List of Excipients in Branded Drug TRESIBA

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Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
A-S Medication Solutions	TRESIBA	insulin degludec	50090-3491	GLYCERIN
A-S Medication Solutions	TRESIBA	insulin degludec	50090-3491	HYDROCHLORIC ACID
A-S Medication Solutions	TRESIBA	insulin degludec	50090-3491	METACRESOL

TRESIBA Excipient Strategy and Commercial Opportunities for Insulin Degludec

Last updated: September 7, 2026

TRESIBA is a long-acting basal insulin containing insulin degludec at 100 units/mL or 200 units/mL. Its commercial differentiation depends on insulin degludec's multihexamer depot, concentration flexibility, long shelf life, and FlexTouch pen platform. The excipient system is relatively simple: glycerol, metacresol, phenol, zinc, and pH-adjusting agents in water for injection. The strongest commercial opportunities are in follow-on insulin development, high-concentration delivery, excipient supply, device-compatible formulation work, and regional manufacturing.

What excipients are used in TRESIBA?

The TRESIBA formulation uses a small excipient package designed to preserve insulin degludec stability, support antimicrobial protection, and enable subcutaneous delivery.

Component	Function in formulation	Commercial relevance
Insulin degludec	Active pharmaceutical ingredient	Long-acting basal insulin
Glycerol	Tonicity and formulation stability	Commodity excipient with established injectable use
Metacresol	Antimicrobial preservative and protein-stabilizing excipient	Requires tight control because of concentration and tolerability
Phenol	Antimicrobial preservative and formulation stabilizer	Important for multidose pen compatibility
Zinc	Supports insulin association and degludec multihexamer formation	Critical functional excipient rather than an inert tonicity agent
Hydrochloric acid and sodium hydroxide	pH adjustment	Manufacturing and release-control materials
Water for injection	Vehicle	Standard parenteral solvent

The U.S. prescribing information identifies glycerol, metacresol, phenol, zinc, hydrochloric acid, sodium hydroxide, and water for injection as formulation components. TRESIBA is supplied as an injection at pH approximately 7.6.[1]

How does insulin degludec use excipients to achieve long action?

Insulin degludec is engineered to form a soluble multihexamer depot after subcutaneous injection. Zinc and formulation conditions support the association state before and after administration. Slow dissociation of insulin monomers from the depot produces the prolonged pharmacokinetic profile.

The excipient strategy therefore has two distinct functions:

1. It maintains the drug in a manufacturable and injectable state.
2. It supports the physical behavior that produces prolonged insulin release.

This differs from a conventional long-acting insulin strategy based primarily on precipitation or protamine complexation. Insulin glargine, for example, relies on pH-dependent precipitation after injection, while insulin detemir uses fatty-acid acylation and albumin binding. Insulin degludec's zinc-supported multihexamer mechanism creates a distinct formulation and intellectual-property profile.

What are the TRESIBA dosage forms and concentrations?

TRESIBA is marketed in two concentrations:

Product	Concentration	Principal commercial use
TRESIBA U-100 FlexTouch	100 units/mL	Basal insulin dosing across adult and pediatric populations
TRESIBA U-200 FlexTouch	200 units/mL	Patients requiring higher daily basal doses with lower injection volume

The U-200 product provides the same number of insulin units in half the injection volume required by U-100. The higher concentration can improve injection burden for patients using high daily doses, but it creates more demanding requirements for dose-counter accuracy, pen-device engineering, container closure integrity, and human-factors validation.

The pen displays insulin units rather than volume. This reduces conversion errors for patients, but a competing product cannot assume that a simple concentration change will be commercially acceptable. The delivery device, dose accuracy, labeling, and training materials are part of the product strategy.

What excipient strategy is required for a TRESIBA follow-on product?

A follow-on developer has two principal options:

1. Formulation matching

The developer can reproduce the reference formulation's excipient composition and concentration range. This approach may reduce formulation risk and support comparative analytical work. It does not eliminate the need to establish biosimilarity or therapeutic equivalence through the applicable regulatory pathway.

