List of Excipients in Branded Drug DANTROLENE SODIUM

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Endo USA Inc	DANTROLENE SODIUM	dantrolene sodium	49884-362	FD&C YELLOW NO. 6
Endo USA Inc	DANTROLENE SODIUM	dantrolene sodium	49884-362	FERRIC OXIDE RED
Endo USA Inc	DANTROLENE SODIUM	dantrolene sodium	49884-362	FERRIC OXIDE YELLOW

Generic Drugs Containing DANTROLENE SODIUM

Company	Ingredient	NDC	Excipient
Amneal Pharmaceuticals of New York LLC	dantrolene sodium	0115-4411	CROSCARMELLOSE SODIUM
Amneal Pharmaceuticals of New York LLC	dantrolene sodium	0115-4411	D&C YELLOW NO. 10
Amneal Pharmaceuticals of New York LLC	dantrolene sodium	0115-4411	FD&C GREEN NO. 3

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

# Of NDCs	Excipient
5	BUTYL ALCOHOL
6	CROSCARMELLOSE SODIUM
11	D&C YELLOW NO. 10

Last updated: September 1, 2026

Dantrolene sodium is a low-cost, off-patent drug with a concentrated commercial opportunity in emergency injectable delivery rather than conventional oral generics. The main value drivers are rapid reconstitution, reduced vial burden, storage stability, excipient tolerability, dose flexibility, and hospital workflow. Ryanodex demonstrates the commercial potential of a high-concentration formulation: a 250 mg vial reduces the number of vials required for malignant hyperthermia treatment compared with conventional 20 mg dantrolene products. Oral capsules remain commercially relevant for chronic spasticity but face intense generic competition and limited formulation differentiation.

Dantene Sodium Excipient Strategy and Commercial Opportunities

Dantrolene sodium is a hydantoin derivative used primarily for malignant hyperthermia, neuroleptic malignant syndrome, and chronic spasticity. Its formulation challenge is poor aqueous solubility and the need for rapid preparation during a medical emergency.

The commercial landscape divides into two segments:

Segment	Representative products	Principal opportunity
Intravenous emergency treatment	Revonto, Dantrium IV, Ryanodex	Faster preparation, lower vial count, ready-to-use presentation, improved stability
Oral chronic treatment	Dantrolene sodium capsules, Dantrium capsules	Low-cost generic supply, improved swallowing, excipient optimization, adherence

The injectable market has stronger differentiation potential because hospitals value preparation time, pharmacy labor, inventory efficiency, and emergency readiness. Oral capsules are easier to develop but have weaker pricing power.

What excipients are used in dantrolene sodium products?

Dantrolene sodium injectable products commonly use mannitol and alkalizing agents to improve solubility. Oral capsules use conventional solid-dose excipients.

Injectable excipients

Conventional intravenous dantrolene formulations generally contain:

• Dantrolene sodium
• Mannitol
• Sodium hydroxide or another alkalizing component
• Water for reconstitution

Mannitol is used as a bulking agent and contributes to the formulation's solid-state properties. The alkaline environment is important because dantrolene sodium has limited solubility under neutral conditions. The formulation is typically supplied as a lyophilized or sterile powder requiring reconstitution before intravenous administration.

Ryanodex uses a proprietary high-concentration formulation that contains dantrolene sodium, mannitol, and polysorbate 80, according to its prescribing information. It is supplied as a 250 mg vial for reconstitution with 5 mL of sterile water, compared with the substantially larger reconstitution volume required for conventional 20 mg vials. [1]

The main injectable excipient functions are:

Excipient	Functional role	Commercial relevance
Mannitol	Bulking agent, cake-forming aid, solubility and tonicity contributor	Supports lyophilized cake formation and product handling
Sodium hydroxide	pH adjustment and solubilization	Controls dissolution and chemical stability
Polysorbate 80	Wetting and solubilization aid	Supports high drug loading and rapid dispersion
Sterile water	Reconstitution vehicle	Determines preparation time and emergency usability

Oral capsule excipients

Generic dantrolene sodium capsules typically use lactose, starch, talc, magnesium stearate, gelatin, titanium dioxide, and colorants, although the precise composition varies by manufacturer and strength. DailyMed labeling should be used to confirm the inactive ingredients for each approved product. [2]

For oral products, excipient selection is driven by:

• Powder flow and content uniformity
• Capsule fill weight
• Dissolution performance
• Moisture control
• Color and strength identification
• Lactose and gelatin compatibility
• Cost and global supply availability

The oral product does not require the same rapid reconstitution performance as the injectable product. This limits the commercial value of complex excipient systems unless they improve tolerability, dissolution, or manufacturing economics.

