IMIPENEM AND CILASTATIN Drug Patent Profile
Which patents cover Imipenem And Cilastatin, and when can generic versions of Imipenem And Cilastatin launch?
Imipenem And Cilastatin is a drug marketed by Acs Dobfar, Hospira Inc, and Hq Spclt Pharma. and is included in four NDAs.
The generic ingredient in IMIPENEM AND CILASTATIN is cilastatin sodium; imipenem. There is one drug master file entry for this compound. Three suppliers are listed for this compound. Additional details are available on the cilastatin sodium; imipenem profile page.
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Questions you can ask:
- What is the 5 year forecast for IMIPENEM AND CILASTATIN?
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- What is Average Wholesale Price for IMIPENEM AND CILASTATIN?
Summary for IMIPENEM AND CILASTATIN
| US Patents: | 0 |
| Applicants: | 3 |
| NDAs: | 4 |
| Finished Product Suppliers / Packagers: | 2 |
| Raw Ingredient (Bulk) Api Vendors: | 20 |
| Clinical Trials: | 46 |
| Patent Applications: | 1,172 |
| DailyMed Link: | IMIPENEM AND CILASTATIN at DailyMed |
Recent Clinical Trials for IMIPENEM AND CILASTATIN
Identify potential brand extensions & 505(b)(2) entrants
| Sponsor | Phase |
|---|---|
| Matthew James | PHASE2 |
| University of Alberta | PHASE2 |
| Alberta Health services | PHASE2 |
Pharmacology for IMIPENEM AND CILASTATIN
| Drug Class | Penem Antibacterial Renal Dehydropeptidase Inhibitor |
| Mechanism of Action | Dipeptidase Inhibitors |
US Patents and Regulatory Information for IMIPENEM AND CILASTATIN
Imipenem and Cilastatin Market Dynamics, Patent Status, Competition, and Financial Trajectory
Imipenem/cilastatin is a mature carbapenem antibiotic with limited branded revenue, broad generic availability, and declining standalone pricing. The original Primaxin franchise has lost meaningful exclusivity in the United States. Commercial value now comes from hospital contracts, injectable supply reliability, combination products such as Recarbrio, and use against multidrug-resistant infections. Biosimilar risk is irrelevant because imipenem and cilastatin are small-molecule drugs.
What is the current market position of imipenem and cilastatin?
Imipenem/cilastatin is an intravenous antibacterial combination used for serious infections caused by susceptible organisms. Imipenem is the antibacterial agent. Cilastatin inhibits renal metabolism of imipenem and increases systemic exposure.
The product was originally marketed by Merck under the Primaxin brand. The FDA approved Primaxin in 1985, making imipenem/cilastatin one of the oldest widely used carbapenem combinations in hospital medicine.[1]
The current market has four defining characteristics:
- Generic competition in multiple injectable presentations.
- Hospital and government procurement rather than consumer prescribing.
- Price pressure from tenders, group purchasing organizations, and local manufacturers.
- Continued clinical demand driven by resistant Gram-negative infections.
Imipenem/cilastatin is usually administered in hospitals, intensive-care units, emergency departments, and transplant or oncology settings. The drug is not a retail pharmacy product and has limited direct-to-consumer commercial visibility.
When did imipenem/cilastatin lose exclusivity?
The original United States composition and formulation patent protection for Primaxin expired many years ago. FDA-approved generic versions are available, and the product does not retain meaningful originator exclusivity for the imipenem/cilastatin combination.
The key commercial milestones are:
| Milestone | Approximate timing | Commercial effect |
|---|---|---|
| FDA approval of Primaxin | 1985 | Established the original branded franchise |
| Original small-molecule patent protection | Expired before the modern generic era | Removed composition-of-matter protection |
| Generic injectable approvals | Began after loss of core exclusivity | Created price competition |
| Primaxin commercial maturity | 2000s onward | Shifted sales toward hospital contracts |
| Recarbrio approval | 2019 | Created a newer, differentiated combination containing imipenem/cilastatin |
| Current market | 2020s | Generic base product with premium value concentrated in new combinations |
Exact patent expiration dates are difficult to equate with current commercial protection because the original product involved multiple patents covering the active ingredients, compositions, manufacturing processes, and formulations. Those rights do not provide a current barrier to ordinary generic imipenem/cilastatin products.
What is the FDA regulatory status of imipenem and cilastatin?
