List of Excipients in Branded Drug EVZIO

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
kaleo Inc	EVZIO	naloxone hydrochloride	60842-051	HYDROCHLORIC ACID
kaleo Inc	EVZIO	naloxone hydrochloride	60842-051	SODIUM CHLORIDE
kaleo Inc	EVZIO	naloxone hydrochloride	60842-051	WATER

Evzio Excipient Strategy and Commercial Opportunities for Naloxone Auto-Injectors

Last updated: August 25, 2026

Evzio is a single-dose naloxone hydrochloride auto-injector developed by kaleo for emergency treatment of known or suspected opioid overdose. Its formulation uses a low-complexity, aqueous, preservative-free strategy: naloxone hydrochloride in water for injection, with sodium chloride for tonicity and hydrochloric acid for pH adjustment. The commercial value is concentrated in the delivery system, human-factors design, packaging, and distribution model rather than in a complex excipient platform. [1]

The strongest opportunities are next-generation naloxone products with improved shelf life, lower manufacturing cost, broader public-access distribution, pediatric or weight-based dosing, and differentiated delivery formats.

What excipients are used in Evzio?

Evzio contains naloxone hydrochloride in an aqueous solution. The FDA-approved prescribing information identifies the inactive formulation components as sodium chloride, hydrochloric acid, and water for injection. Hydrochloric acid is used for pH adjustment rather than as a functional therapeutic excipient. [1]

Component	Function in Evzio	Commercial relevance
Naloxone hydrochloride	Active pharmaceutical ingredient	Competitive API sourcing and concentration control
Sodium chloride	Tonicity adjustment	Supports injection tolerability and solution compatibility
Hydrochloric acid	pH adjustment	Controls naloxone stability and solution performance
Water for injection	Vehicle	Standard parenteral solvent
Preservative	Not identified in the FDA label	Supports single-use, preservative-free positioning

Evzio is supplied as a 2 mg dose in 0.4 mL, equivalent to a 5 mg/mL naloxone hydrochloride concentration. The solution is designed for intramuscular or subcutaneous administration through an integrated auto-injector. [1]

Why does Evzio use a simple excipient system?

Naloxone is a small, water-soluble opioid antagonist that can be formulated as an acidic aqueous solution. A simple formulation reduces risks related to:

• Particulate formation
• Excipient incompatibility
• Container-closure interactions
• Sterilization complexity
• Injection-site tolerability
• Regulatory comparability

The formulation does not require a lipid vehicle, surfactant, suspension system, complexing agent, or lyophilization cycle. That limits formulation patent breadth but can reduce development and scale-up costs.

How does Evzio’s excipient strategy affect product performance?

The principal formulation objectives are chemical stability, sterility, dose uniformity, and reliable delivery after long-term storage.

pH control

Naloxone hydrochloride is formulated as an acidic aqueous solution. pH adjustment can affect:

• Naloxone degradation rate
• Solubility
• Container-closure compatibility
• Injection-site tolerability
• Autoinjector material compatibility

A follow-on product could pursue a distinct pH range, buffer system, or stabilizing environment, but any change would require supporting stability and compatibility data. The regulatory burden would be higher if the change altered degradation products, injection tolerability, or device performance.

Tonicity

Sodium chloride provides a familiar approach to tonicity adjustment. A competitor could evaluate alternative tonicity agents, including dextrose or other pharmaceutically acceptable salts. The commercial benefit would likely be limited unless the alternative improves stability, reduces pain, or solves a device-material problem.

Preservative-free design

A single-use emergency injection does not require repeated withdrawals from a multidose container. Avoiding preservatives reduces the risk of:

• Local irritation
• Hypersensitivity
• Compatibility issues with elastomers and plastics
• Additional extractables and leachables
• Labeling complexity

A preservative-containing formulation could support a multidose presentation, but the market would need to justify the added formulation and safety burden.

Water-based delivery

The aqueous vehicle supports rapid release and avoids the manufacturing burden of suspension products. It also makes the formulation compatible with conventional sterile filling, subject to container-closure and device validation.

What FDA regulatory status does Evzio have?

