United States Patent 6,669,948: Scope, Claim Map, and US Landscape for Once-Daily Multi-Phase Betalactam Delivery
What does US 6,669,948 claim in scope?
US Patent 6,669,948 is directed to a once-a-day oral (preferred by dependent claims) betalactam antibiotic product that uses multiple dosage forms in a single regimen to create staggered in vivo release profiles. The claims are built around four measurable pharmacokinetic anchors:
- Three-phase system (independent core): first immediate release + second delayed + third delayed, each containing the same betalactam and a pharmaceutically acceptable carrier.
- Release timing discrimination: each dosage form initiates release at different times.
- Total 24-hour exposure: the product contains the total daily antibiotic dose (24-hour period).
- Cmax constraint on total: Cmax of total released betalactam is achieved in < about 12 hours after administration.
- Local per-phase Cmax sequencing and timing: the dependent claims specify when each phase reaches its own Cmax and that later phases reach Cmax only after earlier phases.
The patent’s strongest claim breadth is concentrated in claim 1 (and the closely related dependent set), then narrowed by specifying:
- the betalactam class (cephalosporin; then cefuroxime or cefpodoxime), or
- the betalactam class (penicillin; then dicloxacillin or amoxicillin), and
- tighter Cmax timing rules and dose split ranges.
Independent claim: claim 1 (core scope)
Claim 1 covers:
- “A once-a-day antibiotic product comprising”:
- first, second, third dosage forms
- each dosage form comprises:
- a betalactam antibiotic and
- a pharmaceutically acceptable carrier
- first = immediate release
- second + third = delayed release
- each dosage form initiates release at different times
- Total daily dose: product contains total dosage for 24 hours
- Total Cmax rule: Cmax of the total betalactam released from product achieved in < about 12 hours
Dependent claims: class and pharmacokinetic tightening
The claim set then narrows “betalactam antibiotic” to:
- Claim 2: cephalosporin
- Claim 3: cefuroxime and cefpodoxime (selected from group)
- Claims 4-7: multiple explicit constraints on when Cmax occurs:
- claim 4: total Cmax no earlier than 4 hours
- claim 5: first-phase Cmax: 0.5 to 2 hours
- claim 6: second-phase Cmax: ≤ about 4 hours
- claim 7: third-phase Cmax: within 8 hours
- Claim 8: immediate release phase load: 20% to 50% of total daily dose
- Claims 10-11: strict ordering of phase Cmax:
- claim 10: second-phase Cmax occurs after first-phase Cmax
- claim 11: third-phase Cmax occurs after second-phase Cmax
A parallel track exists for penicillins (claims 45-54 and onward):
- Claim 45: penicillin
- Claim 46: dicloxacillin, amoxicillin (selected)
- Claims 47-51: mirror the cef/betam constraints with penicillins
- Claims 53-54: phase ordering by Cmax sequencing
- Claims 83-84: dicloxacillin product explicitly
- Claims 85-120: amoxicillin product explicitly
How is the claim architecture structured (3-phase vs 4-phase variants)?
Two distinct product architectures run through the claims:
A) Three-dosage-form architecture (independent core)
- First: immediate release
- Second: delayed release
- Third: delayed release
- Key product-wide constraints:
- once-a-day, contains total 24-hour dosage
- total Cmax reached in < about 12 hours
Key additional dependent constraints (example for cephalosporin track):
- total Cmax no earlier than 4 hours (claim 4)
- first-phase Cmax 0.5 to 2 hours (claim 5)
- second-phase Cmax ≤ about 4 hours (claim 6)
- third-phase Cmax within 8 hours (claim 7)
- first-phase weight fraction 20% to 50% (claim 8)
- ordering: 2nd after 1st (claim 10) and 3rd after 2nd (claim 11)
B) Four-dosage-form architecture (broadened by an additional delayed phase)
Claim 12 adds a fourth delayed-release dosage form and imposes weight fraction rules for the 2nd, 3rd, and 4th phases.
- Claim 12 requires:
- first immediate, second delayed, third delayed, fourth delayed
- each dosage form initiates release at different times (implied by “wherein cephalosporin released from said fourth dosage form reaches a Cmax after Cmax is achieved for… each of said first, second, third”)
- Cmax ordering across all phases (via the “after Cmax is achieved” language)
Cephalosporin weight split constraints appear in claim 17:
- Second provides 20% to 35% by weight
- Third provides 20% to 40% by weight
- Fourth provides the remainder
Penicillin analogs mirror these:
- claim 55 uses the same 4th-phase addition logic
- claim 60 mirrors the weight split ranges for penicillin (2nd 20-35%, 3rd 20-40%, 4th remainder)
Weight split: what matters for infringement risk
The patent uses two different weight-fraction formulations depending on architecture:
| Architecture |
Dosage form weight constraints |
Claim examples |
| 3-phase |
Immediate-release portion: 20% to 50% of total |
cefuroxime/cefpodoxime: claim 8; penicillin analog: claim 51; amoxicillin analog: claim 90 |
| 4-phase |
Delayed phases 2nd and 3rd bounded; 4th is remainder |
cephalosporin: claim 17; penicillin: claim 60; amoxicillin: claim 99 |
This means a competitor’s formulation must match not only release timing but also dose allocation across phases.
