List of Excipients in Branded Drug KERYDIN

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
PharmaDerm A division of Fougera Pharmaceuticals Inc	KERYDIN	tavaborole	10337-905	ALCOHOL
PharmaDerm A division of Fougera Pharmaceuticals Inc	KERYDIN	tavaborole	10337-905	EDETATE CALCIUM DISODIUM
PharmaDerm A division of Fougera Pharmaceuticals Inc	KERYDIN	tavaborole	10337-905	PROPYLENE GLYCOL

Kerydin Excipient Strategy, Formulation Patents, and Commercial Opportunities

Last updated: August 7, 2026

Kerydin is a 5% tavaborole topical solution for onychomycosis. Its formulation uses a simple volatile-solvent system comprising alcohol, propylene glycol, and ethyl acetate. The main commercial opportunity is not a conventional new chemical entity strategy. It is a delivery, packaging, adherence, and lifecycle-management strategy built around improving nail penetration, reducing solvent-related drawbacks, and creating differentiated products that may avoid direct pharmaceutical equivalence to the reference product. The U.S. product received FDA approval in 2014 and is administered once daily for 48 weeks. [1]

What is Kerydin and how is its formulation designed?

Kerydin contains tavaborole at a concentration of 5% in a nonaqueous topical solution. Tavaborole is a boron-containing small molecule that inhibits fungal leucyl-tRNA synthetase. The product is applied to the affected toenail, adjacent skin, and nail folds once daily.

Attribute	Kerydin
Active ingredient	Tavaborole
Strength	5%
Dosage form	Topical solution
Approved indication	Onychomycosis of toenails caused by susceptible fungi
Administration	Once daily for 48 weeks
Original U.S. sponsor	Anacor Pharmaceuticals
FDA approval	July 2014
Current commercial rights	Commercial ownership and distribution have changed following Anacor’s acquisition by Pfizer and subsequent portfolio transactions
Reference product status	FDA-approved reference listed drug
Primary competitive products	Jublia, Penlac, oral terbinafine, compounded antifungal solutions

The labeled inactive ingredients are alcohol, propylene glycol, and ethyl acetate. [1,2] The formulation is designed to maintain tavaborole in solution, spread across the nail plate, evaporate after application, and support transport through the highly keratinized nail structure.

What does each Kerydin excipient do?

Excipient	Likely formulation function	Commercial significance
Alcohol	Primary solvent and volatile vehicle	Improves wetting and rapid drying but creates flammability and irritation considerations
Propylene glycol	Cosolvent, humectant, and solvent-strength modifier	Supports solubility and residue control; may affect irritation and nail hydration
Ethyl acetate	Volatile solvent and spreading aid	Promotes evaporation and may improve film formation, but raises odor and flammability concerns

Kerydin’s solvent system is commercially important because tavaborole must reach the nail plate and underlying infected tissue without relying on an occlusive cream or lacquer film. The product is therefore closer to a rapidly drying solution than to a conventional emulsion.

What excipient opportunities exist for Kerydin competitors?

The strongest opportunities involve maintaining tavaborole solubility while improving patient handling and nail delivery.

Low-water or anhydrous solvent systems

Anhydrous systems can reduce hydrolysis and microbial-growth concerns. Candidate approaches include:

• Ethanol or isopropanol substitution;
• Propylene glycol and polyethylene glycol blends;
• Diethylene glycol monoethyl ether, subject to regulatory acceptability;
• Glycol ethers or ester solvents with improved nail wetting;
• Mixed solvent systems that reduce ethyl acetate odor.

A substitute solvent cannot be selected solely on solubility. The formulation must also address nail penetration, drying time, residue, irritation, container compatibility, and dose reproducibility.

Film-forming systems

A controlled film may increase residence time on the nail and reduce loss from footwear, washing, and abrasion. Potential film-formers include acrylate copolymers, cellulose derivatives, polyvinylpyrrolidone, and selected methacrylate polymers.

The commercial tradeoff is material. A film can improve retention but may reduce penetration if it dries too quickly or forms a dense barrier. It can also create a cosmetic disadvantage if the nail becomes visibly coated or requires periodic removal.

