List of Excipients in Branded Drug ALOPRIM

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Mylan Institutional LLC	ALOPRIM	allopurinol	67457-187	SODIUM HYDROXIDE
Mylan Institutional LLC	ALOPRIM	allopurinol	67457-978	SODIUM HYDROXIDE

ALOPRIM Excipient Strategy and Commercial Opportunities

Last updated: August 1, 2026

ALOPRIM is an injectable allopurinol sodium product used when oral allopurinol is not feasible, particularly for tumor lysis syndrome and acute hyperuricemia. Its commercial differentiation depends less on active-ingredient exclusivity and more on sterile manufacturing, reconstitution performance, packaging, hospital workflow, and supply reliability. The core formulation is comparatively simple: a lyophilized allopurinol sodium cake in a single-dose vial, reconstituted before intravenous administration. This creates opportunities for ready-to-use presentations, improved stability, lower preparation burden, and differentiated hospital supply models.

What is ALOPRIM and how is it formulated?

ALOPRIM contains allopurinol sodium for injection. The product is supplied as a sterile lyophilized powder in a 500-mg single-dose vial. The labeled product is reconstituted with Sterile Water for Injection before intravenous use.[1]

The principal formulation components are:

Component	Function
Allopurinol sodium	Active pharmaceutical ingredient
Sodium hydroxide	pH adjustment and conversion of allopurinol to the soluble sodium salt
Sterile Water for Injection	Reconstitution diluent, supplied separately or used at the point of care

The formulation is alkaline because allopurinol has limited aqueous solubility in its neutral form. Conversion to the sodium salt and control of solution pH are central to achieving an injectable concentration.

ALOPRIM is not a conventional solution formulation. It is a powder for reconstitution, which reduces the stability burden associated with storing an alkaline aqueous solution but transfers preparation requirements to hospital pharmacy or nursing staff.

What dosage form does ALOPRIM use?

The marketed dosage form is a sterile lyophilized powder for intravenous administration. The product is not an oral tablet, prefilled syringe, premixed infusion bag, or depot formulation.

The powder format provides several technical advantages:

• Reduced exposure to hydrolysis and oxidative degradation during storage.
• Lower risk of precipitation during long-term shelf life.
• Lower shipping weight than a premixed liquid.
• Compatibility with conventional sterile fill-finish and lyophilization operations.

The disadvantages are operational:

• Reconstitution is required before administration.
• Dose preparation introduces container and transfer steps.
• The final solution must be inspected for particulates and discoloration.
• Pharmacy staff must manage diluent, labeling, and beyond-use timing.
• Errors can arise from incorrect reconstitution volume or concentration.

These tradeoffs define the clearest commercial opportunities for an ALOPRIM competitor.

What excipients protect the ALOPRIM formulation?

ALOPRIM’s excipient strategy is narrow. The product does not rely on a complex stabilizer system, lipid carrier, polymer matrix, or proprietary delivery platform. Sodium hydroxide is the key functional excipient identified in the product labeling.[1]

The commercial value of the excipient system lies in process control rather than ingredient count. Important formulation variables include:

• Allopurinol sodium concentration.
• Final solution pH.
• Residual moisture in the lyophilized cake.
• Reconstitution time.
• Cake structure and powder collapse.
• Visible and subvisible particles.
• Solution color after reconstitution.
• Compatibility with common intravenous diluents.
• Container closure integrity.
• Stability after reconstitution and dilution.

A reformulated product could use a phosphate, citrate, carbonate, or other buffering system, but any buffer would need to preserve solubility and avoid adverse interactions with the active ingredient. Introducing additional excipients could increase formulation complexity, extractables and leachables risk, osmolality, impurity formation, and regulatory comparability requirements.

For this product, a minimal-excipient approach is commercially defensible. It reduces the number of variables that must be controlled in a sterile injectable and may simplify development under an abbreviated regulatory pathway.

What are the main excipient-development opportunities for ALOPRIM?

The strongest opportunities are not necessarily new excipients. They are excipient and presentation changes that improve handling, stability, and administration.

1. Ready-to-use or premixed allopurinol sodium solution

A premixed solution could eliminate bedside reconstitution. The main technical barrier is long-term stability in an alkaline aqueous environment. Development would require control of:

• pH drift;
• precipitation;
• degradation products;
• container adsorption;
• oxygen exposure;
• light sensitivity;
• microbial integrity;
• infusion-bag compatibility.

A premixed presentation could be supplied in a flexible intravenous bag or a pharmacy-ready bottle. Its commercial value would be highest in oncology centers, emergency departments, and hospitals with high tumor lysis syndrome volume.

