List of Excipients in Branded Drug ACZONE

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Allergan Inc	ACZONE	dapsone	0023-3670	CARBOMER HOMOPOLYMER TYPE C
Allergan Inc	ACZONE	dapsone	0023-3670	DIETHYLENE GLYCOL MONOETHYL ETHER
Allergan Inc	ACZONE	dapsone	0023-3670	METHYLPARABEN
Allergan Inc	ACZONE	dapsone	0023-3670	SODIUM HYDROXIDE
Allergan Inc	ACZONE	dapsone	0023-3670	WATER
Allergan Inc	ACZONE	dapsone	0023-5206	DIETHYLENE GLYCOL MONOETHYL ETHER
Allergan Inc	ACZONE	dapsone	0023-5206	ISOHEXADECANE

ACZONE Excipient Strategy and Commercial Opportunities in Dapsone Topical Gel

Last updated: August 2, 2026

Aczone is a topical dapsone product for acne with two FDA-approved strengths: 5% gel and 7.5% gel. Its excipient strategy is commercially relevant because the two products use different vehicles, dosing schedules, and formulation technologies. The 5% formulation relies on carbomer and diethylene glycol monoethyl ether, while the 7.5% formulation uses a polymeric emulsion system containing isohexadecane and polysorbate 80. These differences create opportunities in generic substitution, alternative topical vehicles, excipient supply, contract manufacturing, and 505(b)(2) reformulation.

The principal commercial constraint is that an ANDA product must demonstrate pharmaceutical equivalence and bioequivalence to the reference product. A reformulated product with a materially different vehicle would generally require a separate regulatory strategy rather than a conventional generic pathway.

What is Aczone and how is it regulated?

Aczone is a prescription topical gel containing dapsone, an antibacterial and anti-inflammatory sulfone used primarily for acne vulgaris. The product is marketed in the United States in two strengths:

Product	Active ingredient	FDA application	Dosing	Reference product holder
Aczone Gel 5%	Dapsone 5%	NDA 021171	Twice daily in patients aged 12 years and older	Almirall
Aczone Gel 7.5%	Dapsone 7.5%	NDA 208155	Once daily in patients aged 12 years and older	Almirall

Aczone 5% was approved in 2005. Aczone 7.5% was approved in 2015 as a once-daily formulation. The FDA labeling identifies methemoglobinemia and hemolytic anemia as important risks, particularly in patients with glucose-6-phosphate dehydrogenase deficiency. The label also warns about combined use with certain oxidizing agents and other topical products that may increase irritation or oxidative stress [1, 2].

Almirall acquired U.S. rights to Aczone from Allergan in a broader dermatology transaction. The transaction included other dermatology brands and expanded Almirall’s U.S. commercial portfolio [3].

What excipients are used in Aczone 5%?

Aczone 5% uses a relatively simple aqueous gel system. The inactive ingredients listed in the FDA label are:

Excipient	Formulation role	Commercial significance
Carbomer 980	Gelling and viscosity control	Controls spreadability, suspension behavior, and product consistency
Diethylene glycol monoethyl ether	Solvent and penetration-enhancing vehicle	Supports dapsone solubilization and delivery through the stratum corneum
Methylparaben	Preservative	Controls microbial growth in the aqueous formulation
Sodium hydroxide	pH adjustment and carbomer neutralization	Establishes gel structure and target pH
Purified water	Continuous phase	Primary vehicle component

The combination of carbomer 980 and sodium hydroxide is important. Carbomer requires neutralization to develop viscosity, so pH control affects rheology, drug dispersion, skin feel, and manufacturing reproducibility. Diethylene glycol monoethyl ether, also known as Transcutol in certain commercial contexts, provides a potential sourcing and formulation bottleneck because it is doing more than acting as an inert solvent.

A generic manufacturer cannot assume that any carbomer grade or solvent substitute will qualify as interchangeable. Differences in polymer molecular weight, residual solvents, particle size, neutralization behavior, or solvent purity can alter viscosity and drug release.

What excipients are used in Aczone 7.5%?

Aczone 7.5% uses a different vehicle platform:

Excipient	Formulation role	Commercial significance
Acrylamide/sodium acryloyldimethyl taurate copolymer	Emulsion stabilizer, thickener, and rheology modifier	Provides a smooth, structured topical vehicle
Isohexadecane	Emollient and oil-phase component	Improves spreadability and skin feel
Polysorbate 80	Surfactant and emulsifier	Stabilizes the oil-water system
Sodium hydroxide	pH adjustment	Supports formulation stability and rheology
Purified water	Aqueous phase	Continuous phase of the gel-emulsion system

The 7.5% product is not simply a higher-strength version of the 5% product. It uses a separate vehicle design and is dosed once daily. The vehicle may support higher dapsone loading, acceptable cosmetic properties, and controlled drug distribution without reproducing the 5% carbomer/diethylene glycol monoethyl ether system.

