List of Excipients in Branded Drug INSULIN GLARGINE U-300

Insulin Glargine U-300 Excipient Strategy and Commercial Opportunities

Last updated: September 6, 2026

Insulin glargine U-300, marketed by Sanofi as Toujeo, uses a concentrated acidic formulation containing insulin glargine, zinc chloride, m-cresol, glycerol, polysorbate 20, hydrochloric acid, sodium hydroxide, and water for injection. Its commercial differentiation depends on concentration, subcutaneous depot behavior, dosing duration, and delivery-device integration rather than on a novel active ingredient alone. The strongest excipient opportunities involve formulation robustness, surfactant reduction, preservative alternatives, container compatibility, and lower-cost manufacturing.

What excipients are used in insulin glargine U-300?

Toujeo contains insulin glargine at 300 units/mL. The formulation is acidic, with a target pH of approximately 4.0. The principal excipients are:

Component	Function in U-300 formulation	Commercial relevance
Zinc chloride	Promotes insulin association and contributes to subcutaneous depot formation	Critical to release profile and concentration performance
m-Cresol	Antimicrobial preservative	Supports multidose pen stability and in-use sterility
Glycerol	Tonicity and formulation-property adjustment	Supports injection tolerability and solution properties
Polysorbate 20	Surfactant that limits interfacial aggregation and adsorption	Important for vial, cartridge, pen, and manufacturing compatibility
Hydrochloric acid	pH adjustment	Maintains acidic formulation conditions
Sodium hydroxide	pH adjustment	Used to set final formulation pH
Water for injection	Vehicle	Standard parenteral solvent

The FDA prescribing information identifies the inactive ingredients as zinc chloride, m-cresol, glycerol, polysorbate 20, hydrochloric acid, sodium hydroxide, and water for injection. Toujeo Max SoloStar contains the same active formulation at 300 units/mL but delivers up to 160 units per injection, compared with up to 80 units for the standard SoloStar pen (U.S. Food and Drug Administration [FDA], 2024).

How does the U-300 excipient system control insulin release?

The formulation is designed to create a smaller injection volume for the same insulin dose and a compact subcutaneous depot after injection. Insulin glargine precipitates in the neutral subcutaneous environment after administration from the acidic solution. The precipitated depot then releases insulin gradually.

Zinc is central to this behavior. Zinc ions support insulin association and influence the physical state of the depot. At 300 units/mL, the higher concentration produces a smaller depot surface area relative to the amount of insulin delivered. That property contributes to the flatter and longer pharmacokinetic profile reported for U-300 compared with insulin glargine U-100.

The excipient system therefore has a narrow operating window. Changes in zinc concentration, pH, ionic strength, preservative level, or surfactant content can affect:

• Insulin self-association and precipitation.
• Depot morphology after injection.
• Release duration and exposure variability.
• Chemical degradation and aggregation.
• Injection-site tolerability.
• Pen-device dose accuracy.
• Container adsorption and extractables.

A formulation that preserves insulin stability but changes depot kinetics may not be clinically equivalent to Toujeo.

What formulation patents protect insulin glargine U-300?

Protection for U-300 can arise from several patent layers:

1. Insulin glargine composition patents.
2. High-concentration formulations.
3. Zinc-containing depot systems.
4. Excipient combinations and pH ranges.
5. Manufacturing and filling processes.
6. Pen and cartridge configurations.
7. Dosing methods for diabetes treatment.
8. Device-based delivery and dose-selection systems.

The original insulin glargine composition patents have largely reached the end of their principal commercial lives in major markets. The more relevant competitive barriers for U-300 are formulation-specific claims, device claims, manufacturing know-how, regulatory requirements, and clinical comparability.

Sanofi's commercial product is protected through a combination of patents, regulatory exclusivity history, trademarks, manufacturing controls, and device integration. The FDA approved Toujeo on February 25, 2015. Its three-year new-drug exclusivity period would have expired in February 2018, leaving patent and regulatory-comparability issues as the principal barriers to follow-on entry (FDA, 2015).

What is the Orange Book status of Toujeo?

