US Patent 9,833,429: Ingenol-3-Angelate Formulation Claims, Patent Scope, Exclusivity and Competitive Landscape

US Patent 9,833,429 protects topical formulations containing highly enriched ingenol-3-angelate, also identified in the claims as ingenol angelate isoform "b." The patent is formulation-focused rather than directed broadly to the active pharmaceutical ingredient. Its strongest protection covers a refrigerated, acidic gel system containing ingenol-3-angelate, isopropyl alcohol, hydroxyethylcellulose, benzyl alcohol, citrate buffer and water.

The broadest independent claims require:

Ingenol-3-angelate at 0.001% to 0.15% by weight;
A topical dosage form;
A penetration enhancer;
A gelling agent;
An acidifying agent;
A pharmaceutically acceptable solvent; and
Either at least 95% ingenol-3-angelate within the ingenol angelate fraction, or the specific excipient combination recited in claim 11.

The patent does not, based on the supplied claims, cover every ingenol-3-angelate product. A competing formulation could avoid infringement by changing the active-isomer purity, concentration, excipient system, pH, dosage form, or storage profile. The breadth of the independent claims is narrowed by the cumulative ingredient and formulation limitations.

What does US Patent 9,833,429 protect?

US 9,833,429 protects pharmaceutical compositions containing ingenol-3-angelate in a topical formulation. The claims distinguish the protected product from formulations containing a mixed or insufficiently purified ingenol angelate composition.

Claim 1 is the principal broad formulation claim. It requires all of the following:

Claim element	Scope
Active ingredient	Ingenol angelate, with at least about 95% of the ingenol angelate being ingenol-3-angelate isoform "b"
Active concentration	0.001% to 0.15% by weight
Route and dosage form	Topical formulation
Permeation component	Penetration enhancer
Rheology component	Gelling agent
pH-control component	Acidifying agent
Liquid vehicle	Pharmaceutically acceptable solvent

The claim uses "comprising," an open-ended transitional term. A formulation may contain additional excipients, preservatives, buffers, stabilizers or active ingredients unless another claim limits the composition to ingenol-3-angelate as the only active ingredient.

The claim does not require a particular gel, cream or foam. Those forms appear in dependent claim 8. The claim also does not expressly require benzyl alcohol, isopropyl alcohol, hydroxyethylcellulose, citrate buffer or a particular pH. Those limitations appear in dependent claims or the separate claim 11 group.

How do claims 1 through 10 and claim 24 operate?

Claims 1 through 10 and claim 24 form the first claim set.

Purity and active-concentration limitations

Claim 1 requires at least about 95% of the ingenol angelate to be ingenol-3-angelate isoform "b." Claim 24 raises that threshold to at least about 99%.

The purity limitation is material. A product containing the same active concentration but a lower proportion of isoform "b" may fall outside claims 1 and 24, subject to claim construction and any applicable doctrine-of-equivalents analysis.

The concentration range is 0.001% to 0.15% by weight. Dependent claim 1 does not require the commercial concentration to be 0.05%, 0.1% or another specific strength. A product at either endpoint is within the literal numerical range unless the specification or prosecution history imposes a narrower construction.

Excipient and dosage-form limitations

Claim 2 identifies the solvent as one selected from:

Polyethylene glycol;
Methyl ethyl ketone;
Ethyl acetate;
Diethyl ether; or
Benzyl alcohol.

Claim 3 narrows the solvent to benzyl alcohol. Claim 4 further requires 0.9% benzyl alcohol by weight.

Claim 8 covers a gel, cream, ointment, paint, lotion or foam. Because claim 8 depends on claim 1, the dosage form must also contain the penetration enhancer, gelling agent, acidifying agent and solvent required by claim 1.

pH and storage limitations

Claims 5 and 6 create a pH window of 2.5 to 4.5 when read together. Claim 5 requires a pH no greater than 4.5, while claim 6 requires a pH no less than 2.5.

Claims 9 and 10 address storage at 2°C to 8°C. Claim 10 adds a minimum one-year storage period. These claims are directed to formulations having the claimed stability or suitability for refrigerated storage, not merely formulations that can physically be placed in a refrigerator.

Active-ingredient limitation

Claim 7 requires ingenol-3-angelate isoform "b" to be the only active ingredient. The limitation does not prohibit inactive excipients. It does prevent reliance on a second pharmacologically active compound to support literal infringement of that dependent claim.

What formulations are protected by claims 11 through 23?

Claims 11 through 23 define a more specific formulation platform. Claim 11 requires:

Ingenol-3-angelate isoform "b";
Isopropyl alcohol;
Hydroxyethylcellulose;
Benzyl alcohol;
An acid buffer containing citric acid and sodium citrate; and
Water.

