IODOHIPPURATE SODIUM I-131 - Generic Drug Details

What are the generic sources for iodohippurate sodium i-131 and what is the scope of freedom to operate?

Iodohippurate sodium i-131 is the generic ingredient in three branded drugs marketed by Mallinckrodt, Bracco, and Pharmalucence, and is included in three NDAs. Additional information is available in the individual branded drug profile pages.

Summary for IODOHIPPURATE SODIUM I-131

US Patents:	0
Tradenames:	3
Applicants:	3
NDAs:	3
Raw Ingredient (Bulk) Api Vendors:	4
DailyMed Link:	IODOHIPPURATE SODIUM I-131 at DailyMed

US Patents and Regulatory Information for IODOHIPPURATE SODIUM I-131

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Bracco	HIPPUTOPE	iodohippurate sodium i-131	INJECTABLE;INJECTION	015419-002	Approved Prior to Jan 1, 1982		DISCN	No	No
Mallinckrodt	HIPPURAN I 131	iodohippurate sodium i-131	INJECTABLE;INJECTION	016666-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Pharmalucence	IODOHIPPURATE SODIUM I 131	iodohippurate sodium i-131	INJECTABLE;INJECTION	017313-001	Approved Prior to Jan 1, 1982		DISCN	No	No

Iodohippurate Sodium I-131 Market Dynamics, FDA Status, Patent Position, and Financial Trajectory

Last updated: September 8, 2026

Iodohippurate sodium I-131 is an obsolete renal diagnostic radiopharmaceutical with little current commercial relevance in the United States. Its historical use was measurement of renal perfusion, effective renal plasma flow, and tubular extraction. Technetium-99m agents, especially technetium Tc-99m mertiatide, replaced it in most nuclear-medicine workflows because they provide lower radiation burden, better imaging characteristics, and more practical hospital logistics.

The product has no meaningful active patent barrier. Any commercial opportunity would depend on regulatory reactivation, isotope production, radiopharmacy distribution, reimbursement, and clinical substitution rather than exclusivity. Public company filings do not provide a separately reported revenue stream for iodohippurate sodium I-131, preventing a reliable standalone forecast.

What is iodohippurate sodium I-131 used for?

Iodohippurate sodium I-131 is an iodine-131-labeled hippurate compound used for renal imaging and renal function testing. After intravenous administration, the compound is rapidly extracted by the kidneys and excreted into urine. Historically, clinicians used it to assess:

• Renal blood flow
• Effective renal plasma flow
• Relative kidney function
• Renal transit and excretion
• Suspected obstruction
• Unilateral renal impairment

Its diagnostic value came from renal tubular secretion of hippurate. Iodine-131 emits beta and gamma radiation, which creates a higher radiation burden than technetium-99m alternatives and limits its suitability for routine contemporary imaging.

The product should not be confused with sodium iodohippurate labeled with iodine-123, which has different imaging and dosimetry characteristics, or with technetium Tc-99m mertiatide, which became the principal replacement in dynamic renal scintigraphy.

What is the FDA regulatory status of iodohippurate sodium I-131?

Iodohippurate sodium I-131 is a legacy radiopharmaceutical rather than a growing FDA-regulated commercial product. Historical U.S. labeling and drug databases identify I-131 iodohippurate products for diagnostic renal use, but the product is not a current mainstream renal-imaging product.

Regulatory issue	Current commercial implication
FDA approval history	Historical approval and labeling exist for I-131 iodohippurate products
Current routine availability	Limited or absent in ordinary U.S. nuclear-medicine practice
Current clinical standard	Technetium Tc-99m renal agents are generally preferred
NDA economics	No evidence of an active, high-value branded franchise
New-drug exclusivity	Expired for a product with a legacy approval history
Orphan-drug position	Not an orphan-drug commercial opportunity
Supplemental approval opportunity	Would require a sponsor to address manufacturing, safety, labeling, and supply issues

FDA drug databases distinguish between a product’s historical approval record and its current marketing availability. A product can remain identifiable in regulatory records even when it is no longer actively marketed. The FDA Orange Book also does not provide a current commercial protection strategy for this legacy diagnostic agent comparable to the patent estates surrounding newer branded pharmaceuticals (FDA, 2024a; FDA, 2024b).

