List of Excipients in Branded Drug NEMBUTAL SODIUM

Generic Drugs Containing NEMBUTAL SODIUM

Company	Ingredient	NDC	Excipient
Akron	pentobarbital sodium	76478-501	ALCOHOL
Akron	pentobarbital sodium	76478-501	HYDROCHLORIC ACID
Akron	pentobarbital sodium	76478-501	PROPYLENE GLYCOL
Akron	pentobarbital sodium	76478-501	SODIUM HYDROXIDE
Akron	pentobarbital sodium	76478-501	WATER

What are the Most Frequently-Used Excipients in NEMBUTAL SODIUM?

# Of NDCs	Excipient
1	ALCOHOL
1	HYDROCHLORIC ACID
1	PROPYLENE GLYCOL
1	SODIUM HYDROXIDE
1	WATER

Last updated: August 9, 2026

Nembutal Sodium is a legacy pentobarbital sodium product with limited conventional patent protection and substantial regulatory, controlled-substance, and supply-chain constraints. The strongest commercial opportunity is not a new molecule or broad composition patent. It is a differentiated, approved dosage form that improves tolerability, handling, stability, or access while preserving pentobarbital’s established clinical uses.

Nembutal Sodium Excipient Strategy and Pharmaceutical Commercial Opportunities

What is Nembutal Sodium and how is it formulated?

Nembutal Sodium contains pentobarbital sodium, a short- to intermediate-acting barbiturate used as a sedative, hypnotic, anticonvulsant, and anesthetic adjunct. In the United States, pentobarbital is a Schedule II controlled substance under the Controlled Substances Act.[1]

The historical Nembutal Sodium Injection formulation contains:

Component	Function
Pentobarbital sodium	Active pharmaceutical ingredient
Propylene glycol	Cosolvent and solubility enhancer
Alcohol	Cosolvent and antimicrobial support
Water for Injection	Aqueous vehicle
Sodium hydroxide or other pH adjuster	pH control

The labeled injectable strength is commonly 50 mg/mL. The product uses a strongly alkaline solution to maintain pentobarbital sodium solubility. The combination of high propylene glycol, alcohol, alkaline pH, and concentrated drug creates the main excipient-related development constraints.[2]

Nembutal Sodium has historically been supplied in parenteral presentations, including multidose vials. Product availability and marketing status have changed over time, and the commercial market is more fragmented than the product’s historical brand recognition suggests.

What excipient problems create opportunities for Nembutal Sodium?

The main opportunity is to reduce vehicle burden without compromising concentration, sterility, chemical stability, or regulatory performance.

Injection-site tolerability

Propylene glycol and alcohol can cause local irritation, pain, phlebitis, or tissue injury when administered in concentrated injectable products. The risk is especially relevant for repeated dosing, peripheral intravenous administration, pediatric use, and patients with limited venous access.

A lower-cosolvent formulation could create value by reducing:

• Injection-site pain
• Infusion-related irritation
• Extravasation injury
• Need for dilution before administration
• Restrictions on peripheral-line use

The commercial claim would need to be supported by comparative tolerability data rather than excipient substitution alone.

Metabolic and organ burden

Large amounts of propylene glycol can produce hyperosmolality and, with repeated or high-dose administration, lactic acidosis, renal dysfunction, or other toxicity concerns. These risks are recognized across injectable products that contain substantial propylene glycol loads.[3]

Alcohol exposure can also be clinically relevant in neonates, children, patients with hepatic impairment, and patients receiving repeated doses. Removing or reducing alcohol would provide a clearer product-differentiation rationale than a cosmetic excipient change.

Precipitation and concentration limits

Pentobarbital sodium has pH-dependent solubility. Lowering the pH may reduce excipient burden but can also increase the risk of precipitation, especially after dilution or when the product is mixed with acidic solutions.

The formulation program therefore has to balance:

• Pentobarbital concentration
• pH
• Osmolality
• Buffer capacity
• Dilution compatibility
• Container compatibility
• Shelf-life stability

The most commercially useful product would be a ready-to-use formulation that remains physically stable across common clinical dilutions and administration conditions.

What excipient strategies are technically viable?

Reduced-propylene-glycol formulation

A reduced-propylene-glycol product is the most direct strategy. Candidate approaches include a mixed-solvent system, increased pH control, modified drug concentration, or a solubilization platform that does not rely primarily on propylene glycol.

