List of Excipients in Branded Drug CYTARABINE

Generic Drugs Containing CYTARABINE

Company	Ingredient	NDC	Excipient
Sagent Pharmaceuticals	cytarabine	25021-223	HYDROCHLORIC ACID
Sagent Pharmaceuticals	cytarabine	25021-223	SODIUM HYDROXIDE
Sagent Pharmaceuticals	cytarabine	25021-223	WATER

What are the Most Frequently-Used Excipients in CYTARABINE?

# Of NDCs	Excipient
2	BENZYL ALCOHOL
17	HYDROCHLORIC ACID
8	SODIUM CHLORIDE

Cytarabine Excipient Strategy and Commercial Opportunities

Last updated: September 3, 2026

Cytarabine is a mature antimetabolite with limited active-ingredient exclusivity and a fragmented generic market. Commercial value is concentrated in formulation execution: preservative-free injectable products, ready-to-use presentations, high-dose stability, intrathecal administration, liposomal delivery and hospital workflow improvements. The strongest opportunities are differentiated products that reduce preparation risk, extend usable shelf life or improve central nervous system exposure.

What excipients are used in cytarabine products?

Cytarabine products use relatively simple excipient systems in conventional injections but substantially more complex lipid systems in depot formulations.

Product type	Active ingredient	Typical excipient strategy	Primary commercial purpose
Conventional cytarabine injection	Cytarabine	Water for injection, sodium chloride in some presentations, pH adjusters such as hydrochloric acid or sodium hydroxide	Low-cost intravenous and subcutaneous administration
Cytarabine powder for reconstitution	Cytarabine	Minimal excipient load; reconstituted with compatible sterile diluent	Long-term storage and flexible hospital preparation
Preservative-free cytarabine	Cytarabine	Sterile aqueous vehicle without antimicrobial preservatives	Intrathecal use and high-risk pediatric administration
Liposomal cytarabine	Cytarabine encapsulated in multivesicular liposomes	Dioleoylphosphatidylcholine, dipalmitoylphosphatidylglycerol, cholesterol, triolein and water for injection	Sustained release into cerebrospinal fluid
Potential ready-to-use products	Cytarabine	Buffered aqueous system, container-compatible stabilizers and low-particulate packaging	Reduced pharmacy compounding and faster administration

Cytarabine is administered intravenously, subcutaneously and intrathecally. The route determines the acceptable excipient profile. A product intended for intrathecal administration must avoid preservatives and excipients with established neurotoxicity concerns. FDA labeling for cytarabine products places particular restrictions on benzyl alcohol-containing preparations for intrathecal use.[1]

Conventional injection excipients

Conventional cytarabine injections generally rely on an aqueous vehicle and pH adjustment rather than a complex stabilizer system. The formulation challenge is less the solubility of cytarabine than maintaining chemical stability, sterility, low particulate levels and container compatibility through storage and administration.

The most commercially relevant variables are:

• Cytarabine concentration
• Single-dose versus multidose packaging
• Preservative-free status
• Room-temperature stability
• Compatibility with infusion bags and administration sets
• Extractables and leachables from polymer containers
• Light sensitivity and labeling requirements
• Reconstitution time for powder presentations

A simple formulation can support an ANDA only if the applicant matches the reference product’s qualitative and quantitative inactive-ingredient profile where required, or demonstrates that a different excipient system is suitable for the proposed route and dosage form.

Liposomal excipients

DepoCyt, a liposomal cytarabine product, used a multivesicular liposome platform. Its lipid system included dioleoylphosphatidylcholine, dipalmitoylphosphatidylglycerol, cholesterol and triolein.[2] These components formed a depot capable of releasing cytarabine over an extended period in cerebrospinal fluid.

The liposomal system changes the regulatory and technical profile:

• The product is a complex drug product rather than a simple aqueous injection.
• Particle size, morphology, encapsulation efficiency and release rate become critical quality attributes.
• Lipid oxidation and hydrolysis create additional stability risks.
• Sterilization cannot be treated as a routine terminal process without assessing liposome integrity.
• Manufacturing scale-up can alter loading, particle distribution and release kinetics.
• A conventional generic-equivalence pathway is less straightforward than for aqueous cytarabine.

What formulation patents protect cytarabine products?

The original cytarabine compound and conventional injectable formulations are mature technologies. The principal remaining intellectual-property opportunities are formulation-specific rather than molecule-specific.

