Scope and claim coverage analysis of U.S. Patent 7,794,738 (corticosteroid skin delivery using defined penetration enhancer systems)
U.S. Patent 7,794,738 claims methods of topical corticosteroid delivery in which the formulation contains (i) two or more “penetration enhancers” from a defined set, (ii) a critical solvent/emulsifier content threshold (at least about 0.90), (iii) defined composition ratios among the penetration enhancers, and (iv) an explicit exclusion: no monoglyceride of a C6–C10 medium chain fatty acid. Dependent claims further narrow to fluorinated corticosteroids (including fluocinonide and fluocinolone acetonide) and specify corticosteroid strengths (0.10% / ≥0.25% / ≥0.50%), plus specific lists of permissible solvents/emulsifiers and non-solvent/emulsifier ingredients. The estate is highly formulation-process constrained (composition composition, penetrant identity, and exclusion language), which creates design-around space for competitors that can change enhancer identity, adjust ratio, remove or substitute excluded components, or avoid the claimed “solvents and emulsifiers” parameterization.
What patents protect corticosteroids topically delivered with propylene glycol and a second penetration enhancer system?
How claim 1 defines the core inventive concept
Claim 1 is the independent claim and is drafted as a method-of-delivering corticosteroids to skin by topical application of a specific composition package. The claim elements, in operative order:
- Topical application of a composition to skin.
- Composition contains:
- one or more corticosteroids
- two or more penetration enhancers
- one or more of the group consisting of solvents and emulsifiers
- Penetration enhancers ratio limitation
- “penetration enhancers are present in ratio to a total of the penetration enhancers”
- This ties the relative proportions among the penetrant(s) to a claimed ratio structure (even though the exact numeric ratio is not reproduced in the excerpt, the claim text requires such a ratio relationship).
- Solvents and emulsifiers content threshold
- “solvents and emulsifiers of at least about 0.90”
- The excerpt’s wording reads as a quantitative constraint tied to “of at least about 0.90.” As a claim construction matter, this is a hard numerical boundary that must be met by the accused formulation’s “solvents and emulsifiers” parameterization as understood in the patent specification.
- Defined penetrant identities
- Penetration enhancers comprise two or more from this list:
- propylene glycol
- diisopropyl adipate
- dimethyl isosorbide
- 1,2,6 hexanetriol
- benzyl alcohol
- Explicit exclusion
- “composition does not include a monoglyceride of a C6–C10 medium chain fatty acid.”
The practical scope consequence: even if a competitor uses a corticosteroid and propylene glycol and another enhancer, they must also satisfy the solvent/emulsifier numerical threshold and the penetrant ratio requirement, and must avoid the C6–C10 monoglyceride exclusion.
Claim 1 boundary map (what is inside vs. outside)
| Claim element |
What must be present to infringe claim 1 |
What avoids claim 1 (design-around direction) |
| Corticosteroid |
Any “one or more corticosteroids” |
Use a non-corticosteroid or a different therapeutic class (if relevant) |
| Penetration enhancers |
At least 2 enhancers from the enumerated set |
Use only 0–1 enhancers from the set; use enhancers not in the enumerated set (if claim construction requires all enhancers to come from the set) |
| Ratio among enhancers |
Penetrants are present “in ratio to a total” |
Change relative proportions outside the claimed ratio boundary (not just overall penetration enhancer level) |
| Solvents/emulsifiers threshold |
“solvents and emulsifiers of at least about 0.90” |
Reduce “solvents and emulsifiers” parameter below the threshold or change formulation such that the measured parameter does not meet the claimed value |
| Exclusion |
No monoglyceride of a C6–C10 medium chain fatty acid |
Introduce a C6–C10 monoglyceride? (but that would not avoid; it would violate the exclusion). Better: eliminate that class or use different monoglyceride types not within “C6–C10 medium chain fatty acid” or remove monoglycerides entirely |
| Topical method |
Topical application to skin |
Non-topical routes avoid method claims (but may still face other claims if any exist in the patent family, not provided here) |
Dependent claims 2–7: corticosteroid identity and concentration
Dependent claims narrow claim 1 along two axes.
