US Patent 10,086,006: Fosfomycin Resistance-Inhibitory Dosing Claims, Scope, Expiration, and Competitive Landscape

US Patent No. 10,086,006 covers a diagnostic-directed fosfomycin treatment strategy for infections containing antibiotic-resistant subpopulations. The core invention links microbiological identification of a resistant bacterial subpopulation to a dosing interval selected by the fosfomycin resistance inhibitory concentration, or RIC. The issued claims narrow the protected regimen to specified Gram-negative organisms, six- or eight-hour intervals, approximately 100 mg/kg dosing, and a sequential eight-hour-to-six-hour regimen.

The patent is materially different from a conventional fosfomycin composition patent. Its commercial significance depends on whether a competing product or clinical protocol performs all required steps: sampling, identifying or confirming the resistant subpopulation, selecting dosing by RIC, and administering fosfomycin at the claimed interval.

What does US Patent 10,086,006 protect?

The patent protects methods of treating bacterial infections in which the clinician identifies a resistant mutant or antibiotic-resistant subpopulation before selecting fosfomycin dosing.

Claim group	Protected subject matter	Key limitations
Claims 1-2	Diagnostic-directed fosfomycin treatment	Sample collection, identification of resistant subpopulation, RIC-based dosing
Claims 3-4	Fixed dosing intervals	Every six hours or every eight hours
Claims 5-6	Dose-specific regimens	About 100 mg/kg with six- or eight-hour dosing
Claim 7	Adaptive treatment method	Initial and subsequent dosing intervals based on RIC
Claim 8	Sequential interval	Every eight hours initially, then every six hours
Claim 9	Sequential dose-specific regimen	Claim 8 regimen with about 100 mg/kg

The claims are method-of-treatment claims. They do not claim fosfomycin as a chemical compound, a generic injectable formulation, or a composition containing fosfomycin. They also do not expressly claim a diagnostic kit, susceptibility-testing device, or manufacturing process.

The central claim concept is a feedback loop:

Obtain a patient sample.
Identify a resistant subpopulation.
Determine or apply the RIC required to inhibit that subpopulation.
Select the dosing interval and dose.
Administer fosfomycin.
Reduce bacterial density and inhibit the resistant subpopulation.

That sequence creates a narrower infringement theory than a claim directed simply to administering fosfomycin for infection.

Which organisms are covered by the fosfomycin patent?

Claim 1 is directed specifically to E. coli infections containing a resistant mutant subpopulation. Claim 2 and claim 7 extend coverage to a defined group of organisms.

Organism expressly identified	Claims
E. coli	1, 2, 7
Enterobacter spp.	2, 7
Klebsiella oxytoca	2, 7
Klebsiella pneumonia, as stated in the claim	2, 7
Proteus mirabilis	2, 7
Proteus vulgaris	2, 7

The claim language uses “resistant” mutant subpopulation and “antibiotic-resistant subpopulation.” The patent’s specification and prosecution history would be important in determining whether “resistant” requires a particular laboratory threshold, a defined resistance phenotype, or merely a subpopulation capable of surviving a specified fosfomycin exposure.

The list is closed for claims 2 and 7 unless a court applies a doctrine-of-equivalents analysis. A competing regimen directed to Pseudomonas, Acinetobacter, or another organism would not literally fall within those claims based on the listed organisms alone.

How does the RIC limitation affect claim scope?

The RIC limitation is the principal technical limitation in the patent. The claims require administration based on the “resistance inhibitory concentration” necessary to inhibit the resistant subpopulation.

RIC is distinct from the conventional minimum inhibitory concentration, or MIC, for the dominant bacterial population. The patent’s strategy is directed to suppressing a minority population capable of surviving standard exposure. A treatment protocol that uses only routine MIC data may avoid literal infringement if the RIC element is not satisfied.

The RIC limitation creates four potential claim-construction issues:

What does “consistent with the RIC” mean?

Claims 1 and 2 require an “optimum dosing interval consistent with” the RIC. That phrase may be argued to require only that the dosing interval be selected with reference to the RIC. It does not necessarily require an exact measured RIC value in every patient.

A defendant could argue that “consistent with” is indefinite or lacks a sufficiently objective boundary if the patent does not define how the interval is calculated. The patent owner would likely argue that the specification supplies experimental relationships between RIC, dosing interval, and bacterial killing.

