List of Excipients in Branded Drug CISATRACURIUM

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Generic Drugs Containing CISATRACURIUM

Company	Ingredient	NDC	Excipient
Fresenius Kabi USA LLC	cisatracurium besylate	63323-416	BENZENESULFONIC ACID
Hikma Pharmaceuticals USA Inc	cisatracurium besylate	0143-9396	BENZENESULFINIC ACID
Hikma Pharmaceuticals USA Inc	cisatracurium besylate	0143-9396	WATER
Hikma Pharmaceuticals USA Inc	cisatracurium besylate	0143-9397	BENZENESULFINIC ACID
Hikma Pharmaceuticals USA Inc	cisatracurium besylate	0143-9397	BENZYL ALCOHOL
Hikma Pharmaceuticals USA Inc	cisatracurium besylate	0143-9397	WATER

What are the Most Frequently-Used Excipients in CISATRACURIUM?

# Of NDCs	Excipient
1	BENZENESULFONIC ACID

Cisatracurium Excipient Strategy and Commercial Opportunities

Last updated: October 28, 2026

Cisatracurium is an established hospital injectable with limited active-ingredient differentiation and a stronger opportunity in formulation engineering, supply reliability, packaging, and ready-to-use delivery. The commercial target is not a new excipient combination alone. It is a product that improves stability, reduces pharmacy preparation, limits medication errors, or performs reliably across operating-room and intensive-care workflows.

What is the current cisatracurium formulation?

Cisatracurium is marketed primarily as cisatracurium besylate injection, a sterile intravenous solution for neuromuscular blockade during surgery, endotracheal intubation, and mechanical ventilation. The product must be administered by clinicians with access to airway management, ventilation, and neuromuscular monitoring.[1]

Attribute	Typical commercial profile
Active ingredient	Cisatracurium besylate
Dosage form	Sterile aqueous intravenous injection
Common strengths	2 mg/mL and 10 mg/mL presentations, depending on supplier
Administration	Intravenous bolus or infusion
Primary settings	Operating room, intensive care unit, emergency airway management
Typical container	Single-dose vial or ampule
Key inactive components	Water for injection and pH-adjusting acid system; product-specific labeling controls the exact composition
Storage	Refrigerated storage, generally 2°C to 8°C; protect from light and do not freeze
Critical quality attributes	Assay, impurities, pH, sterility, endotoxin, particulate matter, container integrity, and stability

The marketed solution is acidic. The FDA label for Nimbex identifies a pH range of approximately 3.25 to 3.65 and refrigeration requirements.[1] Cisatracurium undergoes Hofmann elimination, a chemical degradation pathway affected by temperature and pH. This makes thermal exposure, excursion management, and dilution stability central to product design.

The besylate component is the salt counterion associated with the active drug substance. It should not be treated as an optional formulation excipient. A developer changing the salt form, concentration, or pH system may create a different drug product that requires a separate regulatory strategy.

Which excipients are most important for cisatracurium?

The highest-value excipient work is likely to involve pH control, water quality, tonicity, dilution compatibility, and container interaction rather than complex multifunctional excipients.

pH-control system

Cisatracurium formulation development must preserve chemical stability while maintaining intravenous tolerability. A low-pH formulation can support stability, but excessive acidity may increase injection-site discomfort or complicate compatibility with other intravenous products.

Potential approaches include:

• Benzenesulfonic acid or another qualified acid system already used in the reference product.
• Controlled use of hydrochloric acid or sodium hydroxide for final pH adjustment.
• A low-capacity buffer system that limits pH drift without accelerating degradation.
• A formulation designed to maintain the target pH after dilution into common infusion fluids.

A strong formulation should demonstrate stability at release, during refrigerated storage, after controlled room-temperature exposure, and following dilution into 0.9% sodium chloride or 5% dextrose. The formulation must also assess precipitation, color change, particulate formation, and loss of potency after dilution.

Water for injection

Water quality is a major part of injectable product performance. Control parameters include conductivity, total organic carbon, bioburden, endotoxin, and particulate burden. A developer should evaluate whether the manufacturing process introduces trace metals or reactive impurities that accelerate cisatracurium degradation.

Tonicity agents

The commercial reference product is not necessarily optimized for tonicity in every administration scenario. Sodium chloride or other tonicity agents could be considered, but their inclusion may create new compatibility and osmolality issues. A concentrated vial intended for dilution has a different design target from a ready-to-administer syringe or infusion bag.

