Carbenicillin disodium - Generic Drug Details

What are the generic sources for carbenicillin disodium and what is the scope of freedom to operate?

Carbenicillin disodium is the generic ingredient in two branded drugs marketed by Roerig and Glaxosmithkline, and is included in two NDAs. Additional information is available in the individual branded drug profile pages.

Summary for carbenicillin disodium

US Patents:	0
Tradenames:	2
Applicants:	2
NDAs:	2
Raw Ingredient (Bulk) Api Vendors:	53
Clinical Trials:	1
DailyMed Link:	carbenicillin disodium at DailyMed

Recent Clinical Trials for carbenicillin disodium

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
Fundação de Amparo à Pesquisa do Estado de São Paulo	Phase 4
Federal University of São Paulo	Phase 4

See all carbenicillin disodium clinical trials

Anatomical Therapeutic Chemical (ATC) Classes for carbenicillin disodium

J01CA	Penicillins with extended spectrum
J01C	BETA-LACTAM ANTIBACTERIALS, PENICILLINS
J01	ANTIBACTERIALS FOR SYSTEMIC USE
J	Antiinfectives for systemic use

US Patents and Regulatory Information for carbenicillin disodium

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Glaxosmithkline	PYOPEN	carbenicillin disodium	INJECTABLE;INJECTION	050298-007	Approved Prior to Jan 1, 1982		DISCN	No	No
Glaxosmithkline	PYOPEN	carbenicillin disodium	INJECTABLE;INJECTION	050298-003	Approved Prior to Jan 1, 1982		DISCN	No	No
Roerig	GEOPEN	carbenicillin disodium	INJECTABLE;INJECTION	050306-004	Approved Prior to Jan 1, 1982		DISCN	No	No

Carbenicillin Disodium Market Dynamics, Patent Status, FDA Position, and Financial Trajectory

Last updated: September 2, 2026

Carbenicillin disodium is a legacy injectable antipseudomonal penicillin with limited commercial relevance in modern human medicine. Its original patent protection has expired, no meaningful biosimilar barrier exists, and the U.S. market lacks a significant active branded franchise. Demand is concentrated in laboratory research, reference use, specialty procurement, and selected international or institutional channels. The drug's financial trajectory is best characterized as long-term erosion followed by niche stabilization rather than renewed pharmaceutical growth.

What is carbenicillin disodium and how is it used?

Carbenicillin disodium is the disodium salt of carbenicillin, a semisynthetic beta-lactam antibiotic. It inhibits bacterial cell-wall synthesis and historically was used against susceptible gram-negative organisms, including Pseudomonas aeruginosa.

Attribute	Carbenicillin disodium
Active ingredient	Carbenicillin
Salt form	Disodium
Drug class	Antipseudomonal penicillin
Molecular formula	C17H16N2Na2O6S
Molecular weight	Approximately 422.36 g/mol
Administration	Parenteral, historically intravenous or intramuscular
Primary historical use	Serious susceptible gram-negative infections
Current commercial profile	Legacy, limited-volume product
Common research use	Selective antibiotic in molecular biology
U.S. patent position	Foundational protection expired
Biosimilar exposure	Not applicable in the biologic sense

Carbenicillin disodium has a higher sodium burden than many modern alternatives and requires parenteral administration. These factors reduced its attractiveness as newer antipseudomonal agents entered the market.

In research, carbenicillin is used in bacterial selection systems, particularly for plasmid-bearing Escherichia coli. Research suppliers generally sell the active ingredient or a laboratory-grade salt rather than a conventional prescription pharmaceutical product.

When did carbenicillin disodium lose exclusivity?

Carbenicillin disodium lost meaningful market exclusivity decades ago. The molecule was introduced in the 1960s, and its original compound and pharmaceutical-use patents are no longer commercially relevant.

The commercial sequence was broadly:

Period	Market event
1960s	Carbenicillin introduced as an antipseudomonal penicillin
1970s	Injectable and oral prodrug forms competed in the anti-infective market
1980s-1990s	Broad-spectrum cephalosporins and newer antipseudomonal agents displaced use
2000s	Product availability became fragmented and increasingly dependent on niche suppliers
2010s-present	Human pharmaceutical use contracted; laboratory and specialty supply remained

No active composition-of-matter patent should block generic manufacture of carbenicillin disodium. Any commercial restriction today is more likely to arise from manufacturing economics, regulatory maintenance, procurement demand, quality systems, or supply-chain decisions than from patent rights.