Evzio was approved by the FDA in April 2014 under NDA 208411 for the emergency treatment of opioid overdose. The product was designed for administration by laypersons or caregivers and incorporated voice instructions into the device. [1,2]

Regulatory item	Evzio status
Active ingredient	Naloxone hydrochloride
Dosage form	Injectable solution in an auto-injector
Route	Intramuscular or subcutaneous
Approved dose	2 mg in 0.4 mL
NDA	208411
Approval pathway	505(b)(1) NDA
Therapeutic category	Opioid antagonist
Biosimilar pathway	Not applicable
FDA exclusivity type	New chemical entity exclusivity was not available because naloxone was previously approved
Device component	Integrated voice-guided auto-injector

Naloxone is a small molecule, so biosimilar competition is not relevant. Competitive entry occurs through abbreviated new drug applications, 505(b)(2) applications, nasal products, conventional injections, and device-based delivery systems.

What patents protect Evzio and its delivery system?

Evzio’s commercial protection is more closely associated with device configuration, automated injection, voice guidance, packaging, and use instructions than with the basic naloxone solution.

The core excipient combination is unlikely to provide strong standalone protection because sodium chloride, hydrochloric acid, and water for injection are conventional parenteral ingredients. A competitor could potentially use the same functional formulation with a different device and labeling strategy, subject to regulatory requirements and any surviving patent claims.

Relevant protection may arise from:

• Auto-injector architecture
• Needle deployment and retraction
• Dose delivery sequence
• Electronic voice guidance
• Audio and visual user instructions
• Tamper-evident packaging
• Two-device emergency kits
• Storage and activation features
• Device-use methods for opioid overdose

Patent scope and enforceability depend on the specific claims, maintenance status, terminal disclaimers, prosecution history, and litigation record. FDA Orange Book listings for an NDA do not capture every device or packaging patent that may affect market entry. [3]

What patent strategy is available for an Evzio follow-on?

A follow-on developer could pursue patents in five areas:

1. Formulation patents: pH-controlled naloxone solutions, stabilizer systems, low-volume high-concentration formulations, or improved storage stability.
2. Device patents: compact autoinjectors, needle-shielding systems, dose confirmation, and simplified activation.
3. Combination patents: naloxone paired with emergency instructions, rescue kits, or other overdose-response components.
4. Use patents: administration protocols based on patient weight, opioid exposure, recurrence of respiratory depression, or repeated dosing.
5. Manufacturing patents: sterile filling, device assembly, low-temperature processing, and container-closure systems.

Formulation claims must overcome prior-art risk because aqueous naloxone injections and conventional tonicity agents have long been known. Device and human-factors claims may provide more defensible differentiation.

When does Evzio lose exclusivity?

Evzio’s product-specific exclusivity and patent protection are separate issues.

The FDA approved Evzio in 2014, but naloxone itself had long been approved. The product therefore did not receive the five-year new chemical entity exclusivity associated with a new active ingredient. Any pediatric exclusivity, orphan exclusivity, or other regulatory exclusivity would depend on FDA records for the specific NDA and indication. [2,3]

The practical loss of exclusivity depends on:

• Listed patents and their expiration dates
• Whether patents were submitted to the Orange Book
• Patent-term adjustment or extension
• Generic applicant certifications
• Paragraph IV litigation
• Device substitutability
• Whether an applicant seeks the same dosage form
• Availability of alternative naloxone products

A generic injection does not automatically substitute for an auto-injector. A nasal naloxone product also competes commercially but follows a different dosage form and device pathway.

What is the Orange Book status of Evzio?

The Orange Book is the principal FDA source for approved drug products, patent listings, and regulatory exclusivity. Evzio should be evaluated by NDA number and product presentation rather than by active ingredient alone. [3]

The key commercial distinction is between:

• The naloxone drug substance
• The injectable drug product
• The auto-injector device
• The voice-guidance system
• Packaging and kit configurations

Orange Book-listed patents generally address the drug product or drug-device combination as submitted to FDA. Separate utility, design, or international patents may not appear in the Orange Book.