The active concentration remains 0.001% to 0.15% by weight.

This claim set is commercially important because it identifies a concrete formulation architecture rather than a functional list of formulation categories. A product omitting any one of the required components may avoid literal infringement of claim 11, although it could still be evaluated against claim 1 or other claims.

Claim	Added limitation
11	Specific active, solvent, gelling agent, benzyl alcohol, citrate buffer and water
12	Ingenol-3-angelate at 0.01% to 0.1%
13	30% isopropyl alcohol
14	1% to 5% hydroxyethylcellulose
15	0.9% benzyl alcohol
16	0.5% to 10% acid buffer
17	0.001% to 0.15% active, 30% isopropyl alcohol, 1.5% hydroxyethylcellulose, 0.9% benzyl alcohol, 0.5% to 10% acid buffer and water
18	pH no greater than 4.5
19	pH no less than 2.5
20	Ingenol-3-angelate as the only active ingredient
21	Gel, cream, ointment, paint, lotion or foam
22	Suitable for storage at 2°C to 8°C
23	Suitable for storage at 2°C to 8°C for at least one year

Claim 17 is likely the narrowest commercially relevant composition claim because it combines the principal formulation ingredients and specified quantities. It is also the claim most likely to require detailed product testing during an infringement analysis.

How broad is the patent’s formulation coverage?

The patent has moderate breadth at claim 1 and substantially narrower protection in claims 11 and 17.

Broad coverage

Claim 1 can reach formulations with different:

Gelling agents;
Acidifying agents;
Penetration enhancers;
Solvents;
Topical dosage forms; and
Excipient concentrations.

The claim is not confined to benzyl alcohol or hydroxyethylcellulose. It also does not expressly limit the formulation to an aqueous system.

Narrower coverage

The claims become materially narrower where they require:

Benzyl alcohol as the solvent;
0.9% benzyl alcohol;
Isopropyl alcohol at 30%;
Hydroxyethylcellulose at 1% to 5%;
Hydroxyethylcellulose at 1.5%;
Citric acid and sodium citrate;
pH between 2.5 and 4.5;
Refrigerated storage for at least one year; or
A defined topical dosage form.

A formulation containing the same active ingredient at the same concentration but using carbomer instead of hydroxyethylcellulose, ethanol instead of isopropyl alcohol, or a non-citrate buffer would require a separate claim-by-claim analysis.

When does US Patent 9,833,429 lose exclusivity?

US Patent 9,833,429 issued on December 5, 2017. The ordinary patent term is generally 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, terminal disclaimers and other statutory adjustments.[1]

The patent’s expiration date should be determined from the USPTO patent-term data rather than calculated solely from the issue date. The claim set and issue date alone do not establish the final enforceable expiration date. The patent is not a biologic patent and does not receive the 12-year reference-product exclusivity period under the Biologics Price Competition and Innovation Act.

The patent’s commercial value is therefore driven by patent term, formulation relevance and the availability of an FDA-approved product that could support an abbreviated regulatory pathway.

What is the Orange Book status of US 9,833,429?

US 9,833,429 is not, based on the supplied subject matter, an automatically enforceable Orange Book patent. Orange Book listing depends on submission by the NDA holder and on whether the patent claims the approved drug substance, drug product or an approved method of use.[2]

A formulation patent may be listed if it claims the approved drug product or an approved formulation. A patent directed to an unapproved active ingredient or an unapproved formulation ordinarily does not create an Orange Book-based Paragraph IV dispute for a different listed drug.

Ingenol-3-angelate is distinct from ingenol mebutate, the active ingredient formerly marketed in Picato. FDA approved Picato for actinic keratosis and later announced withdrawal of the product from the U.S. market after safety concerns involving skin malignancies.[3] The withdrawal of Picato does not convert a patent covering ingenol-3-angelate into a Picato Orange Book patent.

Are Paragraph IV challenges available?

A Paragraph IV certification is available when an ANDA applicant seeks approval of a generic version of an approved reference listed drug and certifies that a listed patent is invalid, unenforceable or not infringed.[2]

For US 9,833,429, the practical analysis is:

Scenario	Paragraph IV relevance
Generic of an FDA-approved ingenol-3-angelate product	Potentially relevant if the patent is listed against that product
Generic of Picato containing ingenol mebutate	Not automatically relevant because the active ingredient differs
505(b)(2) product containing ingenol-3-angelate	Patent certification and notice obligations may apply depending on the relied-upon listed drug and listed patents
Compounded topical formulation	ANDA Paragraph IV framework generally does not govern
New active ingredient with no reference listed drug	ANDA pathway is generally unavailable

A commercial challenger would likely evaluate a 505(b)(2) strategy, a formulation design-around, or a patent invalidity position rather than assume that an ordinary ANDA can target the claims.