Toujeo is an FDA-approved insulin glargine product. FDA moved insulin products from the Federal Food, Drug, and Cosmetic Act framework to the Public Health Service Act framework in March 2020. Approved insulin products are now regulated as biologics, and follow-on development generally proceeds through the 351(k) biosimilar pathway rather than the traditional abbreviated new drug application pathway (FDA, 2020).

That transition limits the usefulness of a conventional Orange Book analysis. A complete assessment requires review of FDA's current Approved Drug Products with Therapeutic Equivalence Evaluations, biologics databases, listed patents, reference-product exclusivity, and product-specific litigation records. Toujeo's risk profile differs from U-100 insulin glargine because a follow-on U-300 product must address the concentrated formulation and delivery system rather than replicate only the active insulin sequence.

What excipient strategies could create commercial opportunities?

Lower-polysorbate or surfactant-free formulations

Polysorbate 20 helps reduce surface-induced aggregation, but it can undergo oxidative and hydrolytic degradation. Degradation products may affect protein quality, particulates, color, and container compatibility.

Potential commercial approaches include:

• Reducing polysorbate 20 concentration while maintaining stability.
• Substituting polysorbate 80 or another approved surfactant.
• Using poloxamers or newer protein-compatible surfactants.
• Developing surfactant-free formulations supported by optimized containers and filling conditions.
• Applying lyophilization or alternative solid-state approaches for selected presentations.

For a concentrated insulin product, a lower-surfactant formulation must be evaluated against adsorption, agitation, freeze-thaw stress, shipping vibration, and pen-device contact surfaces.

Preservative replacement or reduction

m-Cresol is widely used in multidose insulin formulations. It provides antimicrobial protection but can affect local tolerability and may complicate formulation differentiation.

Potential opportunities include:

• Lower m-cresol concentration.
• Alternative phenolic preservatives.
• Preservative systems optimized for single-use cartridges.
• Device architectures that reduce repeated microbial exposure.
• Preservative-free presentations for specific institutional or specialty markets.

A preservative change would require microbiological efficacy testing, extractables and leachables work, container-closure validation, and clinical assessment of injection-site effects.

Zinc optimization

Zinc is a high-value formulation variable because it directly affects the depot and release profile. Commercial opportunities include:

• Narrowing zinc concentration ranges to reduce batch variability.
• Developing alternative zinc salts.
• Adjusting zinc-to-insulin ratios for more predictable precipitation.
• Designing formulations with a flatter release curve.
• Creating concentrated products with lower injection volume and reduced dose burden.

Zinc optimization also creates patent opportunities because the relationship among zinc level, insulin concentration, pH, and duration can support composition and method-of-use claims.

Glycerol and osmolality control

Glycerol contributes to tonicity and formulation consistency. Adjusting glycerol concentration may affect injection comfort, solution viscosity, and compatibility with pen components.

A lower-viscosity formulation could support:

• Faster dose delivery.
• Smaller-gauge needles.
• Reduced injection force.
• Improved performance in high-dose pens.
• Better suitability for autoinjector systems.

Any change must preserve insulin stability and avoid altering the subcutaneous depot in a way that changes clinical exposure.

How does insulin glargine U-300 compare with insulin glargine U-100?

Attribute	Insulin glargine U-100	Insulin glargine U-300
Concentration	100 units/mL	300 units/mL
Commercial reference	Lantus and follow-on products	Toujeo
Injection volume for the same dose	Higher	Approximately one-third of U-100 volume
Depot behavior	Established basal profile	More concentrated, prolonged depot
Primary commercial advantage	Broad availability and lower-cost competition	Lower volume and extended basal coverage
Device importance	High	Very high because dose conversion and maximum dose per injection matter
Biosimilar competition	More developed	More limited and technically complex
Excipient differentiation	Moderate	High because excipients influence depot and release behavior

Toujeo is not interchangeable with insulin glargine U-100 on a unit-for-unit basis without clinical direction. The FDA label reports that patients switching from U-100 to U-300 may require a higher daily dose to achieve comparable glycemic control, reflecting differences in pharmacokinetics and bioavailability (FDA, 2024).