FDA-approved imipenem/cilastatin products are prescription intravenous formulations. Generic versions are approved through abbreviated new drug applications, generally demonstrating pharmaceutical equivalence and bioequivalence or meeting applicable injectable-product requirements.[2]
The original product is associated with several approved indications, including:
- Lower respiratory tract infections.
- Intra-abdominal infections.
- Complicated urinary tract infections.
- Gynecologic infections.
- Bacterial septicemia.
- Bone and joint infections.
- Skin and skin-structure infections.
The FDA labeling also includes limitations relating to organisms, resistance, renal dosing, central nervous system adverse effects, and seizure risk. Dose adjustment is required in patients with impaired renal function.[3]
What is the Orange Book status of imipenem/cilastatin?
The Orange Book contains approved imipenem/cilastatin products and related reference-product information. The original Primaxin franchise does not have a commercially meaningful active patent barrier comparable to newer branded antibiotics.
Orange Book analysis must distinguish between:
- The original imipenem/cilastatin product.
- Generic imipenem/cilastatin products.
- Recarbrio, which contains imipenem, cilastatin, and relebactam.
- Separate products with different active ingredients, such as meropenem or doripenem.
A patent or exclusivity position applicable to Recarbrio does not automatically protect standalone imipenem/cilastatin.
What patents protect imipenem/cilastatin products?
The mature imipenem/cilastatin product is no longer protected by commercially significant composition-of-matter exclusivity in the United States. Patent risk is concentrated in narrower areas:
| Patent area | Relevance to standalone imipenem/cilastatin |
|---|---|
| Imipenem compound patents | Expired |
| Cilastatin compound patents | Expired |
| Original combination patents | Expired or commercially ineffective |
| Injectable formulation patents | Generally expired or avoidable through generic formulation design |
| Manufacturing-process patents | May exist in limited jurisdictions but usually do not block ordinary U.S. sales |
| Stability and container patents | Potentially relevant to specific presentations, not the underlying drug |
| Relebactam combination patents | Relevant to Recarbrio, not ordinary imipenem/cilastatin |
| Method-of-use patents | Limited value for an old broad-spectrum hospital antibiotic |
Generic manufacturers may still face regulatory, manufacturing, or supply requirements. Those requirements are operational barriers rather than durable exclusivity rights.
Are there Paragraph IV challenges to imipenem/cilastatin?
Paragraph IV litigation risk for the original imipenem/cilastatin product is low because the principal patents expired long ago and multiple generic products are already marketed.
Paragraph IV certifications are more relevant to newer combination products. For Recarbrio, a generic applicant would need to evaluate patents covering the relebactam combination, formulation, crystalline or solid-state properties, manufacturing, and approved uses. Those issues are separate from generic entry into the base imipenem/cilastatin market.
For standalone imipenem/cilastatin:
- Generic entry has already occurred.
- The market is not dependent on a future Paragraph IV launch.
- Litigation is more likely to involve supply, substitution, quality, or procurement issues than core patent invalidity.
Which companies compete in the imipenem/cilastatin market?
Competition varies by country and tender system. The relevant supplier groups include the original innovator, large generic injectable manufacturers, regional pharmaceutical companies, and contract manufacturers.
Representative competitors and substitute suppliers include:
- Merck, through the historical Primaxin franchise and Recarbrio.
- Sandoz and other multinational generic companies.
- Viatris and legacy injectable-product businesses.
- Fresenius Kabi.
- Hikma Pharmaceuticals.
- Aurobindo Pharma.
- Cipla.
- Sun Pharma and other regional suppliers.
- Hospital-focused manufacturers in China, India, Europe, Latin America, and the Middle East.
Availability differs materially by market. A company with regulatory approval may not be a consistent commercial supplier if it lacks manufacturing capacity, active pharmaceutical ingredient access, or hospital-tender participation.
How does imipenem/cilastatin compare with meropenem?
| Factor | Imipenem/cilastatin | Meropenem |
|---|---|---|
| Drug class | Carbapenem | Carbapenem |
| Cilastatin required | Yes | No |
| Administration | Intravenous | Intravenous |
| Generic maturity | High | High |
| Hospital demand | Significant | Significant |
| CNS seizure concern | More prominent in labeling | Generally viewed as lower, though risk remains |
| Market competition | Broad generic base | Broad generic base |
| Differentiation | Recarbrio combination | Vaborbactam and other combinations in separate products |
Meropenem is often favored in clinical settings where its dosing, tolerability, or institutional protocols provide an advantage. Imipenem/cilastatin retains demand because of established clinical experience, formulary position, and broad antibacterial coverage.