What patents protect carbenicillin disodium?

No material live patent estate is associated with the original carbenicillin disodium molecule in the United States or other major pharmaceutical jurisdictions.

The patent landscape historically included:

• Composition patents covering carbenicillin and related penicillin derivatives.
• Process patents covering fermentation, synthesis, purification, and salt formation.
• Pharmaceutical formulation claims for injectable preparations.
• Patents relating to oral prodrugs such as carbenicillin indanyl sodium.

Those rights are expired. Later patents covering manufacturing or formulation improvements would also have reached the end of their normal term unless supported by unusually late filings, which is not characteristic of this product.

Are there formulation patents for carbenicillin disodium?

No commercially important live formulation patent estate is apparent for the conventional injectable salt. The product is a mature small-molecule antibiotic with a long-established formulation profile.

Potential formulation claims could historically have addressed:

• Sterile powder for injection.
• Reconstitution solvents.
• Buffering and pH control.
• Freeze-dried or vacuum-dried presentations.
• Container-closure systems.
• Stability under storage and reconstitution conditions.

These issues may still affect product development, but they do not create the type of exclusivity associated with modern lifecycle products. A manufacturer seeking market entry would primarily face chemistry, manufacturing, and controls requirements rather than patent clearance.

Do manufacturing patents create a barrier to entry?

Manufacturing IP is not the principal barrier. The more relevant barriers are:

1. Low and uncertain demand.
2. Cost of sterile injectable manufacturing.
3. Validation and quality-control requirements.
4. Procurement concentration.
5. Competition from better-known antipseudomonal antibiotics.
6. Potential difficulty sourcing qualified active pharmaceutical ingredient.
7. Limited commercial return on regulatory maintenance.

For laboratory-grade supply, production economics are more favorable because suppliers can sell smaller quantities at higher unit prices and avoid the full economics of a high-volume hospital injectable franchise.

What is the FDA regulatory status of carbenicillin disodium?

Carbenicillin disodium has a legacy U.S. regulatory history, but its current commercial status is materially weaker than that of active hospital antibiotics such as piperacillin-tazobactam or cefepime.

FDA regulatory analysis should distinguish among:

• Historical approval.
• Current marketing.
• Availability through a specific manufacturer.
• Drug shortage or discontinuation status.
• Research-grade supply, which is not equivalent to FDA-approved human use.

FDA Drugs@FDA and the Orange Book are the controlling sources for approval and marketing information. A product may have historical approval records even when a commercially active presentation is no longer broadly distributed. The Orange Book also does not transform a research reagent into an approved prescription product. [1][2]

What is the Orange Book status of carbenicillin disodium?

The Orange Book is not a source of meaningful current exclusivity for carbenicillin disodium. Any historical application or discontinued product record would not provide active brand protection against generic entry.

The key commercial implications are:

• No current new-drug exclusivity.
• No pediatric exclusivity of practical relevance.
• No active patent term likely to delay an abbreviated new drug application.
• No modern reference-product franchise comparable to protected hospital antibiotics.
• No meaningful Orange Book-based litigation strategy for an originator.

An applicant would need to establish the applicable regulatory pathway and reference-product relationship. That issue is separate from patent exclusivity.

How strong is the patent estate for carbenicillin disodium?

The patent estate is weak from an enforcement and licensing perspective.

Patent factor	Assessment
Composition-of-matter protection	Expired
Core method-of-use protection	Expired or commercially irrelevant
Injectable formulation protection	No material live estate identified
Manufacturing-process protection	Limited practical value
Orange Book patent leverage	Minimal
Paragraph IV leverage	Low
Settlement leverage	Low
Freedom-to-operate risk	Primarily non-patent regulatory and manufacturing risk

A potential entrant would not normally expect a patent-driven launch delay. The principal question would be whether anticipated demand justifies development and sterile production costs.

Are there Paragraph IV challenges involving carbenicillin disodium?

No significant modern Paragraph IV litigation profile is associated with carbenicillin disodium.

