PENBRITIN Drug Patent Profile

Which patents cover Penbritin, and when can generic versions of Penbritin launch?

Penbritin is a drug marketed by Wyeth Ayerst and is included in three NDAs.

The generic ingredient in PENBRITIN is ampicillin sodium. There are two drug master file entries for this compound. Sixteen suppliers are listed for this compound. Additional details are available on the ampicillin sodium profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Penbritin

A generic version of PENBRITIN was approved as ampicillin sodium by SANDOZ on December 31^st, 1969.

Summary for PENBRITIN

US Patents:	0
Applicants:	1
NDAs:	3
Raw Ingredient (Bulk) Api Vendors:	78
Patent Applications:	3,976
DailyMed Link:	PENBRITIN at DailyMed

US Patents and Regulatory Information for PENBRITIN

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Wyeth Ayerst	PENBRITIN	ampicillin/ampicillin trihydrate	CAPSULE;ORAL	060908-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Wyeth Ayerst	PENBRITIN-S	ampicillin sodium	INJECTABLE;INJECTION	050072-005	Approved Prior to Jan 1, 1982		DISCN	Yes	No
Wyeth Ayerst	PENBRITIN	ampicillin/ampicillin trihydrate	FOR SUSPENSION;ORAL	050019-002	Approved Prior to Jan 1, 1982		DISCN	No	No
Wyeth Ayerst	PENBRITIN-S	ampicillin sodium	INJECTABLE;INJECTION	050072-006	Approved Prior to Jan 1, 1982		DISCN	Yes	No
Wyeth Ayerst	PENBRITIN	ampicillin/ampicillin trihydrate	CAPSULE;ORAL	060908-002	Approved Prior to Jan 1, 1982		DISCN	No	No
Wyeth Ayerst	PENBRITIN	ampicillin/ampicillin trihydrate	FOR SUSPENSION;ORAL	050019-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Wyeth Ayerst	PENBRITIN-S	ampicillin sodium	INJECTABLE;INJECTION	050072-004	Approved Prior to Jan 1, 1982		DISCN	Yes	No

Penbritin Market Dynamics and Financial Trajectory: Ampicillin Brand Analysis

Last updated: July 31, 2026

Penbritin is a legacy brand of ampicillin, a broad-spectrum beta-lactam antibiotic historically associated with Beecham, now part of GlaxoSmithKline’s predecessor corporate lineage. Its commercial value is no longer driven by brand pricing or patent protection. Ampicillin is a mature, off-patent small-molecule antibiotic supplied mainly through generic manufacturers and hospital procurement channels.

No standalone public revenue series for Penbritin is reported by current pharmaceutical companies. Its financial trajectory is therefore best assessed through the commercial position of ampicillin, the status of competing beta-lactams, procurement economics, regulatory supply requirements and the absence of meaningful exclusivity.

What is Penbritin and which drug does it contain?

Penbritin contains ampicillin, a penicillin-class antibiotic that inhibits bacterial cell-wall synthesis. Ampicillin has activity against selected Gram-positive and Gram-negative organisms and has been used in respiratory, urinary, gastrointestinal, bloodstream and neonatal infections.

Penbritin dosage forms and formulations

Historical Penbritin products included oral and injectable presentations. Current ampicillin products are generally supplied as:

Dosage form	Active ingredient	Typical market channel
Capsules or oral suspension	Ampicillin	Retail, institutional and international markets
Injection	Ampicillin sodium	Hospitals and public procurement
Combination or fixed-dose products	Ampicillin with other agents in selected markets	Country-specific markets

The commercial relevance of each formulation differs. Injectable ampicillin is more exposed to hospital formularies, tenders and supply continuity. Oral ampicillin competes with other penicillins and newer oral antibiotics that are often preferred because of dosing convenience, resistance considerations or local treatment guidelines.

FDA-approved ampicillin labeling identifies the drug as a penicillin antibacterial and includes oral and parenteral use depending on the product. Ampicillin sodium injection is supplied for intravenous or intramuscular administration in approved presentations (U.S. Food and Drug Administration [FDA], n.d.-a).

When did Penbritin lose exclusivity?

Penbritin no longer has commercially meaningful exclusivity. Ampicillin was introduced more than half a century ago, and the relevant composition and product patents expired long ago.

Ampicillin patent status

The current commercial position has four characteristics:

1. The core ampicillin molecule is off patent.
2. Generic manufacturers can supply the active ingredient and finished dosage forms subject to local regulatory approval.
3. Historical brand rights do not create present-day market exclusivity.
4. Any remaining patents would relate to a specific formulation, manufacturing process or jurisdiction rather than the basic ampicillin molecule.

