List of Excipients in Branded Drug INOMAX

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
INO Therapeutics LLC	INOMAX	nitric oxide	64693-002	NITROGEN

INOmax Excipient Strategy and Commercial Opportunities in Inhaled Nitric Oxide

Last updated: August 23, 2026

INOMAX, marketed as INOmax, is a nitric oxide inhalation product supplied as a calibrated gas mixture rather than a conventional liquid or solid pharmaceutical. Its formulation contains nitric oxide diluted in nitrogen, with no traditional excipients such as solvents, preservatives, surfactants, or stabilizers. Commercial value therefore concentrates on gas purity, cylinder logistics, delivery-device integration, dose monitoring, nitrogen dioxide control, and hospital workflow rather than on conventional formulation differentiation.

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

INOmax contains nitric oxide as the active ingredient and nitrogen as the balance gas. The U.S. prescribing information describes the product as nitric oxide for inhalation supplied in compressed-gas cylinders at specified concentrations, including 1000 ppm and other labeled strengths depending on presentation and market configuration (Mallinckrodt Pharmaceuticals, 2023).

Formulation element	Function	Commercial relevance
Nitric oxide	Active pulmonary vasodilator	Must reach the patient at a controlled concentration
Nitrogen	Diluent and carrier gas	Supports cylinder stability, metering, and delivery
Oxygen in the patient circuit	Therapeutic co-administered gas	Can react with nitric oxide to form nitrogen dioxide
Water vapor	Circuit environmental component	Affects material compatibility and monitoring
No conventional excipients	No liquid or solid formulation matrix	Reduces formulation complexity but increases device dependence

INOmax is used with mechanical ventilation or other approved respiratory delivery systems. The product does not rely on an excipient to improve solubility, absorption, taste, stability, or release kinetics. Its formulation strategy is a controlled gas composition combined with validated delivery hardware.

Does INOmax contain nitrogen dioxide or preservatives?

Nitrogen dioxide is not an intended excipient. It is a degradation and reaction product that can form when nitric oxide contacts oxygen. The prescribing information requires monitoring of inspired nitric oxide and nitrogen dioxide concentrations and defines controls for nitrogen dioxide exposure (Mallinckrodt Pharmaceuticals, 2023).

The absence of preservatives is commercially important. A competing product does not gain a conventional preservative-free advantage because INOmax is already a gas product administered through a closed or semi-closed respiratory circuit.

How does nitric oxide formulation stability affect excipient strategy?

INOmax stability depends on gas composition, cylinder integrity, moisture control, temperature, oxygen exposure, and validated delivery equipment. The principal chemical risk is oxidation of nitric oxide to nitrogen dioxide.

The formulation and delivery system must control:

1. Nitric oxide concentration over the product shelf life.
2. Formation of nitrogen dioxide during storage and administration.
3. Adsorption or reaction of nitric oxide with cylinder and circuit materials.
4. Delivery accuracy at changing ventilator flows.
5. Dose continuity during cylinder changes or transport.
6. Alarm performance when gas concentration deviates from the prescribed range.

This shifts formulation development toward container-closure and device engineering. Relevant development work includes cylinder metallurgy, internal surface treatment, regulators, tubing, flow sensors, analyzers, and software logic.

What materials are important for INOmax manufacturing and delivery?

Materials in contact with the gas must resist oxidation and avoid catalyzing nitric oxide conversion. Commercial systems generally require validated gas-compatible regulators, tubing, connectors, flow-control components, and analyzers. The precise material specifications and surface treatments are typically controlled through product-development documentation, supplier qualification, and device validation.

This creates an IP and manufacturing barrier even when the active ingredient itself is chemically simple. A low-cost gas supplier would still need validated packaging, calibrated concentration, compatible delivery equipment, quality systems, and hospital acceptance.

What FDA regulatory status does INOmax have?

INOmax is an FDA-approved nitric oxide inhalation product under NDA 20-845. The approved indication is improvement of oxygenation and reduction of the need for extracorporeal membrane oxygenation in term and near-term neonates with hypoxic respiratory failure associated with clinical or echocardiographic evidence of pulmonary hypertension (U.S. Food and Drug Administration, 1999; Mallinckrodt Pharmaceuticals, 2023).

