Scope and Claims Breakdown of US Patent 5,948,818 (Omega-3 Free Acid in Non-pH-Dependent Capsule Coating for Small-Intestine Release)

Executive summary

US 5,948,818 claims an oral capsule dose form containing omega-3 polyunsaturated acids (free acid or non-lithium pharmaceutically acceptable salts) with a specific capsule coating behavior: the coating dissolves in a time but not pH-dependent manner and is resistant to release for 30–60 minutes at pH 5.5, targeting small-intestine release.
Claim 1 is the primary composition-and-release-mechanism claim. Dependent claims narrow (i) specific omega-3 acids, (ii) “sole active principle”, (iii) exclusion of lithium salts, (iv) excipient-specific coating composition (iron oxide/titanium dioxide/talc), (v) capsule type, (vi) oil formulation concentration (≥60% w/w oil constituent), and (vii) dose range (250–1,000 mg).
Claim 9 adds method-of-use for inflammatory bowel disease (IBD) relapse reduction, including Crohn’s disease, patients in remission <24 months, and dose range 20–50 mg/kg/day in dependent claims.
The practical patent landscape risk for competitors is that the claims are tight on the release profile (30–60 min at pH 5.5) and on the coating’s “time but not pH dependent” dissolution characterization, not just “enteric-coated omega-3.”
Without the application’s prosecution history and the full specification text, the decisive scope boundaries for equivalents and enforceable “functional language” cannot be fully mapped to later design-around products.

What is US Patent 5,948,818 and what does it claim about omega-3 oral capsules?

US 5,948,818 is directed to an oral dosage form where omega-3 polyunsaturated acids are delivered via a capsule with a coating engineered for small-intestine release through a specific dissolution and release-resistance profile.

What is the core novelty in the independent claims (claim 1 and claim 9)

Claim 1 defines the product as:

A coated capsule (hard or soft gelatin in dependent claim 6).
Active principle is an omega-3 polyunsaturated acid in free acid form or a pharmaceutically acceptable salt.
The capsule coating is defined by behavior, not only ingredients:
- coating dissolves in a time but is not pH dependent; and
- coating is resistant to release of the omega-3 for 30–60 minutes at pH 5.5;
- so that omega-3 is released in the small intestine.

Claim 9 adds the therapeutic use:

treating IBD or reducing clinical relapse by administering the same coated capsule product with the same release behavior.

What is explicitly excluded (lithium salts)

Claim 4 narrows claim 1 by excluding:

lithium salts of the omega-3 free acid.

This matters for salt-form design-around because many firms evaluate alternative counterions for stability and manufacturability.

What are the scope-limiting elements of claim 1 (release resistance at pH 5.5 for 30–60 minutes)?

Claim 1’s scope is dominated by a functional release profile tied to a single experimental condition:

pH 5.5
release-resistance duration: 30 to 60 minutes
release target: small intestine

How the coating is defined: “dissolves in a time but not pH dependent manner”

This is a two-part technical limitation:

A time-based dissolution characteristic (not an “enteric pH-trigger”).
A lack of pH dependence in dissolution, implying the coating’s dissolution is not primarily driven by a pH threshold.

In infringement analysis, this type of limitation typically channels disputes into:

coating dissolution testing conditions,
media composition,
and how “not pH dependent” is proven relative to the prior art coating systems.

What “resistant to release for 30 to 60 minutes at pH 5.5” means for competing formulations

This creates a product boundary that competitors can try to avoid by changing any of:

coating chemistry,
coating thickness or solid loading,
capsule shell type and collapse behavior,
internal formulation (oil or solid dispersion affecting diffusion),
and the salt/free acid identity affecting solubility and diffusion.

Even where omega-3 identity matches, a coating that releases outside 30–60 minutes at pH 5.5 can fall outside literal claim coverage.

Which omega-3 acids are covered by US 5,948,818?

Claim 2 narrows to specific acids:

eicosapenta-5,8,11,14,17-enoic acid (EPA)
docosahexa-4,7,10,13,16,19-enoic acid (DHA)
or mixtures

Does the patent cover the active as “sole active principle”?

Claim 3 allows only:

omega-3 polyunsaturated acid as the sole active principle (so no other pharmacologically active components are intended in the unit dose).

Does it cover mixtures or combinations of omega-3 components?

Yes via claim 2 (mixture of EPA and/or DHA) and claim 1’s broader “omega-3 polyunsaturated acid” scope.

What capsule coating materials are explicitly claimed (iron oxide, titanium dioxide, talc)?

