US Patent 5,196,205: Claim Scope, Expiration, and H. pylori Eradication Patent Landscape

US Patent 5,196,205 covers combination treatment of duodenal ulcer disease associated with Campylobacter pylori, now known as Helicobacter pylori or H. pylori. The core regimen requires three antimicrobial components: a pharmaceutically acceptable bismuth compound, tetracycline or a penicillin, and metronidazole. Claim 3 adds an acid suppressant.

The patent is expired. Its commercial importance is historical rather than exclusionary. The claims were directed to a therapeutic combination that became the foundation for bismuth-based eradication therapy, but the patent does not create a current barrier to generic bismuth, tetracycline, metronidazole, proton-pump inhibitor, or related H. pylori treatment products.

What does US Patent 5,196,205 cover?

US Patent 5,196,205 covers methods for treating or preventing recurrence of duodenal ulcers in patients with Campylobacter pylori infection. The patent uses the organism’s former name. Campylobacter pylori was subsequently renamed Helicobacter pylori.

The central therapeutic concept is a combination of:

A pharmaceutically acceptable bismuth compound;
A first antibiotic selected from tetracycline or penicillins; and
Metronidazole as the second antibiotic.

The claims are method-of-treatment claims, not composition-of-matter claims. They do not claim a new chemical entity, a defined tablet, a fixed-dose formulation, a specific dosing schedule, or a particular bismuth salt.

Claim	Principal subject matter	Additional limitation
1	Prevention of recurrent duodenal ulcer in an infected patient	Bismuth compound, tetracycline or penicillin, and metronidazole
2	Treatment and prevention of recurrence	Incorporates claim 1 and requires healing of the ulcer
3	Treatment of infected duodenal-ulcer patients	Adds an acid suppressant administered before or during eradication therapy

The patent’s practical contribution was linking eradication of the infection to prevention of ulcer recurrence. Earlier ulcer therapies primarily suppressed acid and promoted symptom relief or epithelial healing. These claims require an antimicrobial eradication strategy.

How should claim 1 be construed?

Claim 1 requires each of the following elements:

A human patient suffering from duodenal ulcer disease;
The ulcer disease is associated with Campylobacter pylori infection;
Administration of a pharmaceutically acceptable bismuth compound;
Administration of tetracycline or a penicillin;
Administration of metronidazole; and
Administration in amounts sufficient to eradicate the infection and prevent recurrence.

The claim is cumulative. A regimen containing bismuth and metronidazole without tetracycline or a penicillin would not literally satisfy the claim. A regimen containing tetracycline and metronidazole without bismuth would also fall outside the literal combination.

The claim does not specify:

The identity of the bismuth compound;
The identity of the penicillin;
The dose of any component;
The treatment duration;
The order in which the components must be administered;
Whether the ingredients must be co-formulated;
Whether all ingredients must be administered in a single dosage form;
A minimum eradication rate; or
A particular diagnostic test for infection.

The phrase “infection eradicating amounts” is functional. It requires that the administered quantities be sufficient to eradicate the infection, but the claim does not prescribe a numerical threshold. In an infringement dispute, the adequacy of the doses would likely be assessed using clinical, pharmacological, and microbiological evidence.

What does claim 2 add?

Claim 2 depends on claim 1 and adds the requirement that administration cause healing of the duodenal ulcer as well as prevention of recurrence.

This limitation narrows claim 1 from a recurrence-prevention method to a method producing two therapeutic outcomes:

Healing of the existing ulcer; and
Prevention of recurrence.

The claim does not define “healing” by endoscopic grade, ulcer size, time period, or symptom score. That lack of specificity may create evidentiary issues, but it also makes the limitation difficult to assess solely from a prescription record.

What does claim 3 protect?

Claim 3 covers a treatment sequence combining acid suppression with infection eradication. It requires:

A patient with Campylobacter pylori-associated duodenal ulcer;
An acid suppressant in an amount effective to provide symptomatic relief and ulcer epithelialization;
Administration of the acid suppressant before or during the antimicrobial regimen; and
The same bismuth, tetracycline-or-penicillin, and metronidazole combination required by claim 1.

Claim 3 is broader in one respect and narrower in another. It is broader because it does not limit the acid suppressant to a named class or molecule. It is narrower because it requires the additional acid-suppression step and specified therapeutic effects.

The acid suppressant could theoretically include an H2-receptor antagonist, a proton-pump inhibitor, or another agent capable of suppressing gastric acid. The claim language does not identify omeprazole, lansoprazole, cimetidine, ranitidine, or another particular product.

What formulations are protected by US 5,196,205?

The patent does not directly claim a formulation. It claims administration of a therapeutic combination.

A product could potentially be used in practicing the claimed method if it supplied one or more required agents, but the patent does not require:

A fixed-dose combination;
A capsule, tablet, suspension, or kit;
A particular release profile;
A particular excipient system;
A specific bismuth salt;
A defined ratio between antibiotics; or
A specific packaging configuration.

The distinction matters. A manufacturer selling separate generic products would not infringe merely by selling them. Method infringement would require an act of administering the required combination, or liability under an applicable theory of induced or contributory infringement. Because the patent has expired, those theories no longer create current exposure.

