United States Patent 5,763,449: Scope, Claims, and US Patent Landscape Analysis
What is the core invention in US 5,763,449?
US Patent 5,763,449 claims ethanol-free, transparent oral liquid formulations that mask the taste of bitter drugs by combining a defined aqueous vehicle with:
- Polyvinylpyrrolidone (PVP): ~5 to ~30 wt% (dependent claim narrows to ~7 to ~15 wt%)
- C3-C6 polyol system: ~45 to ~55 wt% (dependent claims specify mixtures and relative C3/C6 proportions)
- Ammonium glycyrrhizinate: ~0.01 to ~0.5 wt% with a drug:ammonium glycyrrhizinate ratio of ~1:50 to ~1:10
- Flavorants (one or more; not structurally constrained in the independent claim)
The composition must be transparent and have a pleasant oral taste on administration.
This is a formulation claim set with the vehicle composition acting as the principal novelty carrier: the claim recites both solvent constraints (no ethanol; essentially water) and vehicle ratios that define a taste-masking liquid state.
What exactly is claimed in independent claims?
Claim 1 (independent)
Composition type: liquid pharmaceutical composition
Active drug: “a bitter-tasting drug” in pharmaceutically effective amount (no single numeric range in claim 1)
Vehicle: aqueous medium free of ethanol, “consisting essentially of water” plus:
- PVP: ~5 to ~30 wt%
- C3-C6 polyol: ~45 to ~55 wt%
- ammonium glycyrrhizinate: ~0.01 to ~0.5 wt%
- one or more flavorants
Product properties: transparent and pleasant taste when orally administered.
Key structural/numerical anchors
- Ethanol exclusion (“free of ethanol”)
- PVP wt% band
- Polyol wt% band
- Ammonium glycyrrhizinate wt% band
- Functional outcome: transparent + pleasant taste.
Claim 6 (independent, tighter numeric ranges)
Claim 6 provides the same formulation architecture as claim 1, but converts “pharmaceutically effective amount” into explicit concentration bands and locks in the numeric taste-masking system:
- Bitter drug: ~0.5 to ~5 wt%
- Aqueous medium: ethanol-free, essentially water
- PVP: ~7 to ~15 wt%
- C3-C6 polyol: ~45 to ~55 wt%
- ammonium glycyrrhizinate: ~0.01 to ~0.5 wt%
- Flavorants: present
- Ratio constraint: drug : ammonium glycyrrhizinate ~1:50 to ~1:10
- Properties: transparent; pleasant taste orally.
Key practical effect: claim 6 is the most litigation-relevant independent claim for formulation defendants because it supplies hard numeric ranges for most components.
What do the dependent claims add (claim-by-claim scope narrowing)?
Vehicle composition refinements
- Claim 2: PVP is ~7 to ~15 wt% (narrows claim 1’s broader 5–30 wt%)
- Claim 3: C3-C6 polyol is a mixture of C3 polyols and C6 polyols
- Claim 7: depends on claim 6, so repeats the mixture requirement for the tighter independent
- Claim 8: C3 polyol : C6 polyol weight ratio ~1:4 to ~3:5
- Claim 9: polyol other than a C6 polyol constitutes < ~5 wt%
(this limits incorporation of nonconforming polyols within the “C3-C6 polyol” system)
Active drug concentration refinements
- Claim 4: ammonium glycyrrhizinate at a drug-weight ratio ~1:50 to ~1:10 (already in claim 6; it also helps define claim 1’s scope)
- Claim 5: drug present ~0.5 to ~5 wt% (aligns with claim 6’s numeric window)
- Claim 10: drug present ~1 to ~3 wt% (narrows claim 6’s 0.5–5 wt%)
Drug identity limitations (taste-masking exemplars as narrower sub-species)
- Claim 11: specifies a selected list of bitter drugs that can be used
- Claim 12: explicitly sets guaifenesin
- Claim 13: explicitly sets trimethoprim
Implication for scope: claims 12 and 13 provide narrower claim targets for specific actives; claim 11 provides a class of enumerated “bitter-tasting drugs” that strengthens enforceability against formulations using any listed species, even if those actives are not otherwise distinguished by the vehicle.
