Last updated: September 4, 2026
Nedosiran sodium is an RNA interference therapy marketed by Novo Nordisk as Rivfloza for primary hyperoxaluria type 1, or PH1. The FDA approved Rivfloza in October 2023 for patients aged 9 years and older with PH1 and relatively preserved kidney function. Its commercial opportunity is large on a per-patient basis but limited by the ultra-rare disease population, competition from Alnylam’s Oxlumo, high diagnostic barriers, and the narrow approved population.[1]
What is nedosiran sodium and how does Rivfloza work?
Nedosiran sodium is a chemically modified small interfering RNA, or siRNA, conjugated to N-acetylgalactosamine. It is designed to silence hepatic lactate dehydrogenase A, or LDHA, messenger RNA.
LDHA catalyzes the final step in the hepatic pathway that produces oxalate. In PH1, excessive oxalate production leads to calcium oxalate deposition, kidney stones, nephrocalcinosis, chronic kidney damage, and, in advanced cases, systemic oxalosis.
Rivfloza is administered by subcutaneous injection once monthly. The FDA-approved indication covers adults and pediatric patients aged 9 years and older with PH1 and relatively preserved renal function.[1]
Rivfloza approved dosing
| Patient weight |
Monthly dose |
| Less than 25 kg |
40 mg |
| 25 kg to less than 50 kg |
60 mg |
| 50 kg or more |
80 mg |
The treatment objective is sustained reduction of urinary oxalate. The product does not directly reverse established renal damage, so treatment value is highest when diagnosis occurs before substantial loss of kidney function.
When did the FDA approve nedosiran sodium?
The FDA approved Rivfloza on October 3, 2023. The approval was based principally on the PHYOX™ clinical development program, which evaluated urinary oxalate reduction and longer-term treatment effects in patients with PH1.[1]
The approval gave Novo Nordisk a second commercial RNAi product after its acquisition of Dicerna Pharmaceuticals. Novo completed the Dicerna acquisition in 2021 for approximately $3.3 billion, gaining Dicerna’s RNAi platform and development programs, including nedosiran.[2]
FDA regulatory position
| Regulatory item |
Status |
| Product |
Rivfloza |
| Active ingredient |
Nedosiran sodium |
| Sponsor and commercial owner |
Novo Nordisk |
| FDA approval |
October 3, 2023 |
| Disease |
Primary hyperoxaluria type 1 |
| Approved age |
9 years and older |
| Administration |
Monthly subcutaneous injection |
| Regulatory pathway |
New drug application |
| Product type |
Specialty small-molecule RNAi drug |
How large is the nedosiran sodium market?
The PH1 market is an ultra-orphan market. Primary hyperoxaluria affects an estimated 1 to 3 people per million, with PH1 representing the most common genetic subtype.[3] The diagnosed and treated population is therefore small relative to conventional specialty pharmaceuticals.
The commercial model depends on a high annual price per patient rather than broad volume. Key market constraints include:
- delayed or incorrect diagnosis;
- genetic heterogeneity;
- limited metabolic and genetic testing;
- variable disease progression;
- renal impairment that can limit use;
- competition from lumasiran;
- need for long-term adherence to injectable therapy;
- payer controls over specialty-drug access.
The addressable population is narrower than the total PH1 population because Rivfloza is approved for patients aged 9 years and older with relatively preserved kidney function. Patients with advanced renal failure may require dialysis, kidney transplantation, liver transplantation, or combined organ transplantation rather than relying on urinary oxalate reduction alone.
Commercial market structure
The market has two principal RNAi products:
| Product |
Active ingredient |
Company |
Primary target |
FDA approval |
| Rivfloza |
Nedosiran sodium |
Novo Nordisk |
LDHA |
2023 |
| Oxlumo |
Lumasiran |
Alnylam Pharmaceuticals |
HAO1/glycolate oxidase |
2020 |
Both therapies reduce hepatic oxalate production through RNA interference, but they silence different genes. Oxlumo has an earlier commercial position and broader age eligibility in the United States, including pediatric patients younger than 9 years.[4]
How does nedosiran compare with Oxlumo?
Oxlumo has the first-mover advantage. It entered the PH1 market in 2020 and established physician, payer, diagnostic, and treatment-center relationships before Rivfloza’s approval.