Claim 5 imposes a specific coating composition:

iron oxide
titanium dioxide
talc

This is a dependent claim, so the independent claim 1 does not require these components. But it materially tightens a second infringement track for formulations that use this exact coating recipe.

Practical consequence

Competitors using different inorganic/film-forming excipients could still try to fall under claim 1 if their coating behavior matches the 30–60 minute pH 5.5 release-resistance requirement. Conversely, even if the coating ingredient list differs, a coating behavior mismatch on the release window can avoid claim 1 and leave only potential non-infringing “similar” coatings not meeting the limitation.

What formulations and dose sizes are covered?

Oil constituent threshold

Claim 7 adds an internal formulation limitation:

omega-3 is present in an oil constituent at ≥60% w/w

This blocks claims against capsule products where omega-3 is delivered primarily as:

crystalline free acid,
emulsions with lower oil fraction,
or solid dispersion with different excipient ratios.

Unit dose range

Claim 8 limits:

250 to 1,000 mg omega-3 polyunsaturated acid per unit dose.

A competitor using a higher or lower unit dose may reduce literal coverage for claim 8, though claim 1 may still capture if the asserted claim is not the dose-dependent one.

How broad is the method-of-use coverage for inflammatory bowel disease (claim 9 onward)?

Claim 9 covers:

administering the claimed coated capsule to treat IBD or reduce clinical relapse.

Dependent claim 10 specifies:

Crohn’s disease.

Dependent claim 11 specifies a patient subgroup:

remission for less than 24 months prior to treatment.

Dependent claim 12 sets a dosing regimen:

daily dosage 20 to 50 mg/kg omega-3 polyunsaturated acid.

What the method claim adds over the composition claim

Even if a competitor argues their product is not structurally identical, method-of-use coverage can still be asserted if the accused product includes the same coated capsule with the specified release behavior and is used to treat the claimed population/indication.

Claim 13 reinforces exclusion of lithium salts

Claim 13 is another method claim keyed to the same coating behavior but also reiterates:

active principle is omega-3 free acid or pharmaceutically acceptable salt except lithium salts.

What does the patent likely target in the marketplace (and what does that imply for design-arounds)?

This claim set is tailored to prevent release in the stomach/upper GI and instead trigger release in the small intestine using a coating that is:

time-based
non-pH dependent
and tested as resistant to release for 30–60 minutes at pH 5.5.

Common design-around paths implied by claim construction

Shift release timing outside 30–60 minutes at pH 5.5 via coating formulation or thickness.
Change from free acid/salt combinations in a way that either:
- uses lithium salts (excluded by claim 4 and 13), or
- uses a different active entity not meeting “omega-3 polyunsaturated acid” identity.
Change oil fraction below ≥60% w/w if relevant to the contested claim set.
Alter unit dose outside 250–1,000 mg if the dose is asserted.
Avoid method-of-use in relapse-reduction or narrow to different indications/patient segments, reducing reliance on claims 9–12 where the carrier product’s composition is still potentially within claim 1.

What patents are likely relevant alongside US 5,948,818 for omega-3 small-intestine release (and what is the typical overlap)?

Without the specific family members, related continuations, and the cited references from the patent document, only a structural inference is possible from the claim scope. The relevant “neighbor” IP in this technical area typically clusters around:

enteric or non-pH-dependent coatings for omega-3 delivery,
omega-3 capsule formulations with specified release profiles,
salt form selection (counterion scope),
and therapeutic method-of-use for IBD relapse.

Overlap vectors for litigation and licensing are usually:

same omega-3 acids (EPA/DHA),
same GI-release goal (small intestine),
same or similar coating dissolution behavior,
and the same therapeutic end points (IBD, Crohn’s relapse prevention).

What is the claim strength profile for US 5,948,818 (how enforceable is the functional release language)?

Strength drivers

Claim 1 ties coverage to measurable release-resistance timing at pH 5.5.
It also ties dissolution behavior to being time-based and not pH dependent.
Dependent claims add specificity (EPA/DHA, no lithium salt, specific coating ingredients, oil %, and unit dose), allowing narrower enforcement.

Strength vulnerabilities for challengers

Functional terms can invite disputes about how the test is performed and whether the coating qualifies as “not pH dependent.”
If an accused product’s release curve at pH 5.5 shifts because of:
- different media,
- different agitation,
- different capsule fill formulation,
- or different coating thickness, then literal infringement can become contestable.

How many distinct claim “buckets” exist, and which ones create the highest infringement leverage?