Tonicity modification is commercially useful only if it improves administration or dilution performance without reducing chemical stability. It should not be added solely to create a formulation difference.

Antioxidants and chelating agents

Cisatracurium is susceptible to chemical degradation, but the dominant pathway is associated with Hofmann elimination rather than a simple oxidation problem. Antioxidants or chelators may therefore have limited value unless forced-degradation studies identify a meaningful oxidation or trace-metal pathway.

These excipients can also create regulatory and compatibility burdens. Their use should be supported by degradation-mechanism data, not by generic injectable formulation practice.

Preservatives

A preservative-free, single-dose presentation is the commercially safer direction for operating-room and intensive-care use. Preservatives may create toxicity, compatibility, and labeling issues, particularly in critically ill patients and in products administered intravenously.

A multidose preserved product could reduce packaging cost, but it would face a weaker clinical and hospital-pharmacy value proposition than a preservative-free unit-dose product.

What formulation patents could protect cisatracurium products?

A new cisatracurium product would most likely obtain protection from formulation, container, stability, or delivery claims rather than from the active molecule.

Potential claim categories include:

1. A cisatracurium solution within a defined pH and concentration range.
2. A formulation with a specified impurity profile after refrigerated or accelerated storage.
3. A ready-to-administer cisatracurium infusion bag with defined dilution stability.
4. A prefilled syringe with a validated container-closure system.
5. A formulation that remains clear and particulate-free after dilution into a specified infusion fluid.
6. A product with defined stability after temperature excursion.
7. A dual-compartment system separating drug solution from diluent until use.
8. A low-sorption or low-permeability polymer container for cisatracurium.
9. A manufacturing process that reduces Hofmann-degradation impurities.
10. A combination package containing the drug, diluent, and administration instructions.

Weak claims would cover routine selection of water for injection, conventional sodium chloride dilution, or a broad pH range that merely describes the reference product. Stronger claims would link composition to measurable performance, such as a reduced degradation rate, longer in-use stability, or improved container compatibility.

The original product and active-ingredient protection for cisatracurium are legacy rights. Current competition is generally based on abbreviated generic approval, manufacturing capacity, supply contracts, and hospital purchasing rather than an active molecule patent barrier. FDA Orange Book review should be conducted for the specific reference-listed drug and dosage form before filing or licensing decisions.[2]

When does cisatracurium lose exclusivity?

Cisatracurium has already entered the mature generic market in the United States. The commercial question is therefore not the date of first generic entry. It is whether a differentiated product can obtain premium access in a low-margin injectable category.

Exclusivity factor	Commercial status
New chemical entity exclusivity	Expired
Original innovator market protection	Expired
Generic competition	Established
Biosimilar exclusivity	Not applicable
Remaining opportunity	Formulation, packaging, supply, and service differentiation
Primary regulatory route	ANDA for a therapeutically equivalent product; 505(b)(2) may be relevant for a materially different formulation or presentation

What is the Orange Book status of cisatracurium?

Cisatracurium products are regulated as conventional small-molecule injectable drugs, not biologics. The main reference product is Nimbex, cisatracurium besylate injection. Multiple generic products have been approved or marketed over time.

An ANDA product must generally match the reference product in active ingredient, dosage form, route, strength, and key pharmaceutical characteristics. An excipient change is possible if it is justified and does not affect safety, efficacy, bioequivalence, or product performance. A materially different delivery system may require a 505(b)(2) application rather than a conventional ANDA.

Orange Book review should focus on:

• The current reference-listed drug.
• Listed patents and exclusivity entries.
• Approved strengths and presentations.
• Therapeutic-equivalence codes.
• Any discontinued NDA status.
• The specific commercial product that a proposed ANDA would reference.

Are Paragraph IV challenges relevant to cisatracurium?

Paragraph IV litigation risk is limited compared with newer specialty drugs because cisatracurium is a mature generic product. A new ANDA applicant could still challenge any listed formulation or method-of-use patent, but the strategic value of that challenge depends on whether an active patent is listed against the selected reference product.

For a mature injectable, the more likely regulatory path is:

1. Confirm the reference-listed drug and strength.
2. Determine whether any active Orange Book patents remain.
3. File a paragraph III certification where applicable, or a paragraph IV certification if a listed patent is challenged.
4. Assess whether a 30-month stay, litigation cost, or settlement could delay launch.
5. Avoid relying on a patent challenge where the commercial product can be designed around the listed claim.

