Last updated: August 13, 2026
Sodium thiosulfate is a low-cost, long-established generic drug with a newly commercialized premium segment: Fennec Pharmaceuticals’ Pedmark, an intravenous formulation approved to reduce cisplatin-induced ototoxicity in pediatric patients. The commercial market is therefore bifurcated. Generic sodium thiosulfate supplies emergency medicine and off-label uses, while Pedmark monetizes a protected pediatric oncology indication, formulation, manufacturing process, and dosing regimen.
Pedmark is the main driver of branded-market growth. Its FDA approval in August 2022 created a U.S. commercial opportunity supported by orphan-drug exclusivity, pediatric oncology adoption, and patent protection extending into the early-to-mid 2030s. Generic substitution risk is limited in the approved otoprotection indication because sodium thiosulfate products are not automatically interchangeable with Pedmark.
What is sodium thiosulfate used for in the pharmaceutical market?
Sodium thiosulfate is used across several medical settings, but commercial value differs sharply by indication.
| Use |
Product status |
Commercial characteristics |
| Cyanide poisoning |
Generic injectable products, including FDA-approved sodium thiosulfate injection |
Acute-care, low-volume, procurement-driven market |
| Cisplatin-induced ototoxicity prevention |
Pedmark, FDA-approved branded product |
Premium specialty pharmaceutical market |
| Calciphylaxis |
Primarily off-label intravenous use |
Hospital-compounded or generic supply |
| Other toxicology and dermatologic uses |
Off-label |
Fragmented and difficult to quantify |
| Industrial or nonmedical applications |
Nonpharmaceutical |
Outside the prescription-drug market |
Sodium thiosulfate is a sulfur-containing inorganic compound. Its established generic status limits pricing power for traditional indications. Pedmark changes the economics by combining sodium thiosulfate with a specific pediatric oncology indication, ready-to-use formulation, controlled dosing, and commercial distribution.
What is the FDA status of Pedmark?
The FDA approved Pedmark on August 11, 2022, for reducing the risk of ototoxicity associated with cisplatin in pediatric patients 1 month of age and older with localized, nonmetastatic solid tumors.[1]
The approved product is a sodium thiosulfate injection administered intravenously after cisplatin. The product is supplied as a ready-to-use formulation designed for hospital use and pediatric oncology protocols.
What regulatory exclusivity protects Pedmark?
Pedmark received orphan-drug designation, providing seven years of U.S. orphan-drug exclusivity from the approval date, subject to the statutory limits of the Orphan Drug Act. The principal period therefore runs to August 2029.[1][2]
Orphan exclusivity does not prevent all generic or competing sodium thiosulfate products from being marketed. It blocks FDA approval of the same drug for the same orphan indication during the exclusivity period, unless statutory exceptions apply. It does not prevent approval of products for different indications.
Pedmark’s regulatory position includes:
| Regulatory element |
Status |
| FDA approval |
August 11, 2022 |
| Sponsor |
Fennec Pharmaceuticals |
| Active ingredient |
Sodium thiosulfate |
| Dosage form |
Intravenous injection |
| Indication |
Reduction of cisplatin-associated ototoxicity in pediatric patients |
| Orphan exclusivity |
Expected through August 2029 |
| Biosimilar pathway |
Not applicable |
| Small-molecule generic pathway |
Potentially applicable, subject to patents, exclusivity, and product requirements |
What patents protect Pedmark and sodium thiosulfate otoprotection?
The underlying sodium thiosulfate molecule is old and cannot support modern composition-of-matter exclusivity. Pedmark’s protection instead depends on formulation, dosing, treatment timing, patient population, and manufacturing claims.
Fennec’s disclosed patent estate has included U.S. patents directed to sodium thiosulfate formulations and methods for reducing cisplatin-induced ototoxicity. Public company filings and FDA patent listings identify patent protection extending into the 2030s, with relevant patent expirations generally reported in the 2033-2035 period, subject to terminal disclaimers, patent-term adjustments, and any regulatory patent-term extension.[3][4]
What formulations are protected by Pedmark patents?
The commercial differentiation is based on a formulation intended for predictable intravenous administration in pediatric oncology. Patent claims may cover:
- Concentration and pH characteristics.
- Stable aqueous sodium thiosulfate formulations.
- Ready-to-use injectable presentations.
- Administration after cisplatin treatment.
