United States Patent 8,105,618: Scope, Claims, Expiration, and Patent Landscape for Adapalene/Benzoyl Peroxide Gel

U.S. Patent No. 8,105,618 protects a once-daily acne-treatment method using an aqueous gel containing 0.1% adapalene, 2.5% to 5% dispersed benzoyl peroxide, and 3.5% to less than 4% of a specified acrylamide-based gelling system. Its commercial relevance is tied to Epiduo, the adapalene/benzoyl peroxide combination marketed by Galderma.

The claim is narrow in formulation composition but broad in therapeutic use within that formulation window. A competing product must evaluate every limitation, including the precise polymer concentration, aqueous-gel format, benzoyl peroxide range, and once-daily administration condition.

What does U.S. Patent 8,105,618 cover?

The patent covers a method of treating common acne by administering the claimed aqueous gel once daily. It is not, based on the supplied claim, a broad claim to every adapalene and benzoyl peroxide formulation.

Claim element	Scope
Therapeutic indication	Treatment of common acne
Administration	Once daily
Dosage form	Physiologically acceptable aqueous gel
Retinoid	0.1% adapalene and/or an acceptable salt
Oxidizing active	2.5% to 5% dispersed benzoyl peroxide
Gelling system	Acrylamide sodium acryloyldimethyltaurate/isohexadecane/polysorbate 80
Gelling-agent concentration	3.5% to less than 4% by weight
Concentration basis	Weight of the total aqueous gel composition
Claim type	Method of treatment

The combination of concentration limitations is the central enforcement feature. The claim requires the product to contain both active ingredients and the specified gelling agent in the claimed ranges. A formulation outside one required range may avoid literal infringement, subject to prosecution-history estoppel and the doctrine of equivalents.

How should claim 1 of U.S. Patent 8,105,618 be construed?

What does “0.1% adapalene and/or salt” require?

The claim requires 0.1% adapalene, or an amount of an acceptable adapalene salt corresponding to the claimed concentration. The phrase “and/or” creates potential claim-construction issues because it may encompass:

Adapalene alone;
An adapalene salt alone; or
Adapalene together with one or more acceptable salts.

Adapalene is generally used as the active free compound in commercial topical products. A developer using a salt form would need to assess whether the claimed percentage is measured by total salt weight or by adapalene-equivalent weight. The patent specification and prosecution history would control that issue.

What does “2.5% to 5% dispersed benzoyl peroxide” require?

The benzoyl peroxide must be dispersed in the gel and must be present at a concentration from 2.5% through 5%. The lower and upper boundaries are ordinarily treated as inclusive unless the specification or prosecution history indicates otherwise.

The claim does not require the commercial 2.5% concentration specifically. A formulation containing 3%, 4%, or 5% dispersed benzoyl peroxide may fall within the literal concentration range if the remaining limitations are met.

What is the significance of the 3.5% to less than 4% gelling-agent range?

This is the narrowest numerical limitation in the claim. The claimed gelling agent is not merely any carbomer, cellulose derivative, acrylate polymer, or viscosity modifier. It is the specified multi-component system comprising:

Acrylamide sodium acryloyldimethyltaurate;
Isohexadecane; and
Polysorbate 80.

The range begins at 3.5% and stops before 4%. A formulation containing exactly 3.5% is within the claim. A formulation containing exactly 4% is outside the literal claim because the upper boundary is “less than 4%.”

A formulation using the same polymer system at 2%, 3%, or 4% would not literally satisfy this limitation. The commercial and litigation significance of the narrow range is substantial because it creates a direct formulation-design opportunity while preserving a potential equivalents argument.

Does the claim cover a product or only a treatment method?

The supplied claim is a method claim. It does not directly claim:

The gel composition as a composition;
A package or applicator;
The manufacturing process;
A particular particle-size distribution;
A specific pH;
A specific preservative system; or
A specific dosing quantity.

Infringement requires performance of the claimed method. A generic manufacturer could still face induced-infringement exposure if its labeling instructs patients or health-care professionals to use a qualifying product once daily for common acne.

What formulations are protected by U.S. Patent 8,105,618?

The following examples illustrate the literal scope of the supplied claim.