A generic applicant challenging an applicable listed patent could file a Paragraph IV certification. The NDA holder could then initiate patent litigation, potentially triggering a 30-month stay under the Hatch-Waxman framework, subject to statutory conditions and court developments. [4]

Which companies are challenging or competing with Evzio?

Competition comes from several product categories rather than from a single direct generic equivalent.

Competitor category	Representative products or companies	Competitive effect
Naloxone nasal spray	Emergent’s Narcan; Teva’s generic naloxone nasal spray	Strongest public-access and pharmacy competition
Conventional naloxone injection	Hospira, Amphastar and other injectable suppliers	Lower-cost institutional alternative
Prefilled syringes	Multiple injectable manufacturers	Simplifies administration without an autoinjector
Auto-injectors	Device-based naloxone developers	Closest functional competition
Community overdose kits	Public-health agencies, pharmacies, distributors	Expands access outside traditional prescription channels

The principal competitive threat is nasal naloxone. It avoids needles, has a simpler user interface, and fits public-health distribution programs. Evzio’s counterposition is guided operation, compact packaging, and a device designed for users with no injection experience.

What formulation patents could create new commercial value?

The most commercially attractive formulation opportunities are those that solve a measurable problem.

Higher concentration and lower volume

A higher-concentration solution could reduce injection volume and enable smaller devices. The benefit must be balanced against local tolerability, dose accuracy, and API solubility.

Extended shelf life

A formulation that maintains potency under elevated temperature or humidity could improve distribution in ambulances, shelters, schools, correctional facilities, and remote locations. Stability claims would need to be supported by real-time and accelerated studies.

Device-compatible formulations

Formulations can be optimized for:

• Elastomer compatibility
• Low extractables and leachables
• Reduced viscosity
• Reliable autoinjector actuation
• Minimal foaming
• Consistent dose delivery across temperature ranges

These attributes could support combination formulation-device patent claims.

Pediatric or weight-adjusted dosing

A calibrated lower-dose presentation could address pediatric use or reduce unnecessary exposure where clinically appropriate. Separate doses, device color coding, and human-factors controls may be more commercially defensible than a new excipient alone.

Multidose or refill systems

A multidose system could reduce packaging costs for professional responders. It would require a different preservative, sterility, and container-closure strategy and may not be suitable for unsupervised public use.

What manufacturing and IP barriers affect Evzio competitors?

The active ingredient is not the main barrier. Manufacturing difficulty is concentrated in the combination product.

Key barriers include:

• Sterile filling at small fill volumes
• Accurate dose control
• Long-term stability in the final container
• Autoinjector assembly
• Needle-shield and activation reliability
• Human-factors validation
• Voice or electronic instruction systems
• Extractables and leachables testing
• Transportation qualification
• Child-resistant and tamper-evident packaging
• Combination-product quality systems

A company can reproduce a simple naloxone formulation but still fail to commercialize a reliable auto-injector. Device defects, misfires, incomplete needle deployment, or confusing activation steps can create regulatory, recall, and liability exposure.

What licensing deals could support an Evzio-type product?

Licensing opportunities are available in four areas:

1. Naloxone API supply: Dual-source or regional manufacturing agreements can protect against shortages.
2. Autoinjector platforms: A developer can license a validated platform rather than build a device from the ground up.
3. Human-factors and electronic instruction systems: Voice-guidance technology can differentiate a product but adds software and hardware obligations.
4. Public-health distribution: Partnerships with pharmacies, insurers, emergency medical systems, schools, employers, and government agencies can expand market access.

The most valuable deal structure would combine device rights, manufacturing capacity, regulatory support, and distribution commitments. A formulation-only license would likely have lower value because the excipient system is conventional.

How strong is the patent estate for Evzio?

Evzio’s formulation patent position is likely weaker than its device and product-design position. Conventional ingredients such as sodium chloride, hydrochloric acid, and water for injection offer limited room for broad claims. Patent strength may improve where the claims are tied to:

• A specific concentration and fill volume
• Defined stability performance
• A particular container-closure system
• Device-formulation compatibility
• Automated administration
• User instructions integrated into the product

The estate should be assessed claim by claim. Broad functional claims may face enablement, written-description, and prior-art challenges. Narrow device claims may be easier to enforce but easier to design around.