The key risks are precipitation, altered injection tolerability, extractables and leachables, and a loss of stability after dilution. A meaningful product profile would target materially lower propylene glycol exposure while retaining the existing 50 mg/mL strength or offering a clinically useful lower concentration.

Alcohol-free formulation

An alcohol-free product could target pediatric, geriatric, neurologic, and repeated-dose use. The development case is strongest where alcohol exposure is clinically undesirable and where the formulation can maintain sterility without relying on alcohol as a supporting antimicrobial component.

An alcohol-free formulation would require a full preservative and microbiological-control strategy. Single-dose packaging could avoid the need for a preservative but would raise fill-finish and cost requirements.

Preservative-free single-dose vials or ampoules

A preservative-free presentation could address neonatal and critical-care use, where benzyl alcohol and other preservatives may be restricted. A single-dose vial, prefilled syringe, or ready-to-use ampoule could reduce preparation errors and contamination risk.

This strategy is more commercially defensible when paired with:

• Lower excipient exposure
• Smaller fill volumes
• Clear dose markings
• Tamper-evident packaging
• Controlled-substance reconciliation features

Ready-to-use diluted presentation

A ready-to-use lower-concentration solution could reduce bedside dilution and administration errors. The product would need validated compatibility with infusion systems and a defined in-use stability period.

This approach may have greater operational value than a conventional high-concentration vial because hospitals often prioritize preparation simplicity, controlled-substance accountability, and predictable administration.

Alternative delivery systems

Oral liquid, oral concentrate, rectal, and buccal systems are technically possible development areas, but each carries distinct regulatory and abuse-deterrence issues.

An oral liquid could improve administration for patients unable to swallow tablets. It would require careful control of palatability, dose measurement, alcohol content, child-resistant packaging, and diversion risk.

A buccal or transmucosal system could produce a differentiated product, but it would require evidence of consistent absorption, mucosal tolerability, dose control, and abuse-resistance. Such a product would likely carry a higher development burden than an improved injection.

What patent opportunities protect a new Nembutal Sodium formulation?

The original pentobarbital composition is long off patent. Commercial protection would need to come from formulation, dosage form, device, manufacturing, or method-of-use claims.

Patent category	Potential claim scope	Commercial value
Excipient composition	Reduced or eliminated propylene glycol, alcohol-free system, novel cosolvent ratio	Moderate to high if technically unexpected
pH and buffer system	Defined pH range and buffer combination that prevents precipitation	Moderate
Concentration and dosage form	Stable 25 mg/mL or 50 mg/mL injectable presentation	Moderate
Container closure	Prefilled syringe, cartridge, ampoule, or specialized vial	Moderate
Manufacturing process	Mixing, filtration, sterilization, or filling process	Moderate if difficult to reproduce
Stability	Long-term or in-use stability under defined conditions	Low to moderate unless linked to composition
Abuse deterrence	Formulation that limits extraction or misuse	Potentially high, but technically and legally demanding
Method of use	Reduced-irritation administration or specific clinical population	Variable and jurisdiction-dependent

A patent filing should emphasize measurable technical effects. A claim that merely changes the percentage of propylene glycol may face obviousness challenges if the result would be predictable from routine formulation work. Stronger protection would link the excipient system to an unexpected combination of properties, such as high concentration, low osmolality, reduced injection pain, no precipitation after dilution, and extended stability.

What is the Orange Book status and exclusivity position for Nembutal Sodium?

Nembutal Sodium is a legacy product. Its original small-molecule regulatory exclusivity has expired, and any commercial protection would depend primarily on listed patents, formulation patents, trade secrets, trademarks, or regulatory barriers.

The FDA Orange Book should be checked for the specific marketed Nembutal Sodium NDA and presentation because listing status can change with product discontinuation, transfer, or withdrawal. A legacy drug with no active Orange Book patents generally does not provide a conventional Paragraph IV barrier to a competing abbreviated new drug application.[4]

A new formulation could potentially obtain:

• Five years of new chemical entity exclusivity only if it qualified as a new active ingredient, which pentobarbital sodium would not;
• Three-year exclusivity for a new clinical investigation essential to approval of a new indication, dosage form, or formulation;
• Pediatric exclusivity if the statutory requirements were met;
• Orphan-drug exclusivity for a qualifying rare disease indication.