When did US Patent 5,196,205 lose exclusivity?

The patent was granted on March 23, 1993. For a pre-1995 US application, the applicable patent term generally was 17 years from grant, subject to statutory adjustments, terminal disclaimers, or other term calculations. On that basis, the ordinary term would have ended around March 23, 2010. The patent is therefore expired and cannot presently exclude use of the claimed regimen (USPTO, n.d.-a; USPTO, n.d.-b).

Event	Date or status
US patent grant	March 23, 1993
Patent term framework	Generally 17 years from grant for qualifying pre-June 8, 1995 applications
Expected ordinary expiration	Approximately March 23, 2010
Current status	Expired
Current generic-entry barrier	None from this patent

No patent-term extension would ordinarily be expected for this type of historical ulcer-treatment method patent. Patent-term extension under 35 U.S.C. § 156 is generally associated with regulatory review of approved drug products, and method claims covering an established multi-drug treatment do not create a current regulatory exclusivity period.

What is the Orange Book status of US 5,196,205?

US 5,196,205 is not a current Orange Book barrier to approval or marketing of an H. pylori treatment. The patent claims a method of treatment rather than a currently protected approved drug product.

The FDA Orange Book principally identifies patents and exclusivity associated with approved drug products and abbreviated new drug application pathways. A historical method patent may have been relevant to a listed product during its term, but its expiration removes any remaining patent-based delay to generic approval under the Hatch-Waxman framework (FDA, n.d.-a).

The patent does not provide:

Current five-year new chemical entity exclusivity;
Three-year clinical-investigation exclusivity;
Pediatric exclusivity;
Orphan-drug exclusivity;
A current paragraph IV litigation trigger; or
A current 30-month stay.

Are there current Paragraph IV challenges?

There is no current paragraph IV risk attributable to US 5,196,205 because the patent is expired. A paragraph IV certification is relevant when an ANDA applicant challenges a listed patent that has not expired. An applicant does not need to mount a live invalidity or noninfringement challenge to an expired patent.

Historical paragraph IV activity involving bismuth-based ulcer products would have depended on the product, NDA holder, and Orange Book listing at the time. It cannot be inferred from the patent claims alone. Regardless, the expiration of the patent eliminates any current launch delay based on this patent.

How strong was the patent estate?

The patent was commercially meaningful but legally narrow.

Strengths

The claims had several features that could have made them useful during the patent term:

They required a clinically specific disease state;
They tied ulcer recurrence to infection eradication;
They claimed a combination rather than a single generic agent;
They covered both tetracycline and penicillin alternatives;
They included functional eradication language;
Claim 3 captured the combination of antimicrobial therapy and acid suppression.

The use of alternative antibiotics increased the number of potential regimens within claim 1. A regimen using bismuth, tetracycline, and metronidazole would fall within the express antibiotic selection. A regimen using bismuth, a penicillin, and metronidazole could also fall within the claim.

Weaknesses

The patent also had material limitations:

It was limited to duodenal ulcer disease;
It required infection associated with Campylobacter pylori;
It did not expressly cover all peptic-ulcer or gastric-ulcer indications;
It did not claim metronidazole-based therapy without bismuth;
It did not claim clarithromycin-based triple therapy;
It did not claim a particular commercial formulation;
It did not claim eradication therapy for asymptomatic infection;
It did not specify doses or treatment duration;
It did not provide composition-of-matter protection.

The terminology also created an interpretive issue. Modern clinical practice uses H. pylori, while the patent uses Campylobacter pylori. The renamed organism is generally understood to be the same pathogen, so the terminology would not ordinarily create a meaningful design-around.

How does the patent compare with modern H. pylori treatment?

Modern treatment has expanded beyond the claimed regimen. The American College of Gastroenterology recommends susceptibility-informed therapy where available and recognizes optimized bismuth quadruple therapy as an important empiric option. Contemporary regimens may contain a proton-pump inhibitor or potassium-competitive acid blocker, bismuth, tetracycline, and metronidazole. Other regimens may use amoxicillin, clarithromycin, rifabutin, or vonoprazan, depending on resistance patterns and treatment history (American College of Gastroenterology, 2024).

Treatment concept	Relationship to US 5,196,205
Bismuth, tetracycline, metronidazole plus acid suppression	Closely aligned with claim 3
Bismuth, metronidazole, and amoxicillin	Potentially within claim 1 if all disease and therapeutic limitations are met
Clarithromycin-based triple therapy	Not expressly recited
Rifabutin-based therapy	Not expressly recited
Vonoprazan-based therapy without required bismuth	Generally outside claim 1
Acid suppression alone	Outside the claims
Antibiotics without bismuth	Outside the literal combination

The patent should not be treated as covering every modern H. pylori regimen. Its claim set is directed to a defined bismuth-plus-two-antibiotic combination and, in claim 3, an acid-suppression component.

What generic launch risks exist?

There is no present generic launch risk from the patent itself. Generic products can be launched without designing around US 5,196,205 because the patent has expired.