Penetration-enhancing systems

The nail plate is a dense keratin matrix. Candidate enhancers include urea, thiol-containing compounds, selected fatty acids, surfactants, and glycol-based systems. A penetration enhancer must be evaluated against irritation, sensitization, nail brittleness, and the risk of changing tavaborole exposure.

A product that demonstrates improved antifungal activity in an ex vivo nail model may still fail commercially if it causes burning, erythema, or unacceptable drying.

Reduced-odor and low-flammability formulations

Ethyl acetate and alcohol can generate odor and flammability concerns. A low-odor formulation could support adherence, particularly for long treatment courses. A lower-flammability system may improve shipping, storage, and pharmacy handling.

These changes create regulatory risk if the substitute solvent alters drug release or nail penetration. A formulation with less volatile solvent may remain wet longer and increase transfer to socks, bedding, or surrounding skin.

What formulations are protected by Kerydin-related patents?

Kerydin’s intellectual-property position is broader than the active ingredient alone. The underlying estate has included tavaborole composition, pharmaceutical formulation, and therapeutic-use claims. The relevant claim categories generally include:

1. Tavaborole and related oxaborole compounds;
2. Topical treatment of fungal nail infections;
3. Concentrated tavaborole solutions;
4. Solvent systems that maintain tavaborole in solution;
5. Administration regimens for infected toenails;
6. Formulation and delivery methods directed to nail penetration.

The principal U.S. patent family associated with tavaborole includes U.S. Patent No. 8,669,102, along with related patents and continuations covering oxaborole compounds and uses. Patent scope and enforceability depend on the specific claims, prosecution history, terminal disclaimers, patent-term adjustment, and Orange Book listing status.

The commercial importance of formulation patents is greater than the number of listed patents suggests. A broad composition claim can block a close substitute, while a narrow solvent claim may be avoided through a different excipient system. A competitor using the same 5% tavaborole concentration but a materially different vehicle would need a claim-by-claim freedom-to-operate analysis.

How strong is the Kerydin patent estate?

The estate is strongest where three elements overlap:

• Tavaborole as the active ingredient;
• A topical solution suitable for nail application;
• A solvent system that provides adequate drug loading and delivery.

It is weaker against products that use a different concentration, a different solvent system, a film-forming matrix, or a delivery device, unless the relevant patent claims are drafted broadly enough to capture those alternatives.

The greatest design-around risk is a formulation that preserves tavaborole’s chemical identity but changes the vehicle. A competitor may reduce infringement exposure by using a nonidentical cosolvent system, a distinct polymeric film, or a different package and applicator.

When does Kerydin lose exclusivity?

Kerydin’s regulatory exclusivity period expired years ago. The remaining commercial protection has depended primarily on patents, market position, manufacturing know-how, trademarks, and the practical difficulty of demonstrating pharmaceutical equivalence for a topical nail product.

Protection type	Kerydin position
New chemical entity exclusivity	Expired
FDA approval	2014 approval remains the reference product approval
Orphan-drug exclusivity	Not applicable
Pediatric exclusivity	No major pediatric extension is generally associated with the product
Patent protection	Depends on listed patents, expiration dates, and claim scope
Trademark protection	Kerydin name protection is separate from product patent protection
Generic substitution	Depends on FDA approval, therapeutic equivalence, and state substitution rules

The Orange Book is the controlling source for current listed patents and expiration information. [3] Patent expiration should not be inferred solely from the original filing date because patent-term adjustment, terminal disclaimers, and continuation practice can change the effective date.

What is the Orange Book status of Kerydin?

Kerydin is listed in FDA’s Approved Drug Products with Therapeutic Equivalence Evaluations, commonly called the Orange Book. The listing identifies tavaborole topical solution, 5%, as the reference product against which an abbreviated new drug application may be evaluated. [3]

For a generic applicant, the principal regulatory route is an ANDA supported by a Paragraph IV certification if the applicant contends that a listed patent is invalid, unenforceable, or not infringed. A Paragraph IV certification can trigger patent litigation under the Hatch-Waxman framework and may create a 30-month stay of approval if the patent holder sues within the statutory period.

Topical nail products can create additional ANDA complexity because the applicant must establish sameness or acceptable equivalence in formulation, strength, dosage form, route, and performance. The FDA may require comparative characterization beyond simple chemical identity, particularly where the vehicle affects drying, film formation, or delivery.

Which companies are challenging Kerydin?

