Drugs in ATC Class D01BA

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Drugs in ATC Class: D01BA - Antifungals for systemic use

Tradename	Generic Name
GRISACTIN	griseofulvin, microcrystalline
GRIFULVIN V	griseofulvin, microcrystalline
GRIFULVIN V	griseofulvin, microsize

D01BA Systemic Antifungals Market Dynamics and Patent Landscape

Last updated: August 1, 2026

ATC Class D01BA contains systemic antifungals used primarily for dermatophyte infections. The class is commercially mature and dominated by generic oral terbinafine and griseofulvin. Core composition-of-matter, regulatory, and primary formulation patents for both products have expired. Current market access depends mainly on generic manufacturing economics, bioequivalence, supply reliability, physician preference, and lifecycle formulations rather than blocking patent rights. Biosimilar exposure is not relevant because D01BA products are conventional small-molecule drugs.[1][2]

What drugs are included in ATC Class D01BA?

D01BA is the World Health Organization ATC category for antifungals for systemic use. The principal active ingredients are griseofulvin and terbinafine.

ATC code	Active ingredient	Principal systemic dosage form	Main clinical use	Market status
D01BA01	Griseofulvin	Oral tablet, capsule, or suspension	Dermatophyte infections, including tinea capitis	Mature generic
D01BA02	Terbinafine	Oral tablet	Onychomycosis and dermatophyte infections	Mature generic

Griseofulvin is fungistatic and has historically been used for scalp, skin, and nail dermatophyte infections. Terbinafine inhibits squalene epoxidase and generally has higher activity against dermatophytes, particularly in nail disease. Oral terbinafine is commonly used for onychomycosis and tinea infections when topical therapy is inadequate.[3][4]

Other systemic antifungals, including itraconazole, fluconazole, ketoconazole, posaconazole, voriconazole, and amphotericin B, are classified in other ATC categories or therapeutic groupings. They compete clinically with D01BA products in selected indications but are not members of D01BA.

When did systemic antifungal patents expire?

The foundational patent estates for griseofulvin and terbinafine expired decades ago. No active United States composition-of-matter patent is generally recognized as blocking generic oral terbinafine or griseofulvin entry.

Griseofulvin patent timeline

Griseofulvin was discovered in the 1930s and commercialized as an oral antifungal in the mid-20th century. Its original patents and early product protections expired long before the modern generic-drug framework. United States products historically included Gris-PEG and microsize or ultramicrosize formulations.

Current competitive protection is not based on the griseofulvin molecule. Possible residual rights may relate to specific excipient systems, manufacturing processes, trademarks, or product presentations. Those rights do not normally prevent manufacture of a therapeutically equivalent generic product using a different formulation.

Terbinafine patent timeline

Terbinafine was developed by Novartis and commercialized in the United States as Lamisil. The FDA approved oral Lamisil tablets for onychomycosis and related dermatophyte infections in the 1990s.[5]

The principal terbinafine hydrochloride compound patent, original oral-product patents, and ordinary regulatory exclusivity periods have expired. FDA approval of generic terbinafine hydrochloride tablets established a broad multisource market. Generic applicants generally relied on abbreviated new drug applications rather than patent-protected innovation products.[1]

A simplified exclusivity timeline is:

Milestone	Griseofulvin	Terbinafine
Original small-molecule development	1930s-1950s	1970s-1990s
Original U.S. branded launch	Mid-20th century	1990s
Core compound patent status	Expired	Expired
Original U.S. regulatory exclusivity	Expired	Expired
Current generic entry barrier	Low	Low
Biosimilar pathway relevance	None	None

Patent term adjustments, pediatric extensions, and country-specific rights can alter an individual historical patent date. They do not change the present commercial conclusion for standard oral products.

What is the Orange Book status of D01BA products?

The FDA Orange Book lists approved drug products and certain patent and exclusivity information for eligible products. Standard generic terbinafine tablets and griseofulvin products are approved through the ANDA pathway or older abbreviated pathways. The original branded products do not have commercially meaningful active core patent protection remaining for ordinary oral generic entry.[1]

Orange Book analysis should distinguish three categories:

1. Approved generic products. These have therapeutic-equivalence codes and compete directly on price and supply.
2. Branded reference products. These may retain trademarks or limited commercial value without an enforceable patent barrier.
3. Reformulated or specialty presentations. These can have separate patents, but their claims may not cover ordinary generic tablets or capsules.