The U.S. Food and Drug Administration’s Orange Book lists approved drug products and related patent and exclusivity information. Ampicillin products are listed through generic product entries rather than as an active branded franchise with current market protection (FDA, n.d.-b).

How many patents cover Penbritin and ampicillin?

No commercially material active patent estate is associated with the original Penbritin brand or the core ampicillin molecule.

Core compound versus formulation patents

The original compound protection for ampicillin is expired. Potentially relevant intellectual-property categories are limited to:

IP category	Current commercial significance
Core compound patent	Expired
Historical process patents	Generally expired or commercially bypassed
Oral formulation patents	Limited, product-specific and jurisdiction-dependent
Injectable formulation patents	Limited; competition focuses on quality and supply
Method-of-use patents	Generally weak for a mature antibiotic
Manufacturing know-how	Potentially relevant to cost, impurity control and yield
Trademark rights	May restrict use of the Penbritin name but do not block generic ampicillin

For a mature antibiotic, manufacturing know-how can matter more than formal patent rights. Control of impurities, sterility assurance, stability, crystallization and active pharmaceutical ingredient supply can affect market participation even when no blocking patent exists.

What is the FDA regulatory status of Penbritin?

Penbritin is not the principal current FDA regulatory reference for ampicillin. U.S. regulatory activity is conducted through approved ampicillin products identified by generic name and by individual manufacturer or applicant.

FDA status of ampicillin products

Ampicillin products remain regulated prescription antibacterial drugs. Product-specific FDA status depends on the dosage form, strength, route of administration, applicant and approval history.

The FDA-approved labeling for ampicillin sodium injection includes indications, contraindications, dosing information, warnings regarding allergic reactions and instructions for reconstitution and administration (FDA, n.d.-a). The FDA’s Approved Drug Products with Therapeutic Equivalence Evaluations, commonly called the Orange Book, is the principal source for identifying approved reference and generic products (FDA, n.d.-b).

Penbritin should therefore be treated as a historical or country-specific brand name, not as a current U.S. exclusivity platform.

What is the Orange Book status of Penbritin?

The Orange Book does not create a separate commercial moat for Penbritin. Any relevant U.S. products are evaluated under ampicillin product listings and applicant-specific approvals.

Paragraph IV challenges and generic entry

A modern Paragraph IV challenge to Penbritin would have limited commercial logic because:

• The original ampicillin molecule is long off patent.
• Generic ampicillin products are already established.
• There is no evident current brand premium comparable with a protected specialty drug.
• A challenge to a narrow formulation patent would address only that formulation and not the broader ampicillin market.
• Market entry economics are constrained by low prices and procurement competition.

Paragraph IV litigation is therefore more relevant to later ampicillin formulations than to the historical Penbritin brand itself. The relevant competitive event is usually abbreviated new drug application approval, tender qualification or re-entry after a supply interruption rather than a high-value patent challenge.

What is the current market dynamic for ampicillin?

Ampicillin competes in a low-growth, price-sensitive antibiotic market. Demand is shaped by clinical guidelines, antimicrobial resistance, hospital protocols, national essential-medicines lists and supply reliability.

Main demand drivers

Hospital demand remains important for injectable ampicillin, particularly in settings where ampicillin is used for susceptible infections, neonatal care and selected enterococcal infections. Demand can rise temporarily during shortages of substitute beta-lactams or when procurement systems prioritize essential medicines.

Oral demand is more fragmented. Physicians may select ampicillin where local susceptibility patterns support its use, but the product competes with amoxicillin and other oral antibiotics. Ampicillin’s dosing frequency and gastrointestinal tolerability can limit its use relative to alternatives.

Competitive set

Competitor group	Examples	Competitive effect
Penicillin alternatives	Amoxicillin, penicillin G, penicillin V	Substitute therapy in susceptible infections
Aminopenicillin combinations	Amoxicillin-clavulanate	Broader coverage and strong retail presence
Cephalosporins	Cefazolin, ceftriaxone and others	Hospital substitution and broader empiric use
Anti-staphylococcal penicillins	Oxacillin, nafcillin, cloxacillin	Alternative treatment for susceptible staphylococcal infections
Other hospital antibiotics	Piperacillin-tazobactam and carbapenems	Substitution in severe or resistant infections

Ampicillin’s principal commercial constraint is not patent competition. It is therapeutic substitution combined with low generic pricing.

How strong is the Penbritin patent estate?