Liposomal and depot delivery

The strongest historical patent position was associated with multivesicular liposome technology and sustained-release cytarabine. Relevant rights would have been directed to:

• Liposome composition
• Lipid ratios
• Multivesicular architecture
• Encapsulation of cytarabine
• Controlled-release kinetics
• Intrathecal delivery
• Manufacturing and loading processes

The commercial and legal status of those rights depends on jurisdiction, patent-term adjustments, terminal disclaimers and any surviving continuations. A current freedom-to-operate review must be performed by country and claim family. The basic US exclusivity period for the original DepoCyt technology is no longer the principal barrier to conventional cytarabine competition.

Aqueous formulation patents

Aqueous cytarabine products have limited opportunity for broad composition-of-matter protection because the active ingredient is old and widely available. Narrow patent claims could still address:

• Specific concentration ranges
• Stabilizing pH ranges
• Low-degradation impurity profiles
• Ready-to-use bag configurations
• Container closure systems
• Freeze-thaw stability
• Extended in-use stability
• Compatibility with elastomeric pumps
• Automated compounding cartridges

These claims would need meaningful technical differentiation. A patent directed only to routine selection of water, sodium chloride or a conventional pH adjuster is vulnerable to obviousness and lack-of-technical-effect challenges.

When does cytarabine lose exclusivity?

Cytarabine has already lost basic small-molecule exclusivity in the United States and major international markets. Generic cytarabine injections are commercially established, and the market is supplied through multiple manufacturers and contract manufacturers.

Exclusivity category	Cytarabine position
Active-ingredient patent	Expired or commercially irrelevant in major markets
Conventional injection patent estate	Generally weak and fragmented
FDA new chemical entity exclusivity	Expired
Orphan exclusivity	Not a current barrier for conventional cytarabine
Pediatric exclusivity	Not a current market-wide barrier
Liposomal formulation protection	Historically more important; country-specific review required
Biosimilar exclusivity	Not applicable because cytarabine is a small molecule
Generic substitution risk	High for standard injectable presentations

FDA Orange Book listings should be reviewed by product and NDA because listing status can differ between conventional cytarabine products and specialized formulations.[3] An Orange Book listing does not itself establish that every listed patent remains commercially blocking. Patent expiration, delisting, litigation outcomes and settlement terms must be assessed together.

What FDA regulatory status applies to cytarabine formulations?

Conventional cytarabine injections are approved through the full NDA or ANDA framework used for small-molecule injectable drugs. The principal regulatory issues are product quality, sterility, strength, impurity control and route-specific safety.

Liposomal cytarabine follows a more demanding path because it is a complex injectable drug product. FDA review is likely to focus on:

• Lipid raw-material controls
• Particle-size distribution
• Encapsulation efficiency
• Free versus encapsulated cytarabine
• In-vitro release testing
• Sterility and endotoxin control
• Container closure integrity
• Subvisible particles
• Aggregation and leakage during storage
• Comparability after manufacturing changes

DepoCyt was approved in the United States for intrathecal administration in patients with lymphomatous meningitis. FDA later accepted withdrawal of the product at the sponsor’s request. The withdrawal was reported as a commercial decision rather than a withdrawal for safety or effectiveness reasons.[4]

That history creates a potential regulatory opening for a new liposomal cytarabine product, but the development burden remains materially higher than for a conventional injection.

What excipient strategy is strongest for a new cytarabine product?

1. Preservative-free, ready-to-use injection

This is the most practical near-term opportunity. A product could be differentiated through:

• Single-dose, preservative-free vials
• Ready-to-administer infusion bags
• Standardized concentrations
• Reduced pharmacy manipulation
• Longer refrigerated shelf life
• Room-temperature shipping tolerance
• Low-sorption container materials
• Barcode-ready hospital packaging

The commercial case is strongest where hospitals incur high labor costs from reconstitution and cytotoxic handling. A ready-to-use product can compete even when the active ingredient is generic if it reduces medication-preparation time and occupational exposure.

2. High-concentration cytarabine

High-dose cytarabine regimens create demand for concentrated products that reduce infusion volume. The formulation must control precipitation, degradation and delivery-device compatibility. Opportunities include:

• Concentrated vials for dilution
• Pharmacy-ready bags
• Infusion-pump-compatible presentations
• Batch-specific stability documentation
• Reduced overfill and product waste

The product must demonstrate adequate stability after dilution into commonly used infusion fluids. This can create a defensible formulation and packaging package even without broad patent protection.

