Scope, Claims, and US Patent Landscape for US 6,071,523
US 6,071,523 claims a tightly specified oral, “spill-resistant” semi-solid dosing formulation dispensed from a squeezable container and measured in a spoon bowl. The claim scope is driven by (i) rheology measured by Brookfield conditions, (ii) squeeze/flow performance through a narrow channel, (iii) spoon bowl retention time under defined stressors (tilt and vibration), and (iv) compositional constraints on the liquid base (notably glycerin with optional propylene glycol) and the thickener system (cellulose derivatives plus limited water-soluble carboxyvinyl polymer), with a storage stability rheology window for at least 3 months at elevated temperature.
What does US 6,071,523 claim cover (scope in practical terms)?
Core combination required by claim 1
Claim 1 is a closed combination: a spill-resistant pharmaceutical formulation for oral administration from a squeezable container, with mutually compatible components, that meets a full set of performance and stability parameters.
Dispensing and measuring system
- Oral administration from a squeezable container.
- “Channel” through which the formulation is squeezed:
- About 1–1.5 mm (claim 1).
- Measurement on a spoon bowl:
- Must spread “sufficiently quickly for accurate measurement.”
- Must remain in spoon bowl without spilling for defined durations under spoon stress tests:
- ≥ 1 second and < 20 seconds on spoon tilting at 90 degrees.
- ≥ 30 seconds upon spoon vibration at ~120/minute.
Rheology and processing window
- Initial viscosity: 7,500 to 12,500 cps
- Measurement method:
- Brookfield Viscometer
- C spindle
- Helipath movement
- 20 rpm
- 20–25°C
- “Viscometric yield value of a semi-solid” (semi-solid behavior tied to yield response rather than a purely Newtonian fluid).
- Storage stability:
- Properties retained for at least 3 months at elevated temperature
- Viscosity remains within 50% less to 100% more than initial viscosity
Thickener system
- Thickening agent comprises:
- Cellulose derivatives: < 2 weight % by volume
- Water-soluble carboxyvinyl polymer: < 1 weight % by volume
Claim 2 and 3 narrow the storage viscosity window
- Claim 2: after 3 months at 40°C and 75% humidity, viscosity is 7,500 to 25,000 cps
- Claim 3: after storage, viscosity is 7,500 to 12,500 cps (tighter than claim 2)
Claims 4–8 specify carboxyvinyl polymer amount and example cellulose/copolymer selections
- Claim 4: carboxyvinyl polymer: 0.25 to < 1 weight % by volume
- Claim 8: carboxyvinyl polymer: 0.25 to 0.5 weight % by volume
- Claim 6 (example explicit dual cellulose):
- Sodium carboxymethylcellulose ~0.9%
- Microcrystalline cellulose ~0.9%
- Claim 7 adds a specific glycerin/sorbitol solution scheme:
- Cellulose derivatives < 2 wt%
- Glycerin and sorbitol as a ~70% in water solution
- Combined concentration of glycerin and sorbitol solution: ~40%
Claims 5, 10, 17–18 define liquid base compositions (glycerin-centric)
- Claim 5: liquid base comprises glycerin and sorbitol
- Claim 10: cellulose derivatives < 2 wt% and liquid base includes propylene glycol 10–85 wt% by volume
- Claim 17: liquid base contains 30%–50% glycerin
- Claim 18: plus propylene glycol up to ~25 wt% by volume
Claims 9, 16, 13–15 define performance limits for spoon behavior and system packaging
- Claim 9: spill resistance on spoon:
- 1–4 seconds on spoon inversion/tilting at 90°
- Claims 13–16:
- System includes squeezable container:
- claim 13: system with container and ready-to-use delivery system
- claim 14: single dose
- claim 15: multiple doses
- claim 16: spoon bowl receptacle attachable to container
Claims 11–12: pharmaceutical agent lists are broad
Claim 11: pharmaceutical agent can be one of many therapeutic classes (analgesic, NSAID, antihistamine, cough suppressant, expectorant, bronchodilator, anti-infective, CNS, cardiovascular, antineoplastic, cholesterol lowering, anti-emetic, vitamins/minerals, fecal softener).
Claim 12: provides an explicit exemplar set including (non-exhaustive):
- Acetaminophen, aspirin, ibuprofen
- Diphenhydramine, dextromethorphan
- Guaifenesin, pseudoephedrine
- Carbidopa/levodopa, terfenadine, ranitidine
- Ciprofloxacin, triazolam, fluconazole
- Propranolol, acyclovir, fluoxetine, enalapril, diltiazem
- Lovastatin
- Plus pharmaceutically acceptable salts/esters
Landscape impact: the patent strength is mostly in the formulation and dosing/rheology system, not in the identity of the drug.
How broad is claim coverage versus design-around opportunities?
Key “attack surface” for validity and infringement
The claims require all conditions to be met simultaneously. That creates both (i) a narrow infringement test and (ii) a higher burden for defendants to prove they hit every rheology and spoon-performance threshold.
Infringement is likely to turn on measurable parameters:
- Brookfield viscosity at specified spindle/rpm/temperature.