The tradeoff is higher manufacturing and logistics cost. A liquid product also has greater shipping weight and may require more demanding storage conditions.

2. Improved lyophilized cake and rapid reconstitution

A competitor could retain the powder format while improving the user experience. Relevant formulation and process tools include:

• optimized bulking-agent levels;
• controlled nucleation during freezing;
• reduced residual moisture;
• improved cake porosity;
• tighter fill-volume control;
• smaller reconstitution volume;
• validated rapid-dissolution performance.

The company could seek differentiation through reconstitution time, particulate control, and reduced foaming rather than through a new chemical entity.

Any new bulking agent or stabilizer would need to be selected carefully. Common lyophilization excipients such as mannitol or sucrose may affect cake structure, residual moisture, tonicity, and chemical stability. Their use would also create a formulation difference from the reference product that requires analytical and clinical bridging appropriate to the FDA pathway.

3. Dual-chamber vial or vial-plus-diluent system

A dual-chamber system could separate the dry drug from the diluent until use. This would reduce the risk of incorrect diluent selection and could improve pharmacy workflow.

Potential limitations include:

• higher packaging cost;
• specialized device manufacturing;
• device compatibility testing;
• greater complexity in container closure validation;
• more difficult recycling and disposal;
• additional human-factors requirements.

The system would be most commercially attractive if it reduced preparation time without imposing a substantial price premium.

4. Pharmacy-ready kit

A lower-risk opportunity is a kit containing the lyophilized vial, compatible diluent, transfer device, and standardized preparation instructions. The active and excipient composition could remain largely unchanged.

A kit could improve:

• inventory management;
• preparation consistency;
• emergency availability;
• barcode scanning;
• nursing and pharmacy workflow;
• institutional purchasing convenience.

The kit itself may be commercially differentiable even where formulation patent protection is unavailable.

5. Lower-volume and flexible-dose presentations

The current 500-mg vial may produce wastage when patients require lower doses. A portfolio containing 100-mg, 250-mg, and 500-mg vials could reduce waste and improve dosing flexibility.

The opportunity is strongest where hospitals treat patients with variable body weight, renal impairment, or changing clinical status. Smaller vials could also support pediatric or specialty oncology use, subject to labeling and clinical requirements.

What patents protect ALOPRIM?

The core allopurinol composition is not protected by a commercially meaningful U.S. composition-of-matter patent. Allopurinol was discovered and developed decades ago, and the relevant foundational patent rights expired long before the current injectable market.

The commercially relevant protection is therefore likely to be regulatory and operational rather than a live patent estate covering the active ingredient.

Protection category	ALOPRIM position
Active ingredient	Long expired
Injectable formulation	No clearly material current U.S. patent barrier identified from the public FDA product record
Lyophilization process	Potentially protectable if independently novel
Ready-to-use presentation	Potentially protectable through formulation, container, or stability claims
Reconstitution device	Potentially protectable through device and combination claims
Method of use	Limited value where the underlying allopurinol uses are established
Trademark	Brand rights may exist, but trademark protection does not block generic allopurinol sodium products
Regulatory exclusivity	No current new-drug exclusivity appears to provide a durable barrier for the legacy product

The Orange Book should be reviewed for the current NDA and any listed patents before an ANDA or 505(b)(2) filing. For a legacy injectable, the main legal risks are more likely to involve formulation, device, manufacturing, or process patents owned by a later entrant than patents covering ALOPRIM’s basic active ingredient.

When does ALOPRIM lose exclusivity?

ALOPRIM’s core market exclusivity has already expired. The product is a legacy injectable based on an old active ingredient, and any original small-molecule patent protection is no longer commercially relevant.

The important distinction is between:

1. patent exclusivity for allopurinol;
2. regulatory exclusivity for the specific injectable product;
3. market access controlled by manufacturing capacity and hospital purchasing;
4. later patents covering a new formulation or delivery system.

A new competitor could pursue an ANDA if it can demonstrate pharmaceutical equivalence and bioequivalence or satisfy the applicable requirements for an injectable product. A materially different liquid, device, or formulation could instead require a 505(b)(2) strategy, depending on the proposed product and reference-product relationship.[2]

Are there Paragraph IV challenges to ALOPRIM?

A Paragraph IV challenge is unlikely to be the principal barrier because no foundational, active patent estate appears to protect the legacy allopurinol sodium injection. A generic applicant would still need to assess any current Orange Book listings associated with the reference NDA and certify appropriately under the Hatch-Waxman framework.

For this product class, the practical competitive sequence is more likely to be:

1. review the reference-listed drug and its labeling;
2. determine whether an ANDA is available;
3. evaluate injectable equivalence, sterility, strength, and container requirements;
4. identify any listed formulation or method-of-use patents;
5. assess manufacturing economics and supply reliability.