Why is dantrolene sodium difficult to formulate?

Dantrolene sodium presents three core formulation problems: poor water solubility, high-dose requirements, and emergency-use constraints.

Poor aqueous solubility

Dantrolene sodium is difficult to dissolve rapidly in water at clinically useful concentrations. Conventional injectable products therefore use alkaline formulation conditions and require reconstitution immediately before administration. The formulation must dissolve quickly without excessive foaming, precipitation, visible particles, or prolonged manipulation.

High dose requirements

The recommended initial dose for malignant hyperthermia is commonly 2.5 mg/kg intravenously, with additional doses administered as needed. [1,3] A 70 kg adult may require approximately 175 mg for the initial dose, before repeat dosing. A conventional 20 mg vial presentation therefore requires multiple vials.

Ryanodex supplies 250 mg per vial. This can reduce the initial vial requirement for many adult patients to one vial, although the exact number depends on body weight and clinical response.

Emergency preparation

Malignant hyperthermia treatment is time-sensitive. Conventional products may require:

1. Locating multiple vials.
2. Adding sterile water to each vial.
3. Shaking or manipulating the vials.
4. Withdrawing the reconstituted solution.
5. Combining doses for administration.

A commercial formulation that removes steps from this sequence can support premium pricing even when the active ingredient is generic.

What formulation strategies can improve dantrolene sodium injectables?

The highest-value strategies target concentration, reconstitution, storage, and handling rather than simply changing inactive ingredients.

High-concentration lyophilized powder

A high-concentration powder is the clearest commercial strategy. It reduces vial count, reconstitution volume, syringe or bag manipulation, and preparation time.

The formulation must balance:

• Drug loading
• Cake strength
• Reconstitution speed
• Solution clarity
• pH
• Osmolality
• Chemical stability
• Container closure integrity

Polysorbate 80 or another surfactant may improve wetting and dispersion, but surfactant concentration must be controlled because excessive levels can create foaming, oxidation concerns, or compatibility issues.

Ready-to-use liquid injection

A ready-to-use liquid would eliminate reconstitution and could have substantial workflow value. The technical barrier is higher because dantrolene sodium must remain soluble and chemically stable at a clinically useful concentration over the intended shelf life.

Key development risks include:

• Precipitation during refrigerated or frozen storage
• pH-dependent degradation
• Container interaction
• Light sensitivity
• Oxidative degradation
• High osmolality
• Limited concentration

A ready-to-use product may require a specialized container, high-pH solution, stabilizer system, or dual-chamber presentation. The regulatory pathway would require robust extractables and leachables, stability, particulate, sterility, and container-closure data.

Dual-chamber or point-of-care presentation

A dual-chamber vial or syringe could separate the concentrated dantrolene sodium phase from the diluent until use. This approach may provide:

• Simplified preparation
• Lower contamination risk
• Controlled final concentration
• Reduced pharmacy labor
• Improved emergency-cart readiness

The device component would create additional development and manufacturing complexity. It could also support differentiated intellectual property if the claims cover the container, mixing mechanism, formulation, or administration method.

Alternative sterile presentations

Other possible presentations include:

• High-concentration single-dose vials
• Prefilled syringes
• Pharmacy bulk packages
• Cartridge systems for emergency kits
• Lyophilized dual-vial systems
• Ready-to-dilute concentrated solutions

The most practical near-term opportunity is a high-concentration vial because it builds on existing clinical use while reducing formulation and device complexity.

What oral dantrolene sodium formulation opportunities exist?

Oral dantrolene sodium has a lower innovation ceiling but several niche opportunities remain.

Improved capsule swallowing

Dantrolene is used chronically for spasticity, where patients may include older adults, patients with neurologic impairment, and individuals with dysphagia. Potential products include:

• Smaller capsules with equivalent dose flexibility
• Sprinkle capsules
• Oral powder for suspension
• Orally disintegrating dosage forms
• Liquid suspensions

The main challenge is dose accuracy. Dantrolene dosing can require titration, and an oral liquid must maintain uniformity across the labeled shelf life.