- Yield value indicating semi-solid.
- Channel diameter (claim 1: 1–1.5 mm).
- Spoon retention:
- tilt at 90° time bounds (claim 1: ≥1 and <20 seconds)
- vibration time bound (claim 1: ≥30 seconds at 120/min)
- Storage viscosity stability window (claim 1: viscosity after storage within 50% less to 100% more of initial)
Design-around levers typically include:
- Changing rheology outside the viscosity band at the specified Brookfield settings.
- Changing thickener composition (e.g., removing carboxyvinyl polymer or using a different polymer system) or exceeding the stated limits.
- Changing liquid base composition away from glycerin/sorbitol concentration targets, or changing propylene glycol level outside the specified ranges in dependent claims.
- Changing the spoon bowl performance metrics by altering yield and thixotropy so that retention time fails the bounds.
- Changing dispensing geometry (channel size) or using a different delivery device that doesn’t rely on squeeze through the claimed channel dimension.
Claim 19–24: second formulation family with different channel and vibration metrics
Claims 19–24 reframe the formulation with distinct constraints:
- Channel:
- claim 19: 1–5 mm (wider than claim 1)
- Vibration spill resistance:
- claim 19: at least 1 minute (vs claim 1: at least 30 seconds)
- Liquid base:
- claim 19: glycerin 30%–50%
- Thickener quantitative range differs:
- claim 20: cellulose derivatives 0.9–2.5 wt%
- claim 20: carboxyvinyl polymer <1 wt%
- Claims 21–23 specify glycerin level at ~50% or ~30% and propylene glycol up to 25%.
- Claim 24: dual cellulose example again:
- sodium carboxymethylcellulose ~0.9%
- microcrystalline cellulose ~0.9%
Net effect: the claim set includes at least two closely related “rheology regimes” with different mechanical/dosing performance parameters (channel and vibration thresholds). That reduces the likelihood that a single modification fully avoids all asserted claim families.
What is the patent landscape around US 6,071,523 (what to map for freedom-to-operate)?
How to read the landscape question for this specific patent
Based on the claim language provided, the relevant landscape areas to map are not other drugs, but other patents covering:
- Semi-solid oral dosing formulations
- Rheology-controlled semi-solid gels/pastes for dosing accuracy.
- Squeeze-dispensing oral systems
- Delivery from squeezable containers with controlled flow.
- Spill-resistant dosing in a spoon or dosing receptacle
- Retention under tilt and vibration.
- Cellulose derivative + carboxyvinyl polymer thickener systems
- Limited carboxyvinyl polymer levels plus cellulose derivatives under weight % by volume constraints.
- Glycerin-dominant liquid base with optional propylene glycol
- Rheology measured and specified at Brookfield C spindle/20 rpm/20–25°C
- Storage stability windows (viscosity tolerance after 3 months at elevated temperature).
Practical landscape mapping targets (by claim elements)
Because the claims are heavily parameterized, infringement/FTO analysis should treat prior art as “element-by-element” rather than “category-by-category.” For competitor products and formulation patents, you should prioritize:
- Prior art that teaches viscosity 7,500–12,500 cps at specified Brookfield conditions.
- Prior art that teaches semi-solid yield behavior for scoopable/spoonable dosing.
- Prior art that teaches spoon retention metrics (tilt 90° time; vibration time at ~120/min).
- Prior art that teaches thickener packages:
- cellulose derivatives at <2 wt% (or 0.9–2.5 wt% in the second regime)
- water-soluble carboxyvinyl polymer below 1 wt% by volume
- Prior art that teaches glycerin/sorbitol (and glycerin + propylene glycol variants) at ~30–50% glycerin.
- Prior art that teaches the same or analogous channel size for squeeze dispensing (1–1.5 mm vs 1–5 mm).
Business takeaway: the strongest competitor encroachment risk usually comes from patents that are already about “spoonable, pourable but non-drip” semi-solids for dosing from squeezable applicators or containers.
How strong is the enforceable claim scope based on the provided claim set alone?
Strength factors
- Hard numeric limitations reduce ambiguity in infringement and increase the likelihood that a court or examiner treats the claim as narrow and testable.
- Method-like device/behavior requirements (tilt 90°, vibration at ~120/min) create a distinctive performance envelope, which is harder for generic formulation changes to accidentally satisfy.
- Compositional limitations (cellulose derivative and carboxyvinyl polymer amounts; glycerin concentration) provide additional defense against broader prior art.
Weakness factors (for challengers to exploit)
- The drug identity is broadly listed (claim 11–12). If a challenger can find prior art semi-solid spill-resistant oral dosing systems with the same rheology/thickeners for any drug, the drug-identity breadth can make it easier to argue obviousness.
- The thickener categories are broad (“cellulose derivatives” and “carboxyvinyl polymer”) but the quantitative caps are narrow. Prior art that uses related cellulose derivatives below those caps is still potentially close.
