List of Excipients in Branded Drug LOMUSTINE

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Wilshire Pharmaceuticals Inc	LOMUSTINE	lomustine	52536-341	MAGNESIUM STEARATE
Wilshire Pharmaceuticals Inc	LOMUSTINE	lomustine	52536-341	MANNITOL

Generic Drugs Containing LOMUSTINE

Company	Ingredient	NDC	Excipient
Carnegie Pharmaceuticals LLC	lomustine	80005-114	AMMONIA
Carnegie Pharmaceuticals LLC	lomustine	80005-114	FERROSOFERRIC OXIDE
Carnegie Pharmaceuticals LLC	lomustine	80005-114	GELATIN

What are the Most Frequently-Used Excipients in LOMUSTINE?

# Of NDCs	Excipient
1	AMMONIA
1	FERROSOFERRIC OXIDE
1	GELATIN

Lomustine Excipient Strategy, Patent Position, and Commercial Opportunities

Last updated: September 4, 2026

Lomustine is an established oral nitrosourea with a relatively simple dosage form and limited active-ingredient differentiation. Commercial opportunity is concentrated in capsule robustness, moisture protection, dose flexibility, hazardous-drug handling, pediatric administration, global supply, and lifecycle formulations rather than in a conventional new chemical entity strategy. The leading U.S. product, Gleostine, is marketed by NextSource Pharma and is supplied as 10 mg, 40 mg, and 100 mg capsules.

What is lomustine and how is it supplied?

Lomustine, also known as CCNU, is an oral alkylating agent used for brain tumors and Hodgkin lymphoma after failure of primary therapy. The drug is administered as a single oral dose every six weeks, with dosing based on body surface area and hematologic recovery. Its extended dosing interval differentiates it from many continuously administered oral oncology products.

Attribute	Lomustine
Active ingredient	Lomustine
Chemical designation	1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea
Drug class	Nitrosourea alkylating agent
Route	Oral
U.S. reference product	Gleostine
U.S. NDA	NDA 017557
Strengths	10 mg, 40 mg, 100 mg
Main indications	Brain tumors; Hodgkin lymphoma after failure of primary therapy
Dosing pattern	Single dose, generally repeated every six weeks
Regulatory status	Approved prescription drug
Handling category	Hazardous antineoplastic drug

The product is supplied in hard capsules. The FDA label requires administration as a single dose and warns against repeated dosing at intervals shorter than six weeks because of delayed and cumulative bone-marrow toxicity (U.S. Food and Drug Administration [FDA], 2023).

What excipients are used in Gleostine capsules?

Gleostine capsules use conventional capsule excipients, colorants, and shell materials. The label identifies the dosage form as a hard gelatin capsule and lists inactive ingredients by strength. The product uses different capsule colors to distinguish dose levels, reducing medication-error risk in a drug with substantial delayed hematologic toxicity.

Exact excipient composition can vary by strength and market presentation. The relevant excipient functions are:

Excipient function	Commercial purpose
Gelatin capsule shell	Provides a dry, unit-dose container for lomustine powder
Capsule colorants	Differentiates 10 mg, 40 mg, and 100 mg strengths
Titanium dioxide or other opacifier	Controls capsule appearance and light exposure
Fill diluent	Provides bulk and improves dose uniformity
Glidant or lubricant	Supports powder flow and capsule filling
Moisture-control packaging	Protects a moisture-sensitive oncology product

Lomustine is a small, lipophilic molecule with limited aqueous solubility. A dry powder-filled capsule is therefore more commercially practical than an aqueous liquid or conventional solution. Excipients should be selected to maintain chemical stability, reduce powder segregation, support content uniformity, and avoid accelerated degradation under humidity stress.

The product’s principal excipient constraint is not gastrointestinal tolerability. It is physical and chemical stability during manufacturing, storage, dispensing, and handling.

Which excipient attributes matter most for lomustine?

Moisture control

Moisture management is the highest-value excipient and packaging consideration. A capsule formulation should minimize water activity in the fill and limit moisture migration through the shell. Formulators should evaluate:

• Low-moisture diluents
• Desiccant-compatible packaging
• High-barrier bottles or blisters
• Water activity of the finished capsule
• Gelatin-shell moisture transfer
• Stability under ICH long-term and accelerated conditions

Microcrystalline cellulose, anhydrous lactose, dibasic calcium phosphate, and selected co-processed excipients can provide different combinations of flow, compressibility, and moisture performance. The preferred choice depends on lomustine loading, powder density, and compatibility data.

