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Patent landscape, scope, and claims: |
US Patent 5,922,682 Scope, Claim Map, and US Patent Landscape for Star-Shaped Poly(lactic-co-glycolic) Polyol Esters and Depot Formulations
US Patent 5,922,682 claims a specific class of star-shaped polyol esters built around a defined central “polyol residue” (cyclic glucose oligomer or linear mannitol), esterified with lactic and glycolic acid segments (including copolymers with glycolic acid), with defined molecular-weight windows and compositional constraints. Dependent claims extend scope into depot formulations (matrix, implant, microcapsule) using those esters, including listing bromocriptine, ketotifen, and co-dergocrine as exemplar actives.
What does US Patent 5,922,682 claim: star-shaped polyol esters for depots and specific active agents?
Core invention in one line: star-shaped poly(lactic-co-glycolic) (PLGA) polyol ester conjugates, where a defined polyol residue (glucose oligomer cyclic or mannitol linear) acts as the central core, with at least three hydroxyl groups esterified, and the polymer arms are lactic or co-lactic (containing glycolic acid), suitable as depot matrices or compositions in implant or microcapsule form.
Claim 1 (independent): structural and compositional boundaries
Claim 1 elements (fully written scope):
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Compound type and molecular weight
- “A polyol ester having a molecular weight of 20,000 to 200,000.”
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Central polyol residue “consisting essentially of” two alternatives
- Central residue amount: 0.06% to 10% by weight of the polyol ester.
- Central residue identity (two mutually exclusive sub-types):
- (i) Cyclic glucose structure: a cyclic structure having 1 to 8 glucose units containing 4 to 30 hydroxyl groups, or
- (ii) Linear mannitol structure: mannitol containing 3 to 6 hydroxyl groups.
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Polyester arm composition and end-to-end constraints
- Poly(lactic) or copoly(lactic) residue:
- Molecular weight: 5,000 to 85,000
- At least 3 hydroxyl groups in esterified form (ties to star architecture)
- Star-shaped polymer architecture
- “said polyol residue forms a central part surrounded by said polylactic or co-polylactic acid residue”
- Glycolic acid requirement when copoly-lactic is present
- “said co-poly-lactic residue comprises glycolic acid.”
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“Consisting essentially of” effect
- The claim uses “consisting essentially of” only in the context of the polyol residue composition. That phrasing limits the central polyol residue composition to the recited glucose/mannitol options while allowing minor components not materially affecting the core polyol residue. The star-shaped architecture and esterification requirements remain hard limitations.
Practical claim-construction effect (what you can and cannot design around):
- To avoid Claim 1, a competitor must change at least one of: (a) molecular-weight range, (b) central polyol residue identity or amount, (c) star geometry requirement (central residue surrounded by lactic/co-lactic acid residue), (d) esterification count (at least three hydroxyl groups esterified), or (e) copoly-lactic glycolic-acid content if using the co-poly-lactic alternative.
Dependent claims 2, 3, 8: tighter numerical ranges
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Claim 2: narrows molecular weight to “about 20,000 to about 80,000.”
This creates a subset carve-out inside Claim 1. If a product hits 80k to 200k, it can fall outside Claim 2 while remaining within Claim 1.
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Claim 3: tightens glycolic acid content for the copoly-lactic residue to 30 to 70 mole % glycolic acid.
If a formulation uses glycolic acid outside that window (for example, very low glycolide content or high glycolide content), it can potentially avoid Claim 3 while still fitting Claim 1’s broader “comprises glycolic acid.”
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Claim 8: sets central polyol residue content to 0.2% to 1% by weight.
Claim 8 is a narrower numeric subset of Claim 1’s 0.06% to 10% band.
Claim 4–7: depot formulation scope (matrix, implant, microcapsule)
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Claim 4: “A depot formulation comprising a matrix of a polyol ester of claim 1 and a therapeutically effective amount of a pharmacologically active agent.”
This is a “use-in-composition” structure: if a formulation uses the Claim 1 polyol ester as the matrix polymer, it can fall within scope.
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Claim 5: restricts exemplar actives to bromocriptine, ketotifen, or co-dergocrine.
Claim 5 is dependent: it adds active-agent selection, not polymer structure. A depot with other actives can still potentially satisfy Claim 4 if it uses the Claim 1 matrix.
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Claim 6: “implant form.”
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Claim 7: “microcapsule form.”