Fluorinated corticosteroids
- Claim 2: corticosteroid is a fluorinated corticosteroid
- Claim 3: includes fluocinonide
- Claim 4: includes fluocinolone acetonide
Strength ranges
- Claim 5: corticosteroid present at about 0.10%
- Claim 6: at least about 0.50%
- Claim 7: at least about 0.25%
These dependent claims tighten the infringement class substantially. A formulation that satisfies claim 1 but uses a corticosteroid outside the fluorinated set, or uses concentrations not overlapping these ranges (depending on claim construction of “about”), would not infringe the dependent claims, though claim 1 may still be asserted.
Which formulation components and concentration ranges are explicitly protected in U.S. 7,794,738?
What solvents and emulsifiers are recited
Claim 8 lists solvents/emulsifiers comprising one or more of:
- dehydrated alcohol
- alcohol (95% v/v) USP
- 3-Cyclohexene-1-Methanol
- 4-Dimethyl-α-(4-Methyl-3-Pentenyl)-
- Steareth-2
- Steareth-21
- citric acid
- CPE-215
- diisopropanolamine (1:9)
- DIPA/PG (1:9)
- ethoxydiglycol
- Potassium hydroxide (10%)
- PEG-40 Stearate
- PEG-7000
- Polysorbate 60
- potassium hydroxide (1%)
- propylene carbonate USP
- propylethylene glycol 4
- oleyl alcohol
- sodium lauryl sulfate
- sorbitan monostearate
- sorbitan stearate
- 1,2,3-Propanetriyl Ester
Claims 23 and 25 repeat the solvents/emulsifiers and expand non-solvent/emulsifier lists.
What non-solvent/emulsifier ingredients are recited
Claim 10 identifies “non-solvent/emulsifier ingredients” as one or more of:
- Glyceryl Stearate (and) PEG-100 Stearate
- carbopol 980
- cyclomethicone NF
- glyceryl monostearate
- hydroxyethyl cellulose
- hydroxypropyl cellulose
- isopropyl myristate
- methyl paraben NF
- mineral oil
- oleic acid NF
- PEG-100 Stearate
- petrolatum
- propyl paraben NF
- purified water
- stearyl alcohol
- white petrolatum
- white wax
Claims 24–28 constrain the quantity ranges:
- Claim 12: non-solvent/emulsifier ingredients present about 11% to about 53%
- Claim 13: about 11% to about 27%
- Claim 27: repeats about 11% to about 53%
- Claim 28: repeats about 11% to about 27%
What solvent/emulsifier level is recited
- Claim 11 and claim 26: solvents and emulsifiers present at about 4–5%
Interlocking constraints: Claim 1 already includes a “solvents and emulsifiers of at least about 0.90” threshold. Claims 11/26 add an additional numeric level at about 4–5%. As drafted, a formulation must be compatible with both constraints simultaneously. In a dispute, the parties would heavily litigate how these parameters are defined and measured in the specification and claim interpretation.
When do the narrower dependent claims expand or restrict protection?
Claim 9–10 vs. claim 24–25: non-solvent/emulsifier inclusion
Claim 1 does not require non-solvent/emulsifier ingredients; Claims 9–10 add this element. Similarly, Claims 24–25 add this element to the claim 16 lineage. This bifurcation matters for enforcement:
- If an accused product meets claim 1 but does not include the recited non-solvent/emulsifier categories, claim 1 remains a potential target; Claims 9/10 would be harder to assert.
- If an accused product includes the recited non-solvent/emulsifier ingredient classes, quantity limitations in Claims 12–13 (or 27–28) become relevant.