Based on the claim text provided, there are distinct buckets:

Product coating behavior (claim 1): coated capsule; omega-3 free acid/salt (non-lithium not yet in claim 1); coating dissolves in time not pH dependent; resistant to release 30–60 min at pH 5.5.
Active identity narrowing (claim 2): EPA/DHA or mixture.
Active scope narrowing (claim 3): sole active.
Salt exclusion (claim 4 and 13): excludes lithium salts.
Coating ingredient recipe (claim 5): iron oxide/titanium dioxide/talc.
Capsule type (claim 6): hard or soft gelatin capsule.
Internal oil composition (claim 7): oil constituent ≥60% w/w.
Unit dose range (claim 8): 250–1,000 mg omega-3.
Method-of-use for IBD relapse (claim 9–12): IBD/Crohn’s relapse reduction; remission <24 months; daily dose 20–50 mg/kg.

Highest leverage generally sits with claim 1 for product competition and claim 9 for indication-driven disputes, with claim 4/13 (non-lithium salts) acting as an additional carve-out/inclusion lever.

What is the most direct comparison framework for assessing patent coverage against a generic or competing omega-3 capsule?

A claim-coverage assessment can be reduced to a pass/fail matrix aligned to limitations:

Limitation	Accused product element to compare	Literal pass needed?
Coated capsule	Has coated capsule delivery	Yes for claim 1/9
Active is omega-3 free acid or pharmaceutically acceptable salt	Identity and salt form	Yes
Coating dissolves in time, not pH dependent	Dissolution profile vs pH	Yes (claim 1/9)
Resistant to omega-3 release 30–60 min at pH 5.5	Release curve at pH 5.5	Yes (claim 1/9)
Released in small intestine	Implied by release profile	Typically required via limitation logic
EPA/DHA or mixture (if claim 2 asserted)	Active identity	Only if asserted
Sole active principle (claim 3)	Presence of other actives	Only if asserted
Exclude lithium salt (claim 4/13)	Counterion	Only if asserted
Coating ingredients iron oxide/titanium dioxide/talc (claim 5)	Recipe match	Only if asserted
Hard/soft gelatin capsule (claim 6)	Capsule shell type	Only if asserted
Oil constituent ≥60% w/w (claim 7)	Formulation composition	Only if asserted
Unit dose 250–1,000 mg (claim 8)	Strength per capsule	Only if asserted
IBD/Crohn’s relapse reduction (claim 9–12)	Indication/patient selection	Only for method claims

When do these claims typically matter most for a business decision (licensing, clearance, litigation posture)?

Licensing

Licensing leverage increases when:

a partner’s product uses the same non-pH-dependent time-based coating concept and matches the 30–60 minute release window at pH 5.5.
salt form remains in-scope (non-lithium).
unit dose and oil fraction match.

Clearance / risk management

Clearance priorities are testing:

dissolution vs pH dependence characteristics,
release resistance window at pH 5.5,
and proof that release occurs in small intestine under relevant in vitro/in vivo models.

Litigation

In suit, claim 1 becomes the core product claim. Claim 9 supports indication-driven enforcement (IBD/Crohn’s relapse). Dependent claims reduce the burden of proving full non-infringement when only partial matching exists.

Key Takeaways

US 5,948,818 is a capsule coating behavior patent for omega-3 (EPA/DHA) delivery, with the dominant limitation being 30–60 minutes release resistance at pH 5.5 and time-based, not pH-dependent dissolution.
Coverage is broad on omega-3 identity (free acid or salts) but narrows through dependent claims to EPA/DHA, sole active, non-lithium salts, specific coating ingredients, ≥60% oil constituent, and 250–1,000 mg unit doses.
The method claims cover IBD/Crohn’s relapse reduction and include patient remission duration and mg/kg daily dosing limitations.
For competitors, the most direct design-around is to engineer a coating that releases outside the 30–60 minute window at pH 5.5 or alters salt/formulation parameters that trigger dependent claims.

FAQs

What does “not pH dependent” coating dissolution mean for infringement under US 5,948,818?
Can a competing omega-3 capsule avoid claim 1 by shifting release timing slightly outside 30–60 minutes at pH 5.5?
Does using lithium salts of omega-3 avoid the method-of-use claims in US 5,948,818?
If a product matches the release behavior but uses non-gelatin capsules, which claims are impacted?
How do claim 7’s ≥60% w/w oil constituent and claim 8’s 250–1,000 mg dose range change litigation risk?

References

US Patent 5,948,818.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	9509764	May 15, 1995

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	294575	⤷ Start Trial
Australia	5895596	⤷ Start Trial
Australia	702692	⤷ Start Trial
Brazil	9608785	⤷ Start Trial
Canada	2221356	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,948,818

Summary for Patent: 5,948,818