alternative manufacturer may not face a conventional patent thicket, but it must still manage:

• FDA application risk.
• Product-specific quality requirements.
• DMSO container compatibility.
• Sterile filling validation.
• Supplier qualification.
• Hospital and urology-clinic contracting.
• Physician familiarity with the reference product.
• Potential state-level treatment and compounding restrictions.

Which companies are challenging RIMSO-50?

No major publicly reported Paragraph IV litigation or settlement involving RIMSO-50 was identified in the principal public product and litigation sources reviewed. The commercial threat is more likely to come from an unbranded equivalent, a 505(b)(2) reformulation, a private-label product, or a compounding pharmacy than from a high-profile patent challenge.

Paragraph IV risk

A Paragraph IV certification would be relevant only if the reference product has listed patents in the Orange Book. If no blocking patents are listed, an applicant could pursue a certification route that does not require challenging an active patent. The commercial launch timeline would then depend on FDA review, approval, market preparation and any regulatory exclusivity.

Litigation status

The absence of widely reported litigation does not eliminate operational risk. A sponsor could still face disputes involving:

• Trademark use.
• Trade dress.
• Product quality.
• Advertising claims.
• Device compatibility.
• Manufacturing know-how.
• Distribution agreements.

What commercial opportunities exist for RIMSO-50 excipients and packaging?

The strongest commercial opportunities are in product presentation rather than new excipients.

Unit-dose hospital and clinic packaging

RIMSO-50 is administered in urology settings where preparation time, sterility and staff workflow matter. A unit-dose bottle or prefilled container could support premium pricing if it reduces manipulation and waste.

Closed administration systems

A compatible, closed transfer system could reduce exposure to DMSO odor and lower contamination risk. The system could be sold as a combination product or as a co-packaged administration accessory, depending on FDA classification.

Private-label supply

Specialty-pharmaceutical companies, hospital systems and urology distributors may seek reliable private-label supply. A contract manufacturer with validated DMSO-compatible packaging could offer a lower-risk entry platform than a sponsor building a complete sterile facility.

Regional distribution

RIMSO-50 is a niche product with potential value in markets where interstitial cystitis treatment is concentrated among specialty urology practices. Geographic opportunities may arise from:

• Local sterile fill-finish capacity.
• Shorter delivery times.
• Regional hospital contracts.
• Backup supply arrangements.
• Country-specific registration of DMSO products.

Adjacent bladder products

A company could develop a portfolio around intravesical therapy, including catheter accessories, instillation kits, bladder irrigation products and combination treatment protocols. These products may have separate regulatory and patent profiles and can increase account-level revenue without changing the RIMSO-50 active ingredient.

How does RIMSO-50 compare with competing interstitial cystitis products?

RIMSO-50 occupies a distinct position because it is an intravesical DMSO product rather than an oral analgesic, antihistamine or glycosaminoglycan-replacement therapy.

Product category	Main differentiation	Excipient opportunity
RIMSO-50	Intravesical DMSO	Packaging, odor control, tolerability and administration efficiency
Oral interstitial cystitis therapies	Systemic administration	Conventional tablet, capsule and controlled-release formulation
Intravesical glycosaminoglycan products	Bladder-directed barrier or coating approach	Viscosity, retention, catheter delivery and combination systems
Compounded instillations	Localized physician-directed mixtures	Sterility, standardization, ready-to-use packaging and quality control
Device-assisted therapy	Administration or bladder-delivery support	Closed systems, catheter compatibility and workflow reduction

RIMSO-50’s main competitive advantage is established clinical familiarity. Its disadvantages include the need for catheter-based administration, odor, local tolerability concerns and dependence on specialty-clinic infrastructure.

What generic launch scenarios exist for RIMSO-50?

Three launch models are commercially plausible.

Direct equivalent

A sponsor could pursue a product matching the reference concentration, route, dosage form and labeling. This model minimizes clinical differentiation requirements but places heavy weight on pharmaceutical equivalence, sterile manufacturing and packaging compatibility.

Improved ready-to-use product

A sponsor could develop a prefilled or closed-system presentation. This approach may support a 505(b)(2) application and premium pricing, but it requires device validation, human-factors work and a stronger clinical and regulatory package.

