List of Excipients in Branded Drug KLISYRI

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Almirall LLC	KLISYRI	tirbanibulin	16110-391	GLYCERYL MONO AND DIPALMITOSTEARATE	2030-12-28
Almirall LLC	KLISYRI	tirbanibulin	16110-391	PROPYLENE GLYCOL	2030-12-28

KLISYRI Excipient Strategy and Commercial Opportunities in Topical Actinic Keratosis

Last updated: August 8, 2026

KLISYRI is a once-daily, five-day topical treatment containing tirbanibulin 1% ointment for actinic keratosis on the face or scalp. Its commercial value depends on more than the active ingredient. The excipient system supports skin delivery, semisolid stability, patient tolerability, unit-dose compliance, and regulatory differentiation. The formulation contains benzyl alcohol, propylene glycol, glycerin, emulsifying wax, mineral oil, and white petrolatum. Each 250-mg sachet contains 2.5 mg of tirbanibulin, and the approved regimen uses five sachets for a complete treatment course.[1]

The strongest commercial opportunities are in generic formulation development, lower-irritation alternatives, improved packaging, regional manufacturing, and line extensions that preserve the five-day treatment advantage. The principal barriers are topical bioequivalence, excipient-driven skin irritation, control of particle size and content uniformity, and intellectual-property protection around the formulation and use of tirbanibulin.

What is the KLISYRI formulation and which excipients does it contain?

KLISYRI is a white to off-white topical ointment containing tirbanibulin 10 mg/g, equivalent to 1% w/w. The inactive ingredients listed in the U.S. prescribing information are:

Component	Likely formulation role	Commercial relevance
Benzyl alcohol	Preservative and solvent	Can contribute to irritation or sensitization concerns
Propylene glycol	Solvent, humectant, and penetration-supporting excipient	May improve solubilization but can cause stinging or dermatitis in susceptible patients
Glycerin	Humectant and skin-conditioning agent	Supports hydration and spreadability
Emulsifying wax	Ointment structuring and emulsification agent	Controls consistency, phase behavior, and manufacturability
Mineral oil	Occlusive emollient and vehicle	Supports spreadability and barrier retention
White petrolatum	Occlusive base and skin protectant	Improves residence time and reduces water loss

The formulation is designed for local delivery rather than systemic exposure. The vehicle must keep tirbanibulin uniformly distributed across the treatment area, release the drug at the skin surface, and remain acceptable during five consecutive applications. The base also has to support content uniformity at a relatively low drug concentration of 1%.[1]

How does the KLISYRI excipient system support drug delivery?

The formulation uses a mixed hydrophilic-lipophilic vehicle. Propylene glycol and glycerin provide polar functionality, while mineral oil and white petrolatum provide an occlusive lipid phase. Emulsifying wax helps maintain the ointment structure and supports consistent distribution of the active ingredient.

This architecture addresses four formulation requirements:

1. Tirbanibulin must remain uniformly dispersed or dissolved throughout the product.
2. The vehicle must spread across irregular actinic keratosis lesions and surrounding skin.
3. The drug must partition from the ointment into the stratum corneum.
4. The product must remain physically stable over its shelf life and under normal storage conditions.

The occlusive components can increase hydration of the stratum corneum. Hydrated skin may support drug partitioning and local penetration, although higher penetration can also increase irritation. For a cytotoxic or antiproliferative topical agent such as tirbanibulin, the commercial target is controlled local exposure rather than maximum penetration.

What is the commercial advantage of a five-day KLISYRI regimen?

KLISYRI has a five-day, once-daily regimen, which is shorter than many competing actinic keratosis treatments. This reduces the number of treatment decisions required from patients and physicians.

Product or treatment class	Typical treatment burden	Commercial implication
KLISYRI, tirbanibulin 1%	Once daily for 5 days	High convenience and defined course
Imiquimod	Multiple applications over several weeks	Greater adherence burden
5-fluorouracil	Commonly several weeks	Longer visible inflammatory period
Diclofenac gel	Often several weeks	Lower short-term intensity but longer treatment duration
Photodynamic therapy	Procedure-based	Requires clinical administration and scheduling
Cryotherapy	Office procedure	Limited to visible or selected lesions

The short course supports premium positioning, especially for patients who discontinue longer regimens because of inconvenience, local reactions, or uncertainty about duration. The five-sachet presentation also allows pharmacies and manufacturers to sell a complete course rather than a larger multidose tube.