For D01BA, the Orange Book is more relevant for confirming product status and therapeutic equivalence than for identifying a current patent cliff. The main patent cliff occurred before the present generic market structure.

How many patents cover systemic terbinafine and griseofulvin?

The number of historical patents is substantial, but the number of enforceable patents that can block a standard generic D01BA product is effectively zero for the core oral products in the United States.

Patent families historically covered:

• The active chemical compound.
• Salts, including terbinafine hydrochloride.
• Crystal forms and polymorphs.
• Oral tablets and capsules.
• Granulation and coating methods.
• Particle-size control.
• Treatment of nail and skin infections.
• Pediatric dosage forms.
• Suspension and liquid formulations.
• Topical terbinafine products.

Expired compound and product patents remain commercially relevant for freedom-to-operate history, patent litigation analysis, and patent-term benchmarking. They do not generally support an exclusivity premium today.

The most relevant live-rights risk would arise from a later-filed patent on a narrowly defined formulation, manufacturing process, or method of use. Such a patent would need claims that are valid, enforceable, and commercially unavoidable. Generic manufacturers can often avoid infringement by using a different excipient system, process, dosage strength, or label.

What formulations are protected in the D01BA market?

The commercial D01BA market is concentrated in conventional oral dosage forms. Formulation differentiation has limited value because the active ingredients are old and physicians can prescribe inexpensive alternatives.

Griseofulvin formulations

Griseofulvin has been marketed in microsize and ultramicrosize forms. These approaches seek to improve dissolution and absorption. Liquid suspensions and pediatric presentations may have separate formulation and manufacturing considerations.

Potential formulation claims can cover:

• Particle size.
• Solid dispersion systems.
• Suspension stability.
• Taste masking.
• Tablet compression.
• Bioavailability enhancement.

Most formulation concepts associated with legacy griseofulvin products are expired or readily designed around. The principal barriers are manufacturing consistency and product registration, not exclusionary patent rights.

Terbinafine formulations

Generic oral terbinafine is commonly supplied as 250 mg tablets. Potential lifecycle products include:

• Modified-release tablets.
• Pediatric liquid formulations.
• Taste-masked suspensions.
• Combination antifungal products.
• Nail-targeted delivery systems.
• Transdermal or localized delivery systems.

A new formulation could receive patent protection if it provides a credible technical advantage and satisfies novelty and non-obviousness requirements. A formulation patent would usually protect only the specified delivery system, not generic terbinafine tablets as a whole.

Are there method-of-use patents for oral terbinafine?

Method-of-use patents for standard oral terbinafine treatment are unlikely to create a meaningful current barrier because the principal indications, including onychomycosis and dermatophyte infections, were disclosed and clinically established decades ago.

Historically relevant use claims could include:

• Treatment duration.
• Pulse dosing.
• Specific nail-infection regimens.
• Combination treatment with topical antifungals.
• Treatment of selected dermatophyte species.
• Pediatric or geriatric dosing.

Under the Hatch-Waxman framework, a generic applicant may use a section viii statement to omit a patented indication from its label where the remaining label supports approval. This mechanism reduces the risk that a narrow method-of-use patent will block the entire product.[6]

Which companies compete in the systemic antifungal market?

The D01BA market is fragmented among generic manufacturers and distributors. The former branded reference products are less important than the generic supply base.

Representative market participants have included:

• Novartis, historically associated with Lamisil.
• Apotex.
• Teva Pharmaceuticals.
• Mylan, now part of Viatris.
• Sandoz.
• Cipla.
• Dr. Reddy's Laboratories.
• Amneal Pharmaceuticals.
• Zydus Pharmaceuticals.
• Various regional manufacturers and private-label suppliers.

The active manufacturer list varies by country and changes as ANDAs are withdrawn, transferred, or discontinued. Purchasing organizations often prioritize the lowest landed cost and dual-source supply. This creates limited pricing power for any single supplier unless it has a manufacturing or quality advantage.

Which companies are challenging D01BA exclusivity?

The relevant challengers are generic-drug applicants rather than biosimilar developers. Because the core patents and regulatory exclusivities have expired, current entry usually occurs without a commercially significant Paragraph IV dispute.

