List of Excipients in Branded Drug OXLUMO

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Alnylam Pharmaceuticals Inc	OXLUMO	lumasiran	71336-1002	PHOSPHORIC ACID	2035-10-09
Alnylam Pharmaceuticals Inc	OXLUMO	lumasiran	71336-1002	SODIUM HYDROXIDE	2035-10-09
Alnylam Pharmaceuticals Inc	OXLUMO	lumasiran	71336-1002	WATER	2035-10-09

Last updated: September 2, 2026

ecutive summary: OXLUMO (lumasiran) uses a deliberately simple, preservative-free aqueous formulation containing sodium hydroxide, phosphoric acid, and water for injection. The product is supplied as a single-dose subcutaneous injection in 94 mg/0.5 mL and 189 mg/1.5 mL presentations. The excipient profile creates limited direct differentiation for commodity suppliers, but meaningful opportunities exist in sterile fill-finish, container-closure systems, dose-convenience improvements, stability enhancement, pediatric delivery, and follow-on formulations. OXLUMO's principal commercial protection comes from orphan-drug exclusivity, lumasiran and RNA-therapeutic patents, manufacturing know-how, and Alnylam's rare-disease commercial infrastructure rather than from a complex excipient system.

OXLUMO Excipient Strategy and Commercial Opportunities for Lumasiran

What is OXLUMO and how does its formulation work?

OXLUMO is Alnylam Pharmaceuticals' lumasiran injection for primary hyperoxaluria type 1, or PH1. The drug is an RNA interference therapeutic that reduces hepatic production of glycolate oxidase by targeting HAO1 messenger RNA. Lower enzyme production reduces oxalate synthesis, the metabolic driver of PH1 kidney injury.[1]

The FDA approved OXLUMO on November 22, 2020, for adults and children with PH1. The product is administered subcutaneously and has a maintenance schedule of three monthly loading doses followed by dosing once every three months.[1]

Attribute	OXLUMO
Active ingredient	Lumasiran sodium
Therapeutic class	Small-interfering RNA therapeutic
Target	HAO1 mRNA / glycolate oxidase
Indication	Primary hyperoxaluria type 1
Route	Subcutaneous injection
FDA approval	November 22, 2020
Loading regimen	3 mg/kg once monthly for 3 doses
Maintenance regimen	3 mg/kg once every 3 months
Maximum dose	300 mg
Presentations	94 mg/0.5 mL and 189 mg/1.5 mL
Storage	Refrigerated, 2°C to 8°C; protect from light
Preservative	None listed

The active ingredient is a GalNAc-conjugated siRNA. The N-acetylgalactosamine ligand supports uptake by hepatocytes, allowing OXLUMO to avoid the lipid nanoparticle systems used by several earlier RNA medicines. That design materially simplifies the excipient burden and manufacturing process.

What excipients are used in OXLUMO?

The FDA prescribing information identifies three inactive ingredients:

Excipient	Function in formulation	Commercial relevance
Phosphoric acid	pH adjustment and buffering	Low-cost, established parenteral raw material
Sodium hydroxide	pH adjustment	Low-cost, established parenteral raw material
Water for injection	Vehicle	High-volume sterile utility and manufacturing input

The formulation is an aqueous solution without a lipid carrier, surfactant, preservative, or amino-acid stabilizer listed in the commercial formulation.[1]

This excipient strategy has several advantages:

1. It minimizes component count and formulation risk.
2. It avoids lipid nanoparticle manufacturing and associated raw-material controls.
3. It reduces the potential for excipient-mediated injection-site tolerability problems.
4. It supports a ready-to-use sterile product.
5. It simplifies regulatory comparability for manufacturing-site changes.

The formulation also limits the number of attractive proprietary excipient claims. Phosphoric acid, sodium hydroxide, and water for injection are standard materials. A competitor is unlikely to obtain meaningful exclusivity merely by using the same ingredients. Commercial value is more likely to arise from the interaction between lumasiran concentration, pH, aggregation control, container closure, sterilization, and long-term stability.