Lactose-free and gelatin-free capsules

Many conventional capsule products use lactose and gelatin. Lactose-free formulations could target patients with intolerance or reduce excipient restrictions in selected markets. Vegetarian or non-animal capsule shells could support international and institutional procurement requirements.

These changes may qualify for a new drug application or an abbreviated application depending on the formulation, labeling, bioequivalence, and regulatory strategy. A materially different dosage form may require a 505(b)(2) pathway in the United States rather than a standard ANDA.

Modified-release products

A modified-release dantrolene product could potentially reduce dosing frequency or smooth plasma exposure. Its commercial value is uncertain because dantrolene's use in chronic spasticity is already limited by sedation, weakness, hepatotoxicity concerns, and the availability of competing therapies.

A modified-release product would require clinical bridging and may not overcome the low-cost generic market without a clear adherence or tolerability advantage.

What FDA regulatory status applies to dantrolene sodium?

Dantrolene sodium is an FDA-approved drug with established oral and intravenous uses. Generic oral capsules and conventional injectable products are regulated through abbreviated pathways when they demonstrate pharmaceutical equivalence and bioequivalence or applicable injectable-product requirements.

FDA pathways

Product concept	Likely U.S. pathway
Conventional oral capsule equivalent	ANDA
Conventional injectable equivalent	ANDA, subject to product-specific requirements
New liquid injectable formulation	505(b)(2) or NDA strategy
New oral liquid or sprinkle product	505(b)(2) or ANDA, depending on reference and formulation
Device-assisted emergency presentation	NDA or 505(b)(2), with combination-product review likely
New indication	505(b)(2), NDA supplement, or other applicable route

FDA product-specific guidance and the Orange Book should control the final pathway assessment. [4,5]

What is the Orange Book status of dantrolene sodium?

Dantrolene sodium has no meaningful biologic exclusivity issue because it is a small-molecule drug. Biosimilar risk is therefore not applicable. The relevant competitive threats are ANDA-based generic capsules and injectable products, authorized generics, and differentiated branded formulations.

Orange Book review should focus on:

• Listed reference products
• Active formulation or method-of-use patents
• Exclusivity codes
• Therapeutic equivalence ratings
• Patent certifications
• Product-specific recommendations

Older Dantrium and conventional injectable product patents are generally outside their original commercial protection periods. Ryanodex's differentiation has been based on its formulation, concentration, and clinical workflow benefits rather than a newly discovered active ingredient. Current patent status must be checked in the FDA Orange Book and USPTO Patent Center before a launch or licensing decision. [4,6]

When does dantrolene sodium lose exclusivity?

The active ingredient is long off patent, and conventional generic competition is established. The commercial question is not whether dantrolene sodium itself remains protected. It is whether a specific high-concentration formulation, device, method of administration, or newly approved indication retains enforceable protection.

Potential protection categories include:

• Formulation patents
• Lyophilization process patents
• High-concentration composition claims
• Container-closure or mixing-device claims
• Reconstitution-method claims
• Stability claims
• Method-of-use claims for malignant hyperthermia or related syndromes

Patent term generally runs 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and other statutory adjustments. FDA regulatory exclusivity is separate from patent protection. [7]

A high-concentration dantrolene product can therefore remain commercially differentiated even when the active ingredient is generic, but the strength of that position depends on claim scope, design-around risk, Orange Book listings, and actual litigation history.

What patent and litigation risks affect dantrolene sodium?

The main risks are formulation design-around and limited market size.

Paragraph IV challenges

A generic applicant may submit a Paragraph IV certification against an unexpired listed patent. The patent holder may then sue within the statutory period, triggering a potential 30-month stay of approval under applicable Hatch-Waxman rules. [8]

For dantrolene sodium, the most likely targets would be patents covering:

• High drug concentration
• Specific excipient ratios
• Surfactant systems
• Reconstitution volume
• Lyophilized cake attributes
• Device configuration
• Stability during storage

A generic applicant may avoid infringement by using a different surfactant, pH range, concentration, vial size, or reconstitution method. Narrow composition claims are more vulnerable to design-around than claims tied to a clinically necessary performance range.

Litigation status

There is no broadly recognized, current, industry-defining patent dispute comparable to major blockbuster drug litigation associated with dantrolene sodium. Litigation exposure should be assessed at the product level using PACER, the Orange Book, USPTO records, and FDA approval documents.