Regulatory item	Status
Active ingredient	Nitric oxide
Dosage form	Gas for inhalation
FDA pathway	New drug application
Original U.S. approval	1999
Core approved population	Term and near-term neonates with hypoxic respiratory failure
Administration	Inhaled through a validated respiratory delivery system
Primary safety controls	Nitrogen dioxide monitoring, methemoglobin monitoring, controlled delivery

The label warns about methemoglobinemia, rebound pulmonary hypertension, worsening oxygenation, and nitrogen dioxide toxicity. These risks increase the importance of monitoring equipment and trained administration.

What patents protect INOmax and its delivery system?

The commercial protection of INOmax is likely broader than any single formulation patent. It can include:

• Gas composition and concentration ranges.
• Cylinder filling and purification methods.
• Gas delivery systems.
• Nitric oxide and nitrogen dioxide analyzers.
• Ventilator integration.
• Automated concentration control.
• Alarm and fail-safe systems.
• Methods of treating neonatal pulmonary hypertension.
• Device-specific disposable components.

The active compound, nitric oxide, is an old and well-characterized molecule. Composition-of-matter exclusivity for nitric oxide is not a realistic long-term barrier. The defensible IP position is more likely to involve delivery technology, monitoring, manufacturing controls, and method-of-use claims.

What is the Orange Book status of INOmax?

The FDA Orange Book is the relevant source for patent and exclusivity listings associated with an approved small-molecule drug application. INOmax is approved as a drug product, but the practical scope of any listed patents must be assessed against the current Orange Book entry for NDA 20-845 and the relevant supplements (U.S. Food and Drug Administration, n.d.-a).

A competitor should separate three issues:

Issue	Relevance to INOmax
Listed drug patents	May create a formal Paragraph IV pathway
Device patents	May not be listed in the Orange Book and may require separate freedom-to-operate analysis
Method-of-use patents	May affect labeled indications but not necessarily all commercial uses

Because nitric oxide is a simple gas, device and manufacturing patents may matter more commercially than active-ingredient patents. A Paragraph IV strategy, if available, would need to address listed patents and regulatory equivalence while separately managing device-related infringement risk.

When does INOmax lose exclusivity?

INOmax’s original 1999 approval date means the original new-drug exclusivity period has expired. Any remaining market protection depends on later patents, listed exclusivity, regulatory barriers, device integration, manufacturing know-how, and contractual relationships rather than the original five-year NCE exclusivity period.

The key dates are:

Event	Date or implication
FDA approval of INOmax	1999
Original NCE exclusivity	Expired
Active ingredient exclusivity	Not commercially controlling
Current protection	Potentially based on listed patents, device IP, know-how, approvals, and supply infrastructure
Generic entry timing	Depends on the regulatory pathway and enforceable rights at filing

The product does not have biosimilar exclusivity because nitric oxide is not a biologic. A competing nitric oxide product would generally be evaluated as a drug or drug-device combination, not under the biosimilar pathway.

Which companies are challenging or competing with INOmax?

The principal U.S. commercial competitor has been INO Therapeutics/Mallinckrodt’s INOmax franchise against alternative nitric oxide products and delivery systems. Generic and specialty-gas companies may compete through nitric oxide supply, hospital contracts, or alternative administration platforms.

A notable competitor is Genosyl, associated with Vero Biotech, which markets a nitric oxide delivery system and nitric oxide product for inhalation. The competitive distinction is not limited to gas concentration. It includes:

• Portable versus centralized cylinder management.
• Integrated delivery with ventilators.
• Automatic dose control.
• Disposable circuit components.
• Analyzer calibration.
• Emergency transport capability.
• Rental, service, and consumable economics.

Competitive factor	INOmax	Alternative nitric oxide platforms
Active ingredient	Nitric oxide	Nitric oxide
Conventional excipients	None	Generally none
Main differentiation	Established product, installed base, delivery ecosystem	Device portability, workflow, automation, contracting
Biosimilar risk	None	None
Generic risk	Possible drug and device competition	Same
Hospital switching cost	High where equipment and protocols are embedded	Lower where platforms are interoperable

FDA approval of a competing nitric oxide product does not automatically establish substitutability for every hospital, ventilator, or clinical workflow. Device compatibility and protocol validation remain important purchasing factors.