What patents protect iodohippurate sodium I-131?

No commercially meaningful, unexpired U.S. patent estate is expected to protect iodohippurate sodium I-131 as a diagnostic product. The underlying compound, iodination chemistry, renal diagnostic use, and conventional injectable formulation date to technologies that are substantially older than the statutory patent term.

Protection category	Likely status
Active-ingredient patent	Expired
Composition-of-matter patent	Expired
Basic renal diagnostic method patent	Expired
I-131 labeling method	Expired or commercially irrelevant
Conventional injectable formulation	Expired or unprotected
Manufacturing process	Potentially protectable only as know-how, not as a broad product barrier
Delivery-device patent	Not material to the legacy product
Current Orange Book patent leverage	No meaningful listed-patent strategy

The relevant commercial barriers are operational. A manufacturer would need validated radioiodination, qualified iodine-131 supply, sterile manufacturing, radiochemical quality control, calibrated dose distribution, and a hospital or radiopharmacy customer base. These barriers can restrict entry without creating durable pharmaceutical exclusivity.

When does iodohippurate sodium I-131 lose exclusivity?

Any patent and regulatory exclusivity associated with the original product would have expired decades ago. The product’s commercial decline is therefore attributable to technological displacement and market withdrawal rather than a recent loss of exclusivity.

The principal exclusivity milestones are:

Milestone	Assessment
Original compound and use patents	Long expired
Original product approval	Historical
New chemical entity exclusivity	Expired
Pediatric exclusivity	Not commercially relevant
Orphan exclusivity	Not applicable
Current patent cliff	No near-term cliff; the franchise is already post-exclusivity
Generic entry risk	Structurally high, but demand is too limited to support broad generic competition

A new manufacturer could potentially pursue an abbreviated or alternative regulatory pathway depending on the specific product presentation and FDA requirements. That possibility does not create a meaningful patent challenge because there is no apparent active patent estate to defend.

What formulations are protected by iodohippurate sodium I-131 patents?

The historical formulation was an injectable sodium iodohippurate solution containing iodine-131 at a calibrated radioactive concentration. Product value depended on radiochemical purity, sterility, apyrogenicity, radionuclide identity, activity calibration, and shelf-life management.

No current formulation patent is known to create a defensible commercial moat around the legacy injection. A modern sponsor could seek protection for a specific formulation, container, stabilizer system, or manufacturing process, but those claims would need to cover a real technical improvement. Broad claims directed to the basic radiopharmaceutical would face substantial novelty and obviousness concerns.

Potentially protectable technical areas would include:

• Improved radiochemical stability
• Reduced radiolysis during storage
• Longer usable shelf life
• Lower-volume administration
• Automated compounding or dispensing
• Specialized sterile packaging
• Improved dose-calibration methods
• Manufacturing processes that reduce radioactive waste

These areas would create narrow process or product improvements rather than restore the historical franchise.

How does iodohippurate sodium I-131 compare with technetium Tc-99m mertiatide?

Technetium Tc-99m mertiatide is the closest practical comparator and the principal reason I-131 iodohippurate lost commercial relevance.

Attribute	Iodohippurate sodium I-131	Tc-99m mertiatide
Primary use	Renal function and clearance studies	Dynamic renal imaging and differential function
Physical half-life	Approximately 8 days	Approximately 6 hours
Radiation profile	Higher patient radiation burden	Lower radiation burden for routine imaging
Imaging practicality	Inferior for modern dynamic imaging	Well suited to gamma-camera imaging
Supply model	Requires iodine-131 production and distribution	Integrated into established Tc-99m supply chains
Hospital workflow	Less convenient	Standard nuclear-medicine workflow
Current clinical position	Legacy or limited use	Established replacement
Commercial demand	Very low	Established but dependent on nuclear-medicine volumes

Tc-99m mertiatide has stronger clinical utility because it supports dynamic imaging with lower radiation exposure and better compatibility with current equipment. Tc-99m diethylenetriamine pentaacetic acid, or DTPA, and other renal protocols also compete for selected indications.