Strength-dependent risks
A key enforcement pattern in topical corticosteroid patents is that parties often design formulations around the active strength even if the excipient system overlaps. Here:
- 0.10% is explicitly called out (Claims 5, 20).
- ≥0.25% (Claims 7, 22).
- ≥0.50% (Claims 6, 21).
A product outside these ranges could still fall into claim 1 depending on whether claim 1 is asserted alone and whether the corticosteroid in the accused product maps to claim 1’s broad “one or more corticosteroids” language.
What patents are risk-relevant for specific corticosteroids like fluocinonide and fluocinolone acetonide?
Fluocinonide (dependent)
- Claim 3: fluocinonide
- Claim 18: fluocinonide (claim 16 lineage)
Fluocinolone acetonide (dependent)
- Claim 4: fluocinolone acetonide
- Claim 19: fluocinolone acetonide (claim 16 lineage)
Claim 2/17: fluorinated corticosteroid
- Claim 2 and claim 17 cover fluorinated corticosteroids generally.
In licensing and litigation strategy, this matters because it separates broad formulation infringement (claim 1) from a “market-specific” infringement thesis that tracks labeled actives.
Does U.S. 7,794,738 require propylene glycol as a first penetration enhancer?
Yes, in claims 14–15 (propylene glycol as the first penetration enhancer)
Claims 14 and 15 are independent-style recitals that narrow the penetration enhancer pairing and add propylene glycol proportion requirements.
Claim 14 (propylene glycol + second enhancer selection; propylene glycol minimum)
- First penetration enhancer: propylene glycol
- Second penetration enhancer: selected from:
- diisopropyl adipate
- dimethyl isosorbide
- 1,2,6 hexanetriol
- benzyl alcohol
- “propylene glycol is at least 66.8% of the composition.”
Claim 15 (propylene glycol range)
- propylene glycol between 66.8% and 74.9% of the composition.
Claim 16–30: dimethyl isosorbide as the first penetration enhancer (role reversal)
Claims 16 and following switch the anchor penetrant:
- Claim 16: first penetration enhancer is dimethyl isosorbide
- Second penetration enhancer selected from:
- propylene glycol
- diisopropyl adipate
- 1,2,6 hexanetriol
- benzyl alcohol
Dependent claims 29–30 add:
- Claim 29: second penetration enhancer is propylene glycol; propylene glycol at least 66.8% of the composition
- Claim 30: second penetration enhancer is propylene glycol; propylene glycol between 66.8% and 74.9% of the composition
Scope impact:
These claims create a “high propylene glycol fraction” enforcement lane. A formulation that meets claim 1 but uses materially lower propylene glycol fractions may avoid Claims 14–15 and 29–30 while still potentially infringing claim 1 depending on how claim 1 ratio language reads in the specification.
How strong is the patent estate for this formulation class based on claim structure?
Scope strength indicators
Even without the full prosecution history, the excerpted claim language indicates:
- High specificity in penetration enhancer identity (enumerated set).
- High specificity in an excluded excipient category (monoglyceride of C6–C10 medium chain fatty acid).
- Numerical constraints for solvents/emulsifiers (the “at least about 0.90” threshold) and for penetrant mass fraction in certain claims (66.8% to 74.9%).
- Active-specific dependent hooks for fluocinonide and fluocinolone acetonide.
These features typically correlate with enforceability that is strong when competitors copy the claimed formulation pattern, but fragile against conventional reformulation that changes enhancer selection or ratio and rebalances excipient selection.
Litigation leverage points likely to matter
For disputes, the most litigated claim elements in such drafting are usually:
- How “penetration enhancers” are identified and whether the accused excipient qualifies.
- Whether the formulation meets the numerical solvent/emulsifier thresholds (“at least about 0.90” and “4–5%”).
- Whether the excluded monoglyceride is present, including how “monoglyceride of a C6–C10 medium chain fatty acid” is interpreted by the specification and analytical testing.
What generic entry risks exist for topical corticosteroid products under this patent?
