Scope and claims dissection of US Patent 9,155,718 (ibuprofen + diphenhydramine liquid in soft gelatin capsule; PEG reduces interaction)
US 9,155,718 is a formulation patent directed to a specific fixed-dose, capsule-dosed “liquid” composition of ibuprofen plus diphenhydramine (as free base salt forms specified), with polyethylene glycol (PEG) and potassium hydroxide (KOH) in water, filled into a soft gelatin capsule, where PEG is claimed to reduce ibuprofen–diphenhydramine interaction inside the capsule. The enforceable claim scope is concentrated on: (i) composition-by-amount ranges, (ii) the presence of PEG + KOH + water as the liquid system, (iii) soft gelatin capsule packaging as part of the claimed “liquid composition,” and (iv) salt form constraints for diphenhydramine (HCl or citrate) with further preferred quantitative embodiments.
What does US Patent 9,155,718 claim: ibuprofen + diphenhydramine in PEG/KOH/water soft gelatin capsules?
Core claim concept (independent Claim 1): a liquid composition that contains ibuprofen and diphenhydramine in pain-associated sleep disturbance-effective amounts, where the liquid consists of:
- about 200 to 400 mg ibuprofen
- about 10 to 50 mg diphenhydramine
- polyethylene glycol
- potassium hydroxide
- water
- and is formulated inside a soft gelatin capsule
- with PEG “reducing interaction between the ibuprofen and diphenhydramine inside” the capsule.
Scope-limiting “consists of” language: The independent claim uses “wherein the liquid composition consists of” and then lists PEG, KOH, and water as additional components beyond the actives. That “consists of” construct typically bars inclusion of additional non-listed ingredients in the liquid composition (beyond incidental impurities or ingredients that do not change the “consists of” character), so generic or design-around formulations that add common stabilizers, surfactants, buffers, solubilizers, preservatives, flavorants, or alternative polymer systems may fall outside claim scope unless they fit within the listed components.
Packaging is not optional: “Formulated inside a soft gelatin capsule” ties the claimed composition to a particular dosage form architecture. A composition that otherwise matches all listed constituents but is filled into a hard capsule, sachet, tablet, sachet pouch, oral solution bottle, or microsphere/capsule system is a potential non-infringing route because Claim 1 makes capsule formulation part of the claimed invention.
Mechanistic statement tied to PEG: The claim includes a functional/causal limitation: PEG reduces interaction between ibuprofen and diphenhydramine inside the soft gelatin capsule. Practically, this can be used both as an interpretive anchor for what “PEG” must do in the formulation and as a litigation point for whether competing compositions have an equivalent functional effect.
Claim-by-claim scope: what limitations matter most for infringement of US 9,155,718?
Claim 1: the independent composition and capsule limitation
Claim 1 limitations in plain structure:
- A “liquid composition” containing ibuprofen + diphenhydramine in amounts effective to treat a pain-associated sleep disturbance.
- Composition “consists of”:
- ibuprofen ~200–400 mg
- diphenhydramine ~10–50 mg
- PEG
- KOH
- water
- The composition is formulated inside a soft gelatin capsule.
- PEG reduces interaction between ibuprofen and diphenhydramine inside the soft gelatin capsule.
Key scope bottlenecks
- The mg ranges are central. Outside these ranges, there is no literal coverage.
- The actives must coexist in the claimed quantity window.
- The excipient system must be limited to PEG + KOH + water (plus the actives).
- The dosage form must be soft gelatin capsule.
Claim 2: dissolved system
Claim 2 adds: ibuprofen and diphenhydramine are dissolved in the PEG/KOH/water solution.
Practical impact
- If an accused product suspends undissolved ibuprofen (common for ibuprofen) or uses a partially dispersed system rather than a fully dissolved configuration, Claim 2 may narrow. Claim 1 still covers a “liquid composition,” so Claim 2 mainly tightens infringement to formulations where both actives are dissolved in the stated liquid phase.
Claim 3: diphenhydramine salt forms
Claim 3 specifies diphenhydramine is either:
- diphenhydramine HCl, or
- diphenhydramine citrate.
Scope impact
- If a product uses diphenhydramine base (free base) or a different salt form, Claims 3–8 may be avoided. Claim 1 still says “diphenhydramine” generically, so a dispute could arise whether “diphenhydramine” in Claim 1 implicitly covers salts (often yes) or is interpreted narrowly in light of dependent claims. Dependent claims show the patent drafter considered salt specificity as a meaningful axis.
Claims 4–6: HCl quantitative embodiments
- Claim 4: diphenhydramine HCl about 12.5–50 mg
- Claim 5: diphenhydramine HCl about 25–50 mg
- Claim 6: diphenhydramine HCl about 25 mg
Scope impact
- These are specific numeric nests. A product with HCl dose outside these ranges avoids those narrower dependent claims, but it may still fall within Claim 1/2 if the total diphenhydramine amount stays within 10–50 mg and salts are covered.