Does biosimilar risk apply to this patent?

No conventional biosimilar risk applies. Ingenol-3-angelate is a chemically defined small molecule, not a biologic subject to the biosimilar pathway.

The relevant competitors would be:

Generic or follow-on small-molecule products;
505(b)(2) topical products;
Compounded formulations;
Alternative ingenol analogues;
Other actinic-keratosis therapies; and
Non-ingenol topical treatments such as fluorouracil, imiquimod, diclofenac and tirbanibulin.

The patent could still create formulation risk for a small-molecule competitor if the competitor reproduces the claimed excipient system, purity threshold and concentration range.

Which companies are challenging US 9,833,429?

The supplied record does not identify a Paragraph IV notice, ANDA applicant, district-court complaint, or settlement involving US 9,833,429. No challenger should be treated as established solely because generic companies compete in the actinic-keratosis market.

The absence of an identified challenge is commercially relevant. A formulation patent covering an unapproved or commercially limited product may attract less ANDA litigation than a patent listed against a high-revenue reference drug.

What patent litigation affects ingenol angelate formulations?

The main litigation distinction is between litigation involving ingenol mebutate products and litigation involving ingenol-3-angelate formulations.

Picato-related regulatory and patent activity does not automatically establish infringement or invalidity positions for US 9,833,429. The active ingredients, approved indications, formulation disclosures and Orange Book status must be compared separately.

For a dispute involving US 9,833,429, the principal litigation issues would likely include:

Whether the accused product contains at least 95% or 99% isoform "b";
Whether the active concentration falls within 0.001% to 0.15%;
Whether an excipient functions as a penetration enhancer, gelling agent or acidifying agent;
Whether the product contains the specific ingredients required by claim 11;
Whether "acid buffer comprising citric acid and sodium citrate" is satisfied by the accused buffer;
Whether the pH and refrigerated-storage limitations are met;
Whether the patent claims are anticipated or obvious over earlier ingenol formulations; and
Whether the written description and enablement support the full concentration, purity and dosage-form scope.

How strong is the patent estate for ingenol-3-angelate?

US 9,833,429 provides focused formulation protection, but the supplied claims do not show a complete estate covering:

The ingenol-3-angelate molecule itself;
All salts, solvates or polymorphs;
Manufacturing processes;
Synthetic intermediates;
Broad therapeutic methods;
Specific disease indications;
Device or package systems; or
Commercial-scale manufacturing controls.

Its strongest defensive value lies in preventing replication of a particular topical formulation platform. Its weakness is design-around potential. A competitor may seek to preserve the active ingredient and therapeutic concept while modifying the vehicle, buffer, gelling agent, alcohol system, concentration or stability profile.

Patent strength is therefore highest where the commercial product closely matches the claim 17 composition and lowest where the product uses a substantially different formulation technology.

What manufacturing and intellectual-property barriers exist?

Manufacturing risk is concentrated in active-isomer control and formulation stability.

A manufacturer would need to control:

The proportion of ingenol-3-angelate isoform "b";
Assay and impurity specifications;
Isomerization or degradation during manufacture and storage;
Homogeneity at low active concentrations;
Compatibility with alcohol, benzyl alcohol and hydroxyethylcellulose;
pH maintenance within the claimed range; and
Refrigerated stability for products relying on claims 9, 10, 22 or 23.

These technical constraints can create practical barriers even when a formulation is designed outside the literal wording of claim 17. They do not, by themselves, establish patent infringement.

How does US 9,833,429 compare with Picato patents?

Issue	US 9,833,429	Picato-related patent position
Active ingredient	Ingenol-3-angelate isoform "b"	Ingenol mebutate
Main protection	Topical formulation composition	Product, formulation and potentially method claims across the Picato estate
FDA status	The supplied record does not establish an approved ingenol-3-angelate product	Picato was FDA approved and later withdrawn
Orange Book relevance	Depends on an approved product and listing	Historically tied to the Picato NDA and listed patents
Biosimilar pathway	Not applicable	Not applicable
Likely competitor pathway	505(b)(2), formulation design-around or new product development	Generic or follow-on small-molecule pathways, subject to listed patents and regulatory status
Principal technical risk	Isomer purity and excipient architecture	Active-ingredient, formulation and approved-indication requirements

The two patent landscapes should not be combined merely because both involve ingenol compounds.

What generic launch risks exist?

The generic launch risk is limited by the apparent absence of a directly corresponding approved ingenol-3-angelate reference product. The more relevant risk is a follow-on product or 505(b)(2) applicant using a formulation close to the patented composition.