What formulation patents could protect OXLUMO?

The strongest formulation-related protection would generally attach to the active siRNA architecture, conjugation chemistry, sequence, dosing method, manufacturing process, and defined pharmaceutical compositions rather than to the individual excipients.

Potential claim categories include:

Composition claims

These may cover lumasiran sequences, chemical modifications, conjugation to GalNAc, stereochemical configurations, and defined pharmaceutical compositions. Such claims can protect the drug even where the excipient system is simple.

Formulation claims

A formulation patent may define:

• Lumasiran concentration ranges.
• pH ranges.
• Specific buffer systems.
• Aggregate or impurity limits.
• Long-term refrigerated or room-temperature stability.
• Container-closure combinations.
• Low-volume and high-volume dose presentations.

A formulation claim limited to phosphoric acid, sodium hydroxide, and water would face greater vulnerability if the elements are conventional and predictable. Its strength would depend on demonstrated stability, reduced degradation, improved injection performance, or another unexpected technical result.

Manufacturing claims

RNA therapeutics have process-sensitive manufacturing requirements. Protectable subject matter may include:

• Solid-phase oligonucleotide synthesis.
• Conjugation and purification.
• Removal of truncated sequences and process impurities.
• Control of double-stranded RNA contaminants.
• Sterile filtration and aseptic filling.
• Lyophilization or liquid stability processes.
• Analytical methods used to release the drug substance or product.

Manufacturing patents and trade secrets can create a practical barrier even when a competitor can design around a composition claim.

Method-of-use claims

OXLUMO's therapeutic protection can include treatment of PH1, reduction of urinary oxalate, prevention of kidney-stone formation, and use in pediatric or renal-impaired populations. Method-of-use rights are relevant to generic launch strategy because a competitor may need to omit protected indications or accept prescribing and labeling restrictions.

When does OXLUMO lose exclusivity?

OXLUMO received orphan-drug designation and approval for PH1. Orphan-drug exclusivity generally runs for seven years from approval and prevents FDA approval of the same drug for the same indication during that period, subject to statutory exceptions.[2]

Protection	Approximate date or status
FDA approval	November 22, 2020
Five-year new chemical entity exclusivity	Approximately through November 22, 2025
Seven-year orphan-drug exclusivity	Approximately through November 22, 2027
Patent protection	Patent-specific; must be assessed by claim and jurisdiction
Pediatric exclusivity	Any six-month extension depends on FDA-issued written pediatric study requirements and completion

The practical loss-of-exclusivity date may differ from the earliest patent expiration. Patent term adjustment, patent term extension, terminal disclaimers, pediatric exclusivity, orphan exclusivity, and litigation outcomes can alter market entry timing.

Because OXLUMO is an oligonucleotide injection, a first entrant may face a more complicated regulatory pathway than a conventional small-molecule tablet. An ANDA could be available if FDA determines that the follow-on product has the required pharmaceutical equivalence and bioequivalence. A 505(b)(2) application may be considered where reliance on OXLUMO's clinical or scientific information is necessary. The pathway depends on FDA's product-specific requirements and the proposed product's formulation and analytical comparability.

What is the Orange Book status of OXLUMO?

OXLUMO's Orange Book position should be evaluated by reviewing the current FDA listing for lumasiran and identifying every patent submitted by the NDA holder. Relevant fields include:

• Patent number.
• Patent expiration date.
• Pediatric exclusivity indicator.
• Use code.
• Patent type.
• Delisting or expiration status.

The key business issue is whether listed patents cover the active ingredient, a pharmaceutical composition, a method of treatment, or a manufacturing process. Formulation patents may be more relevant to an ANDA Paragraph IV challenge if they cover the marketed concentration or liquid presentation.