What formulation patents protect KLISYRI and tirbanibulin products?

KLISYRI protection can arise from several patent categories:

• Tirbanibulin composition-of-matter or chemical-form patents.
• Topical formulations containing tirbanibulin.
• Methods of treating actinic keratosis.
• Dosing schedules, including once-daily treatment over five days.
• Manufacturing processes for the ointment.
• Packaging, stability, or unit-dose presentation.

The FDA-approved label confirms the product composition and clinical use but does not itself provide a complete, current patent analysis.[1] The relevant U.S. patent position must be assessed through the FDA Orange Book, USPTO records, patent-family data, and litigation filings. Patent scope may differ between the active ingredient, formulation, method of use, and specific dosage regimen.[2][3]

For commercial planning, the most important distinction is between patents that block an ANDA and patents that create litigation risk without necessarily preventing approval. A formulation or method-of-use patent may be listed in the Orange Book if it meets FDA listing requirements. Other patents, including manufacturing or broader chemical patents, may require separate freedom-to-operate analysis.

When does KLISYRI lose regulatory and patent exclusivity?

KLISYRI received FDA approval in December 2020 for actinic keratosis of the face or scalp in adults.[1] FDA approval does not mean that all exclusivity ends on the same date. Market entry depends on:

• New chemical entity exclusivity.
• Any listed patent expiration dates.
• Pediatric exclusivity, if granted.
• The scope of an ANDA applicant’s Paragraph IV certification.
• Litigation and any court-issued stay.
• The enforceability of formulation and method-of-use claims.

A generic applicant may file an ANDA with a Paragraph IV certification before patent expiration. If the patent holder sues within the statutory period after receiving notice, FDA approval may be subject to a 30-month stay, subject to statutory exceptions and court developments.[4]

The commercial risk is therefore staged. A generic may receive approval before a listed patent expires but remain unable to launch without an at-risk decision, a settlement, a license, or a court ruling.

What FDA regulatory issues affect KLISYRI generic development?

A generic tirbanibulin ointment would likely face a demanding topical-product development program. The applicant must demonstrate pharmaceutical equivalence and bioequivalence under FDA requirements for topical dermatological products.[5]

Key development areas include:

Qualitative and quantitative sameness

The reference product uses six listed inactive ingredients. A generic that matches the reference formulation on a qualitative and quantitative basis may reduce formulation risk, but exact sameness does not automatically establish bioequivalence.

Q3 characterization

The generic developer must characterize physical and structural properties such as:

• Droplet or particle size distribution, where applicable.
• Rheology and viscosity.
• pH, if meaningful for the product.
• Globule size and phase structure.
• Drug distribution and content uniformity.
• Water activity and evaporation behavior.
• In vitro release rate.
• Texture, spreadability, and adhesion.

For semisolid products, these characteristics can affect drug release and skin exposure even when the ingredient list is identical.

In vitro release testing

In vitro release testing can compare the rate and extent of tirbanibulin release from the test and reference products. A meaningful release method must distinguish formulation changes that alter drug availability at the skin surface.[5]

Skin permeation and clinical bioequivalence

Depending on FDA requirements and the strength of the development package, the sponsor may need in vitro permeation testing, pharmacodynamic evidence, or comparative clinical studies. Irritation and sensitization testing are also relevant because the formulation contains benzyl alcohol and propylene glycol, both of which can affect tolerability.

What excipient changes could create commercial differentiation?

The most practical opportunities involve improving tolerability without undermining release or local delivery.

Lower-irritation systems

A reformulated product could evaluate reduced benzyl alcohol, alternative preservation systems, or a vehicle with less propylene glycol. Any change would require testing for microbial control, stability, drug release, skin permeation, and local tolerability.

