United States Patent 6,723,341: Scope, Claims, and US Landscape for a Once-Daily, Multi-Stage Antibiotic Release System

US Patent 6,723,341 claims a once-a-day antibiotic product built from multiple antibiotic dosage forms (immediate release plus delayed-release stages), with release timing and exposure (Cmax) constraints designed to deliver the full 24-hour antibiotic dose from a single administration. The claim set then narrows by specific Cmax timing windows, immediate-release fraction by weight, sequencing of stage peaks, and optional expansion to a four-stage release architecture. Method claims cover treating bacterial infection by administering the claimed product once daily, and a dependent set specifies the antibiotic as a salt.

What is claimed at the core?

What does claim 1 lock up?

Claim 1 is the independent product claim and sets the “center of mass” of infringement scope:

Once-a-day antibiotic product comprising three antibiotic dosage forms:
- First dosage form: immediate release
- Second and third dosage forms: delayed release
At least one of the delayed-release forms is pH sensitive
The three dosage forms start release at different times
Exposure constraint (total product):
- Cmax of the total antibiotic released is achieved in less than about 12 hours from administration
Dose coverage constraint:
- Product contains the total dosage of at least one antibiotic for a 24-hour period

This claim is not limited to a particular antibiotic entity in the text provided. It is structural-by-function: the claim captures any antibiotic that is formulated into the required multi-stage release system and meets the Cmax and release timing relationships.

What do the dependent claims narrow?

Dependent claims add quantitative gates. These are the levers that define design-around difficulty and likely claim construction fights.

Cmax timing windows (product-level)

Claim 2: Product Cmax reached no earlier than 4 hours
Claim 3: Immediate release stage reaches Cmax within 0.5 to 2 hours
Claim 4: Second (delayed) stage reaches Cmax in no more than about 4 hours
Claim 5: Third (delayed) stage reaches Cmax within 8 hours

Together, these require a staggered exposure profile where:

the immediate stage peaks early (0.5 to 2 hours),
the second stage peaks by about 4 hours (and cannot peak after it exceeds the constraint),
the third stage peaks by 8 hours,
and the total product peak occurs between 4 and <12 hours (based on Claims 1 and 2).

Immediate release fraction by weight

Claim 6: Immediate release contains 20% to 50% of total antibiotic dose.

This is a formulation-percent claim. It restricts product designs that shift too much drug into delayed stages.

Sequencing of stage peaks

Claim 8: Third-stage Cmax occurs after first-stage Cmax
Claim 9: Third-stage Cmax occurs after second-stage Cmax

Claim 8 and 9 impose a monotonic “peak order” requirement. They do not explicitly demand that first-stage Cmax precedes second-stage Cmax, but Claim 3 and Claim 4 strongly imply that ordering in most constructed release profiles.

Optional expansion: four-stage system

What does claim 10 add?

Claim 10 generalizes the architecture by adding a fourth delayed-release dosage form, also containing antibiotic and carrier, with a further sequencing rule:

There are four dosage forms total:
- First: immediate release
- Second and third and fourth: delayed release
Cmax ordering constraint for total product timing: depends on the claim language
It includes a relative condition:
- Antibiotic released from the fourth dosage form reaches a Cmax after Cmax is achieved for antibiotic released from each of the first, second, and third dosage forms

That is a strict staged peak-lag requirement: the fourth delayed form must peak last.

What additional quantitative gates does claim 15 add?

Claim 15 provides the most explicit proportion constraints in the provided set:

Release initiation order:
- second initiates release before third
- third initiates release before fourth
Weight distribution by stage (as a percent of total antibiotic released by the three delayed stages plus immediate, i.e., total product):
- Second dosage form: 20% to 35% by weight
- Third dosage form: 20% to 40% by weight
- Fourth dosage form: remainder of total antibiotic released by second, third, and fourth dosage forms

Claims 11-14 import the same Cmax timing frameworks as Claims 2-5 but within the four-stage context.

Methods claims: using the product once daily

How broad are the treatment claims?

