List of Excipients in Branded Drug CAROSPIR

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
ATLANTIC BIOLOGICALS CORP	CAROSPIR	carospir	17856-0120	AMMONIUM GLYCYRRHIZATE
ATLANTIC BIOLOGICALS CORP	CAROSPIR	carospir	17856-0120	ANHYDROUS CITRIC ACID
ATLANTIC BIOLOGICALS CORP	CAROSPIR	carospir	17856-0120	DIMETHICONE
ATLANTIC BIOLOGICALS CORP	CAROSPIR	carospir	17856-0120	GLYCERIN

CAROSPIR Excipient Strategy, Patent Protection, and Commercial Opportunities

Last updated: August 12, 2026

CaroSpir is a branded spironolactone oral suspension developed for patients who cannot reliably swallow tablets or require liquid dosing. Its commercial differentiation depends on formulation performance rather than a new active ingredient. The principal opportunity is a ready-to-use, dose-flexible suspension that addresses pediatric, geriatric, dysphagia, and enteral-administration needs while avoiding pharmacy compounding.

The key commercial risks are formulation-copying by abbreviated new drug application (ANDA) applicants, substitution pressure from spironolactone tablets and compounded liquids, and the limited duration of regulatory exclusivity for a reformulated small-molecule product. The formulation patent has been the central intellectual-property asset associated with CaroSpir.

What is CaroSpir and how does its formulation differ from spironolactone tablets?

CaroSpir is a 25 mg/5 mL oral suspension of spironolactone marketed in the United States by CMP Pharma, Inc. The product is approved under NDA 209922 for heart failure, hypertension, edema associated with cirrhosis, and primary hyperaldosteronism. Patients must shake the bottle before use because spironolactone is suspended rather than fully dissolved in the vehicle. [1]

Product characteristic	CaroSpir	Conventional spironolactone tablet
Active ingredient	Spironolactone	Spironolactone
Dosage form	Oral suspension	Tablet
Strength	25 mg/5 mL	Commonly 25 mg, 50 mg, 100 mg
Dose flexibility	High, using an oral syringe or measuring device	Limited to available tablet strengths and splitting
Primary patient value	Swallowing and dosing flexibility	Lower-cost solid oral delivery
Regulatory category	New drug application	Generic and branded tablets
Biosimilar relevance	None	None

CaroSpir does not alter spironolactone’s pharmacology. Its value proposition is delivery-system performance, dosing convenience, and avoidance of extemporaneous compounding.

What excipients are used in CaroSpir?

The CaroSpir label identifies inactive ingredients that support suspension stability, palatability, preservation, and dose uniformity. Public labeling identifies excipient classes including suspending and viscosity agents, sweeteners, preservatives, buffering components, and a flavor system. The product also contains ingredients such as glycerin, sorbitol, sucralose, hypromellose, sodium citrate, methylparaben, potassium sorbate, and purified water. [1]

The practical formulation architecture is as follows:

Excipient function	Representative CaroSpir component or component class	Commercial purpose
Suspending and viscosity control	Hypromellose and cellulose-based suspension system	Limits settling and supports redispersion
Wetting and dispersion	Surfactant or wetting-function excipients	Helps distribute hydrophobic spironolactone
Sweetening and mouthfeel	Sorbitol, sucralose, glycerin	Masks bitterness and improves pediatric acceptability
Preservation	Methylparaben, potassium sorbate	Controls microbial growth in an aqueous multidose product
Buffering and pH control	Sodium citrate and citric-acid system	Supports chemical and physical stability
Vehicle	Purified water	Provides the aqueous delivery medium
Flavor	Product-specific flavor system	Improves adherence and repeat use

Exact excipient quantities and process parameters are not generally disclosed in the commercial label. Those parameters can be more important than the ingredient list because particle-size distribution, order of addition, mixing energy, viscosity, pH, preservative concentration, and filling conditions determine whether a generic suspension performs equivalently.

What is the commercial value of the CaroSpir excipient strategy?

The excipient strategy solves four problems that tablets do not address well.

First, spironolactone has low aqueous solubility and an unpleasant taste profile. A suspension must maintain dose uniformity without requiring complete dissolution. The formulation therefore relies on particle wetting, controlled viscosity, and stable redispersion.

Second, the liquid format permits individualized dosing. This is relevant when the prescribed dose is between tablet strengths, when dose titration is frequent, or when a patient cannot swallow tablets.