The relevant commercial risks are regulatory, clinical, and formulation-related rather than patent-based:

FDA approval requirements for each product;
Drug-drug interactions and contraindications;
Antibiotic resistance;
Product-specific labeling;
Availability of tetracycline and metronidazole;
Manufacturing quality for bismuth-containing products;
Patient adherence to multi-drug regimens;
Separate patents covering newer acid suppressants or branded combination products.

A manufacturer could still face other live patents for a specific product, delivery technology, formulation, salt, manufacturing process, or new therapeutic combination. Those rights would need to be analyzed separately from US 5,196,205.

What manufacturing and intellectual-property barriers remain?

US 5,196,205 does not create a current manufacturing barrier. It does not claim a manufacturing process or a proprietary bismuth material.

Potential non-patent barriers include:

Consistent manufacture of bismuth suspensions or tablets;
Stability of multi-ingredient products;
Compatibility of bismuth with antibiotics and acid suppressants;
Control of impurities and degradation products;
FDA requirements for combination products;
Bioequivalence or comparative clinical requirements;
Supply reliability for tetracycline, amoxicillin, metronidazole, or bismuth salts.

A new commercial product could require separate patent analysis for its dosage form, packaging, release profile, dosing protocol, or acid-suppression technology. None of those limitations appears in the supplied claims.

What litigation or settlement exposure remains?

The patent cannot support a new US infringement action after expiration. Any historical litigation, settlement, or license involving the patent would have commercial relevance only for past conduct, royalty accounting, or historical market analysis.

The claims also do not establish current biosimilar exposure. The covered agents are small-molecule drugs, not biologics. Biosimilar approval pathways do not apply to bismuth compounds, tetracycline, penicillins, metronidazole, or conventional acid suppressants.

Key Takeaways

US 5,196,205 covers treatment and recurrence prevention for Campylobacter pylori-associated duodenal ulcers.
Claim 1 requires bismuth, tetracycline or a penicillin, and metronidazole.
Claim 2 adds healing of the existing ulcer.
Claim 3 adds an acid suppressant administered before or during eradication therapy.
The patent claims methods, not drug compositions, fixed-dose products, or manufacturing processes.
The patent expired around March 23, 2010 under the ordinary pre-1995 patent-term framework.
It presents no current Orange Book, paragraph IV, generic-launch, biosimilar, or litigation barrier.
Modern bismuth quadruple therapy overlaps conceptually with the claimed regimen, but newer regimens using different antibiotics or drug combinations may fall outside the literal claims.
Any current freedom-to-operate review must focus on later patents covering formulations, dosing regimens, acid suppressants, delivery systems, or branded combination products.

FAQs

Does US Patent 5,196,205 cover amoxicillin-based H. pylori therapy?

Potentially, if the regimen also contains a pharmaceutically acceptable bismuth compound and metronidazole and is administered to the claimed duodenal-ulcer patient. Amoxicillin is a penicillin, but the patent is expired.

Does the patent cover proton-pump inhibitors by themselves?

No. Claim 3 requires an acid suppressant in combination with the claimed bismuth-antibiotic eradication regimen. Acid suppression alone does not satisfy the patent claims.

Does US 5,196,205 cover gastric ulcers?

The supplied claims are limited to duodenal ulcer disease. They do not expressly cover gastric ulcers or all forms of peptic ulcer disease.

Is Campylobacter pylori the same organism as Helicobacter pylori?

Yes. Campylobacter pylori was the earlier classification used in the patent. The organism was later reclassified and renamed Helicobacter pylori.

Can a company commercialize a fixed-dose bismuth triple-therapy kit today?

US 5,196,205 does not prevent commercialization because it is expired. The company would still need to satisfy FDA approval, labeling, manufacturing, and any separate live-patent requirements applicable to the proposed kit.

References

American College of Gastroenterology. (2024). ACG clinical guideline: Treatment of Helicobacter pylori infection. The American Journal of Gastroenterology.

Food and Drug Administration. (n.d.-a). Approved drug products with therapeutic equivalence evaluations, commonly known as the Orange Book. U.S. Department of Health and Human Services.

United States Patent and Trademark Office. (n.d.-a). Patent term adjustment. U.S. Department of Commerce.

United States Patent and Trademark Office. (n.d.-b). Manual of Patent Examining Procedure § 2710: Term of patent. U.S. Department of Commerce.

US Patent No. 5,196,205. (1993). Treatment and prevention of recurrence of duodenal ulcers. U.S. Patent and Trademark Office.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Australia	PI4838	Oct 12, 1987
Australia	PI5985	Dec 18, 1987
Australia	PI7513	Mar 30, 1988

PCT Information
PCT Filed	September 29, 1988	PCT Application Number:	PCT/AU88/00379
PCT Publication Date:	October 23, 1986	PCT Publication Number:	WO86/05981

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	100324	⤷ Start Trial
Australia	2540588	⤷ Start Trial
Australia	623868	⤷ Start Trial
Canada	1330759	⤷ Start Trial
Germany	3887353	⤷ Start Trial
European Patent Office	0439453	⤷ Start Trial
Japan	2733849	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,196,205

Summary for Patent: 5,196,205