What is the functional claim perimeter (how an accused product maps)?
US 5,763,449 is likely to be enforced as follows:
1) Ethanol-free aqueous matrix is a gate
- Any accused product using detectable ethanol risks failing the “free of ethanol” limitation (depending on how “free” is construed in litigation and product specification).
2) “Consisting essentially of water” narrows excipients
Because the aqueous medium is “consisting essentially of water,” the vehicle must include the claimed solubilizers/structural excipients and flavorants, but cannot broaden into alternative solvent/excipient systems without raising “essentially” issues.
3) Quantitative vehicle ratios are high-friction design constraints
To fall within the independent claims, a product must land inside multiple overlapping numeric windows:
- PVP band (5–30 in claim 1; 7–15 in claim 6)
- C3–C6 polyol band (45–55)
- ammonium glycyrrhizinate band (0.01–0.5)
- drug band (pharmaceutically effective in claim 1; 0.5–5 in claim 6; 1–3 in claim 10)
- drug:glycyrrhizinate ratio (1:50 to 1:10)
4) Transparency and pleasant taste are required properties
These are not chemistry limitations but can drive evidence requirements (product appearance specifications and sensory testing). In enforcement, they can also become a vulnerability if an accused product shows different appearance or taste performance.
Claim coverage map for business decisioning
The following table shows the “hard boundaries” that define entry into the claimed formulation space.
| Parameter |
Claim 1 requirement |
Claim 6 requirement |
Tightest dependent narrowing |
| Ethanol |
Must be ethanol-free |
Must be ethanol-free |
Not further narrowed |
| Aqueous medium |
Essentially water |
Essentially water |
Not further narrowed |
| PVP |
5–30 wt% |
7–15 wt% |
Claim 2 matches claim 6 band |
| C3-C6 polyol |
45–55 wt% |
45–55 wt% |
Claim 3/7 requires C3 + C6 mixture |
| C3/C6 proportion |
Not quantified |
Not quantified |
Claim 8: C3:C6 = 1:4 to 3:5 |
| Non-C6 polyol presence |
Not quantified |
Not quantified |
Claim 9: non-C6 polyol <5 wt% |
| Ammonium glycyrrhizinate |
0.01–0.5 wt% |
0.01–0.5 wt% |
Claim 4 ratio: drug:glycyrrhizinate = 1:50 to 1:10 |
| Drug concentration |
“Pharmaceutically effective amount” |
0.5–5 wt% |
Claim 10: 1–3 wt% |
| Drug:glycyrrhizinate ratio |
1:50 to 1:10 (via claim 4) |
1:50 to 1:10 |
Same |
| Flavorants |
Present (“one or more flavorants”) |
Present |
Not specified |
| Product properties |
Transparent; pleasant taste orally |
Transparent; pleasant taste orally |
Not further narrowed |
| Drug species |
Any bitter-tasting drug |
Any bitter-tasting drug |
Claims 11-13 list/define sub-species |
What is the practical competitive threat?
US 5,763,449 targets a repeatable formulation chassis. It is not just for a single API; it is for a bitter-drug + ethanol-free PVP/C3-C6 polyol + ammonium glycyrrhizinate + flavorants architecture.
That matters because it can support:
- Multiple product reformulations across different bitter actives (especially those in claim 11)
- Generic or label-driven competition where the active is already known but the taste-masked vehicle is the contested differentiator.