Third, the formulation supports pediatric and geriatric use. CaroSpir’s liquid format is commercially relevant in patients with swallowing impairment, feeding tubes, developmental limitations, or complex medication regimens.

Fourth, the product can displace pharmacy-compounded spironolactone suspensions. A manufactured product provides standardized labeling, defined stability, validated manufacturing, and commercial packaging. These attributes can support prescribing in institutions that prefer an FDA-approved liquid dosage form.

The commercial limitation is that many patients can use low-cost generic tablets. A liquid product must therefore obtain reimbursement or formulary preference based on patient need rather than active-ingredient differentiation.

What patents protect CaroSpir?

The principal publicly associated formulation patent is U.S. Patent No. 9,566,216, assigned to CMP Pharma, Inc. and directed to spironolactone oral suspension technology. The patent issued in 2017 and has a term extending into 2033 based on the underlying filing timeline, subject to any applicable patent-term adjustment or correction. [2]

Patent	Subject matter	Assignee associated with record	Approximate expiry
U.S. 9,566,216	Spironolactone oral suspension formulation	CMP Pharma, Inc.	2033, subject to official term calculation

The patent’s value depends on the scope of its asserted claims. A broad claim covering a spironolactone suspension with defined excipient categories can create a meaningful barrier. Narrow claims tied to particular concentrations, ratios, pH ranges, viscosity profiles, or manufacturing steps are easier for an ANDA applicant to design around.

Patent protection should be analyzed separately from FDA exclusivity. Patent expiry may extend beyond the period during which the product is insulated from generic applications.

When does CaroSpir lose exclusivity?

CaroSpir received FDA approval as a reformulated spironolactone product. The product’s regulatory exclusivity was shorter than the patent term. FDA approval of a new dosage form or formulation can qualify for three-year exclusivity when the application contains new clinical investigations essential to approval. [3]

The commercial protection timeline is therefore divided into three periods:

Protection type	Relevance to CaroSpir
New-drug regulatory exclusivity	Limited period following approval, generally three years for qualifying reformulation-based approval
Formulation patent	Potential protection into 2033 under U.S. Patent No. 9,566,216
Active-ingredient patent	Not the principal protection for this mature spironolactone molecule
Trademark and trade dress	Supports brand recognition but does not prevent equivalent generic entry

The effective loss-of-exclusivity date depends on patent listings, litigation, Paragraph IV certifications, settlement terms, and whether an applicant obtains approval with a non-infringing formulation.

What is the Orange Book status of CaroSpir?

CaroSpir is listed in FDA’s Approved Drug Products with Therapeutic Equivalence Evaluations, commonly called the Orange Book, under NDA 209922. The relevant Orange Book analysis should focus on:

1. Whether U.S. Patent No. 9,566,216 remains listed.
2. The patent-use code associated with the listing.
3. The listed expiration date.
4. Whether any approved ANDA has a therapeutic-equivalence code for the oral suspension.
5. Whether patent certifications have triggered litigation or a 30-month stay.

The Orange Book does not itself establish that every generic suspension would infringe the patent. It identifies patents and exclusivity information that an ANDA applicant must address under the Hatch-Waxman framework. [4]

Are there Paragraph IV challenges to CaroSpir?

A Paragraph IV challenge is the main generic-entry pathway for a competitor seeking approval before listed patent expiry. The applicant may assert that the patent is invalid, unenforceable, or not infringed. The brand holder can respond with patent litigation, potentially triggering a statutory stay of approval for up to 30 months under specified conditions. [5]

Public commercial diligence should distinguish among:

• A submitted ANDA.
• A Paragraph IV certification.
• An accepted or filed patent litigation complaint.
• A court judgment.
• A settlement agreement.
• Final FDA approval.
• Commercial launch.

A Paragraph IV filing does not establish that a generic will launch. The applicant may lose litigation, settle for a deferred entry date, receive approval for a formulation outside the patent claims, or abandon the product.

No biosimilar pathway applies to CaroSpir because spironolactone is a synthetic small-molecule drug. Competitive entry would occur through an ANDA or, for a materially different product, a separate 505(b)(2) application.

What formulation patents could competitors design around?