What generic and biosimilar entry risks exist for U-300?

The most credible near-term competitive risk is not a conventional generic substitution. It is a follow-on insulin glargine U-300 product developed through the biosimilar pathway or as a separately approved concentrated insulin formulation.

A challenger would need to address:

• Analytical similarity of insulin glargine.
• Concentration accuracy at 300 units/mL.
• Impurity and aggregation profiles.
• Zinc-mediated depot formation.
• Pharmacokinetic and pharmacodynamic similarity.
• Pen-dose accuracy and delivery-force performance.
• Cartridge and container compatibility.
• Human factors and labeling.
• Interchangeability requirements, if pursued.
• Manufacturing scale and cold-chain distribution.

The device is a major barrier. A biosimilar manufacturer could initially use a vial or its own pen rather than replicate the SoloStar or Max SoloStar platform. That approach could reduce device patent exposure but would weaken substitution convenience and payer uptake.

Which companies are positioned to challenge insulin glargine U-300?

Major insulin manufacturers with relevant capabilities include Eli Lilly, Novo Nordisk, Biocon Biologics, Viatris, Wockhardt, Ypsomed, and regional insulin producers. Their ability to compete depends on more than insulin glargine manufacturing.

Company type	Competitive capability	Likely U-300 opportunity
Global insulin manufacturers	Protein production, clinical development, regulatory infrastructure	Full biosimilar or follow-on product
Biosimilar specialists	Analytical similarity and lower-cost biologics manufacturing	Price-focused U-300 challenger
Device companies	Pen and cartridge technology	Licensing or co-development
Excipient suppliers	Stabilizers, surfactants, preservatives	Formulation-enabling partnerships
Contract manufacturers	Fill-finish and aseptic processing	Outsourced supply for regional entrants
Regional insulin companies	Local regulatory and distribution access	Country-specific U-300 products

Licensing opportunities are strongest in three areas: high-concentration insulin analytics, pen-device platforms, and excipient systems that preserve depot behavior while reducing cost or injection discomfort. No single excipient change is likely to create a commercially viable product without supporting device and regulatory development.

What regulatory pathway applies to a new U-300 product?

A new insulin glargine U-300 product would generally require a biologics regulatory strategy. In the United States, the 351(k) biosimilar pathway may be available where the product can demonstrate biosimilarity to the reference product. A materially different excipient system, delivery device, or release profile could require a more extensive 351(a) development program.

Key regulatory workstreams include:

• Comparative analytical characterization.
• Forced-degradation and stability studies.
• Pharmacokinetic and euglycemic clamp studies.
• Immunogenicity assessment.
• Device compatibility and dose accuracy.
• Human factors validation.
• Container-closure integrity.
• Extractables and leachables.
• In-use stability after first puncture or pen activation.
• Global bridging across presentations and strengths.

The choice of excipients affects regulatory risk. A well-known excipient at an established parenteral concentration may simplify the review. A novel surfactant or preservative may improve differentiation but increase toxicology, compatibility, and clinical requirements.

How strong is the patent estate for insulin glargine U-300?

The estate is strongest where formulation and device claims overlap. Active-ingredient patents alone provide limited protection because insulin glargine is an established molecule and U-100 follow-on products are commercially available.

The main defensive strengths are:

• Concentrated formulation know-how.
• Zinc and pH control.
• Long-acting depot performance.
• Pen and cartridge integration.
• Manufacturing consistency at high concentration.
• Clinical data supporting dosing and switching.
• Regulatory complexity associated with biosimilarity and interchangeability.

The main weaknesses are the maturity of insulin glargine technology, the expiration of early composition protection, and the availability of alternative insulin manufacturing platforms. A challenger can avoid some device claims by launching a vial or a different pen, although that may reduce market access.

What manufacturing and IP barriers affect commercial entry?

High-concentration insulin manufacturing requires tight control of:

• Protein concentration.
• Zinc stoichiometry.
• pH.
• Mixing and hold times.
• Sterile filtration.
• Low-shear filling.
• Particulate formation.
• Adsorption to process surfaces.
• Container-closure integrity.
• Pen dose delivery.

