United States Patent 5,082,861 Scope, Claims, and Patent Landscape for 2-phenyl-1,3-propanediol Dicarbamate in Partial Complex Seizures

Executive summary: U.S. Patent 5,082,861 claims a narrow therapeutic product around 2-phenyl-1,3-propanediol dicarbamate (dosage-unit compositions and a method of treating partial complex seizures). The claim scope is driven by (i) the drug identity (the dicarbamate), (ii) dose ranges (about 25–500 mg per dosage unit; about 100 mg to 5 g per day), and (iii) the indication (partial complex seizures). The patent landscape around this type of compound-and-dose claim is typically shaped by earlier composition-of-matter and prodrug/derivative filings, later formulation tweaks (capsule/tablet excipients, release/dissolution control), and method-of-use continuations tied to epilepsy subtypes.

What does U.S. Patent 5,082,861 claim for partial complex seizures with 2-phenyl-1,3-propanediol dicarbamate?

Short answer: It claims two dosage-form composition claims (gelatin capsule and tablet) and one method-of-treatment claim for partial complex seizures, all limited to 2-phenyl-1,3-propanediol dicarbamate and specific dose ranges.

Claim 1 scope (gelatin capsule dosage unit)

Type: composition in dosage unit form
Form: gelatin capsule
Active: 2-phenyl-1,3-propanediol dicarbamate
Quantified content: “about 25 to 500 milligrams”
Use/indication: “for the treatment of partial complex seizures”

Practical claim boundaries:

The claim reads on a capsule whose per-unit content of the specified active falls within the claimed 25–500 mg band.
“About” introduces tolerance, but the numerical range is the anchor for infringement design: dosing outside the range is the most direct colorable workaround, though courts often still treat “about” as bounded by reasonable degree of closeness.

Claim 2 scope (tablet dosage unit)

Type: tableted composition in dosage unit form
Form: “solid pharmaceutical carrier” + active
Active: 2-phenyl-1,3-propanediol dicarbamate
Quantified content: “about 25 to about 500 milligrams”
Use/indication: “for the treatment of partial complex seizures”

Practical boundaries:

Claim 2 is less constrained than Claim 1 on capsule vs tablet, but it is still constrained by:
- the active identity
- the per-unit dose window
- the tablet/dosage unit form
- and the therapeutic indication language

Claim 3 scope (method of treatment)

Type: method claim
Administration: to a warm-blooded animal in need
Active: 2-phenyl-1,3-propanediol dicarbamate
Daily dosage: from about 100 mg to about 5 grams
Indication: “for treating partial complex seizures”

Practical boundaries:

This claim is directed at the dosage regimen rather than a specific pharmaceutical shell or excipient system.
Potential “design-around” typically targets either:
- dosage outside the 100 mg/day to 5 g/day band, or
- treating a different seizure phenotype with the same compound (though if the compound is used off-label for the claimed indication, enforcement theories can still arise via evidentiary use).

How strong is the patent estate for U.S. Patent 5,082,861 based on claim structure and likely enforceability?

Short answer: Strength is medium-to-narrow because the claims are tethered to a specific compound plus dosage windows and a particular epilepsy subtype. Strength is higher against competitors that keep the same active and dose, and lower against competitors that alter dose, dosage unit size, or route/formulation strategy.

Key strength drivers

Specific active identity
The claims require 2-phenyl-1,3-propanediol dicarbamate, reducing the field of equivalents.
Quantified dose ranges
The numerical constraints focus infringement analysis on dosing practices and product labeling.
Dosage-unit form language (Claims 1 and 2)
Capsules and tablets are explicitly claimed, so products in those categories are the most direct infringement targets.

Key vulnerability drivers

Indication limitation (partial complex seizures)
If clinical use or marketing is tailored to other seizure types, direct evidence of use for “partial complex seizures” can be contested.
“About” range fuzziness
“About” increases uncertainty. Competitors often litigate “reasonableness” of deviation from the range.
Method claim proof burden
In U.S. practice, method claims can be enforced via prescription patterns, clinical trial data, or label-based evidence. But direct “administering” proof can be harder than product presence.

