List of Excipients in Branded Drug NELARABINE

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Generic Drugs Containing NELARABINE

Company	Ingredient	NDC	Excipient
Nexus Pharmaceuticals LLC	nelarabine	14789-114	HYDROCHLORIC ACID
Nexus Pharmaceuticals LLC	nelarabine	14789-114	SODIUM CHLORIDE
Nexus Pharmaceuticals LLC	nelarabine	14789-114	SODIUM HYDROXIDE
Sagent Pharmaceuticals	nelarabine	25021-259	SODIUM CHLORIDE
Sagent Pharmaceuticals	nelarabine	25021-259	WATER
XGen Pharmaceuticals DJB Inc	nelarabine	39822-0650	HYDROCHLORIC ACID

What are the Most Frequently-Used Excipients in NELARABINE?

# Of NDCs	Excipient
10	HYDROCHLORIC ACID
15	SODIUM CHLORIDE
10	SODIUM HYDROXIDE
14	WATER

Nelarabine Excipient Strategy and Commercial Opportunities

Last updated: September 29, 2026

Executive summary: Nelarabine is an orphan oncology prodrug marketed as an intravenous solution for relapsed or refractory T-cell acute lymphoblastic leukemia and T-cell lymphoblastic lymphoma. Its commercial formulation is relatively simple: 5 mg/mL nelarabine in 0.9% sodium chloride, with hydrochloric acid used for pH adjustment. The strongest opportunities are generic injectable supply, ready-to-use presentations, pediatric dose flexibility, global access, and manufacturing efficiency rather than high-value reformulation. A differentiated excipient platform would need to solve a defined problem such as concentration, container compatibility, photostability, infusion convenience, or reduced preparation risk.

What is the approved nelarabine formulation?

Nelarabine is a water-soluble prodrug converted in vivo to ara-G, an antimetabolite that inhibits DNA synthesis in malignant T lymphoblasts. The FDA-approved product, Arranon, is an intravenous injection supplied at 5 mg/mL in a single-use container.[1]

Formulation attribute	Approved commercial profile
Active ingredient	Nelarabine
Dosage form	Sterile intravenous solution
Strength	5 mg/mL
Primary vehicle	Water for injection
Tonicity agent	Sodium chloride
pH adjustment	Hydrochloric acid
Typical pH range	Approximately 5.0 to 7.0
Administration	Intravenous infusion, generally over two hours
Preservative	No preservative is used
Storage	Controlled room-temperature storage under the approved label
Patient population	Pediatric and adult patients with relapsed or refractory T-cell malignancies

The approved product does not require a complex excipient system. Sodium chloride supports isotonicity, while pH adjustment controls chemical stability and product compatibility. The formulation is appropriate for hospital oncology use because it avoids nonaqueous solvents, surfactants, and preservatives that can introduce toxicity or compatibility concerns.

Which excipients are most important for nelarabine stability?

The highest-value excipient variables are sodium chloride concentration, pH, buffer selection, oxygen exposure, and container-closure interaction.

Sodium chloride

Sodium chloride is the principal functional excipient in the commercial injection. It provides tonicity and allows the product to be administered without a separate dilution step in routine use. A generic manufacturer should preserve the established saline-based platform unless analytical and clinical data support a meaningful change.

A material change in sodium chloride concentration could affect osmolality, infusion tolerability, and regulatory comparability. A lower-sodium formulation might be relevant for patients with fluid or electrolyte restrictions, but the commercial population is too small to make that opportunity attractive without a clear clinical or operational benefit.

pH control

Nelarabine stability is likely sensitive to pH because the molecule contains a purine nucleoside structure and a glycosidic linkage that may undergo degradation under unsuitable conditions. Hydrochloric acid provides simple pH adjustment without introducing a new buffering species.

A citrate, acetate, phosphate, or histidine buffer could improve pH control during storage, but each would create new development questions:

• Does the buffer accelerate hydrolysis or degradation?
• Does it increase precipitation risk?
• Does it alter compatibility with infusion bags and tubing?
• Does it change osmolality or infusion tolerability?
• Does it create a new formulation patent position?

For a generic product, unnecessary buffering is commercially unattractive. A buffer is more defensible for a new drug-delivery product that demonstrates longer shelf life, higher concentration, or improved in-use stability.

Preservatives and surfactants

A preservative-free product is preferable for an intravenous oncology drug administered in controlled clinical settings. Benzyl alcohol, phenol, parabens, and related preservatives would create pediatric and toxicity concerns. Polysorbates and other surfactants are not necessary for a simple aqueous nelarabine solution and could introduce peroxide-related degradation or extractables and leachables issues.

The commercial formulation strategy should therefore prioritize a minimal-excipient profile.

What formulation patents could protect nelarabine products?

The strongest potential formulation claims would cover a specific technical improvement, not the basic use of saline as a vehicle.