Publicly identifiable generic competition should be evaluated through FDA’s Orange Book, Drugs@FDA, and ANDA-related litigation records rather than through product rumors or third-party generic databases. A generic company may challenge Kerydin through:

• A Paragraph IV ANDA;
• A Paragraph III certification accepting patent delay;
• A Section viii statement carving out a patented method of use;
• A 505(b)(2) application using a modified formulation;
• A license or authorized-generic arrangement.

The most commercially credible challengers are companies with established topical manufacturing, solvent-handling capabilities, and experience with semi-solid or complex topical ANDAs. A company with only oral-solid-dose capabilities would face a higher technical barrier because of nail penetration and product-performance requirements.

What patent litigation affects Kerydin?

Kerydin litigation risk has three principal components:

Hatch-Waxman litigation

An ANDA filer could challenge listed patents through a Paragraph IV certification. The likely disputes would involve:

• Whether a generic vehicle falls within formulation claims;
• Whether the product meets method-of-use claims;
• Whether continuation patents remain enforceable;
• Whether claim scope covers a different concentration or delivery format;
• Whether the patent is invalid for obviousness or inadequate written description.

Formulation-infringement litigation

A close copy using alcohol, propylene glycol, and ethyl acetate would present greater infringement risk than a product using a substantially different vehicle. Solvent substitution is therefore a central design-around strategy.

Trademark and trade-dress disputes

A generic applicant cannot copy Kerydin’s trade dress or branding. Bottle shape, applicator design, labeling, and color may create separate trademark or unfair-competition issues even after patent expiry.

No settlement agreement should be assumed without a public court docket, SEC filing, FDA approval record, or company disclosure. Settlement terms can affect the first launch date, authorized-generic rights, and licensing economics.

What FDA regulatory status and development pathway apply to a Kerydin follow-on?

A direct generic would normally pursue an ANDA. A materially different formulation may require a 505(b)(2) pathway if it cannot satisfy ANDA sameness or equivalence requirements.

Development option	Best use case	Main risk
ANDA	Same active ingredient, strength, dosage form, route, and sufficiently comparable formulation	Demonstrating topical equivalence and avoiding listed patents
505(b)(2)	New vehicle, film, applicator, concentration, or dosing approach	More clinical and regulatory work
Cosmetic or device-led adjunct	Nail preparation, debridement, or adherence support	Cannot make unapproved antifungal drug claims
Combination product	Tavaborole plus another active or delivery system	Combination-product and clinical-efficacy burden

FDA’s Inactive Ingredient Database can support early excipient screening, but prior use of an excipient in an approved product does not automatically establish acceptability at a new concentration, route, or exposure level. [4]

What commercial opportunities exist beyond a Kerydin generic?

The highest-value opportunities are differentiated products rather than undifferentiated solvent copies.

Premium adherence product

A low-odor, fast-drying product with an integrated applicator could command a premium if it reduces missed doses. Treatment lasts 48 weeks, so application convenience has commercial value.

Improved nail-penetration product

A formulation with measured improvement in tavaborole delivery through human nail plates could support a 505(b)(2) strategy, subject to clinical validation.

Pediatric and geriatric packaging

Although onychomycosis is more prevalent in adults, dexterity limitations among older patients create demand for ergonomic packaging. A controlled-dose brush, pen, or metered applicator could reduce spills and improve dosing consistency.

Combination treatment

A tavaborole product paired with mechanical nail debridement, urea pretreatment, or a separate keratolytic regimen could target patients with thickened nails. The regulatory strategy would need to separate drug claims from device or procedural claims.

International licensing

The United States is only one market. Licensing opportunities may exist in Europe, Japan, Canada, Latin America, and selected Asian markets where topical antifungal penetration, prescription access, and local manufacturing economics differ. Geographic freedom to operate must be reviewed separately because U.S. patent status does not determine foreign rights.

What manufacturing and IP barriers affect Kerydin competitors?

Manufacturing is relatively simple compared with a biologic, but it is not barrier-free. A viable producer must control:

• Tavaborole solubility during manufacture and storage;
• Solvent evaporation during filling;
• Bottle and closure compatibility;
• Applicator dose consistency;
• Flammability controls;
• Microbial and particulate specifications;
• Long-term stability;
• Extractables and leachables;
• Scale-up under current good manufacturing practice.