Must the clinician calculate RIC for each patient?

The claims require identifying or confirming the resistant subpopulation and administering fosfomycin based on the RIC. A protocol using a fixed six-hour interval could still implicate the claims if the interval was selected because it corresponds to the known RIC profile of the relevant organism.

A protocol that administers fosfomycin every six hours for all patients, without testing or identifying a resistant subpopulation, presents a stronger noninfringement position against claims 1, 2, and 7.

Is laboratory confirmation required?

The claims expressly require obtaining a sample and identifying or confirming the resistant subpopulation. Treatment based solely on a clinical diagnosis, without sample-based identification, may not satisfy the literal claim language.

Is bacterial reduction a separate limitation?

The claims require that bacterial density be effectively reduced and the fosfomycin-resistant subpopulation be inhibited. This language may be treated as a result limitation. If so, the patent owner may need to show that the accused regimen achieves the claimed microbiological outcome, although courts often assess method claims by the steps performed rather than by an independently guaranteed clinical result.

What dosing regimens are specifically protected?

The narrowest issued claims identify specific dosing schedules.

Claim	Dosing interval	Dose
3	Every six hours	Not specified
4	Every eight hours	Not specified
5	Every six hours	About 100 mg/kg
6	Every eight hours	About 100 mg/kg
8	Initially every eight hours, then every six hours	Not specified
9	Initially every eight hours, then every six hours	About 100 mg/kg

Claims 3 through 6 depend on claim 1 or claim 2. Claim 8 depends on claim 7. This means the fixed-interval claims retain the organism, sample, resistant-subpopulation, and RIC limitations of their parent claims.

The phrase “about 100 mg/kg” creates a range question. The permissible range would depend on intrinsic evidence, prosecution history, and how a court interprets “about” in the context of fosfomycin dosing. A regimen of 100 mg/kg is the clearest literal target. A materially lower or higher dose would require an analysis of ordinary meaning and possible equivalents.

The claims do not expressly state the route of administration, formulation, infusion duration, renal-adjustment method, treatment duration, or maximum daily dose. Those omissions leave possible design space around:

Different fosfomycin salts or injectable presentations.
Different doses outside the interpreted “about 100 mg/kg” range.
Intervals other than six or eight hours.
Regimens not preceded by resistant-subpopulation testing.
Treatment of organisms outside the expressly listed group.
Protocols based on MIC, pharmacokinetic exposure, or pharmacodynamic targets rather than RIC.

When does US Patent 10,086,006 lose exclusivity?

The patent’s exact expiration date cannot be established from the issued patent number and claim text alone. The relevant date depends on the patent’s earliest effective nonprovisional filing date, any priority or continuation relationship, patent-term adjustment, and any patent-term extension.

For a post-1995 US utility patent, the baseline term is generally 20 years from the earliest effective US nonprovisional filing date, subject to statutory adjustments under 35 U.S.C. §§ 154 and 156. The front-page patent data, USPTO Patent Center, and the patent’s term-adjustment calculation should control the final date.

The patent issued on October 2, 2018. Issuance does not establish the expiration date. A patent issued in 2018 can expire before, during, or after 2035 depending on its filing history and term adjustment.

Exclusivity issue	Effect on US 10,086,006
Patent term	Based on earliest effective nonprovisional filing date
Patent-term adjustment	May extend the baseline term
Patent-term extension	Potentially relevant only if statutory requirements are met
Regulatory exclusivity	Separate from patent rights
Orange Book listing	Must be confirmed from FDA listing data
Pediatric exclusivity	No conclusion follows from the claim text
Foreign term	Must be assessed separately by jurisdiction

What is the Orange Book status of US Patent 10,086,006?

A patent directed to a method of using fosfomycin is not automatically listed in the FDA Orange Book. Listing depends on whether the patent is associated with an approved drug product and whether it meets FDA listing requirements.

Fosfomycin tromethamine is FDA-approved in the United States as an oral product for certain uncomplicated urinary tract infections. That approval does not establish that US 10,086,006 is listed for the product. The patent’s claims concern RIC-directed treatment of resistant bacterial subpopulations and include parenteral-type dosing levels that are materially different from the standard oral fosfomycin tromethamine indication.

The Orange Book analysis therefore has two separate questions:

Whether an approved fosfomycin product identifies US 10,086,006 as a listed patent.
Whether the approved labeling practices the claimed method.