What formulations are protected by imipenem/cilastatin patents?
Commercially relevant formulations include:
- Powder for intravenous solution.
- Single-dose vials.
- Multiple vial strengths, commonly 250 mg and 500 mg of imipenem with an equal amount of cilastatin.
- Hospital reconstitution systems.
- Combination products containing relebactam.
The original powder-for-injection technology is mature. Generic manufacturers can compete through standard injectable presentations without reproducing every aspect of the originator’s manufacturing process.
The principal technical barriers are:
- Maintaining chemical stability during storage.
- Controlling degradation products.
- Ensuring sterility and endotoxin compliance.
- Managing reconstitution and infusion compatibility.
- Securing reliable sterile manufacturing capacity.
- Meeting regulatory requirements for container closure and labeling.
These barriers can reduce the number of dependable suppliers, but they do not create durable patent exclusivity comparable to a protected new chemical entity.
What is the financial trajectory for imipenem/cilastatin?
The financial trajectory is mature-to-declining for standalone imipenem/cilastatin and more resilient for differentiated combinations.
Standalone product economics
Public company filings generally do not report standalone global revenue for generic imipenem/cilastatin. Revenue is often included in broad hospital-product, anti-infective, or generic-injectable categories. That limits the reliability of molecule-specific market-size estimates.
The economic pattern is clear:
- Original branded sales were strongest before generic substitution.
- Generic entry reduced average selling prices.
- Volume remained supported by hospital demand and resistance-driven use.
- Revenue shifted from product differentiation to supply execution.
- Gross margins became dependent on manufacturing scale, tender awards, and shortages.
Standalone imipenem/cilastatin is therefore a low-growth or declining-value product in mature markets. It can remain profitable when a supplier has low production costs, a dependable sterile facility, or limited local competition.
Recarbrio economics
Merck’s Recarbrio combines imipenem, cilastatin, and relebactam. The FDA approved it in 2019 for specified serious infections, including hospital-acquired and ventilator-associated bacterial pneumonia and certain infections caused by resistant Gram-negative organisms.[4]
Recarbrio has a different commercial profile:
- It contains a novel beta-lactamase inhibitor.
- It targets resistant infections where older carbapenems may be inadequate.
- It is sold as a branded product.
- Its value proposition depends on stewardship, susceptibility testing, hospital protocols, and infectious-disease specialist use.
- Its patent estate is more relevant than the estate for standalone imipenem/cilastatin.
Recarbrio can preserve commercial value around the imipenem/cilastatin platform, but it does not restore exclusivity to the original two-component product.
How strong is the imipenem/cilastatin patent estate?
The patent estate is weak for the standalone product and materially stronger for newer combinations.
| Category | Strength | Reason |
|---|---|---|
| Original active ingredients | Very weak | Long-expired small-molecule protection |
| Original combination | Very weak | Generic substitution is established |
| Injectable formulation | Weak to moderate | Technical variation is generally available |
| Manufacturing process | Moderate in narrow cases | May create process complexity without blocking all competitors |
| Recarbrio combination | Stronger | New relebactam-related rights and regulatory exclusivity |
| Method of use | Limited | Broad hospital indications are difficult to protect today |
| Geographic protection | Variable | Some countries may have fewer approved suppliers, but patent barriers remain limited |
The commercial moat is operational rather than legal. Sterile manufacturing, regulatory approvals, procurement relationships, and product availability matter more than basic patent ownership.
What generic entry risks exist for imipenem/cilastatin?
Generic launch risk is no longer a future event in the United States. It is an established market condition. The main risks to branded or premium-priced suppliers are:
- Additional generic approvals.
- Hospital substitution.
- Tender price reductions.
- New low-cost entrants from India or China.
- Supply normalization after shortages.
- Institutional preference for meropenem.
- Antibiotic stewardship programs that restrict carbapenem use.
- Procurement consolidation through group purchasing organizations.
The countervailing risk is supply disruption. Sterile injectable products can experience shortages because of manufacturing failures, quality investigations, raw-material constraints, or plant shutdowns. A shortage can temporarily increase prices and supplier revenue, but it rarely creates durable franchise value.
What patent litigation and settlement agreements affect the market?
There is no central, commercially significant patent litigation campaign surrounding ordinary generic imipenem/cilastatin in the United States. The product has passed the principal patent-litigation stage.
