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Patent landscape, scope, and claims: |
Executive summary
US Patent 12,005,062 claims a ready-to-use liquid oral formulation of sildenafil citrate (10 mg/mL) with a defined particle size distribution (d90 10–100 microns; narrower ranges in dependent claims) and specific liquid excipient system limits, led by a glycerin wetting agent (100–1,000 mg/mL; narrower subranges), plus optional buffering (selected acids/bases), anti-foaming, viscosity modifiers (water-soluble hydrocolloids), and preservatives. Independent claim scope is broad across excipient selections but is structurally anchored to (i) formulation form (ready-to-use liquid oral), (ii) sildenafil concentration (about 10 mg/mL as sildenafil citrate), (iii) sildenafil particle size d90 band, and (iv) glycerin wetting-agent amount band. Dependent claims then narrow to pH windows (4–8; 4–6; pH ~5) and stability criteria (6 months at 25°C/60% RH with impurity thresholds), and method-of-use claims cover hypertension/pulmonary hypertension/PAH/erectile dysfunction.
This patent’s practical enforceability against generic entrants typically turns on whether the challenger’s product matches the anchored formulation constraints, especially glycerin amount and sildenafil citrate d90. Route-to-design-around is largely via moving outside the d90 particle size band and/or eliminating or materially changing the glycerin wetting-agent concentration while keeping drug concentration at ~10 mg/mL.
United States Patent 12,005,062 sildenafil citrate ready-to-use liquid oral formulation claims scope and excipient particle-size limits
What is the core invention in US 12,005,062?
At the center is a specific liquid oral formulation architecture:
- Dosage form: “ready-to-use liquid oral formulation”
- Active: about 10 mg/mL sildenafil “as sildenafil citrate”
- Particle size: sildenafil citrate d90 = 10 to 100 microns (with multiple dependent narrowing bands)
- Wetting agent: excipients include glycerin at 100 to 1,000 mg/mL (with multiple narrower subranges)
- Optional/Dependent additions: pH control, buffering agents (specific acid/base list), anti-foaming agents, viscosity modifiers (water-soluble hydrocolloids), preservatives (specific list), plus an explicit stability characterization in a dependent claim.
Claim 1 anchor points (scope drivers)
Independent claim 1 binds four measurable parameters:
- Concentration: ~10 mg/mL sildenafil (as sildenafil citrate)
- Particle size distribution: d90 10–100 µm
- Glycerin wetting agent amount: 100–1,000 mg/mL (as a distinct excipient condition)
- “Ready-to-use liquid oral” formulation context (not a concentrate, not a solid dispersion, not an intermediate requiring dilution)
Dependent claims then carve out “bands” that can be targeted in enforcement or in design-around.
How broad is claim 1 across excipients?
Claim 1 requires that excipients include the glycerin wetting agent at a defined level. It does not require inclusion of particular buffering agents, anti-foaming agents, hydrocolloids, or preservatives. That means a generic could potentially keep glycerin within the claim band while swapping other excipients and still fall within claim 1.
How do the particle size and glycerin ranges in US 12,005,062 control infringement risk?
What sildenafil citrate d90 bands are claimed?
Claim 1 sets the outer band; dependent claims narrow:
| Claim |
Sildenafil citrate d90 range (microns) |
Scope implication |
| 1 |
10 to 100 |
Broadest particle-size cover |
| 8 |
10 to 50 |
Removes upper half (50–100) if d90 > 50 |
| 9 |
20 to 50 |
Removes low (10–20) if d90 < 20 |
| 10 |
20 to 30 |
Tightest particle-size cover for a subset product profile |
What glycerin wetting-agent bands are claimed?
Dependent claims define multiple subranges:
| Claim |
Glycerin concentration (mg/mL) |
Scope implication |
| 1 |
100 to 1,000 |
Core glycerin band |
| 11 |
200 to 1,000 |
Upper portion if glycerin ≥ 200 |
| 12 |
200 to 800 |
Upper cut if glycerin > 800 |
| 13 |
200 to 600 |
Narrower |
| 14 |
300 to 500 |
Further narrow |
| 15 |
~400 (about 400 mg/mL) |
If product targets ~400, likely hits multiple dependent tiers |
Practical enforcement lens: a challenger must typically prove the accused product does not satisfy both (i) the d90 band and (ii) the glycerin amount band if claim 1 is asserted. Many design-arounds fail because formulation development keeps glycerin for wetting/handling.
What pH limitations are in US 12,005,062 and how do they narrow claim coverage?
Are pH ranges part of claim 1?
No. pH limitations are in dependent claims 2–4.
| Claim |
pH range |
Direct impact |
| 2 |
4 to 8 |
Intermediate narrowing |
| 3 |
4 to 6 |
Narrower |
| 4 |
about 5 |
Tightest dependent pH |
Infringement impact: if a generic product has correct claim 1 glycerin and particle-size, it could still infringe claim 1 even if pH differs. But it may avoid dependent claims 2–4.