The main technical risks are:

• Insulin degludec aggregation
• Loss of potency during storage
• Adsorption to manufacturing equipment or container surfaces
• Preservative interaction with the protein
• Zinc-mediated changes in association state
• Particulate formation
• Differences in injection force or pen performance
• Extractables and leachables from the primary container and device

2. Formulation differentiation

A developer may seek a proprietary formulation using alternative stabilizers, preservative systems, surfactants, buffers, or container materials. This could create a differentiated product, but it also increases regulatory and comparability risk.

Potential differentiation areas include:

• Lower injection volume
• Improved thermal stability for distribution in emerging markets
• Reduced sensitivity to agitation
• Longer in-use stability after first use
• Alternative preservative systems for patients with excipient sensitivities
• Compatibility with reusable pens or connected delivery systems
• Improved performance in prefilled cartridges or pump reservoirs

For a biosimilar or interchangeable insulin, formulation differentiation must not create clinically meaningful differences in safety, immunogenicity, potency, or delivery performance.

Which excipients create the greatest technical barriers?

Zinc

Zinc is a functional component of the insulin degludec delivery mechanism. Its concentration, ionic form, and interaction with the insulin molecule can affect hexamer formation, particle size, dissociation behavior, and stability.

Small changes in zinc control can create large differences in product performance. Zinc raw material quality, solution preparation, order of addition, mixing energy, and hold times require process controls.

Metacresol and phenol

Metacresol and phenol provide antimicrobial protection in the multidose pen. Their concentrations must balance microbial control, protein stability, container compatibility, and injection-site tolerability.

These preservatives can interact with elastomer closures, plastic components, and other materials in the delivery system. A developer using a different preservative package may need substantial stability, microbiological, toxicological, and device-compatibility data.

Glycerol

Glycerol is widely available and generally presents less strategic differentiation than zinc or preservatives. Its concentration affects osmolality, viscosity, and potentially injection force. Glycerol also has supply-chain value because pharmaceutical-grade material must meet compendial and bioburden requirements.

pH-adjusting agents

Hydrochloric acid and sodium hydroxide are inexpensive but operationally important. Final pH affects insulin solubility, aggregation, preservative performance, and container interaction. Tight pH control is central to batch release and stability.

What commercial opportunities exist in TRESIBA-related excipients?

Pharmaceutical-grade zinc supply

Specialty suppliers can compete on low-metal impurity profiles, lot consistency, traceability, and validated supply for insulin manufacturing. The opportunity is stronger where a manufacturer needs multi-site supply or regional production.

Preservative supply and formulation support

Metacresol and phenol suppliers can offer value through:

• High-purity material
• Low extractables profiles
• Consistent impurity packages
• Regulatory documentation
• Dual sourcing
• Compatibility studies with insulin and pen components

The excipients themselves are generally not high-margin products. The higher-value opportunity is bundled supply, analytical support, and formulation-development services.

High-concentration insulin platforms

U-200 insulin creates opportunities in:

• Prefilled pen manufacturing
• Dose-counter systems
• Cartridge filling
• Primary packaging
• Human-factors engineering
• Connected insulin delivery
• Automated inspection and particulate control

A company that can improve dose accuracy or reduce injection force may create commercial value without changing the active ingredient.

Thermal-stability and global-access formulations

Insulin supply in lower-resource markets is constrained by cold-chain requirements, transport interruptions, and storage conditions. A follow-on formulation with improved temperature excursion tolerance could address a significant commercial need, subject to regulatory approval.

The opportunity is not limited to a new excipient. It may involve a combined package of protein engineering, excipient selection, container design, packaging insulation, and distribution controls.

Contract development and manufacturing

CDMOs with expertise in recombinant proteins, sterile filling, insulin analytics, and pen assembly can pursue TRESIBA-related programs. Relevant capabilities include:

• Insulin degludec expression and purification
• High-resolution aggregate testing
• Zinc and preservative quantification
• Sterile formulation and filling
• Pen assembly
• Container closure integrity
• Device dose-accuracy testing
• Stability under temperature excursion

How does TRESIBA compare with competing basal insulins?