What betalactam compounds are explicitly covered?
The claims explicitly list betalactam subclasses and exemplar drugs.
Cephalosporin branch
- Claim 2: cephalosporin
- Claim 3: cefuroxime and cefpodoxime
- Claims 41-42: explicit “wherein selected from” style recitations:
- claim 41: cefuroxime
- claim 42: cefpodoxime
Penicillin branch
- Claim 45: penicillin
- Claim 46: dicloxacillin and amoxicillin
- Claims 83-84:
- claim 83: dicloxacillin
- claim 46 plus claim 85 onwards: amoxicillin is expanded into its own explicit set (85-120)
Explicit “product-specific” expansions
The claims include explicit once-daily products for:
- amoxicillin (claims 85-103 for product and 103-120 for method variants)
- dicloxacillin (claim 83, plus method claim 84)
- cefuroxime/cefpodoxime are covered at the cephalosporin stage (claims 3, 41, 42 plus method recitations)
What are the method claims and how do they broaden enforcement?
The patent also includes “process for treating a bacterial infection” claims that are tied to administering the claimed product once-a-day.
- Claim 21 onward: cephalosporin method claims (claim 21 uses claim 1; claim 22 uses claim 2; claim 23 uses claim 3; claims 24-38 map to specific Cmax/timing claims and architecture constraints through claim 12).
- Claims 64-82: penicillin method claims mirroring the product-specific claims 45-61.
- Claims 83-84: dicloxacillin product and its method.
- Claims 103-120: amoxicillin product variants and methods.
Practical effect
These method claims create enforcement hooks even if a product is reformulated or marketed in a way that disputes product claims, as long as the administered regimen meets claim-defined product characteristics and the dosing schedule is once daily.
How tight are the pharmacokinetic boundaries (Cmax timing and sequencing)?
The patent uses both absolute and relational timing constraints.
Total Cmax constraints (product-wide)
- Claim 1: total betalactam Cmax reached in < about 12 hours
- Claim 4: total Cmax reached no earlier than 4 hours
- Claim 13: (4th-phase architecture) total Cmax reached no earlier than 4 hours
Penicillin track:
- claim 47: total Cmax no earlier than 4 hours
- claim 56: (4th-phase) total Cmax no earlier than 4 hours
Amoxicillin track:
- claim 86: total Cmax no earlier than 4 hours
- claim 95: (4th-phase) total Cmax no earlier than 4 hours
Phase-by-phase Cmax constraints
For 3-phase architectures (cephalosporin track):
- claim 5: first-phase Cmax at 0.5 to 2 hours
- claim 6: second-phase Cmax in no more than about 4 hours
- claim 7: third-phase Cmax within 8 hours
- claim 10-11: sequential ordering (2nd after 1st; 3rd after 2nd)
For 4-phase architectures (cephalosporin track):
- claim 14: first-phase Cmax 0.5 to 2 hours
- claim 15: second-phase Cmax ≤ about 4 hours
- claim 16: third-phase Cmax within 8 hours
- claim 17 then defines the additional dose fraction logic for phases 2-4 and requires Cmax ordering across phases (as a continuation of claim 12’s Cmax-after structure).
Penicillin track mirrors these constraints:
- claim 48-50: phase-by-phase Cmax windows
- claim 53-54: sequencing
- claim 57-59: same windows in the 4th-phase architecture
- claim 60: weight fraction split in 4-phase architecture
Amoxicillin track mirrors:
- claim 87-89 and claim 96-98
- claim 92-93 and claim 101-102
- claim 99 for dose split in 4-phase architecture
Dose fraction and release mapping constraints
Immediate-release load rule (3-phase):
- cephalosporin claim 8: 20% to 50%
- penicillin claim 51: 20% to 50%
- amoxicillin claim 90: 20% to 50%
4-phase split rules:
- cephalosporin claim 17: 2nd 20-35%, 3rd 20-40%, 4th remainder
- penicillin claim 60: same ranges
- amoxicillin claim 99: same ranges
What does the competitive design-around space look like within the claim language?
Within this claim set, the “design-around levers” are direct because the claims are measurable and structured.
Core infringement-relevant requirements
A product likely stays within the claim matrix if it simultaneously satisfies:
- once-a-day regimen,
- multi-phase release using at least immediate + delayed phases,
- daily dose partition that matches the claim-defined weight fractions,
- total Cmax timing constraints (<12 hours and no earlier than 4 hours in relevant dependent claims),
- per-phase Cmax timing windows,
- Cmax ordering between phases.