A Paragraph IV certification would assert that a listed patent is invalid, unenforceable, or not infringed. The first generic applicant to submit a qualifying Paragraph IV certification may receive 180-day exclusivity, subject to the statutory forfeiture rules. For OXLUMO, the commercial value of such a challenge depends on the size of the PH1 market, the remaining orphan exclusivity period, expected litigation cost, and whether a non-infringing formulation can be developed.

Which companies are challenging OXLUMO exclusivity?

No broadly established commercial generic or biosimilar competitor has displaced OXLUMO in the PH1 market based on the FDA approval record through the latest publicly available information cited here. OXLUMO is a synthetic siRNA drug, not a biologic for purposes of the conventional biosimilar pathway. A follow-on applicant would more likely evaluate an ANDA, 505(b)(2), or another FDA-supported pathway rather than a standard biosimilar application.

The most credible competitive threats are:

1. A direct lumasiran follow-on product after orphan exclusivity expires.
2. A competing RNA therapeutic for PH1.
3. Enzyme replacement or gene-therapy approaches that alter the treatment paradigm.
4. Improved delivery systems that reduce injection frequency.
5. Regional products developed in jurisdictions without U.S.-style orphan exclusivity.

What commercial opportunities exist in OXLUMO excipients?

Sterile excipient supply

The direct excipient opportunity is stable but limited. Pharmaceutical-grade phosphoric acid, sodium hydroxide, and water for injection are widely available. Suppliers can compete on:

• Low extractables and leachables.
• High-purity grades.
• Supply continuity.
• Regional manufacturing redundancy.
• Documentation for oligonucleotide products.
• Batch-to-batch consistency.
• Support for regulatory filings.

Water-for-injection infrastructure has greater operational importance than the unit value of the excipient. A manufacturer that can provide validated sterile water systems, aseptic processing, and reliable utilities may capture more value than a commodity chemical supplier.

Sterile fill-finish

OXLUMO's liquid, single-dose presentation supports contract manufacturing opportunities in:

• Aseptic vial filling.
• Low-volume and high-volume filling lines.
• Visual inspection of clear solutions.
• Sterile filtration.
• Cold-chain packaging.
• Serialization and specialty-pharmacy distribution.

A contract development and manufacturing organization with experience in oligonucleotide products can differentiate through analytical control of particulates, aggregates, concentration, and container-closure integrity.

Container-closure systems

The commercial product is supplied in glass vials. Opportunities include:

• Low-sorption vial and stopper systems.
• Ready-to-use sterilized components.
• Improved break resistance.
• Prefilled syringes.
• Dual-chamber or dose-metering systems.
• Packaging that supports home administration.

Any alternative container would require extractables and leachables studies, compatibility data, stability studies, device validation, and FDA approval of the updated presentation.

Pediatric and home-use delivery

PH1 affects children and adults. The current weight-based dosing model creates an opportunity for more convenient dose delivery. Potential products include:

• Prefilled syringes with weight-based dose selection.
• Autoinjectors.
• Dose bands that reduce calculation and preparation errors.
• Smaller-volume presentations for pediatric patients.
• Home-administration systems supported by trained caregivers.

These are commercial opportunities, not approved OXLUMO product characteristics. They would require human-factors work, device combination-product review, and evidence that the system preserves product quality.

Room-temperature stability

The label permits limited room-temperature handling under specified conditions.[1] A formulation or package that extends room-temperature stability could reduce specialty-pharmacy losses, simplify patient travel, and lower distribution costs. The value would be highest in regions with limited cold-chain infrastructure.

A successful stability improvement would need to demonstrate control of:

• Chemical degradation.
• RNA integrity.
• Conjugate integrity.
• Aggregation.
• Visible and subvisible particles.
• Potency.
• Container-closure interaction.

How strong is the OXLUMO patent estate?