This creates two distinct generic development programs. A company pursuing both strengths must evaluate each reference product independently.

How does the Aczone 5% formulation compare with Aczone 7.5%?

The central distinction is vehicle architecture.

Attribute	Aczone 5%	Aczone 7.5%
Primary gel system	Carbomer 980	Acrylamide/sodium acryloyldimethyl taurate copolymer
Solvent or emollient strategy	Diethylene glycol monoethyl ether	Isohexadecane and polysorbate 80
Preservative listed	Methylparaben	No methylparaben listed in the FDA label
Dosing	Twice daily	Once daily
Formulation complexity	Conventional aqueous gel	Polymer-stabilized emulsion or emulsion-like system
Differentiation opportunity	Preservative, solvent, and sensory profile	Oil-phase feel, polymer system, and once-daily positioning
Generic development risk	Excipient sameness and topical bioequivalence	Vehicle reproducibility and microstructure control

The 5% product may be easier to manufacture because its vehicle has fewer components and a conventional carbomer gel structure. The 7.5% product may offer more room for sensory differentiation but presents greater process-development risk.

What formulation patents protect Aczone?

Aczone’s original patent estate centered on topical dapsone compositions, gel vehicles, and methods for treating acne. Earlier U.S. patents associated with topical dapsone formulations included patents covering compositions containing dapsone and penetration-enhancing or gel-forming excipients. The practical value of those patents has declined as the earliest patent terms expired.

The key distinction is between:

1. Composition patents covering dapsone in a specified topical vehicle.
2. Method-of-use patents covering acne treatment or dosing.
3. Formulation patents covering a particular polymer, solvent, emulsion, or concentration.
4. Manufacturing patents covering mixing, dispersion, filling, or stability controls.
5. Regulatory exclusivity and Orange Book-listed patents.

A patent covering a broad dapsone gel may not block a generic product that uses a different vehicle. Conversely, a narrow formulation patent can remain relevant if the generic deliberately reproduces the reference product’s excipient architecture.

The Orange Book, FDA patent certifications, and court dockets should be reviewed for current listed patents and Paragraph IV activity. Patent status can change through delisting, expiration, litigation, settlements, or pediatric exclusivity. Publicly reported early Aczone patents do not, by themselves, establish a current blocking position.

When did Aczone lose market exclusivity?

Aczone 5% has been commercially exposed to generic competition for several years. The original regulatory and patent barriers associated with the product were not sufficient to preserve a long-term branded monopoly after the principal patent terms expired.

Aczone 7.5% received three years of FDA exclusivity associated with the approval of a new clinical formulation and strength. That exclusivity period did not provide the same duration as five-year new chemical entity exclusivity because dapsone was an established active ingredient.

The commercial protection for Aczone therefore depends primarily on:

• The remaining term of any Orange Book-listed formulation or method patents.
• The number of approved ANDAs.
• Whether generic products have launched.
• The ability of the brand to retain prescriptions through dosing, tolerability, access, and dermatologist preference.
• The availability of authorized generic or licensed generic supply.

Which companies are challenging Aczone?

Generic dapsone gel development has attracted companies with dermatology portfolios, topical manufacturing capabilities, or established ANDA operations. Publicly visible generic activity has included products referencing dapsone gel 5%, and the FDA has approved generic versions of topical dapsone products.

The competitive set can include:

• Large generic manufacturers with topical semisolid facilities.
• Dermatology-focused companies.
• Contract development and manufacturing organizations.
• Specialty pharmaceutical companies using authorized-generic or licensed-brand arrangements.

A precise current list of Paragraph IV challengers requires review of FDA approval letters, the Orange Book, litigation dockets, and commercial launch announcements. An ANDA approval does not establish immediate commercial launch. Companies may delay launch because of settlement terms, manufacturing constraints, patent disputes, or limited expected margins.

What is the Orange Book status of Aczone?

Aczone is listed in FDA’s Approved Drug Products with Therapeutic Equivalence Evaluations, commonly called the Orange Book, under topical dapsone products. The relevant reference products are Aczone 5% Gel and Aczone 7.5% Gel.

Orange Book analysis should distinguish:

• NDA 021171 for Aczone 5%.
• NDA 208155 for Aczone 7.5%.
• Listed patents by strength and dosage form.
• Patent expiration dates.
• TE codes assigned to approved generic products.
• Any pediatric exclusivity or regulatory exclusivity notation.

Topical products can present bioequivalence issues that are more complex than oral tablets. FDA may evaluate formulation sameness, comparative drug release, pharmacodynamic response, or other product-specific evidence. The regulatory pathway can influence the commercial value of a particular excipient system.