Hypothetical formulation	Likely literal scope
0.1% adapalene, 2.5% BPO, 3.5% specified gelling agent, aqueous gel, once daily	Within claim
0.1% adapalene, 5% BPO, 3.9% specified gelling agent, aqueous gel, once daily	Within claim
0.1% adapalene, 2.5% BPO, 4.0% specified gelling agent	Outside literal claim based on upper boundary
0.1% adapalene, 2.5% BPO, 3.0% specified gelling agent	Outside literal claim
0.3% adapalene, 2.5% BPO, 3.8% specified gelling agent	Outside literal claim based on adapalene concentration
0.1% adapalene, 2.5% BPO, carbomer instead of the specified gelling system	Outside literal claim
0.1% adapalene, 2.5% BPO, qualifying gel used twice daily	Potentially outside the method limitation, but label and actual-use issues remain
0.1% adapalene alone	Outside claim because benzoyl peroxide is required
2.5% BPO alone	Outside claim because adapalene is required

The phrase “percentages being based on the weight of the total aqueous gel composition” prevents a developer from calculating the concentration against only the aqueous phase, excluding active ingredients or other formulation components.

When does U.S. Patent 8,105,618 lose exclusivity?

What is the nominal expiration date?

The patent family claims an earlier priority date associated with the development of the adapalene/benzoyl peroxide aqueous gel technology. The ordinary 20-year patent-term calculation is generally assessed from the earliest effective U.S. nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and any applicable pediatric extension.

Public patent records commonly associate the patent family with a November 2003 priority date and a nominal term endpoint in late 2024, although the enforceable expiration date must be taken from the USPTO patent-term record rather than calculated solely from the foreign priority date. [1]

A six-month pediatric exclusivity period, if granted and applicable to the listed product, would extend FDA marketing protection but would not necessarily alter the patent’s underlying statutory expiration date. Patent exclusivity and regulatory exclusivity must be analyzed separately.

What is the FDA exclusivity position?

Epiduo was approved by FDA under NDA 022320 on Dec. 22, 2008. The product contains adapalene 0.1% and benzoyl peroxide 2.5% in a topical gel. [2]

The relevant protection layers are:

Protection	Relevance
U.S. Patent 8,105,618	Method claim directed to once-daily use of the specified gel
Orange Book listing	Determines whether an ANDA applicant must address the patent
NDA exclusivity	FDA regulatory protection separate from patent rights
Pediatric exclusivity	May extend listed patent and exclusivity periods by six months if awarded
Formulation and method patents	May create additional barriers beyond this patent

Because the patent is a method claim, Orange Book listing and ANDA certification practice are important. FDA’s Orange Book identifies patents submitted by the NDA holder and provides expiration and use-code information. [3]

What is the Orange Book status of U.S. Patent 8,105,618?

Patent 8,105,618 is associated with the adapalene/benzoyl peroxide product franchise and has been treated as an Orange Book-relevant patent for the Epiduo product. The practical effect depends on:

Whether the patent remains listed for the relevant NDA;
The listed expiration date;
The approved use code;
Whether a generic applicant files a Paragraph IV certification;
Whether the NDA holder brings an infringement action within the statutory 45-day period; and
Whether the patent is later delisted, expires, or is held invalid or unenforceable.

The Orange Book does not determine patent validity. It records listed patents and regulatory information. Patent validity and infringement are judicial questions.

Which companies have challenged adapalene/benzoyl peroxide patents?

Generic-drug companies have had commercial incentives to challenge Epiduo-related patents because the product combines two established topical actives and can be submitted through the ANDA pathway. The principal potential challengers include companies developing generic adapalene/benzoyl peroxide gel, including major generic manufacturers and specialty dermatology companies.

A Paragraph IV challenge would typically assert one or more of the following:

The patent is invalid for obviousness;
The claims lack adequate written description or enablement;
The proposed product does not infringe;
The patent is unenforceable;
The ANDA label does not instruct the claimed once-daily acne treatment; or
The proposed formulation falls outside the claimed polymer range.

A generic applicant can also file a Paragraph III certification and defer launch until patent expiry, or file a section viii statement carving out a patented method of use if the FDA-approved labeling permits such a carve-out.

What patent litigation affects U.S. Patent 8,105,618?

Litigation risk centers on the tension between a narrow formulation window and a method claim that tracks the approved use of Epiduo.

Infringement theories

A patent holder may allege:

Direct infringement by administering the generic product;
Induced infringement through the product label;
Contributory infringement based on a product specially adapted for the claimed method; and
Infringement under the doctrine of equivalents.