Content uniformity

Lomustine capsules are administered in a narrow therapeutic context, and dose escalation or repetition is constrained by blood counts. A formulation must achieve robust content uniformity across the full capsule-filling run, particularly for the 10 mg strength.

High-potency handling also affects manufacturing design. Low-dose capsules can be vulnerable to segregation when the active ingredient has a substantially different particle size or density from the excipient blend. Particle engineering, geometric dilution, ordered mixing, or a controlled granulation step may improve uniformity.

Capsule-shell performance

Gelatin is familiar, inexpensive, and accepted in the reference product. Hydroxypropyl methylcellulose, or HPMC, could support a differentiated capsule platform where vegetarian labeling, shell moisture performance, or improved supply resilience is commercially important.

An HPMC switch would create development work involving:

• Comparative dissolution
• Capsule-shell moisture behavior
• Mechanical integrity
• Stability after packaging
• Compatibility with the fill blend
• Bioequivalence under an abbreviated application

The change would have commercial value only if it solves a defined problem, such as gelatin supply volatility, animal-origin restrictions, or improved stability.

Color and medication-error control

Strength-specific capsule colors are operationally important. Lomustine toxicity is delayed, and administration errors may not be recognized immediately. Distinctive color coding, printed strength identification, and clear carton labeling can reduce selection errors across the 10 mg, 40 mg, and 100 mg presentations.

A generic product that uses a different color system may still comply with FDA requirements, but it should preserve rapid visual differentiation and avoid look-alike characteristics with other oral oncology capsules.

What formulations are protected or commercially differentiated?

The strongest practical opportunities are formulation improvements that address administration, stability, or dose flexibility. Potential product concepts include:

Formulation concept	Commercial rationale	Main development barrier
Moisture-optimized powder-filled capsule	Longer shelf life and lower stability risk	Must demonstrate equivalent performance
HPMC capsule	Animal-origin-free or supply-chain alternative	Shell compatibility and bioequivalence
Low-dust capsule system	Improved occupational handling	Requires containment and process validation
Pediatric mini-capsule	Easier swallowing and lower dose increments	Pediatric bioavailability and dosing data
Sprinkle or dispersible capsule	Administration for patients unable to swallow	Hazardous-drug exposure and dose uniformity
Unit-dose blister	Better dispensing control and adherence	Packaging cost and stability validation
Multi-strength packaging platform	Reduces pharmacy selection errors	Artwork, serialization, and inventory complexity

A liquid formulation is less attractive because lomustine has limited water solubility, is cytotoxic, and has a relatively infrequent dosing schedule. A liquid or suspension would introduce chemical stability, preservative, dose-measurement, and caregiver exposure issues.

How strong is the patent estate for lomustine?

Lomustine has an old active ingredient and an established oral capsule presentation. The original compound and early product protections are expected to have expired. The commercial defense of the product is therefore based primarily on regulatory requirements, manufacturing know-how, supply reliability, trademarks, and any currently listed product-specific patents rather than basic molecule protection.

IP category	Expected position
Lomustine compound patent	Expired
Original capsule formulation	Expired or commercially nonexclusive
Basic oral use claims	Generally mature and vulnerable to prior art
Modern formulation claims	Potentially available if technically distinct
Manufacturing process claims	Possible, but narrow and process-specific
Trademark protection	Available for brand names such as Gleostine
Trade secrets	Relevant to powder handling, blending, containment, and stability
Regulatory exclusivity	No current new-drug exclusivity expected from the original approval

FDA’s Orange Book should be used to confirm current patent listings for NDA 017557. A sponsor seeking a U.S. generic would generally evaluate an ANDA pathway, including Paragraph IV certification if any unexpired listed patents are identified (FDA, 2024a).

When does lomustine lose exclusivity?

Lomustine’s foundational market exclusivity has already expired. The key timing issue is not loss of original compound exclusivity but the existence of any later-listed patents, pediatric exclusivity, orphan exclusivity, or regulatory barriers associated with the marketed product.