What generic launch scenarios exist for Evzio?

Three entry scenarios are commercially plausible:

Scenario 1: Conventional injectable entry

A low-cost injectable product enters hospitals and emergency systems. This affects institutional pricing but does not fully replace a layperson-oriented auto-injector.

Scenario 2: Nasal naloxone displacement

A nasal product captures public-health, pharmacy, and household demand because it eliminates needle handling. This is the most direct threat to the emergency-use proposition.

Scenario 3: Device-equivalent entry

A competing auto-injector matches Evzio’s ease of use while reducing price. This would create the greatest direct pressure but requires substantial device development and regulatory validation.

Excipient similarity alone does not determine substitutability. Device design, FDA product classification, labeling, pharmacy-channel rules, and payer treatment determine the commercial impact.

What revenue exposure is associated with Evzio?

Evzio’s revenue exposure is tied to the broader naloxone market rather than to formulation complexity. The product competes in a market shaped by opioid-overdose policy, public-health procurement, standing orders, insurance coverage, and OTC availability.

Revenue drivers include:

• Public-sector purchasing
• Pharmacy dispensing
• Emergency medical services
• Employer and school programs
• Correctional facilities
• Harm-reduction organizations
• Insurance reimbursement
• Institutional emergency kits

Nasal naloxone has expanded the addressable market, while low-cost injectables constrain pricing. An Evzio-type product can command a premium only if the device reduces training requirements, improves successful administration, or meets procurement requirements that alternatives do not satisfy.

Key Takeaways

• Evzio uses a simple aqueous naloxone hydrochloride formulation with sodium chloride, hydrochloric acid, and water for injection.
• The formulation is preservative-free according to the FDA prescribing information.
• The core excipient combination offers limited standalone patent leverage.
• The strongest IP opportunities involve the auto-injector, voice guidance, packaging, device compatibility, and stability performance.
• Naloxone has no biosimilar risk because it is a small molecule.
• Nasal naloxone is the principal commercial competitor, while conventional injections compete on cost.
• A follow-on developer can create value through longer shelf life, smaller dose volume, improved device reliability, pediatric presentations, or public-access distribution.
• The key manufacturing barrier is the combination product, not the aqueous naloxone formulation.
• Paragraph IV risk depends on active listed patents, claim scope, certification strategy, and litigation timing.
• Licensing value is highest in validated devices, API supply, combination-product manufacturing, and distribution access.

FAQs

Can a competitor use the same Evzio excipients?

A competitor may be able to use a similar naloxone solution if it does not infringe valid patent claims and satisfies FDA quality, stability, sterility, and device requirements. The excipients themselves are conventional.

Is Evzio protected by a formulation patent?

Any formulation protection would depend on specific claims covering concentration, pH, stability, container closure, or device compatibility. A simple sodium chloride, hydrochloric acid, and water system is unlikely to support broad protection by itself.

Does naloxone require a biosimilar approval pathway?

No. Naloxone is a small-molecule drug. Competitive products generally use an ANDA, 505(b)(2) application, or a conventional NDA, depending on the product and delivery system.

What is the best excipient opportunity for a new naloxone auto-injector?

The strongest opportunity is a formulation that improves stability across temperature conditions, supports a smaller injection volume, or improves compatibility with the selected autoinjector materials.

Can a nasal naloxone product replace Evzio?

A nasal product can replace Evzio for many layperson and public-health uses, but it is not automatically substitutable in every pharmacy, institutional, or emergency-response setting. Delivery route, labeling, procurement rules, and device requirements control the practical competition.

References

1. U.S. Food and Drug Administration. (2018). Evzio (naloxone hydrochloride injection) prescribing information. kaleo, Inc.

2. U.S. Food and Drug Administration. (2014). FDA approves new auto-injector to rapidly reverse opioid overdose. https://www.fda.gov

3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

4. U.S. Food and Drug Administration. (2023). Hatch-Waxman amendments and abbreviated new drug applications. https://www.fda.gov/drugs Abbreviated New Drug Application (ANDA) process.