Preservative-free packaging

Single-use sachets reduce repeated opening and microbial contamination risk. A preservative-free or lower-preservative product could use unit-dose packaging, although the packaging cost and fill-volume control would become more important.

Improved sensory properties

Mineral oil and petrolatum provide occlusion but can feel greasy. A lighter ointment, cream, gel-ointment, or anhydrous structured vehicle could improve cosmetic acceptability. The tradeoff is that a less occlusive product may alter tirbanibulin release and local exposure.

Climate-stable packaging

The five-sachet format can support regional distribution, but hot and humid markets require testing for sachet integrity, leakage, phase separation, viscosity changes, and drug uniformity. Aluminum laminate or high-barrier multilayer sachets may reduce moisture and oxygen transmission.

Pediatric and sensitive-skin formulations

KLISYRI is approved for adults. A lower-irritation formulation could create a future development option for expanded populations, although pediatric actinic keratosis is a limited commercial segment and would require a separate regulatory strategy.

What manufacturing and intellectual-property barriers affect KLISYRI competitors?

The main manufacturing barrier is not the ointment base alone. It is reproducible control of a low-dose active ingredient in a semisolid vehicle.

Critical process parameters may include:

• Order of excipient addition.
• Heating and cooling profile.
• Mixing speed and shear.
• Tirbanibulin addition temperature.
• Homogenization time.
• Deaeration.
• Filling temperature.
• Sachet fill-weight accuracy.

A developer may avoid direct infringement of formulation claims by changing the vehicle, but that change can create bioequivalence and stability risk. Conversely, matching the reference formulation may simplify development but increase patent exposure if the claims cover the composition or manufacturing process.

The most defensible technical strategy is to build a formulation platform with multiple vehicle options, then select the candidate with the strongest combination of release similarity, skin tolerability, stability, and patent clearance.

Which companies are positioned to challenge KLISYRI commercially?

The competitive field includes:

• Generic dermatology companies with topical semisolid manufacturing capacity.
• Specialty pharmaceutical companies focused on actinic keratosis.
• Compounding pharmacies, although compounded products do not generally provide the same regulatory substitute as an approved generic.
• Developers of non-drug alternatives, including cryotherapy and photodynamic therapy providers.
• Companies marketing longer-course topical agents such as imiquimod, 5-fluorouracil, and diclofenac.

A conventional ANDA competitor is the clearest threat after relevant exclusivity expires. A differentiated 505(b)(2) product could compete earlier through a different dosage form, delivery system, or treatment population, but it would require a distinct clinical and regulatory rationale.

What licensing and partnering opportunities exist for KLISYRI excipients?

Excipient opportunities are more likely to involve formulation technology and manufacturing services than a single proprietary ingredient. Potential partnership targets include:

• Specialty excipient suppliers with dermatology-grade emollients.
• Contract development and manufacturing organizations with ointment and sachet capabilities.
• Packaging companies with high-barrier unit-dose systems.
• Companies with topical delivery platforms that can improve spreadability or reduce greasiness.
• Regional commercialization partners for dermatology products.

A licensee could create value by securing rights to a non-infringing vehicle, reducing manufacturing cost, or adding a product format that is easier to use than the reference ointment. The most commercially credible asset would combine a differentiated excipient system with comparative release, stability, and tolerability data.

How strong is the KLISYRI patent estate from an excipient perspective?

Patent strength depends on claim breadth, not the number of patent documents. A narrow claim covering a precise concentration range or excipient combination may be easier to design around than a broad claim covering topical tirbanibulin treatment.

The strongest formulation claims would typically cover:

• A defined tirbanibulin concentration.
• A specific combination of solvent, humectant, emulsifier, and occlusive agents.
• A stable ointment with controlled drug release.
• A unit-dose treatment regimen.
• A manufacturing process that produces uniform tirbanibulin distribution.

The weakest practical position would be a formulation claim that can be bypassed by replacing one excipient without changing clinical performance. For generic strategy, the key question is whether a substitute vehicle can match the reference product under FDA topical bioequivalence standards while avoiding the relevant claims.

What is the generic launch risk for KLISYRI?

Generic launch risk is moderate to high before patent resolution and materially lower after the listed protection period, subject to the actual Orange Book record and litigation outcome.