Paragraph IV litigation is most relevant when:

• A listed patent remains active.
• The reference product has commercially meaningful sales.
• A generic applicant has an economic incentive to challenge the patent.
• The challenger can obtain a 180-day exclusivity position or other launch advantage.

Carbenicillin disodium does not present those conditions in a typical current-market analysis. Its old patent history and limited commercial value make a new Paragraph IV campaign economically unattractive.

Does carbenicillin disodium face biosimilar risk?

Carbenicillin disodium does not face biosimilar risk because it is a conventional small-molecule antibiotic, not a biologic. The relevant competitive threat is generic substitution, not biosimilar interchangeability.

The product's competitive set includes:

• Piperacillin-tazobactam.
• Ceftazidime.
• Cefepime.
• Aztreonam.
• Meropenem.
• Imipenem-cilastatin.
• Other locally preferred antipseudomonal beta-lactams.

These agents benefit from stronger guideline positioning, more familiar dosing protocols, broader institutional use, and better integration into hospital antimicrobial stewardship programs.

How does carbenicillin disodium compare with competing antibiotics?

Product	Main commercial advantage over carbenicillin disodium
Piperacillin-tazobactam	Broad hospital adoption and beta-lactamase coverage
Ceftazidime	Established antipseudomonal cephalosporin use
Cefepime	Broad gram-negative coverage and common formulary placement
Meropenem	Strong activity against resistant organisms and intensive-care use
Aztreonam	Monobactam option in selected beta-lactam allergy situations
Carbenicillin disodium	Historical antipseudomonal activity and laboratory familiarity

Carbenicillin's disadvantages include resistance concerns, older dosing conventions, sodium exposure, parenteral delivery, and limited inclusion in contemporary empiric treatment protocols. These factors reduce the probability of a material commercial rebound even where the product remains technically useful.

What is the financial trajectory for carbenicillin disodium?

There is no widely reported standalone revenue series for carbenicillin disodium from a major public pharmaceutical company. The product is not generally analyzed as a separately disclosed commercial franchise in public company filings.

Its financial trajectory can be divided into four stages:

1. Launch and clinical adoption

Carbenicillin benefited from demand for agents active against difficult gram-negative pathogens, especially before newer antipseudomonal beta-lactams became widely available.

2. Competitive displacement

Revenue declined as hospitals adopted newer antibiotics with improved dosing, broader coverage, stronger stability, and better formulary support. Generic competition further compressed pricing.

3. Market fragmentation

The product shifted from a strategic branded medicine to a low-volume, availability-sensitive product. Sales became dependent on institutional demand and supplier decisions rather than promotional investment.

4. Niche stabilization

Residual demand persists in research, reference laboratories, selected procurement programs, and markets where legacy antibiotics remain available. This residual demand does not support the economics of a large branded franchise but can support specialty catalog sales.

The commercial model therefore resembles a low-volume mature generic or research chemical. Profitability depends on manufacturing scale, batch economics, inventory turnover, and supplier pricing rather than on brand premium or patent protection.

What generic entry risks exist for carbenicillin disodium?

Generic entry risk is structurally high because the product has no meaningful patent barrier. However, the probability of multiple new entrants is constrained by weak demand.

These forces operate in opposite directions:

Factor	Effect on entry
Expired patents	Encourages entry
Low expected volume	Discourages entry
Simple, established active ingredient	Encourages entry
Sterile injectable manufacturing	Discourages entry
Research-grade demand	Supports niche supply
Hospital substitution by newer antibiotics	Discourages large-scale entry
Procurement shortages	Can create temporary opportunity

A new entrant would likely target a specific procurement gap, shortage, geographic market, or laboratory-supply channel rather than pursue broad commercial promotion.

What patent litigation affects carbenicillin disodium?

No major current patent litigation is associated with carbenicillin disodium. The absence of litigation is commercially significant because it confirms that the product's principal risks are operational and regulatory.

Relevant risk areas include:

• FDA approval and manufacturing compliance.
• Sterility assurance.
• API sourcing.
• Product discontinuation by a sole supplier.
• Hospital formulary exclusion.
• Substitution by newer antibiotics.
• International registration requirements.
• Research-grade versus human-use labeling.

There is no evident settlement-driven launch calendar comparable to products protected by active Orange Book patents.

Which companies are challenging or supplying carbenicillin disodium?