Rivfloza’s principal clinical differentiation is its direct targeting of LDHA, a downstream enzyme in oxalate production. Nedosiran’s mechanism may provide activity across substrate sources that feed the final LDHA step, while lumasiran acts upstream by suppressing glycolate oxidase. The commercial importance of that distinction depends on comparative clinical outcomes, treatment durability, safety, dosing convenience, and payer coverage.
| Commercial factor |
Rivfloza |
Oxlumo |
| Company |
Novo Nordisk |
Alnylam |
| Target |
LDHA |
HAO1 |
| Initial U.S. approval |
2023 |
2020 |
| Approved U.S. age |
9 years and older |
Pediatric and adult use, subject to label |
| Administration |
Monthly |
Loading regimen followed by maintenance dosing |
| Competitive position |
Later entrant |
First approved RNAi therapy for PH1 |
| Core advantage |
Downstream LDHA inhibition and monthly dosing |
Established treatment and commercial lead |
The strongest competitive risk to nedosiran is not conventional generic substitution in the near term. It is branded share competition from Oxlumo, treatment selection based on age and renal function, and future therapies that address PH1 with oral or curative approaches.
What is the financial trajectory for Rivfloza?
Novo Nordisk does not generally report Rivfloza revenue as a separately material line item in its public financial reporting. Sales are included within broader reporting categories, which limits independent assessment of product revenue, prescription volume, gross-to-net deductions, and profitability.
The product’s financial trajectory has four stages:
1. Acquisition and development stage
Novo acquired Dicerna to obtain RNAi capabilities and a pipeline that included nedosiran. The transaction created a high strategic value for the platform, but the commercial return depends on whether rare-disease products generate sufficient sales to offset acquisition and development costs.[2]
2. Approval and launch stage
Rivfloza received U.S. approval in late 2023. The first commercial period was therefore a launch phase rather than a mature revenue period. Sales development depends on identifying undiagnosed PH1 patients, obtaining reimbursement, and converting patients from supportive care or Oxlumo.
3. Market penetration stage
Revenue growth will be driven by:
- expansion of genetic testing;
- diagnosis of patients with unexplained kidney stones;
- adoption by metabolic and transplant centers;
- payer approval;
- use in newly diagnosed patients;
- retention under monthly treatment;
- international regulatory approvals.
The small patient population constrains absolute revenue, while the specialty pricing structure can support meaningful revenue per treated patient.
4. Mature or strategic portfolio stage
Rivfloza’s long-term value depends on its position within Novo Nordisk’s rare-disease portfolio. Novo’s public reporting emphasizes larger diabetes and obesity franchises, so Rivfloza is unlikely to become a major groupwide revenue driver. Its value is more likely to be measured through specialty-market share, platform validation, and contribution to the rare-disease portfolio.
What generic entry risks exist for nedosiran sodium?
Generic entry risk is limited in the short term because Rivfloza was approved in 2023 and is an ultra-orphan injectable RNAi product. The more relevant risks are patent challenges, authorized competition, biosimilar-style competition, and product substitution.
Nedosiran is not a biologic for purposes of the traditional FDA biosimilar pathway. A follow-on product would more likely pursue an abbreviated or full drug application route, depending on formulation, analytical characterization, labeling, and reference-product requirements.
Key entry barriers include:
- siRNA sequence and chemical-modification patents;
- GalNAc conjugation and delivery technology;
- formulation and stability protection;
- manufacturing control of the oligonucleotide conjugate;
- analytical comparability;
- clinical requirements for a complex injectable product;
- limited commercial incentive from a small patient population.
What patents protect nedosiran sodium?
Publicly available product-level patent conclusions require a current patent-family and Orange Book review. The relevant protection categories are expected to include:
- composition-of-matter claims covering the siRNA sequence;
- LDHA-targeting RNAi constructs;
- GalNAc conjugates and hepatocyte-delivery chemistry;
- pharmaceutical formulations;
- dosing regimens for PH1;
- manufacturing and purification processes;
- methods for reducing urinary oxalate.
Patent life may extend beyond the basic composition patent through formulation, delivery, method-of-use, and manufacturing patents. Regulatory exclusivity and orphan-drug exclusivity also affect entry timing, but they do not provide the same scope as composition-of-matter protection.
What is the Orange Book status of Rivfloza?
Rivfloza is an FDA-approved prescription drug and is potentially eligible for Orange Book patent listing. The commercial significance of any listing depends on the specific patents submitted by Novo Nordisk, their listed expiration dates, pediatric extensions, and whether they are challenged in an abbreviated new drug application.