Product	Active ingredient	Long-acting mechanism	Formulation or device distinction
TRESIBA	Insulin degludec	Multihexamer depot with gradual monomer release	U-100 and U-200 FlexTouch pens
Lantus	Insulin glargine	pH-dependent precipitation after injection	U-100 and concentrated presentations in some markets
Toujeo	Insulin glargine	More concentrated glargine formulation	U-300 delivery platform
Levemir	Insulin detemir	Albumin binding through fatty-acid acylation	Historically supplied in pen and vial formats
Basaglar	Insulin glargine	Glargine precipitation mechanism	Follow-on insulin glargine
Semglee	Insulin glargine-yfgn	Glargine precipitation mechanism	FDA-approved interchangeable biosimilar to Lantus

TRESIBA's key formulation advantage is the combination of extended duration and high-concentration delivery. Its principal competitive vulnerability is that follow-on developers can target the insulin class with lower-cost products, even when direct substitution is limited by product-specific approvals and device differences.

What is the FDA regulatory status of TRESIBA?

The FDA approved TRESIBA in September 2015 for improving glycemic control in adults and, later, pediatric patients with diabetes mellitus. The product is regulated as a drug rather than a conventional small-molecule generic. A follow-on product may pursue a biosimilar pathway under section 351(k) of the Public Health Service Act or another applicable pathway, depending on the product and development strategy.

TRESIBA's regulatory considerations include:

• Insulin degludec identity and structural characterization
• Potency and receptor activity
• Primary and higher-order structure
• Aggregation and particulate profile
• Immunogenicity
• Pharmacokinetic and pharmacodynamic comparability
• Device performance
• Human-factors validation
• Preservative and container compatibility

The FDA's insulin guidance and biosimilar guidance are central to development planning.[2,3]

What is the Orange Book status of TRESIBA?

TRESIBA is listed in the FDA Orange Book under insulin degludec products associated with Novo Nordisk. Orange Book treatment does not make every formulation, device, manufacturing process, or method-of-use patent commercially decisive. The relevant patent landscape can include:

• Insulin degludec composition patents
• Insulin derivative or analog patents
• Multihexamer or depot-related patents
• Formulation patents
• Pen-device patents
• Manufacturing-process patents
• Method-of-treatment patents

Patent listings and expiration dates can change through correction, litigation, terminal-disclaimer, pediatric-exclusivity, or administrative events. Commercial entry analysis must therefore use the current FDA Orange Book, USPTO records, and court dockets rather than rely on a single reported expiry date.[4,5]

When does TRESIBA lose exclusivity?

TRESIBA's five-year new chemical entity exclusivity period began with its initial U.S. approval and has expired. Later regulatory protections, patent rights, and any product-specific exclusivity must be evaluated separately.

Regulatory exclusivity and patent exclusivity are different:

Protection	Relevance to TRESIBA
New chemical entity exclusivity	Historical five-year protection linked to initial approval
Pediatric exclusivity	May extend applicable exclusivity or patent periods if awarded
Listed patents	Can support patent litigation against an ANDA applicant
Device patents	May affect pen-based competition but may not block a vial or cartridge product
Formulation patents	Can delay a closely matched formulation
Manufacturing patents	May raise freedom-to-operate issues without preventing all market entry
Biosimilar interchangeability	May affect pharmacy substitution and contracting

A generic or biosimilar applicant can challenge listed patents through a Paragraph IV certification where the relevant pathway permits it. The commercial timing then depends on litigation, settlement terms, regulatory review, and the applicant's ability to launch a non-infringing product.

Which companies are challenging TRESIBA?

Publicly identifying a TRESIBA challenger requires current FDA filings and federal court records. A company may prepare a biosimilar or follow-on insulin program without an immediately visible commercial launch. Paragraph IV activity, if filed, is tied to the applicable abbreviated pathway and listed patents.

The more probable competitive routes are:

1. A biosimilar or follow-on insulin degludec product.
2. A lower-cost basal insulin from another molecular platform.
3. A concentrated insulin product using a different active ingredient.
4. A device-led product that competes through convenience and contracting.
5. Regional products manufactured under local regulatory pathways.

The market will likely reward products that combine lower price with reliable pen supply, rather than excipient substitution alone.

What patent litigation and settlement risks affect commercial entry?

For TRESIBA, litigation risk can arise from claims directed to the insulin analog, formulation, manufacturing process, or delivery device. A successful Paragraph IV challenge to one patent does not necessarily clear the entire estate. A challenger may need to design around separate claims covering the active ingredient and pen system.