Design-around logic for formulations
- Avoiding Claim 4 can be done by:
- Using a matrix polymer that does not meet Claim 1’s structural requirements, or
- Avoiding the “matrix of” relationship by changing the formulation architecture such that the star-shaped polyol ester is not the matrix polymer.
How broad are US 5,922,682 claims: composition-only vs formulation-only scope?
Claim 1 breadth is driven by:
- A wide molecular-weight window (20,000–200,000 for the polyol ester; 5,000–85,000 for the lactic/co-lactic residue).
- Two broad central polyol residue categories (glucose cyclic 1–8 units, mannitol linear).
- “At least 3 hydroxyl groups esterified,” enabling multiple substitution patterns as long as star-shaped geometry is satisfied.
- No explicit restrictions on end groups, lactic stereochemistry, or tacticity in the claim text provided.
Claim 4 breadth is driven by:
- “Therapeutically effective amount” and “pharmacologically active agent” (not limited to the enumerated actives in Claim 5).
- Depot architecture is only “matrix of” the Claim 1 polymer; implant and microcapsule are separate dependent narrowing claims.
Net: the patent is composition-forward but has formulation coverage that can catch a wide range of depots if built on the claimed matrix polymer.
What formulation formats are explicitly covered by US 5,922,682: implant vs microcapsule depot?
Explicitly claimed formats
- Implant: Claim 6
- Microcapsule: Claim 7
- Matrix depot concept: Claim 4
Implications
- If a competitor uses the claimed polymer in a depot but not in implant/microcapsule form, it may still fall within Claim 4 depending on whether its architecture still qualifies as a depot “matrix.”
- If the competitor uses microcapsules/implants but the matrix polymer is outside Claim 1, claims 6/7 do not help the patentee.
Which actives are covered: bromocriptine, ketotifen, co-dergocrine and what that means legally?
Claim 5 is an active-agent selector
- Bromocriptine
- Ketotifen
- Co-dergocrine
Legal effect
- Claim 4 is broad enough for other actives (based on the claim language you provided) if the matrix is made from Claim 1’s polyol ester.
- Claim 5 adds an additional layer for these specific drugs, supporting enforceability even if an accused product argues that “the active is not among the examples” (they may still be caught under Claim 4, but Claim 5 can tighten a narrative around known drugs).
Strategic enforcement use
- Enumerated actives often align with known depot product development and can make claim construction less abstract if the patent specification ties those agents to exemplar formulations.
How does the star-shaped architecture limit competitors: what features must be present?
From Claim 1’s language, the following are hard requirements:
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Central polyol residue acts as the core
- It is “central part surrounded by” lactic/co-lactic acid residue.
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Star-shaped polymer structure
- This is not just “branched.” It is defined as central core surrounded by esterified polymer residues.
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At least 3 esterified hydroxyl groups
- Prevents simple mono-/di-functional ester linkages from qualifying.
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Polyol residue identity and hydroxyl count constraints
- Glucose cyclic: 1–8 glucose units, 4–30 hydroxyl groups.
- Mannitol: 3–6 hydroxyl groups.
- Content: 0.06%–10% by weight (and potentially 0.2%–1% for Claim 8).
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Lactic vs co-lactic residue and glycolic acid presence
- If co-poly-lactic is used, it must “comprise glycolic acid.”
- Claim 3 additionally sets 30–70 mole % glycolic acid.
Common potential avoidance routes
- Replace central core with a different polyol residue type (outside glucose cyclic 1–8 units or mannitol).
- Use a linear rather than star-shaped polymer geometry (if it avoids “central part surrounded by” the polymer residue).
- Reduce the number of esterified hydroxyls below 3 (fails the “at least 3” requirement).
- Change molecular-weight distribution outside the claimed ranges.
- For copolymers, shift glycolic acid content outside 30–70 mole % to avoid Claim 3, though Claim 1 still requires glycolic acid presence if relying on co-poly-lactic.
What is the US patent landscape around US 5,922,682: how to evaluate follow-on coverage and design-around space?
Because the prompt provides only the claims text, the full landscape must be evaluated at the “feature level” rather than by naming specific adjacent patents or litigated families. The landscape assessment below therefore focuses on the predictable IP neighborhood such patents usually occupy:
Adjacent US patent “clusters” likely implicated by the claim features
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Star-shaped PLGA or star-shaped lactide copolymer chemistries
- Competitors often use alternative core polyols, different arm lengths, and different branching strategies to obtain depot-controlled release.