US patent landscape: how to think about “scope” versus “blocking” patents
Without retrieving the full prosecution histories and citation network for US 5,763,449, the reliable landscape characterization from the claim text alone is structural:
The patent is framed as formulation-in-vehicle, not method-of-treatment
No dosing regimen claims appear in your claim set. That shifts landscape analysis toward:
- vehicle composition overlap
- solvent exclusion (ethanol)
- specific taste-masking adjuvant choice (ammonium glycyrrhizinate)
- defined polymer + polyol system
Likely “design-around” levers visible from the claim structure
Any product attempting to avoid literal scope would focus on at least one of these:
- introduce ethanol (break “free of ethanol”)
- change PVP concentration outside the claimed bands
- move polyol concentration outside 45–55 wt% or swap away from C3–C6 polyols
- replace ammonium glycyrrhizinate with another sweetener/masking agent (and/or break the drug:glycyrrhizinate ratio)
- remove the transparency requirement (if feasible without compromising oral acceptability)
- adjust drug concentration outside the 0.5–5 wt% (and possibly 1–3 wt% depending on which dependent claim is asserted)
Likely “competitive capture” levers visible from the claim scope
A developer seeking to stay inside the claim space (for licensing or risk avoidance) would:
- keep ethanol absent
- maintain the PVP and polyol wt% targets
- keep ammonium glycyrrhizinate within 0.01–0.5 wt% and meet the drug:glycyrrhizinate ratio
- use C3 and C6 polyols in a controlled ratio (if seeking additional protection under claim 8/9)
- include flavorants
- meet the appearance and taste constraints through formulation and sensory testing
Drug list in claim 11: coverage implications
Claim 11 lists the following bitter-tasting drugs as expressly within the claim’s covered sub-species:
acetaminophen, terfenadine, guaifenesin, trimethoprim, prednisolone, ibuprofen, prednisolone sodium phosphate, methacholine, neostigmine, epinephrine, albuterol, pseudoephedrine hydrochloride, diphenhydramine, chlorpheniramine maleate, phenothiazine, chlorpromazine, chlordiazepoxide, amitriptyline, barbiturates, diphenylhydantoin, caffeine, morphine, demerol, codeine, lomotil, lidocaine, salicylic acid, sulfonamides, chloroquine, and penicillins. (Claim 11 text in provided dataset.)
Sub-species singled out
- guaifenesin (claim 12)
- trimethoprim (claim 13)
From a landscape perspective, this list signals the patent’s intended enforcement posture: it is designed to map to specific formulation opportunities where taste masking is a real development barrier.
Key Takeaways
- US 5,763,449 claims ethanol-free, transparent oral liquid taste-masked compositions using a defined PVP + C3-C6 polyol + ammonium glycyrrhizinate + flavorants vehicle.
- Claim 6 is the most concrete independent claim: it sets explicit bands for drug (0.5–5 wt%), PVP (7–15 wt%), polyol (45–55 wt%), and ammonium glycyrrhizinate (0.01–0.5 wt%), plus the drug:glycyrrhizinate ratio (1:50 to 1:10).
- Dependent claims tighten formulation further via C3/C6 mixture ratios (claim 8) and limit on non-C6 polyols (claim 9), and narrow drug to 1–3 wt% (claim 10).
- Claim 11 enumerates a broad set of bitter actives, with guaifenesin and trimethoprim called out in claims 12 and 13.
- In a competitive landscape, the visible design-arounds are straightforward from the claim text: ethanol inclusion, component substitution (especially ammonium glycyrrhizinate), and out-of-range vehicle concentrations.
FAQs
1) Does US 5,763,449 require ethanol-free formulations?
Yes. Both independent claim 1 and independent claim 6 state the aqueous medium is free of ethanol and “consisting essentially of water” with the specified excipients.
2) Is ammonium glycyrrhizinate mandatory?
Yes. The formulation includes ammonium glycyrrhizinate at 0.01–0.5 wt%, and dependent claim 4/independent claim 6 incorporates the drug:glycyrrhizinate ratio 1:50 to 1:10.
3) Are C3-C6 polyols required?
Yes. The claims require C3-C6 polyol at 45–55 wt%. Dependent claims require a mixture of C3 and C6 polyols (claims 3 and 7).
4) Which claim is most relevant for risk screening of product formulations?
Claim 6, because it contains the tight numeric bands for drug, PVP, polyol, ammonium glycyrrhizinate, and the drug:glycyrrhizinate ratio.
5) Does the patent cover specific drugs or any bitter drug?
Claim 1/6 covers “a bitter-tasting drug.” Claim 11 then provides an enumerated list of bitter drugs within the covered sub-species, with guaifenesin and trimethoprim singled out in claims 12 and 13.
References
- United States Patent 5,763,449 (claims provided in prompt).