For a topical generic, the label is usually the most important evidence. If the proposed label instructs once-daily application for common acne and the formulation falls within the concentration limitations, the risk increases materially.

Validity theories

The most credible invalidity issues are likely to involve obviousness. Before the priority date, adapalene, benzoyl peroxide, aqueous gels, and polymeric gelling agents were individually known. The patent holder’s principal defense would be that the specific combination and narrow gelling-agent range produced unexpected stability, tolerability, homogeneity, or therapeutic results.

A challenger would examine:

Prior art disclosing adapalene and benzoyl peroxide combinations;
Prior art disclosing the specified acrylamide-based gelling agent;
Routine formulation optimization;
Stability data;
Comparative examples;
Unexpected-results evidence; and
Any narrowing amendments made during prosecution.

The narrow 3.5% to less than 4% range can support patentability if the record demonstrates a non-linear or unexpected technical effect. It can also create an obviousness vulnerability if the range represents routine optimization without a demonstrated criticality.

Settlement agreements

A settlement between the NDA holder and an ANDA applicant could establish a permitted launch date, manufacturing restrictions, or an authorized-generic arrangement. Such agreements may be submitted to the Federal Trade Commission and FDA under applicable reporting requirements. The existence, terms, and antitrust treatment of any settlement must be verified from the relevant litigation docket and FTC submissions. The patent itself does not establish whether a settlement exists.

What generic entry risks exist for Epiduo?

Generic entry risk is high after expiration or successful invalidation because the active ingredients are well established and the product is a topical, non-biologic dosage form.

Early-entry scenario

Before patent expiry, a Paragraph IV filer could launch at risk if:

The patent holder does not sue within the statutory period;
The patent is found invalid or not infringed;
The court permits launch after an unsuccessful preliminary injunction request; or
The generic label avoids the patented method.

Post-expiry scenario

After patent expiry, FDA approval of an ANDA can proceed without the same patent-based barrier, subject to any remaining listed patents, regulatory exclusivity, manufacturing requirements, and product-specific bioequivalence obligations.

Design-around scenarios

A formulation developer could target:

A gelling-agent concentration below 3.5%;
A concentration of 4% or more;
A different polymer system;
A different adapalene concentration;
A benzoyl peroxide concentration below 2.5% or above 5%;
A nonaqueous vehicle;
A label that omits once-daily treatment instructions, if clinically and regulatorily permissible; or
A different approved indication or use-code strategy.

Each design-around carries regulatory and clinical constraints. A label carve-out is not available if the omitted use is essential to the approved generic product or if the remaining label still encourages the patented use.

How strong is the patent estate for adapalene/benzoyl peroxide products?

The strength of U.S. Patent 8,105,618 is mixed.

Factor	Assessment
Formulation specificity	Strongly defined
Active-ingredient coverage	Limited to 0.1% adapalene with 2.5% to 5% BPO
Polymer coverage	Narrow and technically specific
Method coverage	Broad within common-acne, once-daily use
Design-around potential	Meaningful
Generic substitution exposure	High after patent barriers fall
Biologic competition	Not relevant
Manufacturing barrier	Moderate; formulation reproducibility and BPO stability matter
Enforcement leverage	Potentially strong if the generic matches the commercial formulation and label

The patent does not create a durable barrier against all acne formulations. It is most valuable against a generic product that copies the Epiduo formulation closely and uses the same once-daily acne label.

How does this patent compare with Epiduo Forte protection?

Epiduo contains 0.1% adapalene and 2.5% benzoyl peroxide. Epiduo Forte contains 0.3% adapalene and 2.5% benzoyl peroxide. [2,4]

Product	Adapalene	Benzoyl peroxide	Relevance to Patent 8,105,618
Epiduo	0.1%	2.5%	Closely aligned with claim 1
Epiduo Forte	0.3%	2.5%	Outside the supplied 0.1% adapalene limitation
Generic adapalene/BPO gel	Variable	Variable	Must be tested against every claim limitation

The supplied claim is therefore more directly relevant to the original Epiduo formulation than to Epiduo Forte. Separate patents, regulatory records, or use protections may apply to the higher-strength product.

Does biosimilar risk apply to U.S. Patent 8,105,618?

No. Adapalene and benzoyl peroxide are small-molecule active ingredients, and Epiduo is a topical drug product rather than a biologic. The relevant competitive pathway is an ANDA for a generic drug, not a biosimilar application under the Public Health Service Act. FDA’s Purple Book is therefore not the primary source for this product. [5]

The core competitive risks are generic formulation replication, Paragraph IV litigation, authorized-generic entry, and post-expiry price competition.