Claims 7–8: citrate quantitative embodiments
- Claim 7: diphenhydramine citrate about 19–38 mg
- Claim 8: diphenhydramine citrate about 38 mg
Scope impact
- The “about” language allows some tolerance, but litigation typically turns on precise composition targets and manufacturing controls.
Claims 9–10: ibuprofen quantitative embodiments
- Claim 9: ibuprofen about 200–300 mg
- Claim 10: ibuprofen about 200 mg
Scope impact
- If an accused product uses 300+ mg (up to 400 mg permitted by Claim 1) it may avoid Claims 9–10 but still fall under Claim 1.
Claim 11: explicit exemplar embodiment
Claim 11 is a compact “specific formulation” claim:
- soft gelatin capsule filled with liquid composition consisting of:
- about 200 mg ibuprofen
- about 38 mg diphenhydramine
- PEG
- KOH
- water
- PEG reduces interaction between ibuprofen and diphenhydramine inside the capsule.
Scope impact
- This is the tightest numerical snapshot among the provided claims: it locks both actives to a specific dose pair (200 mg ibuprofen and 38 mg diphenhydramine) and requires the PEG interaction-reduction feature and the same excipient set.
What is the practical claim “coverage map” for US 9,155,718?
Coverage by element (most-likely infringement levers)
| Element |
Claim dependency |
Typical infringement sensitivity |
| Soft gelatin capsule |
Claims 1, 11 |
High, because product dosage form changes may avoid literal scope |
| Ibuprofen dose |
Claims 1, 9, 10, 11 |
Medium-high; numeric ranges reduce generic design-around flexibility |
| Diphenhydramine dose |
Claims 1, 7, 8, 11 |
Medium-high; numeric ranges and salt embodiments |
| PEG presence |
Claims 1, 2, 11 |
High; “consists of” limits excipient set |
| KOH presence |
Claims 1, 2, 11 |
High; common buffer/reaction controls may be bypassed only if KOH is absent |
| Water presence |
Claims 1, 2, 11 |
Medium; liquid vehicle necessary |
| Dissolved actives |
Claim 2 |
Medium; partial suspension can defeat dissolution limitation |
| Diphenhydramine salt form |
Claims 3–8 |
Medium-high; switching to other salts may avoid dependent claims |
| Salt-specific dose windows |
Claims 4–8 |
High for dependent-claim attacks |
| PEG reduces ibuprofen–diphenhydramine interaction inside capsule |
Claims 1, 11 |
Medium; proof can rely on stability/interaction data |
Where are the weakest points: which design-arounds can fall outside claim scope?
This patent’s enforceable perimeter is narrow because of “consists of” plus the capsule limitation plus numeric mg ranges. Design-around approaches that commonly evade one or more elements include:
-
Change the dosage form from soft gelatin capsule
- Hard gelatin capsule, tablet, oral solution, sachet, or other container formats can avoid the “formulated inside a soft gelatin capsule” limitation.
-
Remove or replace KOH
- Claim 1 and Claim 2 include KOH as part of the “consists of” list. A formulation that uses another base/buffer system without KOH is a potential non-infringing route, at least against “consists of” coverage.
-
Use a different polymer/vehicle system than PEG
- Claim 1 requires PEG. Substituting other polymers or co-solvents can defeat literal coverage (again, “consists of” narrows).
-
Adjust doses outside the claimed windows
- Avoiding ibuprofen outside 200–400 mg or diphenhydramine outside 10–50 mg avoids Claim 1. Avoiding narrower dependent claim windows avoids those narrower embodiments.
-
Use diphenhydramine in a non-HCl/non-citrate salt form
- This targets Claims 3–8 (dependent claims). Depending on how “diphenhydramine” is interpreted in Claim 1, salt switching may or may not avoid the independent claim, but it clearly weakens the dependent-claim coverage.
-
Avoid dissolution of both actives in the liquid phase
- If both actives are not dissolved as required by Claim 2, an accused product can attempt to avoid that dependent claim.
-
Avoid the claimed PEG “interaction reduction inside the capsule”
- In practice, proving non-reduction can be difficult, but an accused formulation with a different excipient rationale may argue the PEG interaction-reduction limitation is not met as required.
Which patents around US 9,155,718 typically create overlap risk? (formulation vs method-of-use vs capsule fill systems)
Without additional bibliographic data for the patent family beyond the claim text provided, the landscape can only be characterized at the functional level implied by the claims:
High-overlap categories
- Combination formulation patents for ibuprofen plus diphenhydramine for sleep interference with pain (method-of-use and formulation both can exist).
- Stability/compatibility patents for ibuprofen + antihistamines in liquid or soft-gel formats, especially where PEG is used to reduce interaction.
- Soft gelatin capsule fill/excipient patents covering formulation vehicles using PEG and base/alkaline components.
- Salt form and dose-range patents for diphenhydramine HCl and citrate in fixed combinations.
Less likely overlaps
- Pure process patents that do not materially change the final liquid composition element-by-element may avoid “composition” claims but still can matter if litigation includes process infringement theories.