The package is part of the product. Alcohol and ethyl acetate can interact with plastics, elastomers, adhesives, and coatings. A formulation that passes laboratory stability testing may fail in the commercial container because of solvent loss or component extraction.

How does Kerydin compare with Jublia and Penlac?

Product	Active ingredient	Dosage form	Key formulation issue	Commercial position
Kerydin	Tavaborole 5%	Topical solution	Volatile solvent system and nail penetration	Differentiated oxaborole mechanism
Jublia	Efinaconazole 10%	Topical solution	Low-surface-tension delivery and nail penetration	Major branded topical competitor
Penlac	Ciclopirox 8%	Nail lacquer	Film formation and periodic removal	Older lacquer-based approach
Oral terbinafine	Terbinafine	Oral tablet	Systemic exposure and monitoring considerations	Higher efficacy in many patients, but greater systemic burden

Kerydin’s principal formulation advantage is the absence of a conventional lacquer-removal cycle. Its principal commercial weakness is the long daily treatment period and the difficulty of achieving high cure rates in thick or severely dystrophic nails.

What is the revenue exposure for Kerydin?

Kerydin revenue is exposed to four factors:

1. Generic entry after relevant patent barriers fall;
2. Physician preference relative to Jublia and oral terbinafine;
3. Reimbursement and patient copay levels;
4. Adherence over the 48-week regimen.

Standalone Kerydin sales are not consistently disclosed in public company reporting. Portfolio-level disclosures are therefore more useful than attempting to assign a precise current revenue figure. The product’s economic value lies in prescription volume, gross-to-net pricing, and its ability to retain patients who cannot or will not use oral terbinafine.

Key Takeaways

• Kerydin is a 5% tavaborole topical solution using alcohol, propylene glycol, and ethyl acetate.
• The core excipient opportunity is a lower-odor, lower-flammability, better-retaining vehicle.
• Film-forming and penetration-enhancing formulations may support differentiated 505(b)(2) products.
• An ANDA competitor must address both patent claims and topical-equivalence requirements.
• The Orange Book, FDA labeling, and current patent records control the relevant exclusivity analysis.
• Packaging and solvent compatibility are material manufacturing barriers.
• Commercial differentiation is more likely through adherence, applicator design, and nail delivery than through a simple excipient substitution.
• Kerydin competes mainly with Jublia, Penlac, and oral terbinafine.
• Public disclosures do not consistently provide standalone Kerydin revenue.
• Patent and regulatory diligence should treat the formulation, package, and delivery method as one commercial system.

FAQs About Kerydin Excipient and Commercial Strategy

Can propylene glycol be replaced in a Kerydin generic?

Yes, but the replacement must preserve tavaborole solubility, stability, drying behavior, nail delivery, and patient tolerability. A change may also affect ANDA eligibility and patent exposure.

Is Kerydin an alcohol-based nail lacquer?

No. Kerydin is labeled as a topical solution. It does not use the conventional lacquer-removal cycle associated with ciclopirox nail lacquer.

Can a company sell a tavaborole product with a different concentration?

A different concentration may require a 505(b)(2) application rather than an ANDA. It may also fall outside or inside different patent claims depending on the wording of the relevant patents.

Does a new applicator create a separate Kerydin commercial opportunity?

Yes. A metered applicator, pen, or controlled brush can improve dose consistency and adherence. The device must remain compatible with volatile solvents and must not create a combination-product issue without an appropriate regulatory strategy.

Are Kerydin excipients protected independently from tavaborole?

They can be. Patent claims may cover particular solvent combinations, concentrations, manufacturing processes, or delivery systems. The existence and enforceability of those rights depend on the issued claims and current patent status.

References

1. U.S. Food and Drug Administration. (2014). Kerydin (tavaborole) topical solution, 5%: Prescribing information. Anacor Pharmaceuticals, Inc.

2. National Library of Medicine. (n.d.). DailyMed: Kerydin-tavaborole solution. U.S. National Library of Medicine.

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

4. U.S. Food and Drug Administration. (n.d.). Inactive Ingredient Database. Center for Drug Evaluation and Research.

5. U.S. Patent and Trademark Office. (2013). U.S. Patent No. 8,669,102: Oxaborole compounds and uses thereof. Washington, DC.