- Pediatric dosing and treatment sequencing.
- Reduction of hearing loss or ototoxicity in defined pediatric populations.
The practical strength of these claims depends on their final scope, prosecution history, claim construction, and whether a generic applicant can design around the formulation or method claims.
How strong is the sodium thiosulfate patent estate?
The estate is stronger for Pedmark’s approved use than for sodium thiosulfate as a molecule.
| Protection category |
Assessment |
| Active ingredient |
Weak, because sodium thiosulfate is long established |
| Pediatric otoprotection method |
Moderate to strong, depending on claim scope |
| Ready-to-use injectable formulation |
Moderate |
| Manufacturing process |
Potentially meaningful if difficult to design around |
| Orphan indication |
Strong through August 2029 for the protected indication |
| Generic competition outside the indication |
High |
| Biosimilar protection |
Not relevant |
The key limitation is that generic sodium thiosulfate is not automatically excluded from all medical uses. A competitor could potentially sell sodium thiosulfate for cyanide poisoning or another indication while avoiding the protected pediatric otoprotection use. The commercial question is whether the competitor can obtain approval for the same indication and whether its product would infringe formulation or method patents.
When does sodium thiosulfate lose exclusivity?
Sodium thiosulfate has no meaningful molecule-level exclusivity. The relevant exclusivity timeline applies to Pedmark.
| Date |
Event |
| 2018 |
FDA orphan-drug designation reported for sodium thiosulfate otoprotection development |
| August 11, 2022 |
FDA approves Pedmark |
| October 2022 |
U.S. commercial launch reported by Fennec |
| August 2029 |
Expected end of seven-year orphan exclusivity |
| 2033-2035 |
Reported range for key U.S. patent expirations, subject to legal adjustments |
| After patent expiry |
Potential for approved generic entry, subject to FDA approval and litigation outcomes |
Patent expiry, rather than orphan exclusivity, is likely to determine the durable branded-versus-generic risk. A generic could face a commercial barrier after orphan exclusivity if relevant formulation or method patents remain listed and enforceable.
What is the Orange Book status of Pedmark?
Pedmark’s Orange Book position is important because listed patents can support a Paragraph IV challenge under the Hatch-Waxman Act.[5]
The relevant listed-patent categories are expected to include patents covering the drug product and methods of use. Orange Book-listed patents can create a 30-month stay when a patent owner timely files infringement litigation after receiving a Paragraph IV notice, although the stay and litigation outcome depend on the specific filing and patent claims.
The Orange Book does not list every patent that could affect commercial competition. Manufacturing patents, unlisted method claims, trade secrets, and contractual restrictions may also influence entry.
Are there Paragraph IV challenges to Pedmark?
Publicly reported company filings through fiscal year 2024 did not identify a completed U.S. Paragraph IV challenge that had resulted in generic market entry for Pedmark.[3] The absence of a disclosed challenge does not eliminate future risk. A generic applicant could submit an abbreviated new drug application with a Paragraph IV certification after gaining sufficient commercial incentive and resolving formulation or clinical-use issues.
A future challenger would likely evaluate:
- Whether listed patents cover the generic’s formulation.
- Whether the proposed label includes pediatric cisplatin otoprotection.
- Whether the generic can omit the protected use through a skinny label.
- Whether method-of-use claims can be enforced against hospital prescribing.
- Whether the expected market justifies litigation expense.
What is the financial trajectory for sodium thiosulfate and Pedmark?
The branded financial trajectory is concentrated in Fennec. Generic sodium thiosulfate revenue is dispersed across hospital suppliers, specialty distributors, compounders, and manufacturers and is not separately reported as a transparent global market.
Fennec’s commercial performance has followed the expected launch pattern for a specialty pediatric oncology drug:
| Period |
Financial development |
| 2022 |
Initial U.S. launch and limited launch-year revenue |
| 2023 |
Expansion of hospital and pediatric oncology account coverage |
| 2024 |
Higher sales from broader account penetration and repeat ordering |
| 2025 onward |
Growth depends on treatment-center adoption, patient identification, reimbursement, and international commercialization |
Fennec’s public filings reported substantial year-over-year growth in Pedmark net product sales after launch, with annual revenue reaching the tens of millions of dollars by 2023-2024.[3] The company’s financial model depends on a narrow patient population, high per-treatment pricing, and hospital adoption rather than broad primary-care prescribing.