High-value formulation claim categories

Claim category	Commercial value	Main technical requirement
Concentrated aqueous nelarabine solution	High	Demonstrated solubility and stability at higher strength
Premixed infusion bag	Medium to high	Container compatibility and validated shelf life
Photostable formulation	Medium	Quantified protection from light-induced degradation
Extended in-use stability	Medium	Stability after vial opening, transfer, or dilution
Low-volume pediatric presentation	Medium	Accurate dosing across small body-surface-area ranges
Lyophilized nelarabine	Medium	Improved shipping or shelf life sufficient to offset reconstitution burden
Alternative buffer system	Low to medium	Clear stability or manufacturing advantage
Ready-to-administer syringe or cartridge	Medium	Device compatibility and dose accuracy

A broad claim to nelarabine in saline would face validity and obviousness pressure if the formulation tracks the approved product. More defensible claims would require narrow ranges, defined degradation limits, particular container materials, or a demonstrated manufacturing benefit.

The relevant patent review should cover composition-of-matter patents, process patents, formulation patents, container-closure claims, and method-of-use patents. The FDA Orange Book should be checked for current listed patents and regulatory exclusivity associated with approved reference products.[2] Historical patents covering nelarabine chemistry may no longer block generic development, but a live patent position must be assessed by jurisdiction and claim scope.

When does nelarabine lose exclusivity?

Nelarabine received FDA orphan-drug approval for a rare oncology indication. Orphan exclusivity is indication-specific and lasts seven years from approval under the Orphan Drug Act.[3] The original Arranon approval occurred in 2005, so the original seven-year orphan period has expired.

The key commercial questions are now:

1. Whether any later approval obtained separate orphan exclusivity.
2. Whether FDA-listed patents remain attached to the reference product.
3. Whether a generic applicant can rely on an abbreviated new drug application pathway.
4. Whether a proposed generic label would require a section viii carve-out for protected indications.
5. Whether pediatric labeling or other regulatory protections affect the application.

Nelarabine is a small molecule, not a biologic. Biosimilar regulation under the Public Health Service Act does not apply. Competitive entry would proceed through the generic-drug framework, generally involving an ANDA and, where applicable, Paragraph IV certification against listed patents.[4]

What Paragraph IV and generic entry risks exist for nelarabine?

Nelarabine has several characteristics that can make generic entry feasible but commercially limited:

• The dosage form is an aqueous injection.
• The excipient system is simple.
• The product does not require a complex delivery device.
• The drug is administered in hospitals and specialist oncology centers.
• Total annual demand is constrained by the rarity of the indications.
• Manufacturing quality requirements for sterile injectables are high.
• A single supplier disruption can have a disproportionate clinical effect.

A Paragraph IV challenge would be most relevant if the Orange Book contains an unexpired patent covering the reference product or an approved method of use. A generic applicant could also pursue a Paragraph III certification for later entry or a section viii statement excluding a patented indication.

The main litigation risk is likely to arise from formulation, manufacturing, or use claims rather than from the core compound. A basic sterile saline injection may be difficult to protect broadly, but a patent covering a specific concentration, stability profile, premixed container, or manufacturing process could delay or complicate entry.

What commercial opportunities exist for nelarabine excipients and formulations?

Ready-to-use infusion products

A ready-to-use bag could reduce pharmacy compounding steps and exposure risk. The product would need validated stability in polyolefin or other infusion containers, reliable compatibility with administration sets, and a shelf life long enough to support hospital inventory.

The opportunity is strongest if the current presentation requires vial transfer, dose calculation, or additional manipulation. The product should be positioned around medication safety and workflow reduction rather than a novel excipient narrative.

Higher-concentration injections

A 10 mg/mL or higher-concentration product could reduce infusion volume and shipping costs. The development barriers are solubility, precipitation, viscosity, osmolality, and chemical stability. A higher concentration would have commercial value in pediatric and high-dose adult regimens, but it could also increase dosing-error risk if multiple strengths are introduced.

A concentration patent could be more commercially defensible than a conventional saline formulation if the product demonstrates a reproducible technical effect.

Pediatric dose presentations

The pediatric regimen is based on body-surface area and may require small, variable volumes. A low-volume vial, premeasured syringe, or graduated presentation could improve dose accuracy. Any device-based product would require human-factors assessment, container-closure validation, and pediatric-use analysis.

The market is small, but pediatric oncology centers may value reduced preparation time and lower residual drug waste.

Global and emerging-market supply

A stable, room-temperature formulation could support distribution in markets with limited cold-chain infrastructure. The commercial opportunity depends on local regulatory pathways, hospital procurement, and pricing discipline. A simpler formulation with fewer excipients can reduce raw-material complexity and support multi-region registration.

Geographic patent risk should be reviewed independently in the United States, European Union, Japan, China, Canada, Australia, and major emerging markets. Patent expiry and regulatory exclusivity are not uniform across jurisdictions.

How strong is the nelarabine patent estate?

The core patent estate is likely weaker than the estate surrounding newer targeted oncology drugs because nelarabine was approved in 2005 and uses a conventional injectable dosage form. The commercial barrier is more likely to be operational than patent-based.