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Core polyol residue variants
- The claim narrows to glucose cyclic structures and mannitol. Landscape work typically searches for:
- other cyclodextrin derivatives,
- other multi-hydroxyl central cores (sorbitol, glycerol-derived dendritic cores),
- other glucose oligomer core forms.
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Glycolic acid ratio control
- Many depot polymer families are built around PLGA ratio tuning (lactide:glycolide). Claim 3’s 30–70 mole % window creates a “notional boundary” that other filings often test with higher or lower glycolide ratios.
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Depot manufacturing formats and encapsulation
- Implant formation methods and microcapsule encapsulation processes tend to be claimed separately or in different families.
- Even when polymer structure is unchanged, manufacturing patents can introduce process-specific barriers.
Landscape evaluation checklist tied to enforceability
- Determine whether an accused polymer matches Claim 1 structural requirements (core polyol + star architecture + esterified hydroxyl count + molecular weight + copoly-lactic glycolic acid presence).
- If polymer matches Claim 1, assess whether formulation is a depot matrix and whether it is implant/microcapsule (Claim 6/7).
- Map the active agent to Claim 5 only if needed; Claim 4 does not appear limited to the listed actives.
When does exclusivity end: what’s the expiration timing for US 5,922,682?
No filing/priority dates, term adjustments, or certificate of extension details are provided in the prompt. Without those, the specific expiration date cannot be computed from the patent number alone within your constraints.
Orange Book status and FDA regulatory posture for products using these depots
No FDA product identity, NDA/BLA numbers, or Orange Book listings are provided in the prompt. Without those, Orange Book status cannot be determined from the claim text alone.
Patent litigation and Paragraph IV or biosimilar risk: what can be inferred?
No litigation docket, parties, or FDA filings are provided in the prompt. Without those inputs, listing actual litigated parties or Paragraph IV events is not possible.
Commercial risk screen: which product characteristics most increase infringement exposure?
An enterprise evaluating risk should treat the following as the highest-signal infringement triggers under the claim text provided:
- Use of a star-shaped polyol ester where the core is glucose cyclic (1–8 units) or mannitol
- Core polyol present at 0.06%–10% by weight (and 0.2%–1% if aiming at Claim 8)
- At least three hydroxyl groups esterified
- Depot matrix built with the claimed polymer
- Implant or microcapsule format
- If the active is bromocriptine, ketotifen, or co-dergocrine, Claim 5 becomes a direct target
Key Takeaways
- US 5,922,682 claims a star-shaped polyol ester with a glucose cyclic (1–8 units) or mannitol central core, esterified with lactic or co-lactic residues containing glycolic acid, with tight molecular-weight and composition bands.
- The most enforceable anchor is Claim 1’s combination of: core polyol identity, core content, star-shaped architecture, at-least-three esterified hydroxyls, and lactic/co-lactic polymer arm molecular weights.
- Formulation claims (Claim 4–7) broaden reach into depot matrices and specify implant and microcapsule forms.
- Claim 5 ties the polymer depot to bromocriptine, ketotifen, and co-dergocrine as exemplar actives, but Claim 4’s depot matrix concept is not limited to those actives based on the provided claim text.
FAQs
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Does US 5,922,682 protect only the polymer or also finished depot products?
The patent includes polymer claims (Claim 1–3 and 8) and formulation claims (Claim 4–7) covering depot matrices in implant and microcapsule forms using the claimed polymer.
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What feature is most critical to avoid infringement under Claim 1?
Matching (or not matching) the star-shaped architecture with the specified central polyol residue identity and esterification count (at least three hydroxyls esterified).
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If a competitor uses PLGA with different glycolic acid mole % than 30–70%, do they avoid the patent?
Claim 3 is avoided, but Claim 1 still requires “co-poly-lactic residue comprises glycolic acid.” Avoiding depends on the overall match to Claim 1, not only Claim 3.
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Are bromocriptine, ketotifen, and co-dergocrine the only actives covered?
Claim 5 lists those actives as dependent scope, while Claim 4’s depot matrix claim is written broadly for “pharmacologically active agent.”
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Do implant and microcapsule claims matter if the polymer itself matches Claim 1?
Yes for narrowing: Claim 6 and 7 add format limitations. But if the polymer matches Claim 1 and the formulation is a depot matrix, Claim 4 can still be implicated even if the product is not strictly characterized as implant or microcapsule.
References
- US Patent 5,922,682, “Polyol esters and depot formulations” (claims as provided in prompt).
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