Settlement analysis should examine:

• Entry date
• Authorized-generic provisions
• Supply or license terms
• Restrictions on formulation or device design
• Geographic scope
• Patent-license field
• Manufacturing rights
• Interchangeability strategy
• Confidentiality and termination provisions

An excipient-only redesign rarely eliminates active-ingredient or device patent risk. It can, however, help create a non-infringing formulation if the patent claims are limited to specified excipient concentrations or combinations.

How strong is the TRESIBA patent estate?

The estate's practical strength depends on claim scope, remaining term, validity, enforceability, and the ability of competitors to design around individual claims. Active-ingredient and analog claims generally present a more significant barrier than claims limited to conventional excipients such as glycerol or pH adjusters.

The strongest potential barriers are likely to involve:

• The insulin degludec molecular structure
• Long-acting insulin derivatives
• Zinc-associated multihexamer behavior
• Specific formulation concentrations
• Pen-device architecture
• Manufacturing controls that preserve product quality

The weakest standalone barriers are usually broad claims to routine injectable excipients unless the claims link those excipients to a defined insulin structure or performance outcome.

What generic launch scenarios exist for TRESIBA?

Scenario 1: Direct biosimilar launch

A competitor launches a highly similar insulin degludec product with a compatible pen. Price competition is strongest if the product obtains interchangeability and secures payer formulary access.

Scenario 2: Non-interchangeable follow-on product

The product reaches the market but requires prescriber-directed switching. Commercial uptake depends on contracting, education, and device familiarity.

Scenario 3: Formulation or device design-around

The competitor uses a different excipient package or pen platform. This may reduce patent exposure but increase development and regulatory complexity.

Scenario 4: Regional manufacturing

A manufacturer targets markets where local approval and supply economics are more important than U.S. interchangeability. Excipient localization and cold-chain resilience become central.

Key Takeaways

• TRESIBA uses insulin degludec with glycerol, metacresol, phenol, zinc, pH adjusters, and water for injection.
• Zinc is the most functionally important excipient because it supports the insulin degludec multihexamer mechanism.
• Metacresol and phenol are central to multidose-pen preservation and device compatibility.
• U-200 concentration and FlexTouch delivery create commercial opportunities beyond the active ingredient.
• Follow-on developers must address protein comparability, preservative performance, device accuracy, and immunogenicity.
• Excipient substitution alone is unlikely to eliminate active-ingredient or device patent risk.
• The strongest opportunities are high-concentration insulin platforms, pen manufacturing, thermal-stability improvements, pharmaceutical-grade zinc supply, and insulin-focused CDMO services.
• Current Orange Book listings, USPTO records, FDA approvals, and litigation dockets are required for a definitive patent-expiry and Paragraph IV assessment.

FAQs

Can TRESIBA be reformulated without zinc?

A reformulation without zinc would need to preserve insulin degludec's required association and release behavior. Removing zinc could materially alter the product's physicochemical and pharmacodynamic profile and would create substantial comparability requirements.

Are metacresol and phenol interchangeable in insulin products?

They are not automatically interchangeable. Each preservative has different effects on antimicrobial performance, protein stability, container compatibility, toxicity assessment, and product quality.

Is TRESIBA U-200 protected separately from TRESIBA U-100?

The concentration, pen, formulation, and device claims may create separate intellectual-property issues. The practical answer depends on the current patent claims and the proposed competing product.

Can a biosimilar manufacturer use the same TRESIBA excipients?

A biosimilar may use the same excipients, subject to regulatory requirements and freedom-to-operate analysis. Matching the excipient system does not by itself establish biosimilarity or interchangeability.

Which TRESIBA-related input has the greatest supply-chain risk?

The most consequential risks are usually recombinant insulin degludec production, sterile filling, pen components, zinc quality, preservative supply, and cold-chain logistics. Conventional glycerol and pH-adjusting agents are generally easier to source than specialized insulin and device inputs.

References

1. U.S. Food and Drug Administration. (2023). TRESIBA (insulin degludec) injection prescribing information. Novo Nordisk A/S.

2. U.S. Food and Drug Administration. (2019). Clinical immunogenicity considerations for biosimilar insulin products: Guidance for industry.

3. U.S. Food and Drug Administration. (2019). Questions and answers on biosimilar development and the BPCI Act: Guidance for industry.

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

5. United States Patent and Trademark Office. (2024). Patent Center and patent term adjustment information.