What drives Pedmark revenue?
The main revenue drivers are:
- Number of pediatric patients receiving cisplatin.
- Share of eligible patients treated with sodium thiosulfate.
- Number of activated pediatric oncology centers.
- Reimbursement and hospital formulary access.
- Product use across multiple cisplatin cycles.
- International approvals and distributor arrangements.
- Physician confidence in hearing-preservation outcomes.
The principal commercial constraints are the small eligible population, treatment-center concentration, variable cisplatin protocols, and the need to administer sodium thiosulfate at the correct time after chemotherapy.
How profitable is the Pedmark business?
Pedmark has the cost structure of a specialty pharmaceutical product rather than a commodity injectable. Its gross margin can be supported by branded pricing, but profitability is affected by:
- Small-scale manufacturing.
- Specialty distribution fees.
- Medical-affairs and oncology sales costs.
- Post-approval studies.
- Regulatory compliance.
- Patient-support programs.
- International market development.
The business can reach profitability without large absolute revenue if pricing and gross margin remain high. Fennec’s principal financial risk is not raw-material cost. It is whether the company can sustain adoption in a limited pediatric oncology market before patent and exclusivity erosion.
Which companies compete with sodium thiosulfate?
Competition differs by market segment.
Generic injectable competitors
Generic sodium thiosulfate may be supplied by hospital injectable manufacturers and specialty pharmaceutical companies. Competition is generally based on:
- FDA approval status.
- Availability during shortages.
- Contract pricing.
- Packaging and concentration.
- Distribution reliability.
- Hospital procurement terms.
These suppliers compete with each other but do not necessarily compete directly with Pedmark in the approved pediatric otoprotection market.
Branded and pipeline competition
Pedmark’s most relevant commercial alternatives are not necessarily other sodium thiosulfate products. They include:
- Use of cisplatin without otoprotective therapy.
- Substitution of another chemotherapy regimen.
- Use of alternative platinum agents.
- Hearing-monitoring and rehabilitation strategies.
- Investigational otoprotective agents.
A competing otoprotective drug with a distinct mechanism could reduce Pedmark’s market even without infringing sodium thiosulfate patents.
What licensing deals and geographic rights affect sodium thiosulfate?
Fennec has used commercial and development relationships to expand Pedmark beyond the United States. The most relevant value drivers are regional licensing, distribution, and regulatory partnerships.
The European Medicines Agency granted marketing authorization for Pedmarqsi, the European product corresponding to Pedmark, in 2023. The European product is marketed under a separate brand and is subject to European regulatory and commercial arrangements.[6]
Geographic value differs by region:
| Region |
Market status |
| United States |
FDA-approved Pedmark; primary commercial market |
| European Union |
Pedmarqsi authorized by the European Commission |
| Canada and other markets |
Potentially addressable through local approval and commercialization agreements |
| Emerging markets |
Greater price pressure and generic substitution risk |
International expansion increases the addressable population but introduces country-specific pricing, reimbursement, patent, and procurement risks. European commercialization can also require pediatric oncology centers to change established cisplatin protocols.
What generic launch scenarios exist for Pedmark?
Three launch scenarios are commercially relevant.
Scenario 1: No near-term generic challenge
Pedmark continues to grow through orphan-exclusivity expiry and retains market share through physician familiarity, supply reliability, and formulation differentiation. This is the highest-value scenario for Fennec.
Scenario 2: Paragraph IV challenge before patent expiry
A generic applicant files an ANDA with a Paragraph IV certification. Fennec initiates litigation, potentially triggering a 30-month stay. Entry could occur after settlement, an adverse judgment, patent expiry, or an authorized generic arrangement.
Scenario 3: Label-limited or off-label competition
Generic sodium thiosulfate is used outside the approved Pedmark indication, including hospital-compounded use. This scenario could pressure pricing without immediately replacing Pedmark in pediatric oncology.
The most likely first competitive pressure is indirect substitution through generic procurement or off-label use, not a biosimilar-style automatic replacement.
Is there biosimilar risk for sodium thiosulfate?
No. Sodium thiosulfate is a small-molecule inorganic compound, not a biologic. Biosimilar rules under the Public Health Service Act do not apply. Any direct generic competitor would generally use the Abbreviated New Drug Application pathway, not a biosimilar application.[5]
The absence of biosimilar risk does not mean low competition. Generic competition can be faster and more price-intensive once the relevant regulatory and patent barriers are removed.