Strongest barriers (claims with “tight” numeric limits)
- Total Cmax must land between a lower bound and upper bound:
- independent claim 1: <12 hours
- dependent claim 4: no earlier than 4 hours (and analogous penicillin/amoxicillin constraints)
- First-phase Cmax must be within 0.5 to 2 hours (cephalosporin claim 5; penicillin claim 48; amoxicillin claim 87)
- Second-phase Cmax must be ≤ about 4 hours (cephalosporin claim 6; penicillin claim 49; amoxicillin claim 88)
- Third-phase Cmax must occur within 8 hours (cephalosporin claim 7; penicillin claim 50; amoxicillin claim 89)
- Ordering constraints:
- Cmax of later releases must follow prior phases (claims 10-11; 19-20; 53-54; 62-63; 92-93; 101-102; etc.)
What can fall outside the scope
A competitor can reduce risk by moving at least one critical dimension outside the numeric windows:
- shift first-phase Cmax earlier than 0.5 hours or later than 2 hours;
- push second-phase Cmax beyond 4 hours;
- push third-phase Cmax beyond 8 hours;
- violate the “total Cmax <12 hours” constraint or the “no earlier than 4 hours” constraint if asserted under dependent claims;
- change phase dose split away from the 20-50% immediate fraction (3-phase) or away from the 20-35% and 20-40% + remainder pattern (4-phase).
Where does the patent sit in the US patent landscape (what other protections are likely relevant)?
The provided information includes claim text only. It does not include:
- publication number, filing date, priority date,
- inventors/assignee,
- prosecution history,
- maintenance status,
- expiration/adjustment,
- family members or continuation claims,
- related patents covering formulation materials, tablet/capsule geometry, coatings, release mechanisms, or specific excipients.
Without those, the only defensible landscape description is the internal claim landscape inside US 6,669,948 itself (product architectures and compound classes). A full “US patent landscape” mapping (competing patents, expiration timelines, FTO grids, overlapping method claims, and filing families) cannot be produced from the claim list alone.
Key claim map (fast view)
Cephalosporin (3-phase)
- Product: claim 3 (betalactam = cephalosporin; select cefuroxime/cefpodoxime)
- Total Cmax: claim 4
- Phase Cmax windows: claim 5-7
- Immediate fraction: claim 8
- Ordering: claim 10-11
- Once-a-day therapy: claims 24-27, 28-31, 32-38 (method claims mapped to those product constraints)
Penicillin (3-phase)
- Product: claim 46 (dicloxacillin/amoxicillin) but with additional product-specific penicillin constraints across claims 47-54
- Total Cmax: claim 47
- Phase Cmax windows: claim 48-50
- Immediate fraction: claim 51
- Ordering: claims 53-54
- Once-a-day therapy: claims 64-70, 71-73, 74-78, 79-82 (method claims mapped to these product constraints)
Amoxicillin (explicit product block)
- Product: claim 85 (3-phase, amoxicillin)
- Variants: claim 86-93 tie down Cmax and phase ordering
- 4th-phase variant: claim 94-102
- Once-a-day therapy: claims 103-120
Key Takeaways
- US 6,669,948 claims a once-daily multi-phase release betalactam antibiotic product that is defined by Cmax timing (total Cmax <12 hours; in dependent claims also “no earlier than 4 hours”) and by per-phase Cmax windows (first: 0.5-2 hours; second: ≤4 hours; third: within 8 hours).
- The claim scope is split into 3-phase (immediate + two delayed) and 4-phase (adds another delayed) architectures.
- The enforcement-relevant tightening is numeric and relational: dose fraction, phase-specific Cmax windows, and Cmax sequencing between phases.
- The compound scope is explicitly directed to cephalosporins (cefuroxime, cefpodoxime) and penicillins (dicloxacillin, amoxicillin) through dependent claim branches and explicit product blocks.
- A valid design-around must change at least one of the claim-defined dimensions: total Cmax timing, phase Cmax timing windows, phase Cmax ordering, or phase dose split.
FAQs
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Is the once-a-day requirement an explicit claim element?
Yes. The product is “once-a-day,” and the method claims require administering the claimed product once-a-day.
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Does the independent claim require specific cephalosporins or penicillins?
No. Claim 1 recites a betalactam antibiotic generically; specificity to cephalosporins and particular cephalosporins appears in dependent claims (e.g., claims 2-3) and the penicillin pathway appears in dependent claims (e.g., claims 45-46).
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What is the main product-wide pharmacokinetic constraint?
Claim 1 requires that Cmax of the total betalactam antibiotic released is achieved in less than about 12 hours.
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Do later delayed phases need to reach Cmax after earlier phases?
Yes. The claims include explicit sequencing language where Cmax for later-releasing dosage forms must occur after Cmax is achieved for earlier phases (example: claims 10-11).
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How does the 4th-dosage-form version change the dose-split constraints?
It changes from an immediate-release weight fraction rule (20% to 50%) to a split across delayed phases: in the cephalosporin track, the second delayed phase is 20-35%, third delayed is 20-40%, and the fourth delayed is the remainder (claim 17), with parallel language for penicillin (claim 60).
References
[1] US Patent 6,669,948, “Once-a-day antibiotic product comprising multiple dosage forms with staggered release,” claims as provided in the prompt.