The method claims (Claims 19-38 in the provided set) are largely straightforward:

Claim 19: administer the product of claim 1 once daily to treat a bacterial infection
Claims 20-23: administer the product of claims 2-5 once daily
Claims 24-32: administer the product of claims 6-14 once daily
Claims 33-36: administer the product of claim 15-16-17-18 once daily (per the mapping shown)
Claims 37-38: specify antibiotic is a salt (product of claim 37) and its use once daily (claim 38)

This means infringement exposure is not limited to “product makers.” It also captures the act of administration in clinical practice when the administered product meets the product claims.

Pharmacokinetic and formulation elements embedded in the claim set

What are the functional elements that define infringement?

Across Claims 1 and 10 (and tightened by 2-6, 11-15), infringement turns on three fact patterns:

Dose staging and number of stages
- Claim 1: three antibiotic dosage forms
- Claim 10: four antibiotic dosage forms
Release modality
- Immediate release stage
- Delayed release stages, with pH sensitivity required for at least one delayed stage (Claim 1)
PK timing relationships
- total product Cmax occurs in < about 12 hours
- total product Cmax is >= 4 hours in Claim 2
- stage Cmax windows:
  - immediate stage: 0.5 to 2 hours (Claim 3)
  - second stage: <= about 4 hours (Claim 4)
  - third stage: <= 8 hours (Claim 5)
- stage peak ordering:
  - third peaks after first and after second (Claims 8 and 9)
  - fourth peaks after each of the first three (Claim 10)

What do these constraints mean operationally?

From a development standpoint, the claim language is “engineered” for measurable endpoints:

Cmax timing implies reliance on in vivo bioequivalence-style testing.
Initiation of release at different times implies dissolution and/or in vivo release behavior.
pH sensitive delayed release implies polymer and coating choices responsive to gastrointestinal pH.

Claim-by-claim scope map (provided text)

Claim	Product structure	Key constraints (as written)
1	3 forms: 1 immediate + 2 delayed (pH sensitive at least one)	Different release initiation times; total-product Cmax in < ~12h; total dose covers 24h
2	Same as 1	Total-product Cmax no earlier than 4h
3	Same as 1	Immediate form Cmax 0.5h to 2h
4	Same as 1	Second form Cmax <= ~4h
5	Same as 1	Third form Cmax within 8h
6	Same as 1	Immediate form is 20% to 50% of total antibiotic dose
7	Same as 1	Product is oral
8	Same as 1	Third form Cmax after first form Cmax
9	Same as 1	Third form Cmax after second form Cmax
10	4 forms: 1 immediate + 3 delayed	Fourth Cmax occurs after Cmax for first, second, and third
11	Same as 10	Total-product Cmax no earlier than 4h
12	Same as 10	Immediate form Cmax 0.5h to 2h
13	Same as 10	Second form Cmax <= ~4h
14	Same as 10	Third form Cmax within 8h
15	Same as 10	Second initiates release before third; third before fourth; second 20-35% by weight; third 20-40% by weight; fourth is remainder
16	Same as 10	Product is oral
17	Same as 10	Second/first peak ordering (after first)
18	Same as 10	Third/second peak ordering (after second)
19-36	Corresponding product claims 1-18	Administer once daily to treat bacterial infection
37	Product claim 1	Antibiotic is a salt
38	Product claim 37	Administer once daily to treat bacterial infection

Practical infringement boundary analysis (what likely triggers “capture”)

Which designs are closest to the literal claim language?

Products that match all of the following are most exposed:

Once-daily oral format (Claims 7 and 16 are dependent but align with market expectations)
Multi-peak staged delivery with:
- immediate stage peaks in the 0.5-2h band,
- second stage peaks by ~4h,
- third stage peaks by 8h,
- total product Cmax occurs between 4h and <12h (Claims 1-2 plus 3-5)
Delayed release stage with pH sensitivity (Claim 1)
Immediate-release dose fraction within 20-50% (Claim 6)
Proper peak sequencing (Claims 8-9 and Claim 10 for the four-stage version)

Where are the claim “escape hatches”?