Risk profile for generics that match excipient systems
Generic risk tracks three factors:
- Whether the generic uses the same corticosteroid (or fluorinated variants).
- Whether it uses penetration enhancers selected from the enumerated set and maintains the required ratio structure.
- Whether it avoids the excluded monoglyceride class and meets solvent/emulsifier numerical thresholds.
Because the claim is method-of-delivering by topical application of a defined composition, a generic developer can reduce risk by redesigning the penetrant system and reformulating out of the defined enhancer set or out of the claimed penetrant fraction bands.
High-risk scenarios
- Copying a patent-protected enhancer blend while maintaining the same corticosteroid strength.
- Copying propylene glycol fraction bands (≥66.8% or 66.8–74.9%) in the presence of a second enumerated enhancer.
Which companies are likely affected?
No company names, product brands, NDA/ANDA holders, or Orange Book listings are provided in the prompt. Without those, company-level mapping would be speculative and cannot be produced as “hard data.”
What is missing from the claim excerpt that affects enforcement mapping?
The prompt includes claim text but not:
- the patent title, abstract, specification definitions,
- claim construction anchors used in the specification (particularly for “solvents and emulsifiers of at least about 0.90” and “penetration enhancers are present in ratio to a total of the penetration enhancers”),
- the full set of independent claims (only one independent claim and multiple “method” claims in the excerpt),
- priority date, expiration date, continuation history, or maintenance fee status.
Because the analysis request is for “scope and claims and patent landscape,” the claim construction-critical missing portions would prevent producing a complete expiration and landscape map tied to litigation or regulatory status.
Key Takeaways
- U.S. Patent 7,794,738 protects a topical corticosteroid delivery method using a tightly defined penetration enhancer system from an enumerated list (propylene glycol, diisopropyl adipate, dimethyl isosorbide, 1,2,6 hexanetriol, benzyl alcohol), with a ratio limitation among penetrants.
- The claim package imposes hard formulation boundaries: a solvents/emulsifiers numeric threshold (“at least about 0.90”), additional dependent constraints including 4–5% solvents/emulsifiers, and explicit prohibition of monoglycerides of C6–C10 medium chain fatty acids.
- Dependent claims materially narrow into fluorinated corticosteroids, especially fluocinonide and fluocinolone acetonide, with explicit active strength anchors (0.10%, ≥0.25%, ≥0.50%).
- Additional claim lanes require propylene glycol (as first enhancer) at ≥66.8% or 66.8–74.9% of the composition, and a parallel lane where dimethyl isosorbide is the first enhancer.
- Enforcement risk for entrants is highest when they replicate the penetrant identities and fraction bands and maintain the solvent/emulsifier parameters, while avoiding the excluded monoglyceride category.
FAQs
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Can a formulation avoid U.S. 7,794,738 by using a different second penetration enhancer not listed in the claim?
The claims restrict “penetration enhancers” to the enumerated set in the independent language; using non-enumerated enhancers is the primary design-around direction.
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If a product uses propylene glycol but at less than 66.8% of the composition, does it avoid claims 14–15 and 29–30?
Those dependent claims require the specified propylene glycol fraction bands; falling below them avoids those dependent limitations while leaving open potential assertion under broader claim 1 language depending on claim construction.
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What does the monoglyceride exclusion practically mean for formulation screening?
Any inclusion of a monoglyceride of a C6–C10 medium chain fatty acid category is a direct exclusion trigger for claim 1.
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Do the non-solvent/emulsifier quantity ranges (11–53% and 11–27%) matter if a competitor omits those ingredients?
Those limits apply in dependent claims; omission of the ingredient category can keep the formulation outside those dependent limitations while still potentially implicating claim 1.
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Is fluocinonide or fluocinolone acetonide required to infringe the patent?
No. Those are dependent, active-specific limitations; claim 1 covers “one or more corticosteroids” if all other composition constraints are met.
References
No cited sources were provided in the prompt.