What generic entry risks exist for Aczone?

Generic entry risk is higher for Aczone 5% than for Aczone 7.5% because the 5% product has had a longer commercial history and a more established generic development pathway.

Aczone 5% risks

The main risks are:

• Multiple approved or near-market generic products.
• Price compression among topical dermatology suppliers.
• Low switching friction at the pharmacy level when therapeutic equivalence is established.
• Availability of low-cost carbomer and solvent-based formulations.
• Limited ability to defend price through clinical differentiation.

The main technical barrier is reproducing the reference product’s physical properties while controlling dapsone content uniformity, viscosity, pH, microbial quality, drug release, and skin deposition.

Aczone 7.5% risks

The 7.5% product may have a more defensible commercial position if fewer generic competitors reproduce the vehicle and once-daily profile. Its barriers include:

• More complex emulsion or polymer microstructure.
• Greater sensitivity to mixing order and shear.
• Potential differences in droplet size and physical stability.
• Higher risk of sensory differences affecting adherence.
• More difficult scale-up and filling behavior.

Those barriers are technical rather than necessarily legal. Once an ANDA product is approved and commercially manufactured, the competitive advantage can narrow quickly.

How strong is the Aczone patent estate?

The Aczone patent estate is best characterized as mature rather than expansive. Broad early patents covering topical dapsone formulations have limited remaining value after expiration. Any residual strength is more likely to come from narrow claims directed to a specific concentration, delivery system, manufacturing process, or method of use.

Patent strength should be evaluated against five factors:

Factor	Assessment
Active ingredient protection	Weak; dapsone is an established active ingredient
Broad topical composition protection	Limited by earlier patent expiration
Vehicle-specific protection	Potentially relevant if claims remain unexpired and are listed
Method-of-use protection	Dependent on claim scope, labeling, and carve-out feasibility
Manufacturing protection	Relevant where process parameters are difficult to design around

A formulation patent is commercially stronger when it claims measurable structural or compositional parameters that generic developers must reproduce. It is weaker when the claims use broad functional language that can be avoided with a different polymer, solvent, or oil phase.

What excipient opportunities exist around Aczone?

The strongest opportunities are in vehicle substitution and supply-chain control.

Excipient supply

Suppliers can target:

• High-purity carbomer 980 or equivalent carbomer grades.
• Diethylene glycol monoethyl ether suitable for pharmaceutical topical use.
• Acrylamide/sodium acryloyldimethyl taurate copolymer.
• Isohexadecane with controlled impurity profiles.
• Polysorbate 80 with low peroxide and aldehyde levels.
• Preservative systems suitable for aqueous dermatologic gels.

Polysorbate 80 quality is particularly relevant because peroxide formation can affect oxidation-sensitive active ingredients and formulation stability. Suppliers that provide tight peroxide, acid value, water content, and impurity specifications can gain an advantage in topical development programs.

Reformulation

A 505(b)(2) sponsor could develop:

• A preservative-free dapsone gel.
• A lower-irritation vehicle.
• A foam, cream, lotion, spray, or pump-delivered formulation.
• A once-daily 5% formulation.
• A vehicle with reduced solvent odor or improved cosmetic acceptability.
• A formulation designed for sensitive or dry skin.

A reformulation would need to address dapsone stability, skin penetration, local tolerability, systemic exposure, methemoglobin risk, and clinical performance. A novel vehicle could support a differentiated label but would face higher development cost than an ANDA.

Manufacturing and contract development

Topical semisolid manufacturing creates opportunities for CDMOs with:

• Vacuum homogenization.
• Controlled polymer hydration.
• Low-shear and high-shear mixing capability.
• In-line pH and viscosity monitoring.
• Aluminum or laminate tube filling.
• Airless pump filling.
• Microbiological control and preservative-effectiveness testing.

The 7.5% formulation has greater potential for process-based differentiation because emulsion stability and polymer hydration can be sensitive to manufacturing conditions.

Can a new Aczone formulation obtain FDA approval?

Yes. A new formulation could proceed through an ANDA only if it meets the applicable pharmaceutical equivalence and bioequivalence requirements for the reference product. A materially different vehicle, dosage form, strength, or dosing regimen may require a 505(b)(2) application.

Potential 505(b)(2) products include a novel delivery system or a different topical vehicle supported by bridging studies and, where required, clinical data. The commercial benefit would be a potentially differentiated product with greater freedom from direct generic substitution. The cost is a more demanding regulatory package and possible new patent challenges.

The strongest development concept is likely a formulation that improves a commercially visible attribute without increasing systemic dapsone exposure. Candidate attributes include reduced irritation, easier application, lower residue, improved cosmetic feel, longer shelf life, or once-daily use.

What licensing deals affect Aczone?