Manufacturing know-how can remain commercially important after patent expiry. Process controls that reduce aggregation or batch-to-batch variability may be difficult to reproduce from public disclosures. Suppliers of specialized tubing, low-binding contact materials, cartridges, siliconization systems, and aseptic fill-finish capacity can capture value even without owning the insulin product.

What is the commercial outlook for U-300 excipient suppliers?

The most attractive opportunities are enabling technologies rather than commodity excipient supply. Suppliers can pursue:

1. Low-peroxide surfactants for concentrated insulin.
2. Protein-compatible alternatives to polysorbate 20.
3. Preservative systems with lower injection-site burden.
4. Zinc-control technologies that improve depot reproducibility.
5. Low-binding primary containers.
6. Pen-compatible elastomers and lubricants.
7. Analytical methods for aggregation and subvisible particles.
8. Contract development packages linking formulation, device, and fill-finish performance.

The commercial value is highest when the excipient package supports a patentable formulation, improves product stability, or reduces manufacturing losses. A lower-cost version that does not deliver equivalent pharmacokinetics or device performance has limited substitution potential.

Key Takeaways

• Insulin glargine U-300 uses zinc chloride, m-cresol, glycerol, polysorbate 20, pH adjusters, and water for injection.
• Zinc, pH, concentration, and injection volume jointly determine the subcutaneous depot and release profile.
• The strongest commercial opportunities involve surfactant reduction, preservative optimization, zinc control, low-binding containers, and pen compatibility.
• U-300 competition is more likely to emerge through biosimilar or follow-on biologic development than through a traditional generic pathway.
• Device integration is a major competitive barrier and a major licensing opportunity.
• Core insulin glargine composition protection is less important than formulation, process, device, and regulatory barriers.
• Excipient changes can create new IP but may also trigger broader clinical and regulatory requirements.
• A commercially viable challenger must reproduce the pharmacokinetic behavior of U-300, not merely its insulin sequence and concentration.

FAQs

Can insulin glargine U-300 be reformulated without zinc?

A zinc-free formulation is technically possible but would need to demonstrate equivalent depot formation, duration, stability, and pharmacodynamic performance. Removing zinc would materially change the formulation risk profile.

Is polysorbate 20 essential in Toujeo?

Polysorbate 20 is part of the approved Toujeo formulation and helps control interfacial aggregation and adsorption. An alternative formulation may use a different surfactant or no surfactant, but it would require new stability and comparability data.

Can a U-300 biosimilar use different excipients?

A biosimilar may use different inactive ingredients if the product remains highly similar and the differences do not affect safety, purity, potency, or clinical performance. A major excipient change can increase development and regulatory requirements.

Are insulin glargine U-100 and U-300 interchangeable?

They are not automatically interchangeable on a unit-for-unit basis. The FDA label identifies clinically relevant differences in dosing and exposure, and switching requires medical supervision.

What is the highest-value formulation patent opportunity for U-300?

The strongest opportunity is a formulation claim linking high insulin concentration with a defined zinc level, pH range, stabilizer system, and sustained-release performance. Device and manufacturing claims can add protection where the formulation alone is vulnerable.

References

1. Sanofi. (2024). Toujeo insulin glargine injection prescribing information. U.S. Food and Drug Administration.

2. U.S. Food and Drug Administration. (2015). FDA approves Toujeo to treat diabetes. https://www.fda.gov

3. U.S. Food and Drug Administration. (2020). Transition plans for insulin and other biological products regulated under the Federal Food, Drug, and Cosmetic Act. https://www.fda.gov

4. Becker, R. H. A., Dahmen, R., Bergmann, K., Lehmann, A., Jax, T., & Heise, T. (2015). New insulin glargine 300 U/mL provides a more even activity profile and prolonged glycemic control at steady state compared with insulin glargine 100 U/mL. Diabetes Care, 38(4), 637-643.

5. Owens, D. R. (2011). Glargine and its duration of action. Diabetes Technology & Therapeutics, 13(Suppl. 1), S5-S14.

6. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. https://www.fda.gov/drugsatfda