What commercial opportunities exist in INOmax excipients and formulation technology?

The largest opportunities do not involve selling a novel excipient. They involve replacing or improving the functional components surrounding the gas.

1. Alternative carrier-gas and cylinder platforms

A supplier could compete through:

• Lower-cost nitrogen carrier gas.
• Improved cylinder utilization.
• Smaller cylinders for transport.
• Higher-fill-pressure systems.
• Longer shelf life.
• Reduced residual gas losses.
• Automated cylinder inventory management.

The product must maintain concentration uniformity and comply with medical-gas manufacturing requirements.

2. Delivery-system licensing

Device companies can pursue licensing or co-development in:

• Ventilator-integrated nitric oxide delivery.
• Transport-compatible systems.
• Neonatal intensive-care-unit interfaces.
• Closed-loop dose control.
• Low-flow administration.
• Remote monitoring and alarm management.

This is likely the highest-value commercial segment because hospitals purchase an administration system, not only a gas cylinder.

3. Nitrogen dioxide mitigation

Technology that reduces nitrogen dioxide formation or detects it earlier has commercial value. Potential products include:

• Higher-sensitivity analyzers.
• Faster-response sensors.
• Improved mixing chambers.
• Low-dead-volume circuits.
• Optimized tubing and connector materials.
• Automated shutoff or dilution functions.

Any system that changes the gas path would require substantial validation and may create new regulatory and patent issues.

4. Reusable and disposable circuit components

Consumables can generate recurring revenue through:

• Patient interfaces.
• Sampling lines.
• Filters.
• Gas-delivery modules.
• Calibration cartridges.
• Sensor assemblies.
• Specialized neonatal connectors.

Hospitals may prefer systems that reduce setup time and prevent cross-contamination without increasing delivery variability.

5. Hospital service contracts

Commercial models can include:

• Cylinder supply plus equipment rental.
• Per-treatment pricing.
• Annual analyzer maintenance.
• Staff training.
• 24-hour technical support.
• Inventory management.
• Managed gas-delivery services.

The recurring service component can reduce the importance of the raw-gas price.

What formulation and manufacturing barriers limit generic INOmax entry?

A competing product must demonstrate more than nitric oxide purity. It must control the full delivery chain.

Key barriers include:

Barrier	Entry consequence
Gas concentration consistency	Requires validated filling and testing
Cylinder and valve qualification	Adds packaging and supply-chain complexity
Nitrogen dioxide control	Requires validated chemistry and monitoring
Device compatibility	Limits use with existing ventilators
Clinical dosing accuracy	Requires performance testing under variable flow
Hospital protocols	Creates switching friction
Medical-gas quality systems	Requires specialized manufacturing controls
Emergency continuity	Requires dependable cylinder logistics and backup supply

A generic entrant could pursue a gas-only model, but hospitals may still require a compatible delivery and monitoring system. A fully integrated competitor would face higher development cost but could compete more effectively on workflow and total cost of care.

What patent litigation and settlement risks affect INOmax competition?

Potential disputes can arise in four areas:

1. Patents covering nitric oxide delivery devices.
2. Patents covering concentration control or gas monitoring.
3. Method-of-use patents for neonatal pulmonary hypertension.
4. Trade-secret claims involving manufacturing, filling, calibration, or device software.

A Paragraph IV challenge would create litigation risk if relevant patents are listed for the reference product. A competitor could also face infringement claims based on unlisted device patents, which would not necessarily block an ANDA in the same way as an Orange Book-listed patent but could still create damages or injunction exposure.

Settlement terms could include delayed launch, licenses, supply agreements, geographic restrictions, or limits on particular indications. Publicly available litigation and settlement records should be reviewed by patent family and product configuration because a gas product and its delivery device may have different owners and expiration profiles.

How strong is the INOmax patent estate?