A Paragraph IV certification states that a listed patent is invalid, unenforceable, or not infringed. It can trigger patent litigation and, in some cases, a 30-month stay of FDA approval under the Hatch-Waxman Act.[6] For mature oral terbinafine and griseofulvin products, the practical importance of Paragraph IV litigation is low because applicants can often rely on patent expiration, non-infringement, or the absence of relevant listed patents.

A later-formulated product could create a new Paragraph IV event if its reference product has active Orange Book-listed patents. That scenario would apply to a specific reformulation, not to the established D01BA molecules generally.

What patent litigation affects systemic antifungals?

There is no broad, current patent litigation risk comparable to active oncology, immunology, or rare-disease products. Historical Lamisil-related disputes centered on generic entry, formulation rights, and product patents. Those disputes have largely lost commercial force as the relevant patents expired.

Current litigation exposure is more likely to involve:

• Product liability.
• Manufacturing quality.
• Trademark or trade dress.
• Distribution contracts.
• Regulatory compliance.
• Drug shortages and allocation disputes.
• Patents covering a new delivery system.

A patent clearance review should examine United States, European, Canadian, Japanese, and emerging-market records separately. Patent expiry is jurisdiction-specific, and a company may face process or formulation claims in one country even when the active ingredient is unprotected elsewhere.

How strong is the D01BA patent estate?

The patent estate is weak for standard oral products and potentially moderate for new delivery technologies.

Patent category	Current strength for generic oral products	Commercial effect
Core compound patents	None for standard products	No barrier
Salt patents	Generally expired	No material barrier
Conventional tablet patents	Generally expired	No material barrier
Method-of-use patents	Limited and often avoidable	Narrow label risk
Pediatric liquids	Product-specific	Possible niche protection
Modified-release systems	Depends on claim scope	Potential lifecycle value
Manufacturing patents	Process-specific	Can affect selected suppliers
Device or localized delivery patents	Potentially meaningful	Relevant to new products

Patent strength depends on claim breadth, remaining term, validity under obviousness standards, enablement, written description, and whether manufacturers can design around the claims. For legacy D01BA tablets, these factors favor generic competition.

What generic entry risks exist for branded or reformulated products?

Generic entry risk is high for conventional oral terbinafine and griseofulvin. A new branded product would need protection beyond the active ingredient.

The principal generic-entry scenarios are:

1. Immediate multisource competition after approval if no enforceable patent is listed.
2. Paragraph IV filing against a formulation or method patent.
3. Delayed launch caused by patent litigation.
4. At-risk launch after a favorable invalidity or non-infringement position.
5. Restricted launch using a label that omits a patented indication.
6. Authorized-generic competition from the branded sponsor or licensee.

Revenue durability is therefore limited unless a product has a differentiated dosage form, a specialized patient population, or a delivery technology that improves adherence or tolerability.

What is the commercial outlook for D01BA antifungals?

D01BA is a low-growth, price-sensitive market. Demand is recurring because fungal skin and nail infections are common, but product value is constrained by:

• Low-cost generic substitution.
• Short treatment courses for many skin infections.
• Availability of topical therapies.
• Physician monitoring requirements for oral therapy.
• Competition from itraconazole and other systemic agents in selected indications.
• Limited brand loyalty.
• Weak patent protection.

Terbinafine retains strong clinical relevance in dermatophyte infections and onychomycosis. Griseofulvin remains useful in selected pediatric and scalp infections, particularly where clinical experience and pathogen sensitivity support its use. Product volume can remain stable even when revenue declines because price competition transfers value from manufacturers to payers and pharmacies.

Revenue exposure

Branded revenue exposure is low for the legacy products. The largest commercial risks affect companies relying on:

• Premium pricing for branded oral tablets.
• Single-source manufacturing.
• A narrow distributor network.
• High-margin private-label contracts.
• A reformulation without enforceable differentiation.
• Regulatory exclusivity that has already expired.

Generic suppliers can achieve acceptable returns through scale, reliable supply, low manufacturing costs, and regulatory execution. A small manufacturer with limited capacity is exposed to price erosion and supply interruptions.

Do licensing deals affect the D01BA market?

Licensing is more relevant to distribution, geographic commercialization, and new formulations than to the original molecules. Historical branded rights involved development and commercialization arrangements associated with terbinafine. Current transactions are more likely to concern:

• Regional marketing rights.
• Private-label supply.
• Contract manufacturing.
• Authorized generics.
• Combination products.
• Novel delivery systems.