3. Intrathecal cytarabine

Intrathecal cytarabine requires a strict excipient strategy:

• No benzyl alcohol
• No antimicrobial preservatives
• Low endotoxin burden
• Low particulate load
• Single-use packaging
• Route-specific labeling and handling controls

A preservative-free product designed specifically for intrathecal administration could command a premium over multipurpose presentations. The market is clinically narrow, but the safety and workflow requirements create differentiation.

4. Liposomal cytarabine

A next-generation liposomal product could target the same clinical rationale as DepoCyt while improving manufacturing consistency or administration convenience. Potential areas include:

• More reproducible particle-size distribution
• Lower free-cytarabine fraction
• Improved storage stability
• Smaller injection volume
• Longer release duration
• More predictable cerebrospinal-fluid exposure
• Improved syringeability and suspension uniformity

The technical barrier is high. A liposomal product must establish a reliable relationship between formulation attributes and pharmacokinetic or clinical performance. The formulation may also require a 505(b)(2) strategy in the United States if it relies on an approved reference product while introducing a meaningful delivery change.

5. Lyophilized cytarabine

Lyophilization can reduce degradation during long-term storage and support global distribution. The opportunity is most relevant where cold-chain access is limited or where liquid cytarabine has a short usable life after manufacture.

Potential excipients include bulking agents and cryoprotective or lyoprotective materials. Each excipient introduces new questions about reconstitution, osmolality, particulate formation and compatibility with intrathecal use. A lyophilized product for intravenous use may be easier to justify than a product intended for direct intrathecal administration.

How strong is the cytarabine patent estate?

The conventional cytarabine patent estate is weak because:

1. The active ingredient is old.
2. Multiple generic injections are established.
3. Basic aqueous excipients are difficult to protect broadly.
4. Routine concentration and packaging changes may face obviousness challenges.
5. Commercial barriers are more likely to arise from manufacturing controls, quality data and hospital contracts than from blocking patents.

The stronger positions are narrow and product-specific:

Technology	Patent strength	Regulatory complexity	Commercial attractiveness
Standard aqueous vial	Low	Low	Moderate
Preservative-free intrathecal vial	Low to moderate	Moderate	Moderate
Ready-to-use infusion bag	Moderate	Moderate	High
High-concentration product	Moderate	Moderate	Moderate to high
Lyophilized formulation	Moderate	Moderate to high	Moderate
Multivesicular liposomal product	Moderate to high if claims remain active	High	High but specialized
Novel depot or implant system	Potentially high	High	Uncertain

Patent value will depend on whether claims cover the product as sold, not merely an internal manufacturing parameter. Process claims can add leverage, but they are harder to detect and enforce against third-party manufacturing.

Which companies are challenging conventional cytarabine products?

Competition is primarily from generic injectable manufacturers rather than branded innovators. The market structure typically includes:

• Large generic injectable manufacturers
• Hospital-focused suppliers
• Contract development and manufacturing organizations
• Regional oncology-drug manufacturers
• Specialty manufacturers with sterile cytotoxic capacity

A biosimilar challenge is not relevant. Cytarabine is a chemically synthesized small molecule, so competitors use ANDA, 505(b)(2), hybrid or national generic pathways rather than biosimilar applications.

Paragraph IV litigation is most relevant when a company seeks approval for a differentiated formulation with Orange Book-listed patents. Standard cytarabine injection products generally have lower litigation exposure because the core product is off-patent and generic competition is already present. A new liposomal or depot product would create a more credible Paragraph IV risk if an innovator lists formulation or method-of-use patents.

What licensing deals could create value?

The most relevant licensing targets are platform technologies rather than cytarabine compound rights.

Potential deal structures include:

• License of multivesicular liposome technology
• Regional rights to an intrathecal depot product
• Co-development of a ready-to-use oncology injectable
• Transfer of sterile cytotoxic manufacturing capacity
• License of container or delivery-device technology
• Hospital-system supply agreements tied to standardized concentrations
• Acquisition of an abandoned or discontinued cytarabine formulation

A buyer should separate three assets in diligence: regulatory rights, formulation know-how and manufacturing capability. A product may have limited patent value but still hold commercial value through validated sterile processes, customer contracts and regulatory history.

What generic launch risks exist for cytarabine?

A conventional cytarabine launch faces low patent risk but meaningful execution risk.