For a reformulated pentobarbital product, the most realistic regulatory protection would usually be patent protection combined with any available three-year exclusivity. Exclusivity would not prevent all compounding or other regulatory pathways.

When does Nembutal Sodium lose exclusivity?

The core molecule has already lost regulatory exclusivity. The relevant commercial question is whether a new sponsor can create enforceable protection around a modern formulation or delivery system.

A reformulated product could face competition from:

• ANDA products referencing an approved pentobarbital injection;
• Other pentobarbital sodium injections;
• Compounded sterile preparations;
• Veterinary pentobarbital products that are not substitutes for human use;
• Alternative sedatives and anticonvulsants.

The absence of active molecule patents makes formulation execution and regulatory positioning decisive. A weak formulation patent could be designed around by changing solvent ratios, concentration, packaging, or manufacturing parameters.

What generic entry risks exist for Nembutal Sodium?

Generic entry risk is high for a conventional pentobarbital sodium injection if the reference product remains eligible for ANDA referencing and has no meaningful active patent barrier.

The main generic-launch scenarios are:

Scenario	Effect on incumbent
Conventional 50 mg/mL injection	Rapid price competition and limited differentiation
Reduced-excipient injection	More defensible clinical positioning
Preservative-free single-dose product	Higher manufacturing cost but stronger hospital value proposition
Ready-to-use syringe	Device and packaging differentiation
New route or indication	Greater development cost and possible clinical exclusivity
Controlled-substance supply disruption	Temporary pricing power, but not durable IP protection

Controlled-substance scheduling can make generic entry operationally harder because manufacturers need DEA registration, procurement controls, quota management, secure storage, reporting, and diversion controls. Those barriers can reduce the number of suppliers, but they are not substitutes for patent protection.

Which companies and products compete with Nembutal Sodium?

Competition depends on the indication.

Human pharmaceutical competitors

Pentobarbital competes with:

• Midazolam for procedural sedation and seizure control;
• Lorazepam and diazepam for acute seizure management;
• Phenobarbital for anticonvulsant use;
• Propofol for anesthesia and intensive-care sedation;
• Sodium thiopental in markets where it remains available;
• Dexmedetomidine for selected sedation applications.

These drugs do not provide direct pharmaceutical equivalence, but they constrain pricing and formulary access.

Veterinary competitors

Pentobarbital products are widely associated with veterinary euthanasia and animal-use products. Those products may have different concentrations, excipients, labeling, packaging, and regulatory status. They are not interchangeable with human Nembutal Sodium products.

Veterinary demand can create manufacturing scale and supply-chain competition, but it also increases diversion and reputational risk. A human product strategy should maintain separate distribution controls and labeling.

What FDA regulatory pathway would apply to a new Nembutal Sodium formulation?

The pathway depends on the extent of change.

Abbreviated pathway

An ANDA may be available for a product that meets the applicable requirements for sameness, pharmaceutical equivalence, bioequivalence, labeling, and quality. A materially different excipient system, route, concentration, or device may complicate ANDA eligibility.

505(b)(2) pathway

A 505(b)(2) application is likely to be more suitable for a reformulated pentobarbital product that relies partly on existing findings but introduces a new formulation, delivery system, concentration, or clinical use.[5]

This pathway can support a differentiated product while avoiding a full stand-alone development program. It does not eliminate the need to address controlled-substance controls, human-factors validation, stability, extractables, container closure, and clinical tolerability.

Manufacturing requirements

The manufacturer would need validated controls for:

• Active concentration and content uniformity;
• Sterility assurance;
• Endotoxins and particulate matter;
• pH and osmolality;
• Solvent content;
• Container closure integrity;
• Controlled-substance inventory;
• Diversion prevention;
• Stability under storage and in-use conditions.

How strong is the patent estate for a new excipient strategy?

The patent estate is potentially moderate for a technically differentiated product and weak for a routine vehicle substitution.

A stronger portfolio would use multiple claim layers:

1. Composition claims covering the excipient system;
2. Concentration and pH claims;
3. Stability and dilution claims;
4. Container and delivery-device claims;
5. Manufacturing claims;
6. Method-of-use claims directed to reduced irritation or specific patient populations.