The absence of a major active patent barrier does not guarantee rapid entry. Sterile injectable manufacturing, validation, facility capacity, and FDA review can be more important than litigation risk.

What is the FDA regulatory status of ALOPRIM?

ALOPRIM is an FDA-approved prescription injectable product identified in the FDA’s drug-labeling and product databases. Its active ingredient is allopurinol sodium, and its labeled route is intravenous administration.[1]

The main regulatory pathways for a competing product are:

ANDA pathway

An ANDA is potentially suitable for a product that matches the reference product in active ingredient, strength, dosage form, route, and other relevant characteristics. Injectable products may not require conventional pharmacokinetic bioequivalence studies in the same manner as oral products when the formulation and route support an appropriate waiver or equivalence approach.

The applicant would still need to address:

• sterility assurance;
• particulate matter;
• bacterial endotoxins;
• container closure integrity;
• stability;
• reconstitution;
• compatibility;
• manufacturing controls;
• labeling differences;
• inactive-ingredient justification.

505(b)(2) pathway

A 505(b)(2) application could be considered for a materially different presentation, such as:

• premixed solution;
• new concentration;
• novel diluent;
• dual-chamber container;
• new administration device;
• modified stability profile;
• different excipient system.

This pathway could support product differentiation but would increase development and regulatory costs.

What generic entry risks exist for ALOPRIM?

Generic entry risk is high at the active-ingredient level and moderate at the commercial level.

Risk category	Assessment
Core composition patent	Low barrier
Orange Book patent litigation	Likely limited unless later listings exist
Formulation patent risk	Moderate for new liquid or device presentations
Sterile manufacturing	High execution barrier
API supply	Moderate, depending on qualified allopurinol sodium supply
Hospital conversion	Moderate
Pricing pressure	High
Product shortage exposure	Meaningful opportunity for reliable suppliers
Brand loyalty	Limited for a hospital injectable
Regulatory complexity	Moderate to high

The principal threat to a new entrant is not a patent injunction. It is failure to achieve reliable commercial supply at acceptable cost.

How strong is the ALOPRIM patent estate?

The patent estate is weak for the legacy product’s core formulation and strong only where a later entrant creates genuinely differentiated technology.

Patentable areas may include:

• stabilized aqueous allopurinol sodium solutions;
• defined pH and excipient ranges;
• lyophilized compositions with specified residual moisture;
• rapid-reconstitution formulations;
• container systems that improve stability;
• dual-chamber delivery systems;
• premixed infusion products with extended shelf life;
• manufacturing processes that reduce impurities;
• methods for preventing precipitation during dilution.

Patent strength would depend on whether the claims cover a real technical effect, such as improved stability or reconstitution, and whether competing formulations can design around the claimed ranges.

Broad claims to “allopurinol sodium plus sodium hydroxide” would face substantial validity and obviousness pressure because the product concept is established. Narrow claims tied to validated stability data, a specific container, or a defined process are more defensible but provide narrower commercial coverage.

Which companies could challenge or compete with ALOPRIM?

Competition is likely to come from generic injectable manufacturers, specialty hospital suppliers, and companies with sterile fill-finish capacity. The most relevant competitors are not necessarily branded allopurinol companies. They include manufacturers capable of producing:

• allopurinol sodium injection;
• hospital-dose lyophilized injectables;
• premixed oncology supportive-care products;
• compounded or outsourced sterile preparations;
• shortage-sensitive generic injectables.

The competitive landscape should be assessed through FDA Orange Book records, FDA drug-shortage data, approved drug-product databases, institutional contracts, and distributor listings.[2,3]

A company with an existing sterile injectable portfolio has an advantage because it can use established quality systems, vial lines, lyophilization capacity, and hospital sales channels.

What commercial opportunities exist for ALOPRIM excipients and formulation technology?

The best opportunities are concentrated in workflow and supply-chain improvements.

High-value opportunity areas

Opportunity	Commercial rationale	Development burden
Premixed infusion	Eliminates reconstitution	High
Pharmacy-ready kit	Reduces preparation errors	Low to moderate
Faster-reconstituting vial	Improves emergency and oncology workflow	Moderate
Smaller vial sizes	Reduces drug waste	Moderate
Improved stability after dilution	Supports pharmacy batching	Moderate to high
Dual-chamber container	Simplifies preparation	High
Domestic or redundant supply	Reduces shortage exposure	Operational
Contract manufacturing	Provides reliable institutional supply	Moderate

The strongest near-term opportunity is likely a differentiated lyophilized product or kit rather than a fully reformulated liquid. A liquid product offers greater workflow value but carries higher stability, packaging, and regulatory risk.