Which buffering systems are covered by US 12,005,062 dependent claims?
Buffering agents: selected acids/bases lists
Claim 5 adds the concept of a buffering agent; claims 6–7 list permitted buffering agents:
- Claim 6: buffering agent comprising at least one from a long enumerated list (acetic, adipic, ammonium carbonate, ammonium hydroxide, ammonium phosphate, boric acid, citric acid, fumaric acid, malic acid, phosphoric acid, propionic acid, potassium acetate/bicarbonate/citrate/metaphosphate/phosphate, sodium acetate/bicarbonate/citrate/glycolate/lactate/phosphate/propionate, succinic acid, tartaric acid, tri-sodium citrate, triethanolamine, tromethamine/trolamine, triethylamine, and more).
- Claim 7: narrower subset buffering agents (acetic acid, adipic acid, boric acid, citric acid, fumaric acid, malic acid, phosphoric acid, propionic acid, succinic acid, tartaric acid, plus combinations).
Scope implication: dependent claims do not force buffer presence, but if the formulation uses buffering agents from the listed sets and satisfies claim 1’s anchors, it can stack dependent infringement.
What anti-foaming, viscosity-modifying, and preservative excipients are claimed?
Anti-foaming agent coverage
Claim 16 includes anti-foaming agent selection; claims 17–18 quantify specific bands:
- Claim 16: anti-foaming agent chosen from simethicone / simethicone emulsion / organic phosphate / paraffin oil / stearate / glycol (or combinations)
- Claim 17: same concept with amount 0.1 to 100 mg/mL
- Claim 18: a specific combination and amount about 0.5 mg/mL
Viscosity modifying agent coverage (hydrocolloids)
- Claim 19: adds viscosity modifying agent
- Claim 20: viscosity agent comprising one or more water-soluble hydrocolloids
- Claim 21: concentration 1 to 20 mg/mL
- Claim 22: long list of eligible hydrocolloids including acacia, agar, alginic acid, carbomer, carmellose sodium, dextrin, gelatin, veegum, gellan gum, sodium alginate, methylcellulose, hydroxyethyl cellulose, hypromellose, maltodextrin, modified starch, pectin, poloxamer, polycarbophil, PEG, polyvinyl acetate/pyrrolidone, pregelatinized starch, carboxymethyl cellulose, microcrystalline cellulose (among others), xanthan gum, and more
- Claim 23: narrower sublist (e.g., acacia, agar, alginic acid, gelatin, gellan gum, gum arabic, karaya gum, sterculia gum, tragacanth, xanthan gum, carageenan, guar gum, and combinations)
Preservatives coverage
- Claim 24: preservatives selected from a list (ethanol, chlorobutanol, phenoxyethanol, potassium benzoate, benzyl alcohol, benzoic acid, potassium sorbate, sorbic acid, benzalkonium chloride, benzethonium chloride, etc., plus parabens and phenolic preservatives)
- Claim 25: narrower selection and concentration 0.1 to 100 mg/mL
Stacking risk: If a product uses the listed preservatives/hydrocolloids/anti-foaming agents while meeting claim 1 anchors (10 mg/mL sildenafil, d90 band, glycerin band), then dependent claims can materially strengthen position.
What stability characterization is claimed in US 12,005,062 and why it matters for enforcement?
Claim 26 (dependent) is a defined stability test
Claim 26 states the formulation is “stable for up to six months when stored at 25°C and 60% relative humidity,” with impurity thresholds:
- Any individual impurity < 0.2%
- Total impurities < 1.0%
Enforcement implication: this is a secondary technical hook. If claim 1 is met, claim 26 can support inducement/validation of the exact formulation profile if accused products were developed using the same impurity profile targets. If a challenger’s formulation uses different impurity behavior, it may avoid claim 26 while still infringing claim 1.
What method-of-use claims does US 12,005,062 cover and what conditions are explicitly listed?
Independent therapeutic use concept
Claims 27–30 cover administration of the claim 1 formulation to treat:
- Claim 27: hypertension, pulmonary hypertension, arterial hypertension, pulmonary arterial hypertension, and erectile dysfunction
- Claim 28: hypertension, pulmonary hypertension, arterial hypertension, pulmonary arterial hypertension
- Claim 29: pulmonary arterial hypertension
- Claim 30: erectile dysfunction
Method-of-use infringement practicalities
Because method claims tie to “administering … a therapeutically effective amount” of the claimed formulation, a litigant can pursue either:
- Direct product infringement where sales and labeling implicate these conditions; and/or
- Induced/contributory theories tied to instruction to treat these indications with the accused product.
What is the likely geographic and Orange Book posture for US 12,005,062?