Almirall’s acquisition of U.S. rights to Aczone from Allergan is the principal publicly disclosed commercial transaction associated with the brand. The transaction placed Aczone within Almirall’s U.S. medical dermatology portfolio [3].

Potential licensing value now lies less in the original molecule and more in:

• Authorized generic rights.
• Regional commercialization rights.
• Novel vehicle technology.
• Dermatology-focused co-promotion.
• Contract manufacturing arrangements.
• Bundled access to dermatologist networks and payer contracts.

A licensing transaction should separate rights to the Aczone trademark, NDA, formulation patents, manufacturing know-how, regulatory files, and authorized-generic supply. These rights have different economic value and different transfer requirements.

What geographic opportunities exist for dapsone topical products?

The United States is the most developed market for Aczone-branded and generic products because of the FDA-approved reference product, Orange Book listings, and established dermatologist prescribing.

Other opportunities may exist in:

• Canada, subject to local product registration.
• Europe, where dapsone topical products may have different regulatory histories.
• Latin America, where acne treatment markets can favor lower-cost topical products.
• Asia-Pacific, where local manufacturing and dermatology distribution can reduce cost.
• Emerging markets where gel, cream, and lotion formats may have different patient preferences.

Geographic expansion requires review of local dapsone approvals, patent status, excipient restrictions, labeling, pharmacovigilance, and whether the product is regulated as a prescription medicine or another category.

What is the commercial outlook for Aczone?

Aczone’s revenue exposure is concentrated in dermatology prescriptions and is vulnerable to generic substitution. Brand value is more likely to persist in the 7.5% once-daily segment if the product retains dermatologist preference and payer access. The 5% product has a larger installed base but faces greater generic price pressure.

Commercial opportunities divide into three categories:

1. Low-cost ANDA products using closely matched vehicles.
2. Premium reformulations with improved application or tolerability.
3. Enabling products, including excipients, packaging, and CDMO services.

For investors and licensors, the most attractive asset is unlikely to be a broad dapsone patent. It is more likely to be a differentiated vehicle with demonstrable patient or manufacturing value and a defensible regulatory position.

Key Takeaways

• Aczone 5% and 7.5% are separate formulation platforms, not simple strength variants.
• Aczone 5% uses carbomer 980, diethylene glycol monoethyl ether, methylparaben, sodium hydroxide, and water.
• Aczone 7.5% uses acrylamide/sodium acryloyldimethyl taurate copolymer, isohexadecane, polysorbate 80, sodium hydroxide, and water.
• Generic opportunity is strongest for manufacturers with topical semisolid scale-up and bioequivalence capabilities.
• The 7.5% vehicle offers more technical differentiation but has higher development complexity.
• A novel vehicle would generally require a 505(b)(2) strategy rather than a standard ANDA.
• Excipient suppliers can compete through pharmaceutical-grade polymers, low-peroxide surfactants, solvent purity, and formulation support.
• The mature patent estate makes vehicle performance, regulatory execution, manufacturing cost, and commercial access more important than broad active-ingredient protection.
• The main commercial risks are generic substitution, price erosion, limited brand differentiation, and formulation complexity.

FAQs

Is diethylene glycol monoethyl ether essential to Aczone 5%?

It is a listed excipient and important vehicle component, but an ANDA applicant must determine whether it is necessary to reproduce the reference product’s performance. A different solvent could move the product outside a conventional sameness strategy.

Does Aczone 7.5% have the same excipients as Aczone 5%?

No. Aczone 7.5% uses a different polymer and includes isohexadecane and polysorbate 80. It does not use the same carbomer-based vehicle listed for Aczone 5%.

Can a company launch a preservative-free dapsone gel?

A preservative-free formulation is possible as a development concept, but it would require adequate microbial control, container-closure protection, stability data, and a regulatory pathway appropriate to the formulation differences.

Is Aczone suitable for an authorized-generic strategy?

Yes. An authorized generic could use the approved product or a licensed version of the reference formulation. Its commercial value depends on supply economics, channel strategy, patent rights, and the number of competing ANDA products.

Which Aczone strength is more attractive for reformulation?

Aczone 7.5% may provide greater reformulation potential because its once-daily positioning and more complex vehicle create opportunities to improve sensory properties, delivery, and packaging. Aczone 5% may offer a lower-cost generic opportunity because its vehicle is simpler and more established.

References

1. U.S. Food and Drug Administration. (2023). Aczone (dapsone) gel, 5% prescribing information. FDA-approved labeling.

2. U.S. Food and Drug Administration. (2023). Aczone (dapsone) gel, 7.5% prescribing information. FDA-approved labeling.

3. Almirall, S.A. (2019). Annual report and corporate information concerning the acquisition of U.S. dermatology products from Allergan. Almirall.

4. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. FDA Orange Book.

5. U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs database. FDA.