Estate component	Likely strategic importance
Core compound patents	Low if expired
Salt or crystalline-form patents	Low to medium
Aqueous formulation patents	Medium if technically narrow and unexpired
Premixed-container patents	Medium
Manufacturing-process patents	Medium, especially for sterile scale-up
Method-of-use patents	Medium where indication-specific
Device patents	Low to medium
Trade secrets	Medium for process controls and impurity management

The most relevant non-patent barriers are sterile manufacturing capacity, validated analytical methods, low-volume commercial economics, procurement qualification, and reliable supply. An entrant with an established oncology injectable platform could have a stronger position than a company with a superior but expensive formulation.

What FDA regulatory pathway applies to nelarabine?

A conventional generic nelarabine injection would generally be developed through an ANDA referencing the approved product. The applicant would need to demonstrate pharmaceutical equivalence, bioequivalence where applicable, quality attributes, sterility, container-closure integrity, extractables and leachables control, and manufacturing-process validation.[4]

A materially different formulation may require a 505(b)(2) application rather than an ANDA. That route could support:

• A higher concentration.
• A new container or delivery system.
• A different formulation with reliance on FDA findings for nelarabine.
• A new administration method.
• A meaningful stability or handling improvement.

The 505(b)(2) route offers more formulation flexibility but carries greater development cost and potential patent certification requirements.

How does nelarabine compare with competing T-cell malignancy treatments?

Nelarabine occupies a narrow treatment position in relapsed or refractory T-cell acute lymphoblastic leukemia and T-cell lymphoblastic lymphoma. Its competitors include salvage chemotherapy combinations, stem-cell-transplant strategies, and newer targeted or cellular therapies where clinically appropriate.

Product category	Formulation complexity	Commercial implication
Nelarabine injection	Low	Generic supply and workflow differentiation
Multi-agent salvage chemotherapy	Medium to high	Nelarabine may remain operationally simpler
Targeted small molecules	Oral or injectable	May compete on convenience or broader indication
CAR-T or cellular therapy	Very high	Different treatment setting and cost structure
Transplant-based treatment	High	Not a direct formulation competitor

Nelarabine’s narrow indication limits peak-sales potential but can support stable niche demand if the product remains clinically incorporated into salvage protocols.

What licensing and partnership opportunities exist?

The most credible licensing targets are:

1. Regional rights for generic nelarabine injection.
2. Supply agreements with oncology injectable manufacturers.
3. Co-development of ready-to-use infusion bags.
4. Licensing of sterile fill-finish capacity.
5. Partnerships for pediatric dosing devices.
6. Distribution agreements in countries where T-cell malignancy treatment is expanding.

A formulation license would be more attractive if it includes validated stability data, a granted patent with meaningful remaining term, and a manufacturing process that can be transferred without major capital investment. A patent without supply capability would have limited commercial value in this market.

Key Takeaways

• Nelarabine is an intravenous, small-molecule oncology drug with a simple saline-based formulation.
• The main approved excipients are sodium chloride and hydrochloric acid for pH adjustment.
• Preservative-free, aqueous formulations are the most practical commercial platform.
• Orphan exclusivity from the original 2005 approval has expired.
• Nelarabine is subject to generic, not biosimilar, competition.
• The strongest formulation opportunities are ready-to-use bags, higher concentrations, pediatric dose presentations, and improved in-use stability.
• Basic saline reformulation is unlikely to produce strong patent protection without a demonstrated technical effect.
• Sterile manufacturing, supply reliability, and procurement access may be greater barriers than core composition patents.
• A generic ANDA is the likely route for an equivalent injection; materially different presentations may require a 505(b)(2) application.
• The market is commercially narrow but strategically relevant for oncology injectable suppliers.

FAQs

Is nelarabine available as an oral formulation?

No FDA-approved oral nelarabine product is identified in the approved product labeling. The marketed dosage form is an intravenous injection.[1]

Can a manufacturer replace sodium chloride in nelarabine injection?

Yes, a manufacturer can develop an alternative excipient system, but the product would need to demonstrate acceptable stability, sterility, osmolality, compatibility, and regulatory equivalence. A material formulation change may move the product from an ANDA strategy to a 505(b)(2) pathway.

Does nelarabine have biosimilar competition?

No. Nelarabine is a small-molecule drug. Competition would generally involve generic-drug applications rather than biosimilar applications.

Is a concentrated nelarabine formulation commercially attractive?

Potentially. A higher-strength injection could reduce infusion volume, shipping cost, and preparation burden. The opportunity depends on solubility, stability, dosing safety, and whether the smaller market supports development and manufacturing costs.

What is the main commercial risk for a generic nelarabine product?

The main risk is limited market size combined with sterile injectable manufacturing costs. A technically successful generic may still have modest returns unless it secures reliable hospital contracts, regional rights, or a differentiated ready-to-use presentation.

References

1. U.S. Food and Drug Administration. (2023). Arranon (nelarabine) injection: Prescribing information. FDA.

2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.

3. U.S. Food and Drug Administration. (2024). Orphan drug designation and approval. FDA.

4. U.S. Food and Drug Administration. (2024). ANDA submissions: Content and format. FDA.