Settlement agreements

Any settlement involving a listed patent, Paragraph IV certification, or licensed generic should be reviewed for:

• Authorized-generic launch timing
• License territory
• Supply obligations
• Royalty structure
• Restrictions on formulation
• Acceleration or forfeiture provisions
• Antitrust risk

No settlement should be assumed solely from the presence of generic competition.

How strong is the patent estate for dantrolene sodium?

The patent estate is weak for the active ingredient and conventional oral dosage forms but potentially stronger for differentiated injectable delivery.

Asset type	Expected protection strength	Design-around risk
Dantrolene sodium molecule	Low	Not applicable; expired
Standard oral capsule	Low	High
Conventional 20 mg injectable vial	Low to moderate	High
High-concentration injectable composition	Moderate	Moderate
Specific excipient ratio	Moderate	Moderate to high
Ready-to-use liquid	Potentially moderate to strong	Moderate
Dual-chamber device	Moderate to strong	Moderate
Method-of-use claim	Variable	Depends on prior art and clinical scope

The strongest portfolio would combine composition claims, process claims, container claims, and method-of-use claims. A single narrow excipient claim would provide limited commercial security.

What commercial opportunities exist for dantrolene sodium?

The largest opportunity is hospital emergency preparedness.

High-concentration injectable product

A high-concentration product can create value through:

• Lower storage volume
• Fewer emergency-cart vials
• Reduced pharmacy labor
• Faster preparation
• Lower risk of preparation error
• Lower disposal burden
• Simplified inventory management

Hospitals may accept a higher unit price if the product reduces total treatment cost and improves readiness. The economic proposition should be measured by total cost per treated patient, not price per milligram.

Emergency kit integration

A manufacturer could package dantrolene sodium with:

• Sterile water
• Transfer devices
• Syringes
• Labels
• Temperature indicators
• Emergency-cart accessories

This would create a systems product rather than a standalone vial. The commercial advantage would be strongest in ambulatory surgery centers, hospitals, dental surgery facilities, and other locations required to maintain malignant hyperthermia response capability.

Contract manufacturing and licensing

Licensing targets include:

• Injectable formulation developers
• Lyophilization specialists
• Emergency-care pharmaceutical companies
• Hospital-supply distributors
• Medical-device companies
• Generic manufacturers with sterile manufacturing capacity

A formulation owner may license regional rights while retaining manufacturing control. A generic manufacturer may prefer a technology-transfer agreement covering formulation, analytical methods, sterile filling, and stability data.

Geographic expansion

Demand is strongest in markets with established malignant hyperthermia protocols and mandatory emergency preparedness. Geographic opportunities include:

• United States
• Canada
• Western Europe
• Japan
• Australia
• Gulf-region hospital systems
• Large private hospital networks in Latin America and Asia

Regulatory requirements differ. Some markets may accept reliance on an established reference product, while others require local clinical, stability, or device documentation. Supply-chain reliability is particularly important because dantrolene is an emergency product that hospitals must stock even when utilization is low.

How does dantrolene sodium compare with competing emergency products?

Dantrolene sodium has no direct pharmacologic substitute for malignant hyperthermia treatment. The competitive comparison is therefore primarily between product presentations.

Attribute	Conventional 20 mg vial	Ryanodex-type 250 mg vial	Future ready-to-use product
Drug concentration	Low	High	Potentially high
Vial burden	High	Low	Low
Reconstitution	Labor-intensive	Simplified	Eliminated or minimized
Excipient complexity	Lower	Higher	Highest
Manufacturing difficulty	Established	Moderate	High
Differentiation	Limited	Strong	Potentially strongest
Patent opportunity	Limited	Formulation and device	Formulation, device, process

Ryanodex has shown that preparation efficiency can support a differentiated commercial product in an otherwise generic market. A future product would need a measurable advantage over Ryanodex, such as no reconstitution, longer room-temperature stability, lower cost, improved syringe compatibility, or broader global regulatory acceptance.

What generic launch risks exist for dantrolene sodium?

Generic launch risks are moderate for oral capsules and higher for differentiated injectables.