Claim-by-claim scope map (what each dependent claim adds)
| Claim |
Adds/Changes |
Practical scope effect |
| 1 |
Baseline spill-resistant semi-solid; Brookfield viscosity 7,500–12,500 cps; channel ~1–1.5 mm; tilt 90°: ≥1 and <20 s; vibration: ≥30 s; stability 3 months with viscosity 50% less to 100% more; thickener: cellulose derivatives <2 wt%/vol + carboxyvinyl polymer <1 wt%/vol |
Anchor claim; defines the infringement “sweet spot” |
| 2 |
Storage at 40°C, 75% RH: viscosity 7,500–25,000 cps |
Adds storage robustness band |
| 3 |
After storage: viscosity 7,500–12,500 cps |
Tightens to initial band |
| 4 |
Carboxyvinyl polymer: 0.25 to <1 wt%/vol |
Limits lower and upper polymer range |
| 5 |
Liquid base includes glycerin + sorbitol |
Composition-specific variant |
| 6 |
Thickener example: Na CMC ~0.9% + microcrystalline cellulose ~0.9% |
Narrow embodiment |
| 7 |
Adds glycerin/sorbitol solution scheme: ~70% solution, combined concentration ~40% |
More specific base preparation |
| 8 |
Carboxyvinyl polymer: 0.25–0.5 wt%/vol |
Narrower polymer window |
| 9 |
Tilt/inversion spill resistance tightened: 1–4 s |
Narrows the spoon retention range |
| 10 |
Liquid base includes propylene glycol 10–85 wt%/vol |
Expands liquid base alternatives |
| 11 |
Drug class list |
Broad drug coverage under same formulation/device constraints |
| 12 |
Example drugs list |
Confirms non-limiting exemplars for same formulation scope |
| 13 |
Adds squeezable container system |
Converts formulation into a delivery system claim set |
| 14 |
Single dose container |
Device embodiment |
| 15 |
Multiple doses container |
Device embodiment |
| 16 |
Spoon bowl receptacle attachable |
Delivery system packaging |
| 17 |
Glycerin in base 30%–50% |
Base concentration band |
| 18 |
Propylene glycol up to ~25 wt%/vol |
Optional base tuning |
| 19 |
Second regime: channel 1–5 mm; vibration ≥1 minute; stability + viscosity window retained; base glycerin 30%–50% |
Different mechanical thresholds |
| 20 |
Thickener in second regime: cellulose derivatives 0.9–2.5 wt% + carboxyvinyl polymer <1 wt%/vol |
Tightens cellulose in second family |
| 21 |
Base glycerin ~50%; carboxyvinyl polymer 0.25–1 wt% |
More specific |
| 22 |
Add propylene glycol up to 25 wt% |
More specific variant |
| 23 |
Base glycerin ~30%; cellulose derivatives 0.9–2.5 wt% |
More specific variant |
| 24 |
Thickener example: Na CMC ~0.9% + microcrystalline cellulose ~0.9% |
Narrow embodiment |
Key Takeaways
- US 6,071,523 is a rheology-and-performance driven patent: infringement depends on matching Brookfield viscosity, yield semi-solid behavior, and defined spoon bowl retention under tilt and vibration, plus meeting strict thickener and liquid base constraints.
- The claim set has two principal formulation regimes: claim 1 uses a narrower squeeze channel (1–1.5 mm) and lower vibration retention threshold (≥30 s), while claim 19 expands channel size (1–5 mm) and raises vibration retention (≥1 minute).
- Drug identity is broad, so the patent landscape risk concentrates on formulation thickener packages (cellulose derivatives + limited carboxyvinyl polymer), glycerin-centered liquid bases, and device-linked spill resistance behavior rather than on any single active ingredient.
- For freedom-to-operate, the highest-value prior art mapping targets are patents that match the same measured viscosity band under Brookfield C/20 rpm/20–25°C and replicate the spoon tilting and vibration performance metrics.
FAQs
1. What are the defining rheology limits in claim 1?
Initial Brookfield viscosity is 7,500 to 12,500 cps using Brookfield C spindle, Helipath movement, 20 rpm, 20–25°C, and viscosity after 3-month elevated storage stays within 50% less to 100% more of the initial viscosity.
2. What thickener constraints does claim 1 impose?
Cellulose derivatives are <2 weight % by volume, and water-soluble carboxyvinyl polymer is <1 weight % by volume.
3. What spoon performance must the formulation meet?
On 90° tilt, it must remain in the spoon bowl at least 1 second and less than 20 seconds (claim 1), and on spoon vibration at ~120/min, it must remain for at least 30 seconds (claim 1). Claim 9 narrows tilt/inversion retention to 1–4 seconds.
4. How does claim 19 differ from claim 1?
Claim 19 expands the squeeze channel to 1–5 mm and increases the vibration retention requirement to at least 1 minute, while keeping viscosity stability within the same relative window.
5. Does the patent cover multiple drugs?
Yes. Claims 11 and 12 list many therapeutic classes and specific exemplar actives, but coverage still requires the same formulation/device performance constraints.
References
[1] US Patent 6,071,523. “Spill resistant pharmaceutical formulation for oral administration from a squeezable container.” (Claims as provided in the prompt).