- Broad antihistamine formulations lacking PEG/KOH/water and without the capsule interaction-reduction feature likely do not overlap strongly.
Litigation leverage from dependent claims
The dependent structure is designed for claim stacking:
- If an accused product matches Claim 1 but misses salt dose windows, the patent can still argue Claim 1 coverage.
- If an accused product targets a salt form or dose within Claim 1’s broad range, dependent claims can provide narrower handles (Claims 4–8, 9–10, 11).
How strong is US 9,155,718 claim strength vs common generic or reformulation challenges?
Strength drivers
- “Consists of” limits are strong for composition-by-component analysis.
- Numeric mg windows narrow the design space.
- Inclusion of both excipient controls (PEG + KOH + water) and a packaging constraint (soft gelatin capsule) can reduce easy workarounds.
- Dependent claims capture specific salt forms and exemplar dose pairings.
Weakness drivers
- If a competitor avoids soft gel or KOH or PEG, literal coverage drops quickly.
- The mechanistic “PEG reduces interaction inside the capsule” can become a contested factual issue in infringement, especially if the accused formulation uses PEG but changes microenvironment, ratios, or pH profile.
Net assessment
- The patent is best positioned to block close “same product, different label” competition that uses the same soft gel capsule architecture and same PEG/KOH/water excipient set within the same mg ranges.
What is the likely Orange Book / regulatory impact of a formulation patent like US 9,155,718?
Regulatory linkage depends on whether the ibuprofen + diphenhydramine combination is an FDA-approved product listed in the Orange Book and whether US 9,155,718 is listed for that NDA in the Orange Book (patent number, expiry date, and “drug product” or “method of use” listing). The claim set provided is formulation-focused, so the key question in practice is whether the patent is listed as a drug product patent tied to a particular dosage form (soft gelatin capsule) and composition.
Litigation posture if Orange Book listed
- If US 9,155,718 is listed for a covered drug product, an ANDA/Paragraph IV filing would likely be assessed against these formulation elements: PEG/KOH/water system, mg dosages, soft gel fill, and salt form.
This section cannot be completed with hard Orange Book status, expiry dates, or FDA approval particulars because those data are not present in the prompt.
Generic entry risks for ibuprofen + diphenhydramine soft gelatin capsule: what would a Paragraph IV challenger need to avoid?
A Paragraph IV strategy against a composition patent like US 9,155,718 generally targets one or more of the following:
-
Non-infringement
- Different dosage form (hard capsule/tablet/solution).
- Excipient change (no PEG, no KOH).
- Dose redesign outside Claim 1 ranges.
- Salt selection outside HCl/citrate windows and possibly non-salt diphenhydramine form.
- Ensure at least one “consists of” element is not present.
-
Invalidity
- If prior art exists describing similar ibuprofen + diphenhydramine combinations in soft gels with PEG/KOH (or similar compatibility agents), challengers can argue lack of novelty/obviousness.
- The interaction-reduction limitation can be attacked if prior art shows that PEG (or similar excipients) reduces drug-drug interaction in such systems.
Because the prompt does not include citations, priority dates, or family members, a prior-art chart cannot be produced here.
Key takeaways
- US 9,155,718 is a narrow formulation claim built around a PEG/KOH/water liquid filled into soft gelatin capsules containing ibuprofen (200–400 mg) and diphenhydramine (10–50 mg).
- The strongest enforceable elements are the “consists of” excipient list (PEG + KOH + water), the soft gelatin capsule packaging, and the dose ranges.
- Dependent claims add salt-form specificity (diphenhydramine HCl or citrate) and dose-specific embodiments, culminating in a tight exemplar in Claim 11 (200 mg ibuprofen + 38 mg diphenhydramine in the PEG/KOH/water soft gel liquid system).
- Design-arounds that change dosage form, remove KOH or PEG, or shift doses/salt forms present the most direct non-infringement paths.
FAQs
1. Does US 9,155,718 require a soft gelatin capsule for infringement?
Yes. Claim 1 and Claim 11 explicitly require the liquid composition to be formulated inside a soft gelatin capsule.
2. Can a product with diphenhydramine base (free base) infringe dependent Claims 3–8?
Dependent Claims 3–8 require diphenhydramine HCl or diphenhydramine citrate. A non-HCl/non-citrate salt (or free base) would avoid those dependent claims.
3. If a competitor uses PEG but not potassium hydroxide, does it avoid Claim 1?
Potentially. Claim 1’s “consists of” list requires PEG and potassium hydroxide plus water.
4. Is dissolving both actives required?
Dissolution of ibuprofen and diphenhydramine in the PEG/KOH/water solution is required by Claim 2, not by Claim 1 (based on the provided text).
5. What is the most specific composition covered by the provided claim set?
Claim 11: about 200 mg ibuprofen and about 38 mg diphenhydramine with PEG, potassium hydroxide, and water in a soft gelatin capsule, with PEG reducing interaction inside the capsule.