Risk factor	Impact on generic entry
Five-day regimen	Increases commercial attractiveness
Simple topical route	Reduces systemic clinical development burden
Semisolid formulation	Increases bioequivalence complexity
Six-excipient reference system	Creates opportunities for Q1/Q2 matching
Benzyl alcohol and propylene glycol	Creates tolerability differentiation opportunities
Unit-dose sachets	Adds packaging and filling requirements
Method-of-use claims	May require carve-outs or Paragraph IV strategy
Formulation patents	May delay or redirect launch strategy

The highest-value generic strategy is likely a reference-matched ointment supported by strong Q3 characterization and a carefully designed patent certification. A differentiated cream or gel may offer better commercial positioning but carries greater regulatory and technical risk.

What is the commercial outlook for KLISYRI excipient innovation?

Excipient innovation can support three business models:

1. A lower-cost generic with equivalent performance.
2. A branded reformulation with better tolerability or cosmetic acceptability.
3. A platform product licensed to multiple topical developers.

The most attractive near-term opportunity is a lower-irritation, unit-dose topical system that preserves the five-day regimen. A lighter vehicle may improve patient preference, but it must maintain the reference product’s local delivery profile. A preservative-reduced or preservative-free product could have value in sensitive-skin populations, provided packaging and microbiological controls are robust.

Key Takeaways

• KLISYRI contains tirbanibulin 1% in an ointment with benzyl alcohol, propylene glycol, glycerin, emulsifying wax, mineral oil, and white petrolatum.
• The excipient system balances drug distribution, skin hydration, occlusion, spreadability, and local residence.
• The five-day regimen is the product’s main commercial advantage over longer-course actinic keratosis therapies.
• Generic development is technically feasible but requires detailed semisolid characterization, release testing, stability work, and topical bioequivalence analysis.
• The principal differentiation opportunities are lower irritation, improved sensory properties, preservative reduction, and unit-dose packaging.
• Patent risk may involve active-ingredient, formulation, method-of-use, manufacturing, and packaging claims. The current Orange Book and USPTO records control the final entry assessment.
• A reference-matched generic offers the lowest technical risk. A new cream, gel, or lighter ointment offers more differentiation but greater regulatory uncertainty.
• Excipient and packaging suppliers can create licensing value if they provide measurable improvements in tolerability, stability, manufacturability, or bioequivalence performance.

FAQs

Can propylene glycol be removed from a tirbanibulin ointment?

Yes, but removing propylene glycol could change tirbanibulin solubilization, release, skin permeation, viscosity, and stability. The replacement system would require comparative formulation and bioequivalence testing.

Is KLISYRI suitable for a preservative-free formulation?

Potentially. The five-sachet unit-dose format is compatible with a preservative-free strategy, but the product would require validated microbial controls, package-integrity testing, and stability data.

Could a cream formulation compete with KLISYRI ointment?

Yes. A cream could improve cosmetic acceptability and reduce greasiness. It would also create a larger regulatory burden because the dosage form and microstructure could differ materially from the reference ointment.

Does a generic need to use the same KLISYRI excipients?

Not necessarily. A generic may use different inactive ingredients if it satisfies applicable FDA pharmaceutical-equivalence, safety, stability, and bioequivalence requirements. Matching the reference excipients may reduce development risk.

What is the most valuable excipient innovation for tirbanibulin?

A vehicle that reduces stinging and greasiness while maintaining equivalent local drug release and skin exposure has the strongest commercial rationale. Its value would depend on comparative clinical tolerability and freedom to operate.

References

1. U.S. Food and Drug Administration. (2020). KLISYRI (tirbanibulin) ointment, 1% prescribing information.
2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, commonly known as the Orange Book.
3. United States Patent and Trademark Office. (2024). Patent Center and Patent Examination Data System.
4. U.S. Food and Drug Administration. (2024). ANDA submissions: Amendments and requests for final approval to tentatively approved ANDAs.
5. U.S. Food and Drug Administration. (2022). Acyclovir, metronidazole, and other topical dermatological drug products: Product-specific bioequivalence guidance and related topical product guidance.