A Paragraph IV challenge could trigger patent litigation and a potential 30-month stay of approval for a qualifying generic application under the Hatch-Waxman framework.[5] No public commercial analysis should treat generic entry as imminent without confirmed Orange Book listings, an ANDA filing, a Paragraph IV notice, or district-court litigation.
Which companies are challenging nedosiran sodium?
The principal competitive company is Alnylam Pharmaceuticals, through Oxlumo. No conventional generic competitor has established a visible commercial position comparable to Alnylam’s branded product.
Potential future competition could come from:
- additional RNAi therapies;
- oral small-molecule inhibitors of oxalate production;
- gene-editing or gene-therapy programs;
- improved transplant strategies;
- next-generation therapies for patients with renal failure.
The market is also indirectly shaped by specialty pharmacies, diagnostic laboratories, transplant centers, and payer organizations. These groups influence treatment initiation and persistence even when they do not compete with Novo directly.
How strong is the nedosiran sodium commercial position?
Nedosiran has a strong scientific and regulatory position but a narrower commercial position.
| Factor |
Assessment |
| Mechanism |
Strong, genetically validated LDHA target |
| FDA status |
Approved in the United States |
| Disease market |
Small and ultra-orphan |
| Competitive timing |
Disadvantaged versus Oxlumo’s earlier launch |
| Dosing |
Monthly subcutaneous administration |
| Diagnosis |
Major bottleneck |
| Payer exposure |
High because of specialty pricing |
| Generic risk |
Low near term |
| Branded competition |
High |
| Revenue visibility |
Limited because sales are not separately reported |
The product’s main upside is increased diagnosis and adoption in PH1 patients who need durable oxalate reduction. Its main downside is that the total treated population may remain too small to support a large commercial franchise, particularly if Oxlumo retains treatment-center loyalty.
What litigation and settlement risks affect Rivfloza?
The main potential litigation categories are:
- patent infringement claims against generic or follow-on applicants;
- validity challenges involving RNAi sequence or delivery patents;
- inventorship and ownership disputes;
- licensing disputes involving Dicerna-derived technology;
- product-liability litigation;
- payer and reimbursement disputes.
No confirmed major public Paragraph IV settlement should be treated as part of the current Rivfloza commercial forecast without a documented court filing or company disclosure.
Key Takeaways
- Nedosiran sodium is marketed by Novo Nordisk as Rivfloza for PH1.
- The FDA approved Rivfloza in October 2023 for patients aged 9 years and older with relatively preserved kidney function.
- Rivfloza targets LDHA, while Alnylam’s Oxlumo targets HAO1.
- The market is ultra-orphan, diagnosis-constrained, and commercially dependent on high revenue per treated patient.
- Oxlumo has a meaningful first-mover advantage.
- Novo Nordisk does not separately disclose Rivfloza revenue at a level that permits a reliable standalone financial model.
- Near-term generic risk is limited, but branded competition and patent challenges remain relevant.
- Long-term value depends on diagnosis expansion, payer access, treatment persistence, and differentiation from Oxlumo.
FAQs About Nedosiran Sodium and Rivfloza
Is nedosiran sodium approved for primary hyperoxaluria type 2?
No. Rivfloza was approved for primary hyperoxaluria type 1. Its label does not establish approval for PH2.
Is Rivfloza a gene therapy?
No. Rivfloza is an siRNA therapy. It temporarily suppresses LDHA messenger RNA and does not permanently alter the patient’s DNA.
Can Rivfloza replace kidney transplantation?
No. Rivfloza is intended to reduce oxalate production. It does not replace transplantation for patients with irreversible kidney failure or advanced systemic oxalosis.
Does Novo Nordisk disclose Rivfloza sales separately?
Generally, no. Novo Nordisk reports most products within broader business segments, limiting public visibility into Rivfloza-specific sales and margins.
What is the biggest commercial risk to nedosiran sodium?
The largest commercial risk is limited market penetration against Oxlumo in a small, highly specialized patient population. Diagnostic delays and payer restrictions can reduce the number of patients who start and maintain therapy.
References
- U.S. Food and Drug Administration. (2023). Rivfloza (nedosiran) prescribing information.
- Novo Nordisk A/S. (2021). Novo Nordisk to acquire Dicerna Pharmaceuticals.
- National Organization for Rare Disorders. (n.d.). Primary hyperoxaluria.
- U.S. Food and Drug Administration. (2020). Oxlumo (lumasiran) prescribing information.
- U.S. Food and Drug Administration. (2024). Orange Book: Approved drug products with therapeutic equivalence evaluations.