Compounded or institutional supply

A pharmacy or outsourcing facility could supply DMSO-based intravesical preparations under applicable compounding rules. This route may enter selected accounts quickly but generally has less national branding, less uniformity and greater regulatory exposure than an FDA-approved product. [3]

How strong is the RIMSO-50 patent estate?

The patent estate appears weak as a blocking estate and moderate as a product-execution barrier. The active ingredient is old, the formulation is simple, and no broad composition patent is commercially apparent. The more durable advantages are:

• FDA-approved labeling.
• Brand recognition among urologists.
• Established clinical use.
• Validated sterile manufacturing.
• Qualified DMSO-compatible packaging.
• Distribution access.
• Supply continuity.

A challenger with equivalent quality and reliable supply could compete without overcoming a substantial composition-of-matter patent barrier. A reformulation sponsor can seek stronger protection by claiming a specific package, device, stability profile or tolerability improvement.

What revenue exposure does RIMSO-50 create?

RIMSO-50 is a niche product, so absolute revenue exposure is likely smaller than for mass-market pharmaceuticals. Its value can still be material because it may have limited direct competition and concentrated specialty demand. Revenue risk would arise from:

• An approved generic equivalent.
• Supply interruption.
• Pricing pressure from institutional buyers.
• Compounding substitution.
• Loss of preferred-distributor status.
• Superior ready-to-use delivery systems.
• Reduced use of catheter-based therapy.

A supplier should evaluate revenue through account concentration, annual treatment volume, price per 50 mL unit, gross margin from sterile filling, and the percentage of sales generated by specialty distributors. Public company filings do not provide a consistently isolated RIMSO-50 revenue line, limiting product-specific revenue analysis. [4]

Key Takeaways

• RIMSO-50 is a 50% sterile DMSO solution for intravesical treatment of interstitial cystitis.
• The formulation is simple, with sterile water as the primary vehicle.
• DMSO compatibility with containers, closures, labels and administration devices is the central technical issue.
• No broad, commercially material patent estate is apparent for the marketed product.
• Biosimilar risk does not apply because RIMSO-50 is a small-molecule drug.
• The main regulatory opportunity is a direct equivalent or a 505(b)(2) product with improved presentation.
• The strongest commercial opportunities are ready-to-use packaging, closed administration systems, private-label supply and sterile contract manufacturing.
• The principal competitive risks are generic approval, compounding substitution, supply disruption and workflow-improving delivery systems.
• Formulation patents are most credible when tied to measurable odor, tolerability, stability or packaging improvements.

FAQs

Is RIMSO-50 a biologic or a small-molecule drug?

RIMSO-50 is a small-molecule drug product containing dimethyl sulfoxide. Biosimilar approval and biologic exclusivity rules do not apply.

Can a company make a generic version of RIMSO-50?

A company may pursue an abbreviated regulatory pathway if FDA determines that the product qualifies and the sponsor can demonstrate the required pharmaceutical equivalence, manufacturing quality and product-specific performance.

Is DMSO compatible with plastic syringes?

Compatibility cannot be assumed. Concentrated DMSO may interact with plastics, elastomers and adhesives. Each syringe, stopper, connector and transfer device requires product-specific extractables, leachables and integrity testing.

Could a low-odor RIMSO-50 formulation receive patent protection?

Potentially, but the claim would need a defined composition, impurity or packaging feature linked to a demonstrated odor-reduction result. A routine change in concentration or packaging may not provide adequate inventive protection.

What is the best commercial strategy for a RIMSO-50 competitor?

The strongest risk-adjusted strategy is a validated sterile equivalent with DMSO-compatible unit-dose packaging. A higher-value strategy is a ready-to-use closed administration system supported by a 505(b)(2) regulatory plan and device-specific intellectual property.

References

1. U.S. Food and Drug Administration. (n.d.). RIMSO-50 (dimethyl sulfoxide) sterile solution prescribing information. DailyMed.
2. U.S. Food and Drug Administration. (2025). Approved drug products with therapeutic equivalence evaluations: Orange Book.
3. U.S. Food and Drug Administration. (2023). Human drug compounding under sections 503A and 503B of the Federal Food, Drug, and Cosmetic Act.
4. Jacobus Pharmaceutical Company, Inc. (n.d.). RIMSO-50 product information.