The Penbritin patent estate is commercially weak because the core product is mature, genericized and not supported by current exclusivity.

Patent-strength assessment

Factor	Assessment
Core molecule protection	None of current commercial significance
Remaining exclusivity	None identified for the historical brand
Formulation protection	Potentially narrow and product-specific
Method-of-use protection	Limited practical value
Manufacturing barriers	Moderate for sterile injectable supply
Generic substitution risk	High
Pricing power	Low
Litigation leverage	Low
Regulatory complexity	Higher for injectable products than oral products

The strongest defensible position in ampicillin is operational rather than patent-based. A manufacturer with validated sterile facilities, reliable API sourcing, strong quality records and established government-tender access can retain share without owning meaningful patent rights.

What financial trajectory can be expected for Penbritin?

Penbritin’s financial trajectory is consistent with the lifecycle of a legacy antibiotic brand:

1. Initial growth followed by broad clinical adoption.
2. Loss of exclusivity and entry by generic suppliers.
3. Declining brand contribution as prescriptions shift to generic names.
4. Continued residual demand in institutional and international markets.
5. Revenue dependence on supply contracts, geographic availability and manufacturing economics rather than brand differentiation.

Revenue exposure

Current standalone Penbritin revenue is not disclosed in the public financial reporting of major multinational pharmaceutical companies. GSK reports business performance at portfolio and segment levels rather than providing a separate Penbritin revenue line. The historical brand is therefore unlikely to be a material contributor to current consolidated pharmaceutical revenue.

The economic value of ampicillin is distributed across:

• Generic finished-dose manufacturers
• Active pharmaceutical ingredient suppliers
• Hospital distributors
• Government procurement agencies
• Contract manufacturers
• Regional pharmaceutical companies

The market has low unit prices but can generate recurring volume where ampicillin is included in essential-medicines procurement. Profitability depends on production scale, tender discipline, capacity utilization, sterility compliance and avoidance of manufacturing disruptions.

What manufacturing and supply barriers affect ampicillin?

Ampicillin has low patent barriers but meaningful technical and regulatory requirements.

Oral manufacturing

Oral capsules and suspensions are comparatively accessible to established generic manufacturers. Competitive requirements include:

• API quality and consistency
• Finished-product stability
• Dissolution and content uniformity
• Packaging suitable for humidity and temperature exposure
• Bioequivalence or applicable national requirements
• Reliable distribution through public and private channels

Injectable manufacturing

Ampicillin sodium injection has higher operational barriers because manufacturers must demonstrate:

• Sterile manufacturing controls
• Validated aseptic processing
• Endotoxin control
• Sterility testing
• Container-closure integrity
• Reconstitution stability
• Consistent supply of sterile vials and packaging components

These requirements can reduce the number of reliable suppliers even when several companies hold marketing authorizations. Hospital buyers may pay a modest premium for supply reliability, but procurement remains highly price-sensitive.

Which companies are challenging Penbritin commercially?

There is no current high-value company-versus-company challenge centered on the Penbritin brand. Competition comes from generic ampicillin suppliers and substitute antibiotics.

Competitive landscape

The relevant competitors are manufacturers with approved or locally registered ampicillin products, not companies seeking to invalidate a current Penbritin patent. In many markets, competition is determined by:

• National registration status
• Hospital tender awards
• GMP inspection history
• Product availability
• API sourcing
• Distributor relationships
• Price and payment terms

The most significant commercial substitution comes from amoxicillin, amoxicillin-clavulanate, ceftriaxone and other hospital beta-lactams. These products can reduce ampicillin volume even where ampicillin remains clinically appropriate.

Is biosimilar risk relevant to Penbritin?

No. Biosimilar competition does not apply to Penbritin because ampicillin is a chemically synthesized small-molecule drug, not a biologic.

The relevant risks are generic substitution, therapeutic substitution and supply-driven switching. FDA approval pathways for ampicillin generic products generally rely on abbreviated applications and therapeutic-equivalence standards appropriate to small molecules, rather than the biosimilar pathway under the Public Health Service Act (FDA, n.d.-c).

What patent litigation and settlements affect Penbritin?

No current major U.S. patent litigation or settlement involving the historical Penbritin brand defines its market position. Any dispute involving ampicillin would more likely concern:

• A specific formulation
• A manufacturing process
• Product quality or regulatory compliance
• Trademark use
• Distribution or supply agreements
• Country-specific registration rights

A branded-generic settlement would have limited value unless a defendant were attempting to enter a protected reformulation. The original Penbritin product does not present the litigation profile of a newly approved branded medicine.