The commercial timeline is:

Milestone	Timing or status
Original lomustine development	1960s-1970s
U.S. NDA approval	1976
Original molecule and early formulation protection	Expired
Current branded product	Gleostine
Generic pathway	ANDA, subject to Orange Book review
New excipient formulation	Could obtain patent protection if novel and nonobvious
New delivery system	Could support method, composition, or device claims
Biosimilar pathway	Not applicable

Because lomustine is a chemically synthesized small molecule, biosimilar risk does not apply. The competitive issue is generic entry, not biosimilar substitution.

Which companies are challenging lomustine exclusivity?

The generic competitive field is structurally more important than the biosimilar field. Potential ANDA sponsors include established generic manufacturers with oncology capsule capabilities, high-containment facilities, and experience with hazardous active pharmaceutical ingredients.

Publicly confirmed Paragraph IV litigation, settlement terms, and ANDA applicant identities should be assessed through FDA litigation records, federal court dockets, and current Orange Book data. No assumption should be made that a generic competitor has market authorization merely because lomustine is an old drug. The applicant must still satisfy pharmaceutical equivalence, bioequivalence, manufacturing, stability, labeling, and hazardous-drug controls.

A generic entrant would likely compete on:

• Wholesale acquisition price
• Reliable availability of all three strengths
• Pharmacy inventory support
• Unit-dose packaging
• Hospital contracting
• Patient-assistance programs
• Ability to maintain supply during oncology shortages

What FDA regulatory status affects excipient strategy?

Lomustine is approved under a conventional NDA framework, and a generic sponsor would typically rely on an ANDA if it can demonstrate pharmaceutical equivalence and bioequivalence to the reference product. A formulation that changes capsule shell, fill excipients, colorants, packaging, or release characteristics may remain suitable for an ANDA, but the product must still meet applicable FDA requirements.

Critical regulatory controls include:

1. Same active ingredient and dosage form.
2. Equivalent strength and route of administration.
3. Comparable labeling, subject to permitted generic changes.
4. Demonstrated bioequivalence.
5. Acceptable dissolution behavior.
6. Stability through the proposed shelf life.
7. Validated content uniformity.
8. Compliance with current good manufacturing practice.
9. Appropriate containment for a cytotoxic compound.

A materially different dosage form, such as a liquid suspension or modified-release product, would likely require a different regulatory strategy and could move beyond a straightforward ANDA.

What generic launch risks exist for lomustine?

The main launch risks are operational rather than scientific.

Supply and manufacturing risk

Lomustine requires controlled handling because it is a cytotoxic alkylating agent. Facilities must manage operator exposure, cross-contamination, waste, cleaning validation, and environmental controls. These requirements reduce the number of qualified manufacturers.

Dose-strength risk

A sponsor must support 10 mg, 40 mg, and 100 mg strengths or explain the commercial rationale for a limited presentation. Omitting the 10 mg strength can reduce pharmacy utility because dosing is based on body surface area and may require fine dose adjustment.

Stability risk

A generic capsule can fail commercially if it has a shorter shelf life, requires special storage, or shows moisture-related degradation. Stability data should be generated early, particularly for capsule-shell and packaging changes.

Market-size risk

Lomustine is a niche oncology product. Development costs for hazardous-drug manufacturing, bioequivalence, and multiple strengths may be significant relative to addressable volume. A sponsor needs a credible reimbursement and supply strategy before committing to a full-strength portfolio.

What commercial opportunities exist beyond a standard generic?

Pediatric and dysphagia-focused products

Brain-tumor patients may include children or patients with impaired swallowing. Mini-capsules, carefully controlled sprinkle systems, or pharmacist-administered dose adaptations could address an unmet administration need. These products require strict control of powder release because opening a cytotoxic capsule can expose caregivers and healthcare workers.

Hospital and specialty-pharmacy supply

A dependable three-strength portfolio can support oncology wholesalers, specialty pharmacies, and hospital systems. Packaging that reduces dispensing errors has commercial value even without clinical differentiation.

International formulations

Some markets may prefer gelatin-free shells, blister packaging, or multilingual strength coding. A global platform using the same fill blend with region-specific shells and packaging could reduce development duplication.

Lifecycle patents

New patentable subject matter may exist in:

• Low-moisture excipient systems
• Specific particle-size distributions
• Capsule-shell compositions
• High-barrier packaging combinations
• Improved dose-uniformity processes
• Pediatric dosage forms
• Hazardous-drug containment systems
• Stability-enhancing manufacturing processes

Patent strength would depend on comparative data showing a measurable technical effect. Broad claims covering "lomustine plus a conventional diluent" would face substantial prior-art risk because the drug and capsule format are longstanding.