What is the market size and revenue exposure?

There is no reliable public market-size estimate or separately reported revenue figure for iodohippurate sodium I-131. Manufacturers of radiopharmaceuticals typically report revenues by business segment, geography, or broad product category rather than by individual legacy diagnostic agent.

The commercial market is best characterized as:

• Niche or effectively inactive in the United States
• Dependent on occasional institutional demand
• Constrained by substitution with Tc-99m agents
• Highly sensitive to isotope availability and radiopharmacy logistics
• Unsuitable for conventional branded-drug revenue forecasting

A bottom-up revenue model would require the number of active sites, doses per site, dose price, production frequency, wastage, distribution radius, and reimbursement. Those inputs are not established in public company disclosures. A revenue forecast based on historical renal-imaging volumes would overstate the addressable market because most contemporary renal studies use technetium-based agents.

The economic profile is closer to an on-demand hospital radiopharmaceutical than to a scalable outpatient pharmaceutical. Fixed costs for radioactive manufacturing, quality systems, and distribution can be high relative to the number of doses sold.

What generic entry risks exist for iodohippurate sodium I-131?

Patent-based generic entry risk is high because the product has no meaningful remaining exclusivity. Commercial entry risk is different. A potential entrant would face a small and declining market, uncertain demand, short practical shelf life, radioactive-material handling requirements, and competition from established alternatives.

The main entry barriers are:

1. Radioisotope sourcing and reactor or isotope-supplier access.
2. Licensed radiopharmaceutical manufacturing.
3. Sterile injectable production.
4. Validation of radioiodination and quality-control methods.
5. State and federal radioactive-material licensing.
6. Radiopharmacy distribution.
7. Hospital formulary adoption.
8. Reimbursement and procedure economics.
9. Clinical acceptance against Tc-99m alternatives.

These barriers favor established radiopharmaceutical manufacturers and large radiopharmacy networks. They do not support premium pricing unless supply is constrained or a hospital has a specific clinical need.

Are there Paragraph IV challenges or patent litigation?

No significant recent Paragraph IV campaign or patent litigation involving iodohippurate sodium I-131 is apparent in the public profile of this legacy product. The absence of litigation is consistent with the product’s expired patent position and limited commercial value.

A new sponsor would more likely face:

• FDA review of product quality and manufacturing
• Questions about current clinical relevance
• Supply-chain reliability requirements
• Institutional substitution by Tc-99m products
• Reimbursement uncertainty

The litigation risk is therefore operational and regulatory rather than patent-driven. There is no evident settlement structure comparable to those used in high-revenue branded drug patent disputes.

What is the Orange Book status of iodohippurate sodium I-131?

The Orange Book is not a meaningful source of current commercial protection for this product. Historical FDA records may identify approved iodohippurate sodium I-131 products or discontinued products, but a listed historical product does not establish current market availability or active patent protection.

For transaction or diligence purposes, the product should be classified as:

• A legacy approved radiopharmaceutical
• Without a material active patent estate
• Without meaningful regulatory exclusivity
• With uncertain or limited current marketing status
• Dependent on product-specific FDA and facility compliance

Orange Book review should be combined with FDA approval-history records, current labeling databases, National Drug Code records, and radiopharmaceutical supplier information. No single database reliably establishes active commercial supply.

Which companies are challenging or supplying the product?

No major current competitive field has formed around iodohippurate sodium I-131. The relevant competitive landscape consists of replacement products rather than direct I-131 iodohippurate suppliers.

The principal competitive categories are:

• Tc-99m mertiatide products
• Tc-99m DTPA products
• Renal ultrasound
• CT and MR urography in selected settings
• Other renal-function testing approaches

Commercial pressure comes from radiopharmaceutical manufacturers, hospital radiopharmacies, and nuclear pharmacies supplying Tc-99m agents. The competitive question is not which company will win an I-131 iodohippurate patent dispute. It is whether any supplier can justify the cost of reintroducing a clinically displaced product.

How strong is the patent estate for iodohippurate sodium I-131?