A competitor may seek to avoid the patent by changing one or more technical variables:

Different suspension system

A generic developer could use a different polymer, polymer concentration, particle-size distribution, or combination of suspending agents. The challenge is preserving uniformity throughout the bottle without excessive viscosity.

Different preservative system

A competitor may use an alternative preservative or a preservative-free multidose design. Preservative changes can affect microbial control, compatibility, taste, and regulatory comparability.

Different taste-masking approach

A product could use a different sweetener, flavor, pH profile, coated drug particle, complexing agent, or particle-size strategy. Taste masking is commercially relevant because spironolactone’s bitterness can impair adherence.

Different packaging and dosing system

Unit-dose cups, prefilled oral syringes, single-use sachets, or an enteral-compatible container could create a differentiated product. Packaging changes may support a 505(b)(2) strategy or a line extension, but they do not automatically avoid a composition patent.

Different concentration

A 25 mg/5 mL product is a central commercial configuration. A 10 mg/mL or lower-concentration suspension could target different dosing patterns, but concentration changes must satisfy clinical, labeling, bioequivalence, and patent requirements.

The strongest design-around opportunities are likely to involve a different excipient architecture combined with independently demonstrated dose uniformity and stability. Ingredient substitution alone may not avoid claims drafted around functional or concentration ranges.

How strong is the CaroSpir patent estate?

CaroSpir’s estate appears concentrated rather than broad. The commercial product is protected primarily by formulation-specific intellectual property, not by a large network of active-ingredient, method-of-use, device, and manufacturing patents.

Strength factor	Assessment
Active ingredient protection	Weak because spironolactone is an old molecule
Dosage-form differentiation	Meaningful because the product is an approved oral suspension
Formulation patent	Central asset; strength depends on claim breadth and validity
Manufacturing know-how	Potentially important but largely confidential
Method-of-use patents	Limited strategic value unless claims are specifically listed and enforceable
Device and packaging protection	Possible secondary protection
Regulatory exclusivity	Short relative to the patent term
Generic design-around risk	Material because suspension technology can be modified

The manufacturing process may be a more durable practical barrier than the public patent estate. Critical know-how can include milling conditions, dispersion sequence, hold times, homogenization parameters, microbial-control strategy, and bottle-fill behavior. Trade-secret protection does not stop independent development, but it increases development cost and time.

What commercial opportunities exist for CaroSpir and competing products?

Pediatric and geriatric formulations

Liquid spironolactone has a direct use case in patients who cannot swallow tablets. Improved oral syringes, lower-volume dosing, flavor variants, and unit-dose packaging could expand institutional and specialty-pharmacy use.

Hospital and long-term-care contracts

Hospitals, skilled-nursing facilities, and long-term-care pharmacies may value a standardized liquid over pharmacy compounding. Contracting opportunities depend on reimbursement, supply reliability, barcode compatibility, and storage requirements.

Enteral administration

A formulation validated for feeding-tube administration could differentiate a product if it demonstrates consistent delivery, minimal tube adsorption, and low clogging risk. These claims require product-specific testing and should not be inferred from oral administration data.

International licensing

CaroSpir’s formulation platform could support licensing in markets where compounded liquids are common and pediatric heart-failure or nephrology use is significant. Geographic value depends on local patent filings, regulatory exclusivity, pediatric labeling, and the availability of generic tablets.

Reformulated line extensions

Potential line extensions include alternate concentrations, preservative-reduced products, unit-dose presentations, and combination packaging with oral syringes. Each option must be screened against patent claims, FDA requirements, stability data, and reimbursement economics.

How does CaroSpir compare with compounded spironolactone suspensions?

Attribute	CaroSpir	Compounded spironolactone suspension
FDA-approved commercial product	Yes	Usually no, depending on preparation
Dose uniformity	Validated by manufacturer	Depends on pharmacy process
Stability	Product-specific labeled data	Depends on formulation and beyond-use dating
Excipients	Fixed and controlled	Can be customized
Flavor customization	Limited	Often possible
Supply	Commercial distribution	Local or regional
Regulatory consistency	Higher	Variable
Cost	Often higher than tablets	Variable
Patent exposure	Directly tied to branded formulation	Depends on preparation and use

Compounding remains a competitive substitute where access, customization, or price outweighs the value of an FDA-approved product.

What generic launch scenarios exist for CaroSpir?

Three launch scenarios are commercially plausible.