Litigation and settlements are more relevant to newer beta-lactam/beta-lactamase inhibitor products, including combination therapies that use imipenem/cilastatin as the antibacterial backbone. A settlement involving a newer combination should not be interpreted as protection for generic Primaxin-equivalent products.
Potential disputes in the broader market may concern:
- Recarbrio patents.
- ANDA certifications for combination products.
- Manufacturing and quality obligations.
- Hospital contract awards.
- Trademark use involving Primaxin or related names.
- Product liability and adverse-event claims.
What are the geographic market dynamics?
The United States, Europe, Japan, China, India, and Latin America have different market structures.
United States
The market is genericized, hospital-centered, and influenced by FDA supply requirements and group purchasing contracts. FDA approval does not guarantee national availability because suppliers must maintain viable sterile production and commercial distribution.
Europe
National procurement systems and hospital tenders exert strong price pressure. Competition is shaped by country-specific marketing authorizations, centralized purchasing, and local supplier participation.
China and India
Domestic manufacturers can compete aggressively on price, but regulatory status, quality standards, export approvals, and procurement policies determine access. Local volume may be significant even where international branded revenues are limited.
Emerging markets
Imipenem/cilastatin can command higher prices where fewer suppliers are registered. However, revenue potential is constrained by public-health budgets, procurement controls, and inconsistent distribution.
What is the outlook for imipenem/cilastatin through 2030?
The base-case outlook is stable clinical demand with declining or flat value for the standalone product.
| Driver | Expected effect |
|---|---|
| Antimicrobial resistance | Supports volume and clinical relevance |
| Generic competition | Reduces price and margin |
| Hospital stewardship | Limits unnecessary use |
| Injectable manufacturing constraints | Creates episodic price and supply volatility |
| Recarbrio adoption | Supports premium value for the newer combination |
| Meropenem competition | Limits standalone growth |
| Public procurement | Compresses prices |
| New beta-lactamase inhibitors | Moves value toward differentiated combinations |
The highest-value segment is likely to remain branded or protected combinations designed for resistant infections. The lowest-value segment is undifferentiated generic imipenem/cilastatin sold through competitive hospital tenders.
Key Takeaways
- Imipenem/cilastatin is a mature carbapenem antibiotic approved by the FDA in 1985.
- Standalone patent protection has expired, and generic competition is established.
- The original Primaxin franchise has limited current exclusivity value.
- The market is driven by hospital procurement, sterile manufacturing, supply reliability, and antimicrobial resistance.
- Standalone financial growth is limited because price competition is intense and company filings rarely disclose molecule-specific revenue.
- Recarbrio provides a newer, more defensible commercial platform through the addition of relebactam.
- Biosimilars are irrelevant because imipenem and cilastatin are small molecules.
- The main commercial risk is margin erosion; the main operational opportunity is supply reliability during injectable-product shortages.
- Patent strength is weak for generic imipenem/cilastatin and stronger for newer beta-lactam/beta-lactamase inhibitor combinations.
FAQs
Is imipenem/cilastatin still a branded drug?
Primaxin is the historical branded product. The active combination is widely available from generic manufacturers. Recarbrio is a newer branded combination containing imipenem, cilastatin, and relebactam.
Does imipenem/cilastatin have biosimilar competition?
No. Biosimilar regulation applies to biologic products. Imipenem and cilastatin are small-molecule drugs and compete through generic drug approvals.
Can a generic company launch imipenem/cilastatin without a Paragraph IV challenge?
Yes. Because the core product patents expired long ago, a generic applicant does not need to rely on a future challenge to establish ordinary market entry.
Why can imipenem/cilastatin remain profitable after patent expiry?
Profit can come from manufacturing scale, hospital contracts, supply shortages, geographic markets with limited competition, and low-cost sterile production.
Is Recarbrio protected by the same patents as imipenem/cilastatin?
No. Recarbrio has a separate legal and regulatory profile because it includes relebactam. Patents and exclusivity for Recarbrio do not generally block generic standalone imipenem/cilastatin.
References
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U.S. Food and Drug Administration. (1985). Primaxin approval history and prescribing information. FDA Drugs@FDA.
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U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
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U.S. Food and Drug Administration. (2023). Imipenem and cilastatin for injection prescribing information. FDA.
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U.S. Food and Drug Administration. (2019). FDA approves new treatment for hospital-acquired and ventilator-associated bacterial pneumonia. FDA.
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Merck & Co., Inc. (2024). Annual report 2023. Merck & Co., Inc.
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World Health Organization. (2023). WHO bacterial priority pathogens list, 2024. World Health Organization.
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