What manufacturing and intellectual-property barriers exist?
Manufacturing barriers are moderate. Sodium thiosulfate itself is inexpensive and well known, but pharmaceutical-grade injectable production requires:
- Validated sterile manufacturing.
- Stability data.
- Container-closure compatibility.
- Control of concentration and pH.
- Consistent supply of active pharmaceutical ingredient.
- Pediatric dosing and administration instructions.
- Compliance with FDA current good manufacturing practice requirements.
Pedmark’s manufacturing and formulation know-how may delay competition if the product’s stability or ready-to-use presentation is difficult to replicate. These barriers are less durable than composition-of-matter patents because experienced injectable manufacturers can often develop alternative processes.
How does sodium thiosulfate compare with other specialty pediatric oncology drugs?
| Attribute |
Pedmark |
Generic sodium thiosulfate |
Conventional pediatric supportive-care drug |
| FDA-approved pediatric otoprotection |
Yes |
Not necessarily |
| Pricing |
Branded specialty pricing |
Commodity or contract pricing |
| Patent value |
Formulation and method patents |
Limited or none |
| Regulatory exclusivity |
Orphan exclusivity reported |
Generally none |
| Market size |
Small, focused |
Broad but fragmented |
| Substitution risk |
Moderate after exclusivity |
High |
| Biosimilar risk |
None |
None |
| Commercial concentration |
High |
Low |
Pedmark’s value comes from clinical positioning and regulatory specificity. Generic sodium thiosulfate’s value comes from availability and price.
Key Takeaways
- Sodium thiosulfate is a mature generic ingredient with limited molecule-level patent protection.
- Pedmark is the principal branded commercial opportunity and was FDA-approved in August 2022 for pediatric cisplatin-associated ototoxicity.
- Orphan-drug exclusivity is expected to run through August 2029.
- Key patent protection has been reported into the 2033-2035 period, depending on the patent and applicable adjustments.
- Fennec’s revenue trajectory is driven by Pedmark adoption, hospital coverage, reimbursement, and international expansion.
- Generic competition outside the approved otoprotection indication already exists or can develop independently.
- No biosimilar pathway applies because sodium thiosulfate is a small-molecule drug.
- The main future market risk is a Paragraph IV challenge or off-label generic substitution after orphan exclusivity.
- The principal commercial barrier is clinical and hospital adoption, not the cost of sodium thiosulfate API.
- European authorization under the Pedmarqsi brand expands the market but adds country-specific reimbursement and patent risks.
Frequently Asked Questions
Is sodium thiosulfate an expensive drug?
Generic sodium thiosulfate is generally low cost, while Pedmark carries specialty-drug pricing because it is an FDA-approved pediatric oncology product with formulation, clinical, and regulatory differentiation.
Can hospitals substitute generic sodium thiosulfate for Pedmark?
Hospitals may use an approved generic product where legally and clinically appropriate, but automatic substitution depends on product approval, formulation, labeling, institutional policy, and the prescribed indication.
Does sodium thiosulfate have composition-of-matter patent protection?
No meaningful modern composition-of-matter protection should be expected for sodium thiosulfate itself. Commercial protection is concentrated in formulation, manufacturing, dosing, and method-of-use patents.
What is the main indication supporting Pedmark sales?
The principal indication is reduction of cisplatin-associated ototoxicity in pediatric patients with localized, nonmetastatic solid tumors.
Could a new otoprotective drug replace Pedmark?
Yes. A competing drug with stronger efficacy, easier administration, broader labeling, or lower cost could reduce Pedmark’s market without directly challenging sodium thiosulfate patents.
References
-
U.S. Food and Drug Administration. (2022). FDA approves sodium thiosulfate to reduce the risk of ototoxicity associated with cisplatin in pediatric patients. FDA.
-
U.S. Food and Drug Administration. (n.d.). Orphan drug designation and exclusivity. FDA.
-
Fennec Pharmaceuticals Inc. (2024). Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934, Form 10-K. U.S. Securities and Exchange Commission.
-
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
-
U.S. Congress. (1984). Drug Price Competition and Patent Term Restoration Act of 1984. Pub. L. No. 98-417.
-
European Commission. (2023). Pedmarqsi: European public assessment report and marketing authorization information. European Medicines Agency.