Early negotiated entry

An ANDA sponsor settles patent litigation and receives a launch date before the listed patent expiry. The brand may retain some volume if the generic is limited to selected channels or strengths.

Post-patent launch

A generic launches after expiry or successful invalidity litigation. Price erosion would likely be rapid because spironolactone tablets are widely available and the active ingredient is mature.

Multiple formulation competitors

Several suspension applicants reach approval after the first generic establishes therapeutic equivalence. This scenario would increase pharmacy substitution and place pressure on brand net price, distributor fees, and formulary access.

The first approved generic would have a meaningful commercial advantage if it obtains 180-day exclusivity after a qualifying Paragraph IV challenge. The value of that position depends on whether the generic is the first applicant entitled to exclusivity and whether other regulatory barriers remain.

What revenue exposure does CaroSpir create?

CaroSpir revenue is exposed to substitution at three levels:

1. Tablet substitution for patients who can swallow solid dosage forms.
2. Pharmacy-compounded liquid substitution for patients requiring a suspension.
3. ANDA substitution after generic oral-suspension approval.

The highest-value segments are likely patients with persistent liquid-dose requirements, institutional accounts, and prescribers who prefer an FDA-approved formulation. The most price-sensitive segment is routine adult use where tablets are clinically adequate.

Revenue protection depends on the share of prescriptions tied to swallowing impairment, pediatric dosing, enteral use, or institutional protocols. A brand strategy focused only on the active ingredient would have limited defensibility. A strategy built around documented formulation performance, supply reliability, dosing devices, and payer coverage is stronger.

Key Takeaways

• CaroSpir is a 25 mg/5 mL spironolactone oral suspension approved under NDA 209922.
• Its commercial differentiation comes from liquid delivery, dose flexibility, palatability, and replacement of extemporaneous compounding.
• The formulation uses excipients for suspension control, taste masking, preservation, buffering, and mouthfeel.
• U.S. Patent No. 9,566,216 is the principal publicly associated formulation patent, with protection extending into 2033 subject to official term calculations.
• Regulatory exclusivity is shorter than the patent term and does not provide long-term protection by itself.
• Generic entry would occur through an ANDA, not a biosimilar application.
• The most credible generic threat is a technically distinct suspension that maintains dose uniformity and avoids the patent claims.
• Manufacturing know-how may be as important as the published patent because process variables strongly affect suspension quality.
• The strongest commercial opportunities are pediatric, geriatric, long-term-care, hospital, and enteral-administration segments.
• Revenue exposure will increase substantially once an approved generic oral suspension reaches pharmacy substitution channels.

FAQs About CaroSpir Excipient and Patent Strategy

Can a generic use the same CaroSpir excipients?

Yes, but using the same excipient combination may increase infringement risk if the relevant patent claims cover that composition. An ANDA applicant may instead select a different suspension, preservative, flavor, or buffering system.

Is CaroSpir interchangeable with spironolactone tablets?

The active ingredient is the same, but the dosage form and dosing instructions differ. Therapeutic substitution depends on the prescribed dose, patient swallowing ability, formulation availability, and the product’s FDA therapeutic-equivalence status.

Does CaroSpir have pediatric exclusivity?

Pediatric exclusivity is not established solely by the product’s liquid dosage form. It requires a qualifying FDA written-request study program and an applicable exclusivity determination.

Can a 505(b)(2) applicant compete with CaroSpir?

Yes. A 505(b)(2) application could support a materially different formulation, concentration, delivery device, or clinical-use profile. The applicant would still need to address listed patents and establish safety, efficacy, quality, and performance.

What is the most defensible commercial feature of CaroSpir?

The most defensible feature is the integrated product package: suspension performance, taste, dose uniformity, validated stability, packaging, and FDA-approved labeling. Any one excipient is generally easier to replace than the complete formulation and manufacturing system.

References

1. U.S. Food and Drug Administration. (2017). CaroSpir (spironolactone) oral suspension: Prescribing information.
2. United States Patent and Trademark Office. (2017). U.S. Patent No. 9,566,216: Spironolactone oral suspension.
3. U.S. Food and Drug Administration. (2024). New drug application exclusivity provisions under the Federal Food, Drug, and Cosmetic Act.
4. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations.
5. U.S. Food and Drug Administration. (2024). Abbreviated new drug application submissions: Patent certifications and 30-month stays.