Designs can reduce literal infringement risk by breaking at least one “gate”:

Move total Cmax earlier than 4h or out beyond ~12h (Claims 1-2).
Alter immediate-stage Cmax outside 0.5-2h (Claim 3).
Alter second-stage peak time beyond ~4h (Claim 4).
Alter third-stage peak time beyond 8h (Claim 5).
Alter immediate-stage dose fraction outside 20-50% (Claim 6).
Avoid pH-sensitive delayed-release characteristics in all delayed forms (Claim 1 requires at least one pH-sensitive delayed form).
Alter staged peak order to violate the “after” constraints (Claims 8-9 and Claim 10).

Because the claim set includes explicit numeric PK constraints, the main commercial risk hinges on in vivo performance characterization rather than only formulation architecture.

US patent landscape implications (scope and competitive positioning)

How does the claim architecture likely play in freedom-to-operate?

This patent’s scope is not “antibiotic-specific.” It is platform-like: once-daily antibiotic delivery using staged release and measured Cmax relationships.

That creates two landscape effects:

Broader chemical coverage, narrower performance envelope
- The antibiotic identity does not appear in the provided claim text, so multiple antibiotic actives can fall within the same platform if their formulations hit the same exposure windows.
High sensitivity to PK outcomes
- Competitors who use the same general multi-layer concept can still avoid infringement by adjusting release kinetics so that Cmax timing or peak ordering fails the claim thresholds.

What does the four-stage dependent claim do to competitor design?

Adding the fourth delayed stage in Claim 10 expands the “engineering space” but tightens sequencing:

Fourth stage must peak after peaks for first, second, and third.
Claim 15 adds weight distribution and stage initiation order constraints.

A four-stage product is harder to “accidentally” land in without meeting these additional sequencing and proportion requirements, but if a competitor optimizes a four-stage PK curve, it can land directly in-scope.

Method claims raise “use” risk

If a once-daily product meets the product claims, a method-of-treatment claim can create:

prescriber liability theories (jurisdictions vary),
payer and manufacturer risk tied to labeling and dissemination,
and stronger leverage for enforcement where the product’s PK profile is marketed or evidenced.

Key Takeaways

US 6,723,341 claims a once-daily antibiotic system with 3 (or 4) dosage forms and measurable Cmax timing constraints that define both product structure and in vivo performance.
The independent scope is governed by staged release timing, pH-sensitive delayed release (at least one delayed stage), and total-product Cmax < ~12 hours while covering a 24-hour dose.
Dependent claims impose numeric PK windows (total Cmax no earlier than 4h; immediate form Cmax 0.5-2h; second <= ~4h; third <= 8h) and dose fraction limits (immediate stage 20-50%).
The four-stage option adds a strict “last peak is the fourth stage” requirement and further tightens initiation order and weight distribution (Claim 15).
Treatment method claims extend exposure to once-daily administration for bacterial infection whenever the administered product meets the product claim elements.
In competitive terms, the primary escape routes are violating at least one of the PK timing/ordering gates or the pH sensitivity requirement.

FAQs

1) Does this patent require a specific antibiotic molecule?

The provided claim language does not specify an antibiotic identity in the independent claim text; it claims a once-daily product comprising at least one antibiotic, formulated into the required staged release system. The only explicit limitation in your excerpt is that the antibiotic can be a salt in Claim 37.

2) What is the single biggest numeric constraint in claim 1?

Claim 1 requires that Cmax of the total antibiotic released is achieved in less than about 12 hours from administration while delivering the total 24-hour dose.

3) How does claim 2 narrow the total-product peak?

Claim 2 adds that the product Cmax is reached no earlier than four hours after administration.

4) What staging requirements drive literal infringement risk for the immediate release portion?

Claim 3 sets a 0.5 to 2 hour immediate-stage Cmax window, and Claim 6 sets the immediate-stage dose fraction at 20% to 50% of the total antibiotic dose.

5) Is pH sensitivity required in all delayed-release forms?

No. Claim 1 requires that at least one of the delayed-release forms (second or third) is a pH sensitive dosage form.

References

[1] United States Patent 6,723,341 (claims provided in prompt).

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Details for Patent: 6,723,341

Summary for Patent: 6,723,341