How does ALOPRIM compare with oral allopurinol?

Attribute	ALOPRIM	Oral allopurinol
Active ingredient	Allopurinol sodium	Allopurinol
Route	Intravenous	Oral
Use case	Patients unable to take oral therapy; acute hospital use	Chronic urate reduction and routine treatment
Formulation	Lyophilized injectable	Tablets or oral dosage forms
Excipient complexity	Low to moderate	Generally low
Manufacturing barrier	Sterile injectable	Nonsterile solid oral
Commercial price pressure	High	Very high
Differentiation opportunity	Reconstitution, premix, packaging, supply	Dose flexibility, adherence, combination products
Patent barrier	Minimal for legacy product	Minimal for legacy product

ALOPRIM occupies a narrower but more technically demanding market. The product’s value is tied to clinical availability when oral therapy is impractical, not to broad chronic-use volume.

What manufacturing and intellectual-property barriers matter most?

Sterile manufacturing is the central barrier. A developer needs validated controls for:

• aseptic processing;
• lyophilization;
• endotoxin removal;
• particulate control;
• vial and stopper compatibility;
• process hold times;
• reconstitution and dilution;
• stability-indicating analytical methods.

API sourcing is also important. Allopurinol sodium must meet injectable-grade specifications, and the manufacturing process must control related substances, water content, microbial quality, and elemental impurities.

For a reformulated product, intellectual property should cover several layers:

1. composition claims;
2. concentration and pH ranges;
3. lyophilization-cycle parameters;
4. container and closure configuration;
5. reconstitution or dilution method;
6. stability claims;
7. manufacturing process claims.

A layered portfolio is stronger than a single narrow formulation patent. Trade secrets may be more valuable than patents for cycle parameters, impurity control, and aseptic process settings.

Key Takeaways

• ALOPRIM is a legacy intravenous allopurinol sodium product supplied as a 500-mg lyophilized vial.
• Sodium hydroxide is the principal functional excipient identified in the product labeling.
• The core allopurinol and legacy injectable concepts have little remaining exclusivity value.
• Generic entry risk is high, but sterile manufacturing and supply reliability create practical barriers.
• The best formulation opportunities are premixed solutions, rapid-reconstitution vials, smaller vial sizes, pharmacy-ready kits, and dual-chamber systems.
• A minimal-excipient strategy is likely to reduce development and regulatory risk.
• New patents are more defensible when tied to measurable stability, reconstitution, packaging, or manufacturing improvements.
• The strongest near-term commercial model is likely a reliable hospital injectable with reduced preparation burden rather than a broad branded reformulation.

Frequently Asked Questions

Is ALOPRIM a biologic with biosimilar risk?

No. ALOPRIM is a small-molecule allopurinol sodium injection. Biosimilar regulation does not apply. Competitive products would generally use generic-drug or 505(b)(2) pathways rather than the biosimilar pathway.

Can a company sell an allopurinol sodium premixed infusion?

Potentially, but a premixed infusion would require evidence supporting stability, sterility, container compatibility, particulate control, and labeling. The regulatory pathway would depend on how closely the product matches the reference product.

Does sodium hydroxide create a patent opportunity in ALOPRIM?

Sodium hydroxide alone is unlikely to support meaningful broad patent protection. A stronger patent position would require a defined formulation or process that demonstrates an unexpected improvement in stability, solubility, reconstitution, or impurity control.

Is ALOPRIM suitable for 505(b)(2) reformulation?

A materially different presentation, such as a ready-to-use solution, novel delivery container, or new stability profile, could support evaluation of a 505(b)(2) strategy. The pathway would depend on the extent of difference from the reference product and the data required to bridge that difference.

What is the most attractive commercial presentation for an ALOPRIM competitor?

A pharmacy-ready kit or rapid-reconstitution vial offers the best balance between commercial differentiation and development risk. A premixed bag has greater workflow value but faces higher formulation, packaging, stability, and regulatory costs.

References

1. DailyMed. (n.d.). ALOPRIM- allopurinol sodium injection, powder, for solution. U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/

2. U.S. Food and Drug Administration. (n.d.). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/

3. U.S. Food and Drug Administration. (n.d.). Approved drug products and drug shortages databases. https://www.fda.gov/drugs

4. U.S. Food and Drug Administration. (2019). ANDA submissions: Content and format of abbreviated new drug applications. https://www.fda.gov/drugs

5. U.S. Food and Drug Administration. (n.d.). 505(b)(2) applications. https://www.fda.gov/drugs/development-approval-process-drugs/fda-drug-approval-process-505b2-applications