What patents are likely to protect 2-phenyl-1,3-propanediol dicarbamate around this era in the U.S.?

Short answer: The broader landscape typically splits into:

earlier filings on the compound itself (composition-of-matter),
later filings on epilepsy/partial seizure method-of-use,
and formulation patents focused on capsule/tablet excipients and dosing unit optimization.

Landscape clusters you should map around 5,082,861

Because 5,082,861 is a composition and method claim centered on a specific chemical and dose range, the most commercially relevant adjacent patent families in the U.S. usually fall into these buckets:

1) Compound and derivative families

Claims likely cover:
- the dicarbamate structure,
- alternative esters/amides,
- salt forms or polymorphs (if later discovered),
- prodrugs or closely related analogs.

Enforcement impact: If an earlier composition-of-matter patent exists on the same active, it often dominates expiration and licensing leverage over dose/formulation claims.

2) Method-of-use families

Claims can broaden from “partial complex seizures” to other partial seizure subsets, refractory epilepsy, or broader seizure classifications.

Enforcement impact: Method claims can reach physicians and companies through promotion/use evidence even when formulation design is changed.

3) Formulation and dosing regimen families

Variants include:
- capsule fill optimization,
- controlled-release or dissolution profiles,
- tablet compression/excipient selections,
- combinations with other antiseizure actives.

Enforcement impact: Formulation patents can be layered on top of compound and method protection, adding a second wall against “same active, different dosage form” workarounds.

When does U.S. Patent 5,082,861 lose exclusivity based on filing and expiration mechanics?

Short answer: A precise expiration date depends on the patent’s filing date and any patent term adjustments or extensions, none of which are provided in the prompt.

Because no filing date, priority date, maintenance status, or PTA/extension data is included, this analysis cannot produce an exact “loss of exclusivity” timeline.

What generic entry risks exist if a competitor launches a capsule or tablet containing 2-phenyl-1,3-propanediol dicarbamate?

Short answer: The primary infringement risk is high if:

the product is a gelatin capsule or tablet,
it contains about 25–500 mg per dosage unit,
and it is marketed or used for partial complex seizures.

Risk matrix by product design

Competitor design choice	Claim impact
Capsule, 25–500 mg per unit, labeled for partial complex seizures	Direct hit on Claim 1
Tablet, 25–500 mg per unit, labeled for partial complex seizures	Direct hit on Claim 2
Capsule/tablet, active amount outside 25–500 mg band	Weaker on per-unit composition claims; still vulnerable if “about” is argued
Different seizure indication (non-partial complex) with same dosing	Less direct on indication-limited claims; method-of-use evidence becomes key
Tablets/capsules at same dose but different active	Avoids the active identity requirement; not within these claims
Different dosing schedule but same daily total within 100 mg–5 g	Potentially still within Claim 3 if administration practice matches

How would a Paragraph IV challenge or ANDA strategy likely be framed for this patent?

Short answer: A Paragraph IV theory against 5,082,861 would usually target at least one of:

invalidity of the claims (anticipation/obviousness),
non-infringement due to dose range or dosage form,
or design-around shifting to non-capsule/tablet formats or dosing outside the claimed windows.

Because the prompt does not supply the patent’s prosecution history, claim construction guidance, cited art, or the identity of any ANDA/suit, this analysis cannot map a specific Paragraph IV argument set tied to known litigation.

What claim terms drive infringement and invalidity fights for 5,082,861?

Short answer: The infringement and validity focus typically concentrates on the following claim terms: the compound definition, the “about” dose ranges, and the therapeutic indication language.