How does Penbritin compare with amoxicillin?

Amoxicillin generally has the stronger commercial position in outpatient markets because of broader physician familiarity, convenient dosing and extensive generic availability. Ampicillin retains relevance in selected clinical and hospital settings but has less brand-driven pricing power.

Measure	Penbritin / ampicillin	Amoxicillin
Patent position	Long expired	Long expired
Brand value	Historical or market-specific	Larger surviving generic and branded-generic presence
Oral outpatient use	Mature and selective	Broad
Injectable hospital use	Relevant	Less directly comparable by formulation
Price power	Low	Low to moderate by market and combination
Main risk	Therapeutic substitution and supply volatility	Combination-product competition and resistance management
Biosimilar exposure	None	None

What generic launch scenarios exist for Penbritin?

Because the core product is genericized, the principal launch scenarios are operational:

Standard generic entry

A manufacturer launches an approved oral or injectable ampicillin product after completing applicable regulatory requirements. Price competition is immediate, particularly in public tenders.

Shortage-driven entry

A supplier enters or expands during a shortage affecting existing manufacturers. Commercial success depends on rapid regulatory activation, inventory and hospital contracting.

Geographic expansion

A regional manufacturer registers ampicillin in additional countries, often targeting essential-medicine tenders. Local registration and pharmacopoeial requirements become the main barriers.

Reformulation entry

A manufacturer develops a differentiated suspension, packaging system or administration presentation. Any protection is likely to be narrow, and commercial value depends on demonstrable convenience or supply advantages.

What geographic markets remain relevant?

Ampicillin’s commercial relevance is highest where it remains included in national treatment protocols and essential-medicines lists. Market performance can vary sharply by country because of:

• Local antimicrobial resistance
• Public-sector procurement
• Hospital formulary policy
• Availability of alternative beta-lactams
• Registration status
• Imported API dependence
• Currency and tender pricing
• Manufacturing disruptions

The brand name Penbritin may retain recognition in selected non-U.S. markets, but generic ampicillin is the more relevant economic unit for current market analysis.

Key Takeaways

• Penbritin is a legacy brand of ampicillin.
• Ampicillin’s core patent protection expired long ago.
• No current Penbritin brand franchise with meaningful exclusivity is evident.
• The FDA regulates current products under ampicillin-specific approvals, not through a protected Penbritin platform.
• Paragraph IV litigation and biosimilar competition are not major current risks.
• Injectable ampicillin has higher manufacturing and quality barriers than oral products.
• Revenue is driven by generic volume, hospital tenders and supply reliability.
• The principal competitors are generic ampicillin suppliers and substitute antibiotics, especially amoxicillin, amoxicillin-clavulanate and cephalosporins.
• Standalone Penbritin revenue is not reported in current public pharmaceutical-company financial disclosures.
• The brand’s current financial value is likely residual and geography-specific, while ampicillin remains commercially relevant as a mature essential antibiotic.

FAQs

Is Penbritin still available?

Penbritin availability depends on the country and local marketing authorization. Ampicillin remains available in multiple markets through generic oral and injectable products.

Is Penbritin the same as amoxicillin?

No. Both are aminopenicillin antibiotics, but Penbritin contains ampicillin and amoxicillin is a separate active ingredient with different formulations and dosing characteristics.

Can a generic company launch ampicillin without a Penbritin license?

Generally, a company can seek approval for an ampicillin product without licensing the historical Penbritin brand, subject to applicable regulatory, trademark, quality and market-entry requirements.

Does Penbritin have exclusivity in the United States?

No current commercially meaningful exclusivity is associated with the historical Penbritin brand in the United States. Relevant products are evaluated under generic ampicillin approvals.

What is the main investment risk in the ampicillin market?

The main risks are low pricing, therapeutic substitution, procurement concentration, API dependence, sterile-manufacturing interruptions and regulatory supply constraints.

References

1. U.S. Food and Drug Administration. (n.d.-a). Ampicillin sodium injection prescribing information. https://www.accessdata.fda.gov/

2. U.S. Food and Drug Administration. (n.d.-b). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

3. U.S. Food and Drug Administration. (n.d.-c). Generic drugs. https://www.fda.gov/drugs/generic-drugs

4. World Health Organization. (2023). WHO model list of essential medicines: 23rd list. https://www.who.int/publications/i/item/WHO-MHP-HPS-EML-2023.02

5. GlaxoSmithKline plc. (2024). Annual report 2023. https://www.gsk.com/en-gb/investors/annual-report/