A license covering ordinary terbinafine or griseofulvin tablets is unlikely to create durable exclusivity unless it is paired with a protected formulation, brand, channel, or geographic right.

What geographic patent coverage remains relevant?

Patent risk differs by jurisdiction.

Region	Standard oral D01BA patent position	Main commercial issue
United States	Core patents expired; generic market established	ANDA status, supply, product quality
European Union	Core patents expired; national enforcement largely historic	Tender pricing and local registrations
Japan	Mature generic market	Local approval and reimbursement
China	Core molecule mature; local process and formulation rights may differ	Domestic manufacturing and price controls
India	Mature generic manufacturing base	Process patents and export markets
Latin America	Generic availability varies by country	Registration, trademarks, and local patent records
Emerging markets	Patent and registration positions vary	Import controls and local manufacturing

International freedom-to-operate analysis must review national patent registers, supplementary protection certificates, pediatric extensions, and local data-exclusivity rules. Patent expiry in the United States does not establish freedom to launch in every market.

What manufacturing and intellectual-property barriers remain?

Manufacturing is a greater barrier than patent protection for most D01BA products. Key operational risks include:

• Active pharmaceutical ingredient qualification.
• Control of impurities and degradation products.
• Consistent particle size for griseofulvin.
• Tablet dissolution and content uniformity.
• Stability in liquid formulations.
• FDA inspection outcomes.
• Backup-site qualification.
• Supply-chain concentration.
• Bioequivalence failure.

For terbinafine, process patents may cover selected synthetic routes or impurity-control methods. A generic producer can reduce risk by using a documented alternative process, obtaining a freedom-to-operate opinion, and separating API and finished-dose manufacturing rights.

Key Takeaways

• D01BA primarily covers systemic griseofulvin and terbinafine.
• Core compound and conventional oral-product patents have expired.
• Standard oral terbinafine and griseofulvin face high generic-entry risk and low patent barriers.
• Paragraph IV litigation is not a major current constraint for legacy products.
• Formulation, pediatric, modified-release, and localized-delivery patents can create narrower protection.
• Biosimilars are irrelevant because these are small-molecule antifungals.
• Market competition is driven by generic pricing, quality, supply reliability, and regulatory execution.
• Manufacturing capability and API security are more important than legacy patent ownership.
• New commercial value requires differentiated delivery, formulation, indication, or distribution rights.

FAQs

Is oral terbinafine still patent protected?

The original terbinafine compound and conventional oral-product patents have expired. Standard generic terbinafine tablets can compete without a core patent barrier.

Is griseofulvin a generic drug?

Yes. Griseofulvin is an established generic small-molecule antifungal. Any remaining protection is generally product-specific, such as formulation, trademark, or manufacturing rights.

Can a generic company launch terbinafine without a Paragraph IV filing?

Yes. A generic applicant may rely on expired patents, the absence of relevant listed patents, or certifications that do not require a Paragraph IV challenge. The filing strategy depends on the reference product and applicable Orange Book listings.

Are there biosimilars for systemic D01BA antifungals?

No. Terbinafine and griseofulvin are chemically synthesized small molecules approved through generic-drug pathways, not biologics subject to biosimilar approval.

What could create new exclusivity in the systemic antifungal market?

Potential sources include a novel pediatric formulation, modified-release dosage form, improved nail-delivery system, combination product, new indication, or manufacturing technology with patentable technical advantages.

References

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

2. World Health Organization Collaborating Centre for Drug Statistics Methodology. (2024). ATC/DDD index: D01BA Antifungals for systemic use. https://atcddd.fhi.no/atc_ddd_index/

3. U.S. Food and Drug Administration. (2012). Lamisil tablets: Prescribing information. Novartis Pharmaceuticals Corporation.

4. U.S. Food and Drug Administration. (2023). Griseofulvin microsize and ultramicrosize products: Prescribing information. FDA drug labeling database.

5. U.S. Food and Drug Administration. (1996). Lamisil approval history and labeling. Drugs@FDA.

6. U.S. Food and Drug Administration. (2024). Abbreviated new drug application submissions: Patent certifications and exclusivity provisions. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/anda-submissions-patent-certifications-and-exclusivity