Potential launch pathways include:

A formulation that uses a different gelling agent;
A non-citrate buffer;
A different penetration enhancer;
A different solvent system;
An active concentration outside the claimed range;
A lower isoform "b" proportion, if scientifically and regulatorily acceptable;
A non-refrigerated formulation that does not rely on the storage claims; or
A different dosage form not satisfying the relevant dependent claim.

A design-around must be assessed against every independent and dependent claim. Avoiding claim 17 does not avoid claim 1 if the alternative still contains the required functional excipients and active-purity range.

What is the geographic coverage of US 9,833,429?

US 9,833,429 provides protection only in the United States. Parallel rights would depend on corresponding national patents or granted applications in other jurisdictions.

International commercialization requires a separate review of:

The PCT application;
European regional prosecution;
Canadian, Australian and Japanese family members;
National-stage claim scope;
Local patent-term dates;
Supplementary protection certificates, where applicable; and
Litigation or opposition history.

A U.S. freedom-to-operate conclusion cannot be extended to Europe or other markets without reviewing the relevant family members.

Key Takeaways

US 9,833,429 is a formulation patent centered on topical ingenol-3-angelate isoform "b."
Claim 1 requires the active, purity, concentration, topical route, penetration enhancer, gelling agent, acidifying agent and solvent.
Claim 11 protects a specific system containing isopropyl alcohol, hydroxyethylcellulose, benzyl alcohol, citrate buffer and water.
Claim 17 is the most commercially specific formulation claim, with 30% isopropyl alcohol, 1.5% hydroxyethylcellulose and 0.9% benzyl alcohol.
Claims 5, 6, 18 and 19 create a pH range of 2.5 to 4.5 when read together.
Claims 9, 10, 22 and 23 add refrigerated-storage protection, including one-year storage for the narrower claims.
The patent does not create biosimilar risk because ingenol-3-angelate is a small molecule.
Paragraph IV relevance depends on an approved reference product and an Orange Book listing; the claims alone do not establish either condition.
Picato and ingenol mebutate should not be treated as the same product or patent landscape.
The principal design-around opportunities involve excipient selection, buffer chemistry, active concentration, isoform purity and dosage form.
The final expiration date must be taken from USPTO patent-term data, including any patent-term adjustment or terminal disclaimer.

FAQs About US Patent 9,833,429

Does US 9,833,429 cover ingenol mebutate?

No. The supplied claims identify ingenol angelate and ingenol-3-angelate isoform "b." Ingenol mebutate is a different ingenol ester.

Does using 0.05% ingenol-3-angelate avoid the patent?

No. A 0.05% concentration falls within the claimed 0.001% to 0.15% range. All other claim elements must also be evaluated.

Does a formulation with carbomer instead of hydroxyethylcellulose avoid claim 17?

It would not satisfy the literal hydroxyethylcellulose limitation in claim 17. It could still require analysis under claim 1 if it contains the required functional formulation components.

Is a refrigerated product automatically covered by claims 9 or 10?

No. Refrigeration alone is insufficient. The formulation must satisfy the underlying claim 1 requirements and, for claim 10, be suitable for storage at 2°C to 8°C for at least one year.

Can a company launch a compounded ingenol-3-angelate formulation without addressing this patent?

No categorical launch conclusion follows from the claims alone. Compounding does not eliminate patent risk, and the formulation must be compared against the issued claims and any applicable enforcement defenses.

References

United States Patent and Trademark Office. (2017). U.S. Patent No. 9,833,429, formulations comprising ingenol angelate.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, Orange Book.
U.S. Food and Drug Administration. (2020, February 26). FDA warns of increased risk of death and/or heart attack and stroke with use of Picato (ingenol mebutate) gel.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Leo Labs	PICATO	ingenol mebutate	GEL;TOPICAL	202833-001	Jan 23, 2012		DISCN	Yes	No	9,833,429	⤷ Start Trial	Y				⤷ Start Trial
Leo Labs	PICATO	ingenol mebutate	GEL;TOPICAL	202833-002	Jan 23, 2012		DISCN	Yes	No	9,833,429	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	1988877	⤷ Start Trial	C300682	Netherlands	⤷ Start Trial
European Patent Office	1988877	⤷ Start Trial	PA2014030	Lithuania	⤷ Start Trial
European Patent Office	1988877	⤷ Start Trial	CA 2014 00042	Denmark	⤷ Start Trial
European Patent Office	1988877	⤷ Start Trial	C20140025 00111	Estonia	⤷ Start Trial
European Patent Office	1988877	⤷ Start Trial	C01988877/01	Switzerland	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 9,833,429

Which drugs does patent 9,833,429 protect, and when does it expire?

Summary for Patent: 9,833,429