If the patent is not listed, an ANDA applicant generally would not have a statutory Paragraph IV certification obligation directed to this patent. The patent could still be asserted under ordinary infringement theories if the accused product and labeling induce performance of the claimed method.

Are Paragraph IV challenges likely against this patent?

A Paragraph IV challenge would be relevant only if the patent is listed against an approved reference product. The practical grounds would likely include:

Lack of infringement

An ANDA label may omit the diagnostic-directed RIC language, resistant-subpopulation identification, and six-hour or eight-hour regimen. A product label that does not encourage the claimed sequence could reduce induced-infringement exposure.

Anticipation

Prior art could defeat the claims if it disclosed, before the relevant filing date, all elements of the claimed method in combination: resistant-subpopulation testing, RIC-directed fosfomycin dosing, and the specified organism or dosing regimen.

Obviousness

The strongest validity challenge would combine prior work on:

Fosfomycin heteroresistance or resistant mutant suppression.
Pharmacodynamic optimization by dosing interval.
Time-dependent or exposure-dependent fosfomycin activity.
Six-hour or eight-hour parenteral dosing.
Resistance prevention in Enterobacterales.

The combination would need to show more than routine administration. The patent owner would likely rely on the claimed relationship between shortened interval and increased bacterial killing, particularly the transition from every eight hours to every six hours.

Written description and enablement

The claims cover multiple bacterial genera and require an RIC-based treatment decision. A challenger could examine whether the specification supports the full organism list and provides enough technical guidance to select effective dosing for each claimed species and resistant subpopulation.

What patent landscape surrounds fosfomycin?

The surrounding patent landscape is divided into four categories.

Composition and salt patents

These cover fosfomycin salts, crystalline forms, pharmaceutical compositions, and excipients. They are distinct from US 10,086,006, which does not claim the fosfomycin molecule or a formulation.

Formulation and delivery patents

Potentially relevant patents cover intravenous preparations, stability, infusion systems, premixed solutions, and combination products. These rights may create barriers even when a competitor avoids the RIC method claims.

Method-of-use patents

This patent belongs to the method-of-use category. Other method claims may cover fosfomycin treatment of complicated urinary tract infection, osteomyelitis, multidrug-resistant infections, or combinations with beta-lactams and other antibiotics.

Manufacturing and process patents

Manufacturing patents may cover fermentation, purification, stereochemical control, salt formation, or injectable-grade production. These rights can affect supply and licensing even when the treatment method is outside the scope of US 10,086,006.

How strong is the patent estate for commercial enforcement?

The patent is technically differentiated but operationally narrow.

Its strongest features are:

A required diagnostic step.
A defined resistant subpopulation.
RIC-directed dose selection.
Specific six-hour and eight-hour intervals.
A sequential eight-hour-to-six-hour regimen.
Coverage of clinically important Enterobacterales.

Its principal weaknesses are:

No composition or product claim.
No express formulation or manufacturing claim.
Dependence on a potentially contestable RIC definition.
Requirement for sample collection and resistant-subpopulation identification.
Limited organism list.
Possible difficulty proving that a commercial label encourages every claimed step.
Unclear relationship between the claim language and standard FDA-approved fosfomycin labeling.

The patent is more valuable as a barrier to a labeled, protocol-driven intravenous fosfomycin product than as a barrier to all generic fosfomycin sales.

Which companies could challenge or design around the patent?

Potential challengers include generic manufacturers of fosfomycin products, sponsors developing intravenous fosfomycin, hospital-focused anti-infective companies, and companies developing fosfomycin combinations.

The most direct design-around paths are:

Use a dosing interval other than six or eight hours.
Avoid a label that instructs clinicians to identify a resistant subpopulation.
Base dosing on MIC, pharmacokinetic exposure, or renal function rather than RIC.
Use a dose outside the interpreted “about 100 mg/kg” range.
Target a non-listed organism.
Omit the sequential eight-hour-to-six-hour transition.
Use a formulation or treatment protocol that does not encourage the claimed diagnostic sequence.

These strategies may reduce literal infringement risk but do not eliminate separate exposure under other fosfomycin patents, labeling theories, or combination-product rights.

What litigation and settlement issues matter?