Risk	Business impact	Mitigation
Sterile manufacturing failure	Supply interruption and FDA action	Qualified redundant manufacturing sites
Cytotoxic-containment limitations	Capacity constraints	Dedicated or validated segregated suites
Short dating period	Inventory write-offs	Stability program and optimized container system
Hospital purchasing pressure	Price erosion	Ready-to-use or workflow-based differentiation
Drug shortages	Regulatory scrutiny and supply obligations	API redundancy and safety stock
Intrathecal-use errors	Product liability and recalls	Route-specific packaging and labeling
Liposome batch variability	Approval delay or clinical comparability problems	Tight critical-quality-attribute controls
Low volume in specialty indications	Weak manufacturing economics	Regional licensing or portfolio bundling

Cytarabine API supply and sterile fill-finish capacity are more important competitive barriers than basic formulation patents. Cytotoxic handling requirements can limit the number of reliable suppliers and create opportunities for contract manufacturing partnerships.

How does cytarabine compare with competing oncology injectables?

Cytarabine differs from many older oncology injectables because route of administration is a major value driver. Unlike a standard intravenous-only generic, cytarabine has an intrathecal use case and a historical liposomal delivery platform.

Product category	Formulation differentiation	Patent risk	Workflow opportunity
Cytarabine injection	Limited	Low	Ready-to-use packaging
Liposomal cytarabine	High	Moderate to high	Extended dosing interval
Methotrexate injection	Moderate	Low	Preservative-free and ready-to-use products
Fludarabine injection	Moderate	Low	Stability and reconstitution
Gemcitabine injection	Moderate	Low	Concentration and ready-to-use bags
Pegylated oncology products	High	Often higher	Long-acting delivery and reduced dosing frequency

Cytarabine’s best commercial positioning is a hospital product that reduces preparation burden or a specialized CNS-delivery product that changes dosing frequency.

What is the revenue exposure and commercial outlook?

Public company filings generally do not isolate cytarabine revenue from broader generic injectable or oncology portfolios. Product-level revenue exposure therefore cannot be reliably quantified from public disclosures alone.

The commercial outlook is segmented:

• Standard cytarabine: high volume potential, low margin and strong price competition.
• Preservative-free intrathecal cytarabine: lower volume, stronger differentiation.
• Ready-to-use products: moderate volume with potential hospital-contract premium.
• Liposomal cytarabine: specialty-market opportunity with higher development and manufacturing costs.
• Lyophilized products: regional opportunity tied to distribution and cold-chain economics.

A differentiated presentation should be evaluated on total treatment cost, pharmacy labor, waste reduction, shortage resilience and administration safety rather than unit price alone.

Key Takeaways

• Cytarabine compound exclusivity is exhausted in major markets.
• Conventional aqueous formulations have weak patent potential.
• Preservative-free, intrathecal and ready-to-use products offer the most practical commercial opportunities.
• Liposomal cytarabine has the highest technical differentiation but also the highest regulatory burden.
• Biosimilar risk does not apply; competition comes through generic, hybrid and 505(b)(2) pathways.
• Manufacturing capacity, sterile cytotoxic controls and supply reliability are stronger barriers than basic excipient patents.
• FDA Orange Book and Paragraph IV risk are most relevant to specialized formulations, not standard cytarabine injections.
• A formulation patent should tie measurable performance to a product characteristic, such as stability, release, particle size or administration safety.

FAQs

Can benzyl alcohol be used in intrathecal cytarabine?

Benzyl alcohol-containing cytarabine preparations should not be used intrathecally. Intrathecal products should be preservative-free and specifically qualified for that route.[1]

Is liposomal cytarabine still marketed in the United States?

DepoCyt was withdrawn from US marketing at the sponsor’s request. FDA reported that the withdrawal was not based on safety or effectiveness concerns.[4]

Does cytarabine have biosimilar competition?

No. Cytarabine is a small-molecule drug. Competitors use generic or hybrid regulatory pathways rather than biosimilar applications.

Can a new cytarabine formulation receive 505(b)(2) approval?

A materially modified product, such as a depot or liposomal formulation, may be eligible for a 505(b)(2) pathway if it relies partly on an FDA-approved reference product and supplies the required bridging and clinical evidence.

Which excipient opportunity has the shortest path to commercialization?

A preservative-free, ready-to-use aqueous cytarabine presentation generally has a shorter development path than a liposomal or depot formulation, provided stability, container compatibility, sterility and route-specific requirements are established.

References

1. U.S. Food and Drug Administration. (n.d.). Cytarabine injection prescribing information.
2. U.S. Food and Drug Administration. (n.d.). DepoCyt cytarabine liposome injection prescribing information.
3. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
4. U.S. Food and Drug Administration. (2017). Withdrawal of approval of new drug application for DepoCyt. Federal Register.