Method-of-use patents are less likely to create a broad barrier because cisatracurium is used across established surgical and critical-care indications. A formulation patent could have greater relevance if it covers a specific concentration, stabilizer system, container, or ready-to-use presentation.

What FDA regulatory strategy fits an improved cisatracurium product?

Conventional generic injection

An ANDA is the lowest-risk route when the product remains pharmaceutically equivalent to the reference drug. This approach is appropriate for a standard vial or ampule using a comparable aqueous formulation.

The principal development risks are:

• Demonstrating impurity control.
• Matching pH and concentration.
• Establishing dilution compatibility.
• Validating container closure.
• Showing sterile manufacturing control.
• Managing refrigerated distribution and excursion data.

Ready-to-use syringe

A prefilled syringe could reduce pharmacy preparation and improve dosing consistency. The regulatory pathway depends on how closely the product matches the reference product and whether the syringe changes administration, concentration, or labeling.

The key technical issues are syringe-material compatibility, extractables and leachables, drug adsorption, plunger performance, siliconization, particulate control, and long-term stability.

Ready-to-administer infusion bag

A cisatracurium infusion bag could have the clearest hospital value. It would eliminate bedside dilution and reduce compounding steps. The product would need validated stability in the final bag, including under refrigerated storage, room-temperature use, light exposure, and administration through standard tubing.

This format could justify a 505(b)(2) strategy if the presentation materially differs from the reference product. The commercial advantage would depend on hospital purchasing rules, pharmacy-and-therapeutics approval, bar-code integration, and inventory turnover.

Dual-chamber delivery system

A dual-chamber device could separate cisatracurium from a diluent until administration. It would improve shelf-life flexibility but increase device-development cost, assembly complexity, and regulatory burden. This option is more likely to be attractive for specialized markets than for standard operating-room demand.

What commercial opportunities exist for cisatracurium excipient innovation?

Ready-to-use hospital products

The strongest near-term opportunity is a ready-to-use, preservative-free product in a validated infusion presentation. Hospitals face pressure to reduce sterile compounding, preparation time, and medication errors. A ready-to-administer product can compete on total treatment cost even when the active ingredient is generic.

Temperature-excursion resilience

Cisatracurium generally requires refrigeration. A product with better short-term room-temperature stability could reduce product loss during transport, pharmacy handling, and operating-room use. This opportunity requires real-time and accelerated stability data, not only a revised excipient list.

A commercially meaningful claim could involve a defined period of stability after removal from refrigeration, provided the data support the proposed labeling.

Low-volume and emergency presentations

Smaller, clearly differentiated unit doses can support emergency airway management and operating-room workflows. The product should minimize dose-selection errors between 2 mg/mL and 10 mg/mL presentations. Color coding, barcode readability, and standardized labeling may have greater commercial value than a novel excipient.

Global-market formulations

Many markets have different cold-chain infrastructure and procurement requirements. A formulation optimized for room-temperature handling, or a package with stronger temperature-excursion protection, could support emerging-market distribution.

The commercial case depends on local registration requirements, hospital tender systems, and whether the manufacturer can produce multiple strengths without creating manufacturing complexity.

Contract manufacturing and supply partnerships

Cisatracurium is suitable for a supply-focused strategy. Hospitals and wholesalers may value dual sourcing, reliable fill-finish capacity, and consistent availability. Licensing opportunities could involve:

• A formulation platform with improved stability.
• A ready-to-use bag or syringe device.
• Regional manufacturing rights.
• A hospital injectable portfolio transaction.
• Contract filling for prequalified generic suppliers.

A formulation patent has limited value if the manufacturer cannot demonstrate dependable sterile production and distribution.

How does cisatracurium compare with other neuromuscular blockers?

Product	Commercial distinction	Excipient opportunity
Cisatracurium	Organ-independent Hofmann elimination; refrigerated injectable	Stability, ready-to-use infusion, temperature-excursion control
Atracurium	Similar class and degradation profile; established injectable	Packaging and stability differentiation
Rocuronium	Widely used nondepolarizing blocker; common vial presentation	Ready-to-use formats and storage convenience
Vecuronium	Lyophilized product requiring reconstitution in many presentations	Reconstitution elimination and presentation redesign
Succinylcholine	Depolarizing blocker with distinct clinical use and stability constraints	Cold-chain and preservative strategy, but different clinical positioning

Cisatracurium’s strongest clinical-commercial position is its established use where clinicians value organ-independent elimination. A formulation product should preserve that clinical identity while reducing preparation and storage friction.