No Orange Book status, application/approval linkage, or jurisdictional maintenance data is provided in the input. Without the associated drug product identity and the patent’s Orange Book entry, a complete, accurate US exclusivity and paragraph IV analysis cannot be produced from the claim text alone.
How does the dependent claim narrowing strategy affect generic entry risk for sildenafil liquid oral products?
The claim set is layered: broad claim 1 plus multiple dependent “precision bands”
- Claim 1: wide, anchored on d90 10–100 µm and glycerin 100–1,000 mg/mL
- Dependent claims: tighten on d90 10–50, 20–50, 20–30 and glycerin 200–1,000, 200–800, 200–600, 300–500, ~400
- Additional dependent constraints: pH windows, buffer selection, anti-foaming category and amount, hydrocolloid type and amount, preservative category and amount, and stability criteria
Design-around map (what to change to avoid claim 1 vs avoid dependents)
- To avoid claim 1: change either the sildenafil citrate d90 out of 10–100 µm or shift glycerin outside 100–1,000 mg/mL, or avoid the “ready-to-use liquid oral” format and/or “about 10 mg/mL” sildenafil concentration.
- To avoid only dependents:
- adjust pH away from 4–8 / 4–6 / ~5 to avoid claims 2–4
- adjust glycerin away from listed subranges to avoid claims 11–15
- adjust particle size into a band not covered by dependents (but still within claim 1 if enforcing against claim 1 only)
- select buffers/preservatives/hydrocolloids/anti-foaming agents outside the enumerated sets, or adjust their amounts away from the enumerated ranges
How strong is the patent estate for protecting a sildenafil citrate liquid formulation conceptually?
Strength factors inherent in the claim language
- The claim is tied to measurable formulation attributes: d90 and glycerin mg/mL
- It covers form + concentration + particle size + excipient amount, not merely a general concept of “liquid sildenafil”
- It adds multiple dependent constraints that can be used to argue that an accused formulation matches a specific technical recipe
Vulnerability factors inherent in the claim language
- The breadth of glycerin and d90 ranges can make infringement factual disputes likely, centered on:
- method of measuring d90
- selection of sampling/handling conditions
- formulation quantification of glycerin and sildenafil concentration
- Dependent constraints that rely on enumerated lists can be avoided by choosing non-listed excipients or different functional categories, if the product still avoids claim 1.
Key Takeaways
- US 12,005,062 protects a ready-to-use liquid oral sildenafil citrate formulation with ~10 mg/mL sildenafil, sildenafil citrate d90 of 10–100 µm, and glycerin wetting agent at 100–1,000 mg/mL as the core claim 1 anchors.
- Dependent claims materially narrow into d90 10–50, 20–50, 20–30 µm and glycerin 200–1,000; 200–800; 200–600; 300–500; ~400 mg/mL bands.
- Additional dependent layers cover pH (4–8; 4–6; ~5), buffer systems (listed acids/bases), anti-foaming agents (listed categories and amounts), water-soluble hydrocolloid viscosity modifiers (listed excipients and 1–20 mg/mL), preservatives (listed categories and 0.1–100 mg/mL), and a 6-month stability test with impurity limits.
- Method-of-use claims cover hypertension/pulmonary hypertension/PAH and erectile dysfunction, tied to administration of the claim 1 formulation.
FAQs
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What parameters must a sildenafil liquid oral generic match to infringe US 12,005,062 claim 1?
It must meet the combined requirements of ready-to-use liquid oral format, ~10 mg/mL sildenafil as sildenafil citrate, sildenafil citrate d90 of 10–100 µm, and glycerin wetting agent at 100–1,000 mg/mL.
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How can a challenger avoid infringement of US 12,005,062 without changing sildenafil concentration?
By moving sildenafil citrate d90 outside the claim band and/or moving glycerin outside the 100–1,000 mg/mL range, while also managing formulation category and “about 10 mg/mL” constraints.
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Do pH limitations in US 12,005,062 matter if claim 1 is satisfied?
They are in dependent claims (2–4). A product matching claim 1 can still infringe regardless of pH, but it may avoid those dependent claims by choosing a pH outside the covered windows.
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Which dependent claims are most likely to be avoided via excipient substitution?
Buffering (claims 6–7), anti-foaming (claims 16–18), viscosity modifiers (claims 20–23), and preservatives (claims 24–25) can be avoided by selecting excipients outside the enumerated sets and/or adjusting quantities away from the cited ranges.
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Does US 12,005,062 cover both pulmonary arterial hypertension and erectile dysfunction?
Yes. The method-of-use claims expressly include pulmonary arterial hypertension (claim 29) and erectile dysfunction (claim 30), as well as broader hypertension-related groupings.
References (APA)
- United States Patent 12,005,062. (Claims excerpt provided in prompt).
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