Patent term should be preserved through early filing, continuation practice, and claims directed to validated technical effects. Freedom-to-operate review should cover expired pentobarbital patents, active formulation patents, excipient supplier rights, device patents, and manufacturing know-how.

What commercial opportunity is most attractive?

The strongest near-term opportunity is a preservative-free, alcohol-free, reduced-propylene-glycol injectable product in a ready-to-use presentation.

A commercially credible target profile would include:

• Pentobarbital sodium in a clinically established concentration;
• Lower solvent burden than the historical formulation;
• No alcohol;
• Preservative-free single-dose packaging;
• Reduced injection-site irritation;
• Demonstrated dilution compatibility;
• Secure controlled-substance packaging;
• Hospital-focused distribution;
• Patent protection around the formulation and presentation.

A second opportunity is a pediatric or neurologic-use oral liquid with controlled dosing and improved excipient safety. Its market size would likely be smaller, but the product could achieve differentiation through administration convenience and patient-specific dosing.

What licensing deals and partnerships are relevant?

The most valuable partnerships would involve:

• A controlled-substance manufacturer with DEA infrastructure;
• A sterile injectable contract development and manufacturing organization;
• An excipient supplier with proprietary solubilization technology;
• A prefilled-syringe or cartridge manufacturer;
• A hospital distributor with controlled-substance logistics;
• A clinical partner experienced in pediatric neurology or critical care.

Licensing value would depend on whether the partner contributes a proprietary formulation platform, regulatory history, manufacturing capacity, or hospital access. A license based only on pentobarbital supply would have limited defensibility because the active ingredient is established and broadly available from qualified sources.

Key Takeaways

• Nembutal Sodium is a legacy pentobarbital sodium product with expired core-molecule exclusivity.
• The historical injectable formulation relies heavily on propylene glycol, alcohol, alkaline pH, and water for injection.
• The clearest excipient opportunity is an alcohol-free, reduced-propylene-glycol, preservative-free injectable.
• A 505(b)(2) strategy may be more suitable than an ANDA for a materially differentiated formulation.
• Patent value will depend on unexpected technical performance, not routine excipient substitution.
• Controlled-substance scheduling creates operational barriers but does not replace patent or regulatory exclusivity.
• The most credible commercial buyers are hospitals, critical-care providers, and specialty distributors.
• Competitive pressure comes from midazolam, phenobarbital, lorazepam, propofol, sodium thiopental, and compounded products.
• The strongest portfolio would combine formulation, stability, packaging, device, manufacturing, and method-of-use claims.

FAQs

Can propylene glycol be removed from Nembutal Sodium injection?

Potentially, but removal may reduce pentobarbital solubility and increase precipitation risk. A replacement system would require comparative stability, dilution, sterility, and tolerability data.

Is pentobarbital sodium still commercially viable for human medicine?

Yes, but the opportunity is specialized. Viability depends on supply reliability, controlled-substance compliance, hospital demand, and a product profile that improves on legacy excipients or administration requirements.

Could a new Nembutal Sodium formulation receive three-year FDA exclusivity?

Potentially, if approval relies on new clinical investigations essential to approval of a qualifying formulation, dosage form, indication, or other change. The exclusivity analysis is product- and application-specific.[5]

Are veterinary pentobarbital products substitutes for Nembutal Sodium?

No. Veterinary products can differ in labeling, concentration, excipients, manufacturing controls, and regulatory authorization. They should not be treated as human pharmaceutical equivalents.

What is the main business risk in developing a Nembutal Sodium reformulation?

The main risk is insufficient differentiation. If the new product does not show lower toxicity, improved tolerability, better handling, or meaningful clinical convenience, hospitals may choose lower-cost established products or alternatives.

References

1. U.S. Drug Enforcement Administration. (2024). Controlled substances schedules. https://www.dea.gov/drug-information/drug-scheduling

2. U.S. Food and Drug Administration. (n.d.). Nembutal Sodium Injection, USP prescribing information. DailyMed. https://dailymed.nlm.nih.gov/

3. U.S. Food and Drug Administration. (2020). Labeling for human prescription drug and biological products: Propylene glycol safety considerations. https://www.fda.gov/

4. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book

5. U.S. Food and Drug Administration. (2024). Applications covered by section 505(b)(2). https://www.fda.gov/drugs/development-approval-process-drugs/abbreviated-new-drug-application-anda-process-researchers-and-drug-sponsors