Term-by-term friction points

“2-phenyl-1,3-propanediol dicarbamate” (active identity)
- Disputes can arise over purity, structural identity, isomer/tautomer presence, or whether a competitor uses a salt/polymorph still chemically identical in active content.
“about 25 to 500 milligrams” and “about 100 milligrams to about 5 grams”
- “About” is litigated. Competitors try to push outside reasonable boundaries.
- For infringement, both per-unit label strength and actual administration practices can matter.
“gelatin capsule” and “tableted composition”
- Dosage form classification disputes can arise if the product uses atypical capsule shells, coated tablets, or multipart dosing units.
“for the treatment of partial complex seizures”
- Indication-limited claims require evidence that the accused product is used and/or marketed for the claimed seizure type.

Which competing products or companies are most exposed under the claim scope?

Short answer: Exposure concentrates on market participants that sell or market 2-phenyl-1,3-propanediol dicarbamate in capsule or tablet strengths within the claimed windows for partial complex seizures.

Because the prompt does not provide:

the marketed product(s) containing this active,
NDA/ANDA holders,
Orange Book listings,
or any party names from litigation, this analysis cannot name specific exposed companies.

What formulations are covered, and what are the main “design-around” formulation paths?

Short answer: The claims cover a gelatin capsule dosage unit and a tablet dosage unit containing the active within the specified per-unit amount ranges. The most direct design-around is to change the dosage form and/or dosing amount so the product no longer falls within the “about” bands.

Covered formulations

Gelatin capsule with ~25–500 mg active per capsule
Tablet with solid carrier plus ~25–500 mg active per tablet

Likely design-around formulation options (at the claim text level)

Capsule shell swap away from “gelatin capsule”
Tablet form factors that do not fit how the dosage unit is characterized (coated vs uncoated could still be argued as “tableted composition”)
Shifting strength away from 25–500 mg per dosage unit
Changing the regimen so daily administered dose is outside ~100 mg to ~5 g

Design-around risks remain if courts treat “about” broadly or treat equivalents as meeting the limitation.

How does 5,082,861 compare with typical epilepsy patent estates (capsule/tablet + method) in the U.S.?

Short answer: It follows a classic structure: active-specific composition claims (capsule/tablet) paired with an active-specific method-of-use claim anchored to seizure subtype and dose.

Typical implications

If an earlier compound patent exists, 5,082,861 is less strategically unique; it becomes one of several layers.
If later formulation or method-of-use continuations exist, the estate can extend practical exclusivity through additional narrow claims around dose and seizure subtype.
If there is a weak prosecution record or broad prior art on seizure dosing of the same active, the “about range” limits become the main defense lever in litigation.

Key Takeaways

U.S. Patent 5,082,861 is tightly focused on 2-phenyl-1,3-propanediol dicarbamate for partial complex seizures, with capsule (Claim 1), tablet (Claim 2), and method dosing (Claim 3) anchored to quantitative ranges.
Infringement exposure is highest for products that keep the same active, fall within the ~25–500 mg per dosage unit band (capsule/tablet), and are used/marketed for partial complex seizures.
The strongest litigation levers are likely the “about” dose ranges and the indication limitation.
Exact expiration timing cannot be produced from the provided prompt because no priority/filing, PTA, or extension data is supplied.

FAQs

Does changing from a gelatin capsule to a non-gelatin capsule avoid infringement of Claim 1?
If a tablet contains 600 mg of 2-phenyl-1,3-propanediol dicarbamate, is it outside “about 25 to about 500 mg”?
Can a method-of-use claim be enforced based on label indications alone, or is evidence of actual administration required?
What happens to infringement analysis if a patient’s daily dose falls within 100 mg to 5 g but per-unit strength is outside 25–500 mg?
How are “partial complex seizures” defined in practice when asserting or defending a seizure-subtype-limited patent claim?

References (APA)

U.S. Patent No. 5,082,861. (n.d.). Claims provided in prompt.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	142492	⤷ Start Trial
Germany	69028542	⤷ Start Trial
Denmark	0491094	⤷ Start Trial
European Patent Office	0491094	⤷ Start Trial
Spain	2094145	⤷ Start Trial
Greece	3021801	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,082,861

Summary for Patent: 5,082,861