The patent estate is stronger as a platform and delivery estate than as a conventional pharmaceutical formulation estate.

Estate component	Relative strength
Nitric oxide composition of matter	Low because the molecule is old
Gas mixture concentration claims	Moderate, subject to prior art and claim scope
Cylinder and packaging technology	Moderate
Delivery hardware	Potentially strong
Monitoring and control software	Potentially strong
Neonatal method-of-use claims	Variable and indication-specific
Manufacturing know-how	Potentially strong but difficult to enforce
Regulatory and hospital integration	Commercially meaningful, even without exclusivity

The practical moat is a combination of regulatory history, installed equipment, validated clinical workflows, supply reliability, service coverage, and device-related IP.

What revenue exposure does INOmax face from generic entry?

Revenue exposure depends on the share of sales tied to gas supply versus equipment, disposables, and services. A gas-only entrant could compress unit pricing while leaving the incumbent’s device and service revenue intact. A fully integrated entrant could exert more pressure by replacing cylinders, analyzers, disposables, and support contracts at the same hospital.

The highest-risk accounts are likely those with:

• High nitric oxide utilization.
• Standardized ventilator fleets.
• Centralized procurement.
• Strong sensitivity to per-treatment cost.
• Multiple qualified gas suppliers.
• Limited dependence on incumbent equipment.

The most defensible accounts are likely hospitals that value emergency availability, established neonatal protocols, integrated monitoring, and technical support.

Key Takeaways

• INOmax has no conventional excipient strategy. It is nitric oxide diluted in nitrogen and delivered through validated respiratory equipment.
• Nitrogen functions as the carrier gas, not as a conventional formulation excipient.
• Nitrogen dioxide formation is the central chemical and safety issue.
• The active molecule offers limited composition-of-matter protection because nitric oxide is an old compound.
• Commercial differentiation centers on delivery devices, analyzers, cylinders, software, consumables, logistics, and service contracts.
• INOmax’s original FDA exclusivity has expired; current competitive protection depends on patents, device rights, know-how, regulatory requirements, and hospital switching costs.
• Biosimilar competition is not applicable.
• The most attractive commercial opportunities are alternative delivery platforms, nitrogen dioxide monitoring, transport systems, hospital service models, and recurring disposable components.
• Generic entry risk is greater for gas supply than for a fully integrated hospital delivery ecosystem.
• Any Paragraph IV or freedom-to-operate analysis must address Orange Book-listed patents separately from unlisted device and manufacturing patents.

FAQs

Can INOmax be reformulated with a liquid excipient?

No. A liquid formulation would change the approved dosage form and administration route. The commercial opportunity lies in improving gas delivery, packaging, and monitoring rather than converting INOmax into a liquid product.

Is nitrogen in INOmax an active pharmaceutical ingredient?

No. Nitrogen is the diluent and carrier gas. Nitric oxide is the pharmacologically active component.

Can a hospital substitute another nitric oxide gas for INOmax?

Substitution depends on the competing product’s FDA approval, concentration, delivery equipment, monitoring controls, hospital protocols, and procurement requirements. Gas concentration alone does not establish operational interchangeability.

Is INOmax eligible for a biosimilar application?

No. Nitric oxide is a chemically defined small-molecule drug, not a biologic. A competitor would use an applicable drug approval pathway rather than the biosimilar pathway.

Which INOmax component offers the best licensing opportunity?

Delivery and monitoring technology offers the strongest licensing potential. High-value areas include closed-loop dose control, portable neonatal systems, nitrogen dioxide sensors, ventilator integration, and lower-cost disposable gas-path components.

References

1. Mallinckrodt Pharmaceuticals. (2023). INOmax (nitric oxide) gas for inhalation prescribing information.
2. U.S. Food and Drug Administration. (1999). INOmax approval letter and labeling for NDA 20-845.
3. U.S. Food and Drug Administration. (n.d.-a). Approved drug products with therapeutic equivalence evaluations: Orange Book.
4. U.S. Food and Drug Administration. (n.d.-b). Inactive ingredient database.
5. U.S. Food and Drug Administration. (n.d.-c). Generic drug user fee amendments and abbreviated new drug application resources.