What generic launch risks exist?

The main launch risks are operational rather than patent-based.

Risk	Impact	Mitigation
Cold-chain failure	Potency loss or shortened shelf-life	Excursion studies, temperature indicators, robust logistics
Concentration confusion	Medication error	Distinct labeling, barcode controls, limited SKU strategy
Dilution incompatibility	Precipitation or potency loss	Data across saline, dextrose, tubing, and administration times
Container interaction	Adsorption, leachables, or particulate formation	Container-closure screening and extractables studies
Sterile manufacturing failure	Batch rejection or supply interruption	Redundant sites, validated aseptic process, supplier qualification
Low generic pricing	Weak return on formulation investment	Target premium presentations and hospital contracts
Limited formulary adoption	Slow conversion	Pharmacy workflow studies and implementation support

How strong is the cisatracurium patent estate?

The active-ingredient patent estate is weak as a current barrier because the product is a mature generic. The most defensible new rights would relate to a specific formulation or delivery system with demonstrated technical performance.

Patent strength should be evaluated against four factors:

1. Whether the claims cover a commercially necessary feature.
2. Whether a competing manufacturer can substitute another acid, container, or concentration.
3. Whether the claimed stability benefit is measurable and clinically relevant.
4. Whether the claims can be enforced against ANDA products without relying on broad, vulnerable language.

A narrow formulation patent may be commercially useful if it protects a high-value ready-to-use product. It will have limited value if the market can revert to conventional vials with minimal switching costs.

Key Takeaways

• Cisatracurium is a mature generic injectable; active-ingredient exclusivity is not the principal commercial barrier.
• The most important formulation variables are pH, temperature, dilution stability, impurity control, and container compatibility.
• Preservative-free, ready-to-use syringes or infusion bags offer the clearest commercial differentiation.
• Excipient changes alone are unlikely to justify a premium unless they produce longer stability, easier administration, or lower pharmacy workload.
• Formulation and delivery patents are more relevant than legacy molecule patents.
• An ANDA fits a reference-like product; a materially different presentation may require a 505(b)(2) strategy.
• Supply reliability, cold-chain performance, and hospital workflow integration may generate more value than a novel excipient.
• Paragraph IV risk is likely to be limited, but product-specific Orange Book review remains necessary for any filing decision.

FAQs

Can cisatracurium be formulated without refrigeration?

A room-temperature product would require supporting stability data demonstrating acceptable potency, impurity levels, sterility assurance, and container compatibility. The commercial value would be high because refrigerated storage is a major operational constraint.

Is sodium chloride a suitable excipient for cisatracurium?

Sodium chloride may be used as a diluent or tonicity agent, but suitability depends on concentration, pH, dilution ratio, storage time, container, and administration conditions. Compatibility must be established for the proposed product rather than assumed from routine intravenous practice.

Does cisatracurium need a preservative?

A preservative-free single-dose presentation is generally the stronger hospital product strategy. A preservative may be considered for a multidose design, but it introduces additional safety, compatibility, and regulatory requirements.

Can a ready-to-use cisatracurium bag receive patent protection?

Yes, if the claims cover a specific composition, concentration, container, stability profile, or preparation method that is novel and non-obvious. A claim covering only a conventional cisatracurium dilution is less defensible.

Is cisatracurium a biologic requiring biosimilar approval?

No. Cisatracurium is a small-molecule drug. Competing products generally use the ANDA pathway when they are pharmaceutically equivalent to the reference product. A materially different formulation may require a 505(b)(2) application.

References

1. U.S. Food and Drug Administration. (2021). Nimbex (cisatracurium besylate) injection prescribing information.
2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
3. National Library of Medicine. (2024). DailyMed: Cisatracurium besylate injection product labeling.
4. U.S. Food and Drug Administration. (1995). Nimbex approval package and prescribing information.
5. U.S. Pharmacopeial Convention. (2024). United States Pharmacopeia and National Formulary: Sterile products and injectable preparations.