The claim set raises several litigation issues:

Whether “resistant mutant subpopulation” has a defined technical meaning.
Whether RIC is objectively measurable and reproducible.
Whether a fixed six-hour regimen is “consistent with” RIC.
Whether an accused label induces sample collection and subpopulation confirmation.
Whether the bacterial-reduction limitation is an enforceable result limitation.
Whether treatment by a hospital involves divided infringement among the laboratory, physician, pharmacist, and provider.
Whether a settlement can restrict generic labeling, launch timing, or use of specific dosing protocols.

No litigation outcome, Paragraph IV dispute, or settlement term can be inferred from the claims alone. A current litigation assessment must be based on the USPTO, PACER, FDA, and relevant commercial databases.

What is the biosimilar risk for fosfomycin?

Biosimilar risk is not the relevant framework. Fosfomycin is a small-molecule antibacterial, not a biologic. Competitive entry would generally involve an ANDA, a 505(b)(2) application, or a full NDA, depending on the product, route, formulation, and reference product.

The principal regulatory distinction is between oral fosfomycin tromethamine and any proposed intravenous fosfomycin product. A sponsor seeking approval for an injectable product could face a different clinical, labeling, formulation, and patent landscape from a sponsor marketing an oral generic.

Key Takeaways

US Patent 10,086,006 claims diagnostic-directed fosfomycin treatment, not fosfomycin itself.
The core limitation is dosing selected according to the RIC needed to inhibit a resistant bacterial subpopulation.
Claims 1 and 2 cover E. coli and specified Enterobacterales organisms.
Claims 3 through 6 specify six-hour or eight-hour intervals, with dependent claims covering approximately 100 mg/kg.
Claims 7 through 9 cover an adaptive regimen beginning every eight hours and moving to every six hours.
The patent’s commercial reach depends heavily on clinical protocols and product labeling.
The principal validity issues are RIC definiteness, enablement across the listed organisms, and obviousness based on prior fosfomycin pharmacodynamics.
The patent is not equivalent to an Orange Book-listed product patent, and its listing status must be verified independently.
Biosimilar analysis does not apply; generic, 505(b)(2), and NDA pathways are more relevant.
Exact patent expiration and current litigation status require review of the patent’s complete prosecution, term-adjustment, FDA, and court records.

Frequently Asked Questions

Does US Patent 10,086,006 cover oral Monurol?

Not broadly. The claims require sample-based identification of a resistant subpopulation and RIC-directed dosing. They do not claim all oral fosfomycin use or the fosfomycin tromethamine composition.

Can a generic manufacturer avoid the patent by using a 12-hour dosing interval?

A 12-hour regimen would not literally satisfy the dependent claims requiring every six or eight hours. It would still require analysis under the broader independent claims and the doctrine of equivalents.

Does the patent cover fosfomycin combination therapy?

The supplied claims do not expressly require or exclude combination therapy. A combination regimen could fall within the claims if it performs all recited steps and uses fosfomycin according to the required RIC-directed method.

Is a laboratory required to test for fosfomycin resistance before treatment?

The claims require obtaining a sample and identifying or confirming the resistant subpopulation. A protocol that does not perform those steps may present a noninfringement argument, subject to claim construction and inducement analysis.

Can the patent block intravenous fosfomycin development outside the United States?

No. A US patent has no direct legal effect outside the United States. Foreign equivalents, national-phase patents, supplementary protection certificates, and local regulatory rights must be reviewed separately.

References

United States Patent and Trademark Office. (2018). U.S. Patent No. 10,086,006, Methods of treating bacterial infections.
U.S. Food and Drug Administration. (n.d.). Fosfomycin tromethamine prescribing information.
35 U.S.C. § 154. Patent term.
35 U.S.C. § 156. Extension of patent term.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations. Orange Book.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Meitheal	CONTEPO	fosfomycin disodium	POWDER;INTRAVENOUS	212271-001	Oct 22, 2025		RX	Yes	Yes	10,086,006	⤷ Start Trial				TREATMENT OF PATIENTS WITH COMPLICATED URINARY TRACT INFECTIONS INCLUDING ACUTE PYELONEPHRITIS CAUSED BY SUSCEPTIBLE ISOLATES OF ESCHERICHIA COLI AND KLEBSIELLA PNEUMONIAE	⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Details for Patent: 10,086,006

Which drugs does patent 10,086,006 protect, and when does it expire?

Summary for Patent: 10,086,006