The market does not have a clear, high-profile challenger landscape. Supply is more likely to come from:

• Legacy generic injectables manufacturers.
• Contract manufacturers.
• Regional pharmaceutical companies.
• Laboratory reagent suppliers.
• Chemical and life-science catalog companies.

Research suppliers may list carbenicillin disodium under catalog names such as carbenicillin disodium salt or carbenicillin sodium, but catalog availability does not establish FDA approval for injection. Commercial diligence must separate pharmaceutical-grade, sterile injectable product from laboratory-grade material.

What geographic markets remain relevant?

The United States and Western Europe are unlikely to support large growth for carbenicillin disodium. More relevant opportunities may exist in:

• Markets with continued use of older injectable antibiotics.
• Public-sector procurement channels.
• Hospitals with constrained formularies.
• Academic research institutions.
• Laboratory supply markets.
• Regions where newer antipseudomonal agents are costly or inconsistently available.

Geographic opportunity is therefore tied to procurement access and registration status. Patent freedom is broad, but regulatory approval, local manufacturing requirements, pharmacopoeial compliance, and tender eligibility can still restrict entry.

What is the outlook for licensing and business development?

Licensing value is limited. A conventional territorial license for the original molecule would have little strategic appeal because the patent estate has expired and commercial demand is small.

Potentially actionable transactions would more likely involve:

• A supply agreement for a qualified sterile injectable.
• A contract manufacturing arrangement.
• A regional registration transfer.
• A laboratory reagent distribution agreement.
• An API sourcing partnership.
• A portfolio acquisition involving several legacy anti-infectives.

A standalone carbenicillin disodium licensing deal would require a specific supply, geographic, or institutional rationale. Patent-based royalty economics are unlikely.

Key Takeaways

• Carbenicillin disodium is a legacy antipseudomonal penicillin with limited modern pharmaceutical demand.
• Foundational patents and any meaningful exclusivity have expired.
• No material current biosimilar issue exists because the product is a small molecule.
• Paragraph IV litigation and patent settlements are not meaningful current risks.
• The Orange Book does not provide a practical exclusivity strategy for the product.
• Revenue is not separately disclosed in a reliable public series.
• The financial profile is declining-to-niche, with residual demand in research and specialty procurement.
• Generic entry is legally feasible but economically constrained by low volume and sterile manufacturing costs.
• Newer agents, including piperacillin-tazobactam, cefepime, ceftazidime, and carbapenems, are the main commercial substitutes.
• The strongest business opportunity is in supply continuity, regional access, or research-grade distribution rather than branded pharmaceutical development.

FAQs About Carbenicillin Disodium Market and Patent Position

Is carbenicillin disodium still commercially available?

Availability is fragmented. Research-grade material is more consistently encountered than broadly distributed FDA-approved human injectable product. Catalog listing and clinical availability are separate issues.

Is carbenicillin disodium a generic antibiotic?

It is an old small-molecule antibiotic for which patent protection has expired. Any current pharmaceutical product would compete in a generic or legacy-product market rather than under active brand exclusivity.

Can a company launch carbenicillin disodium without a patent license?

Patent licensing is generally not the central issue because the original patent estate has expired. The company would still need to satisfy applicable regulatory, manufacturing, quality, labeling, and registration requirements.

Why did carbenicillin disodium lose hospital market share?

Hospitals shifted toward newer antipseudomonal agents with more favorable dosing, broader clinical utility, improved formulary support, and better resistance-management profiles.

Is carbenicillin disodium useful for pharmaceutical investment?

As a standalone branded investment, it has limited appeal. Its more plausible value lies in niche supply, specialty distribution, contract manufacturing, or inclusion in a broader portfolio of mature anti-infective products.

References

1. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: 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. (2024). Drugs@FDA. https://www.accessdata.fda.gov/scripts/cder/daf/

3. National Center for Biotechnology Information. (2024). PubChem compound summary for carbenicillin. PubChem. https://pubchem.ncbi.nlm.nih.gov/

4. U.S. Food and Drug Administration. (2024). DailyMed and labeling information for human prescription drugs. https://dailymed.nlm.nih.gov/dailymed/

5. World Health Organization. (2023). WHO model list of essential medicines. https://www.who.int/teams/health-product-and-policy-standards/standards-and-specifications/essential-medicines-selector-tool