How does lomustine compare with competing oral oncology drugs?

Lomustine competes clinically with other therapies used in glioma and relapsed brain tumors, including temozolomide and selected targeted or biologic treatments depending on tumor type and treatment line. Its commercial profile differs from newer agents:

Factor	Lomustine	Newer oral oncology products
Dosing	Intermittent single dose	Often daily or cyclic
Dosage form	Conventional capsule	Capsule, tablet, or specialized delivery
Patent position	Mature	Often active composition and method patents
Excipient differentiation	Limited but feasible	Frequently linked to complex formulations
Toxicity management	Delayed marrow suppression	Product-specific
Generic exposure	High	Often limited before patent expiry
Commercial opportunity	Supply, price, packaging, administration	Clinical differentiation and patent lifecycle

Lomustine’s low patent barrier increases generic risk, but its hazardous manufacturing requirements and small market can limit the number of credible entrants.

What patent litigation and settlement issues matter?

For an old small-molecule capsule, litigation is most likely to arise from later formulation, manufacturing, or branded-product patents rather than the lomustine molecule itself. A Paragraph IV challenge could target any unexpired Orange Book-listed patent. Settlement agreements may include delayed entry, authorized generic rights, license terms, or restrictions on specific presentations.

The relevant diligence points are:

• Current Orange Book patents for NDA 017557
• FDA-listed exclusivity codes
• ANDA litigation under the Hatch-Waxman framework
• Federal court docket activity
• Authorized generic arrangements
• Product-specific manufacturing patents
• Brand and generic supply agreements

Key Takeaways

• Lomustine is a mature oral nitrosourea supplied as 10 mg, 40 mg, and 100 mg hard capsules.
• Excipient strategy should prioritize moisture control, content uniformity, capsule-shell compatibility, and hazardous-drug manufacturing.
• HPMC capsules, unit-dose blistering, pediatric mini-capsules, and stability-enhanced fills offer the clearest lifecycle opportunities.
• Foundational lomustine patent protection has expired; commercial barriers are more likely to involve regulatory compliance, manufacturing capability, and supply reliability.
• Biosimilar competition is irrelevant because lomustine is a synthetic small molecule.
• Generic entry risk is real, but the niche market and cytotoxic handling requirements may limit the number of viable competitors.
• Strong lifecycle patents require comparative technical data, not merely substitution of a familiar excipient.
• FDA Orange Book and litigation records determine the current U.S. patent and Paragraph IV position.

FAQs

Is lomustine a good candidate for an excipient-based reformulation?

Yes, but the opportunity is narrow. The strongest candidates are moisture-optimized capsule fills, alternative capsule shells, pediatric presentations, and packaging systems that reduce handling and dispensing risk.

Can lomustine be formulated as a liquid?

Technically possible, but commercially difficult. Limited aqueous solubility, cytotoxicity, chemical stability, preservative requirements, and caregiver exposure make a liquid less attractive than a dry capsule.

Does lomustine have biosimilar competition?

No. Lomustine is a chemically synthesized small molecule. Competition would occur through generic drug applications rather than biosimilar applications.

Can a gelatin-free lomustine capsule receive patent protection?

Potentially. A patent would require a novel and nonobvious capsule-shell or formulation combination, supported by technical advantages such as improved stability, reduced moisture uptake, or manufacturing performance.

What is the largest commercial risk for a lomustine generic?

The largest risk is achieving sustainable supply at a viable margin. Cytotoxic containment, multiple strengths, stability requirements, and a relatively small oncology market can make manufacturing economics challenging.

References

1. DailyMed. (2023). Gleostine: Lomustine capsule prescribing information. U.S. National Library of Medicine.

2. National Cancer Institute. (2024). Lomustine. National Cancer Institute Drug Dictionary.

3. U.S. Food and Drug Administration. (2023). Gleostine (lomustine) capsules: Prescribing information. FDA.

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

5. U.S. Food and Drug Administration. (2024b). FDA guidance for industry: ANDAs for certain highly purified synthetic peptides and complex drug products. FDA.

6. National Institute for Occupational Safety and Health. (2023). NIOSH list of hazardous drugs in healthcare settings. Centers for Disease Control and Prevention.