The patent estate is commercially weak to nonexistent. Its strength can be summarized as follows:

Factor	Rating	Explanation
Composition patent	0/5	Historical technology with expired protection
Method-of-use protection	0/5	Conventional renal diagnostic use
Formulation protection	0/5	Legacy injectable formulation
Manufacturing know-how	2/5	May create operational friction but not durable exclusivity
Regulatory exclusivity	0/5	No current high-value exclusivity identified
Switching costs	1/5	Hospitals have established alternatives
Supply-chain barriers	3/5	Radioactive manufacturing and distribution remain difficult
Overall commercial defensibility	1/5	Weak product moat; operational barriers dominate

Any investment thesis based on patent value would be unsupported. A viable project would need to rely on a new formulation, a different isotope, a specialized indication, or a supply-constrained niche.

What is the likely financial trajectory?

The historical financial trajectory is one of secular decline:

Period	Commercial trajectory
Early adoption	Used as a renal diagnostic radiopharmaceutical
Replacement phase	Tc-99m renal agents gained clinical and operational preference
Mature phase	Demand narrowed to specialized or legacy use
Current phase	Limited, intermittent, or discontinued commercial relevance
Forward outlook	Flat at a very low base, with downside risk from further substitution

A return to material revenue would require a new clinical rationale or supply advantage. Reintroducing the historical product without a differentiated value proposition would face weak demand, low pricing power, and high manufacturing overhead.

Potential upside scenarios include a temporary shortage of competing renal agents, a specialized international market, or a sponsor’s ability to manufacture the product as part of a broader radiopharmaceutical portfolio. These scenarios would support incremental portfolio revenue, not a large standalone franchise.

Key Takeaways

• Iodohippurate sodium I-131 is a legacy renal diagnostic radiopharmaceutical.
• Its main commercial use was displaced by technetium Tc-99m mertiatide and other renal-imaging approaches.
• Original patents and regulatory exclusivity are expired or commercially irrelevant.
• No material current Orange Book patent position, Paragraph IV campaign, or settlement structure is associated with the product.
• Public disclosures do not support a standalone revenue estimate.
• Commercial barriers are based on radioactive manufacturing, licensing, distribution, and limited demand.
• The product has low patent strength, weak pricing power, and a declining or inactive market trajectory.
• A viable modern opportunity would require a differentiated formulation, new isotope strategy, or specialized clinical indication.

FAQs

Is iodohippurate sodium I-131 still commercially available in the United States?

Routine U.S. availability appears limited or absent. Historical FDA records do not establish that a product remains actively marketed or consistently supplied.

Is I-131 iodohippurate the same as Tc-99m MAG3?

No. I-131 iodohippurate is an iodine-131-labeled renal agent. Tc-99m MAG3 is technetium Tc-99m mertiatide, a different radiopharmaceutical with lower radiation burden and greater contemporary clinical use.

Can a generic manufacturer launch iodohippurate sodium I-131 without a patent license?

Patent licensing is unlikely to be required because the historical product and its basic uses are long past patent expiration. FDA approval, radioactive-material licensing, sterile manufacturing, and supply-chain compliance remain necessary.

Why did technetium-based renal agents replace I-131 iodohippurate?

Technetium-based agents offer more favorable imaging workflows, shorter physical half-life, lower radiation exposure, and better integration with modern nuclear-medicine practice.

Does iodohippurate sodium I-131 have investment value as a specialty radiopharmaceutical?

Its standalone investment value is low. Any potential value would come from portfolio fit, specialized supply, or a differentiated re-formulation rather than from patent exclusivity or broad market demand.

References

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

2. U.S. Food and Drug Administration. (2024b). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/

3. U.S. National Library of Medicine. (2024). DailyMed: Current medication information. https://dailymed.nlm.nih.gov/dailymed/

4. Society of Nuclear Medicine and Molecular Imaging. (2018). SNMMI procedure standard for diuretic renal scintigraphy in adults. Journal of Nuclear Medicine Technology.

5. U.S. Food and Drug Administration. (2024c). Nuclear medicine and radiopharmaceutical products. https://www.fda.gov/drugs/biologics-genetic-therapies/nuclear-medicine-and-radiopharmaceutical-products