The estate's commercial strength is likely to depend more on layered protection than on excipient novelty. A robust position would combine:

Layer	Strategic value
siRNA sequence and chemical modification	Blocks close copies of the active molecule
GalNAc conjugation	Protects liver-targeted delivery architecture
Pharmaceutical composition	Covers commercial product attributes
PH1 treatment methods	Supports indication-specific enforcement
Dosing schedule	Protects quarterly maintenance use where claims permit
Manufacturing process	Raises technical and regulatory entry costs
Trade secrets	Protects process parameters and analytical controls

The weakest standalone layer is likely to be the use of conventional phosphoric acid, sodium hydroxide, and water for injection. The strongest commercial barrier may be the combination of active-molecule rights, regulatory exclusivity, manufacturing complexity, clinical familiarity, and the small specialist market.

What generic launch risks exist for OXLUMO?

A follow-on applicant would face five principal risks:

1. Orphan-drug exclusivity may delay approval for the same PH1 indication until approximately late 2027.
2. Listed patents may require Paragraph IV litigation or a section viii label carve-out.
3. Oligonucleotide analytical comparability can be more demanding than conventional small-molecule equivalence testing.
4. A low-volume rare-disease market may not justify development and litigation costs.
5. Alnylam may defend the product through composition, conjugate, use, dosing, and manufacturing patents.

A non-infringing formulation using a different buffer or concentration could reduce formulation-patent exposure, but it would not necessarily avoid active-ingredient, conjugate, method-of-use, or manufacturing claims.

Key Takeaways

• OXLUMO uses a simple aqueous formulation with phosphoric acid, sodium hydroxide, and water for injection.
• The product avoids lipid nanoparticles and does not list a preservative or surfactant.
• Direct excipient sales are commodity-oriented; higher-value opportunities are in sterile fill-finish, packaging, stability, and delivery devices.
• Formulation patents are more defensible when tied to stability, concentration, impurity control, or container performance.
• OXLUMO received FDA approval in November 2020 and has orphan-drug exclusivity expected to run approximately through November 2027.
• OXLUMO is an siRNA drug, not a conventional biologic biosimilar product.
• Generic entry is likely to depend on the interaction between FDA exclusivity, Orange Book patents, analytical comparability, and market economics.
• The strongest competitive moat is the combined active-molecule, conjugate, manufacturing, regulatory, and commercial infrastructure estate.

FAQs

Can OXLUMO be reformulated with a different buffer?

Yes. A different buffer could be developed, but the sponsor would need to establish equivalent potency, stability, impurity control, injection performance, and container compatibility. A reformulation may also trigger new patent and regulatory analysis.

Does OXLUMO require a lipid nanoparticle excipient?

No. OXLUMO uses a GalNAc-conjugated siRNA delivery design and does not require a lipid nanoparticle system in its commercial formulation.[1]

Is OXLUMO suitable for a prefilled syringe?

The drug's aqueous, ready-to-use presentation could support evaluation of a prefilled syringe, but the commercial product would require device compatibility, stability, extractables and leachables, dose accuracy, and human-factors validation.

Can a generic manufacturer use the same OXLUMO excipients?

Potentially, subject to regulatory and patent analysis. The excipients themselves are conventional, but the proposed product must satisfy FDA requirements and avoid applicable composition, formulation, manufacturing, and method-of-use claims.

What is the most valuable excipient opportunity around OXLUMO?

The highest-value opportunity is unlikely to be phosphoric acid or sodium hydroxide supply alone. It is more likely to involve integrated sterile manufacturing, container-closure technology, extended room-temperature stability, or a patient-friendly delivery system.

References

1. U.S. Food and Drug Administration. (2024). OXLUMO (lumasiran) injection, prescribing information. https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/214103s006lbl.pdf

2. U.S. Food and Drug Administration. (2023). Orphan drug designation and exclusivity. https://www.fda.gov/industry/developing-products-rare-diseases-conditions/designating-orphan-product-drugs-and-biological-products

3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book

4. Alnylam Pharmaceuticals, Inc. (2024). Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934. https://investors.alnylam.com/financial-information/sec-filings