What manufacturing and IP barriers remain after patent expiry?

Patent expiry does not eliminate all commercial barriers. A generic manufacturer must still demonstrate:

Consistent dispersion of benzoyl peroxide;
Chemical and physical stability of adapalene and benzoyl peroxide;
Uniformity across the gel;
Appropriate viscosity and spreadability;
Microbiological quality;
Container-closure compatibility;
Bioequivalence or equivalent topical performance under FDA requirements; and
Compliance with current good manufacturing practice.

The specified gelling system may be commercially available, but sourcing, batch consistency, and process control can affect approval and product performance. These are manufacturing barriers rather than independent patent rights.

Key Takeaways

U.S. Patent 8,105,618 is a method patent focused on once-daily treatment of common acne.
The claimed formulation contains 0.1% adapalene, 2.5% to 5% dispersed benzoyl peroxide, and 3.5% to less than 4% of a specified acrylamide-based gelling agent.
The claim is closely aligned with the original Epiduo formulation.
Exact boundary conditions matter: 3.5% is included, while 4% is excluded under the literal wording.
A generic product may design around the claim through a different polymer, concentration, active strength, vehicle, or label.
The principal legal risks are Paragraph IV litigation, induced infringement based on labeling, obviousness, and claim construction.
Biosimilar risk does not apply; generic-drug competition is the relevant pathway.
Patent expiration, Orange Book listing, pediatric exclusivity, and FDA regulatory exclusivity must be analyzed separately.
The patent estate is commercially meaningful against close copies but does not broadly cover all adapalene/benzoyl peroxide acne products.

FAQs

Can a generic use 2.5% benzoyl peroxide and avoid Patent 8,105,618?

No, not solely by using 2.5% benzoyl peroxide. That concentration is within the claimed 2.5% to 5% range. The generic would also need to avoid another limitation, such as the adapalene concentration, specified gelling system, gelling-agent range, aqueous-gel format, or once-daily method.

Is a 4% concentration of the claimed gelling agent covered?

Not literally under the supplied claim. The claim requires 3.5% to less than 4%. A formulation containing exactly 4% could still raise an equivalents issue, depending on the patent record and litigation history.

Does using a different brand of the same gelling polymer avoid infringement?

Not necessarily. Infringement depends on chemical composition, not the supplier’s brand name. A different commercial source containing the same specified acrylamide sodium acryloyldimethyltaurate/isohexadecane/polysorbate 80 system may still satisfy the claim.

Can a generic avoid the patent by instructing twice-daily use?

Possibly, but the strategy is not automatic. The formulation must still avoid direct or induced infringement, and the FDA label must be clinically justified and consistent with the reference product’s approved use.

Does Patent 8,105,618 protect Epiduo Forte?

The supplied claim does not literally cover a formulation containing 0.3% adapalene because it requires 0.1% adapalene. Epiduo Forte may be subject to separate patents, regulatory protections, or other intellectual-property rights.

References

United States Patent and Trademark Office. (2012). U.S. Patent No. 8,105,618, aqueous gel composition comprising adapalene and benzoyl peroxide.
U.S. Food and Drug Administration. (2008). Epiduo (adapalene and benzoyl peroxide) gel, 0.1%/2.5%: Prescribing information.
U.S. Food and Drug Administration. (2025). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (2015). Epiduo Forte (adapalene and benzoyl peroxide) gel, 0.3%/2.5%: Prescribing information.
U.S. Food and Drug Administration. (2025). Purple Book: Database of licensed biological products.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
France	01 16747	Dec 21, 2001

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	1458369	⤷ Start Trial	CA 2008 00029	Denmark	⤷ Start Trial
European Patent Office	1458369	⤷ Start Trial	08C0024	France	⤷ Start Trial
European Patent Office	1458369	⤷ Start Trial	SPC/GB10/005	United Kingdom	⤷ Start Trial
European Patent Office	1458369	⤷ Start Trial	C01458369/01	Switzerland	⤷ Start Trial
European Patent Office	1458369	⤷ Start Trial	380	Finland	⤷ Start Trial
European Patent Office	1458369	⤷ Start Trial	SZ 31/2008	Austria	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,105,618

Summary for Patent: 8,105,618