Oral products

Risks include:

• Low reimbursement
• Multiple generic competitors
• Manufacturing scale pressure
• Limited brand loyalty
• Low switching barriers
• Commodity pricing

Injectable products

Risks include:

• Sterile manufacturing failures
• Shortages of specialized excipients
• Container-closure defects
• Reconstitution variability
• Particulate contamination
• Hospital formulary resistance
• Low annual utilization
• Need for reliable emergency inventory

The commercial model must account for stocking requirements. Hospitals purchase availability and reliability, not only doses administered.

What manufacturing and intellectual-property barriers matter most?

The main manufacturing barrier is consistent sterile production of a high-pH, high-concentration formulation with rapid reconstitution and acceptable stability.

Critical development work includes:

• Excipient compatibility screening
• pH and buffer optimization
• Lyophilization-cycle development
• Residual moisture control
• Particulate testing
• Reconstitution-time testing
• Container-closure integrity
• Light and temperature stability
• Compatibility with syringes and infusion systems
• Extractables and leachables assessment

The best IP strategy would use several independent claim categories:

1. Composition claims covering concentration and excipient ranges.
2. Process claims covering preparation and lyophilization.
3. Container claims covering vial, syringe, or dual-chamber systems.
4. Use claims covering rapid treatment or simplified emergency administration.
5. Stability claims covering storage conditions and shelf life.

Key Takeaways

• Dantrolene sodium is off patent as an active ingredient, making conventional oral capsules a low-margin generic opportunity.
• Injectable formulation is the principal source of commercial differentiation.
• Mannitol and alkaline pH control are central to conventional dantrolene sodium injectable products.
• Polysorbate 80 can support a high-concentration injectable formulation but creates additional compatibility and stability requirements.
• Ryanodex demonstrates the value of reducing vial count and reconstitution burden.
• The strongest future opportunity is a high-concentration, ready-to-use, or dual-chamber emergency presentation.
• Biosimilar risk does not apply because dantrolene sodium is a small-molecule drug.
• Paragraph IV risk depends on the specific formulation and device patents listed for the product, not on the dantrolene sodium molecule.
• Hospital emergency preparedness, ambulatory surgery centers, and international hospital networks are the main commercial targets.
• A defensible patent estate should combine formulation, process, container, stability, and method-of-use claims.

FAQs

Can dantrolene sodium be formulated as a ready-to-use injection?

Yes, but the principal challenge is maintaining solubility and chemical stability at a clinically useful concentration. A ready-to-use product would require extensive control of pH, precipitation, container compatibility, sterility, and shelf life.

Which excipient is most important for injectable dantrolene sodium?

The formulation system is more important than any single excipient. Mannitol supports the solid dosage form, while an alkaline environment drives solubility. Surfactants such as polysorbate 80 may help wetting and high-concentration dispersion.

Is Ryanodex protected by patents?

Ryanodex may have formulation, process, device, or method-of-use protection separate from the expired dantrolene sodium molecule. Current enforceability and Orange Book relevance must be confirmed through FDA and USPTO records for the specific product.

Is dantrolene sodium suitable for a 505(b)(2) product?

A materially different dosage form, concentration, ready-to-use presentation, or emergency-delivery system may support a 505(b)(2) strategy. A conventional equivalent capsule or injectable product would generally be evaluated under the applicable abbreviated pathway.

What is the best commercial formulation opportunity for dantrolene sodium?

A high-concentration injectable that minimizes preparation time and vial burden offers the clearest opportunity. A ready-to-use or dual-chamber system could provide further differentiation if it achieves acceptable stability and manufacturing economics.

References

1. Eagle Pharmaceuticals, Inc. (2023). Ryanodex (dantrolene sodium) for injectable suspension: Prescribing information. U.S. Food and Drug Administration.

2. National Library of Medicine. (n.d.). DailyMed: Dantrolene sodium capsule and injection labeling. U.S. National Library of Medicine.

3. Malignant Hyperthermia Association of the United States. (n.d.). Managing a malignant hyperthermia crisis. MHAUS.

4. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations. FDA, Center for Drug Evaluation and Research.

5. U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application process. FDA, Center for Drug Evaluation and Research.

6. U.S. Patent and Trademark Office. (n.d.). Patent Center. USPTO.

7. U.S. Code, 35 U.S.C. § 154. (2024). Contents and term of patent; provisional rights.

8. U.S. Food and Drug Administration. (n.d.). Hatch-Waxman amendments and patent certification requirements. FDA.