United States Patent 5,595,760: Scope, Claim Map, and Landscape

US Patent 5,595,760 claims sustained-release delivery of peptides via a formulation that is solid or semisolid at dosing, then automatically forms an in vivo gel after contact with bodily fluids, releasing peptide continuously for at least 3 days. The core novelty sits in the combination of (i) a soluble, gelable peptide salt, (ii) a limited amount (up to 30 wt%) of a soluble, monomeric carrier, and (iii) reduced solvent in a semisolid form so the preparation gels in vivo after a single parenteral injection. Claim coverage spans methods, in situ gels, and compositions (solid cylindrical and semisolid suspensions).

What are the claim pillars that define infringement risk?

1) One-injection, continuous release over at least three days

Independent method claim 1 requires:

Continuous peptide delivery within the patient
Extended period of at least 3 days
One injection (no repeated dosing schedule)

Independent composition claims 15 and 18-22 anchor the same in vivo performance:

Gel formation after interaction with bodily fluids
Continuous release for at least 3 days after formation

2) In situ gel formation from a “soluble, gelable peptide salt”

Every major claim is built on a peptide entity that is:

A peptide salt that is soluble
Gelable so it forms a gel upon interaction with bodily fluids
The gel is what enables sustained release

The claims do not limit the mechanism as “thermal,” “ionic strength,” “pH-triggered,” or polymer-like gelation. What matters legally is that the preparation:

automatically forms a gel after interaction with the patient’s bodily fluids

3) Limited soluble monomeric carrier (up to 30 wt%) or no carrier

The formulation language is bounded:

Carrier: up to 30 percent by weight
Carrier is pharmaceutically acceptable, soluble, monomeric
If present, peptide salt and carrier must be soluble in aqueous liquids

Claim 6 introduces a “no carrier” variant:

Solid composition comprises no carrier

Claim 7 specifies carrier candidates:

mannitol, sorbitol, or lactose

4) Parenteral administration route and “one injection” delivery

Claim 2 narrows the method to injection routes:

intramuscularly, subcutaneously, or intradermally

Claims 10 and 20 similarly require parenteral administration in one injection of a semisolid suspension.

5) Physical form limits: cylindrical solid under 3 mm diameter

Claim 8 adds a structural limitation:

Solid composition in the form of a cylinder
Diameter < 3 mm

This is a meaningful design-around lever because it is a specific geometry claim element.

6) Solvent-limited semisolid suspension: “less than 50%” and “less than 10%”

Claims 10, 17, 20, and 21 require reduced solvent amounts for semisolid preparations:

A semisolid suspension includes an aqueous solvent amount:
- < 50% of the solvent needed to dissolve the peptide salt and provide semisolid consistency
Dependent claims tighten:
- < 10% of the solvent needed

The language creates a quantifiable formulation boundary tied to the dissolution threshold.

7) Peptide scope is broad by identity class

The claims explicitly list peptide targets, but they also provide “analog” coverage.

Claim 3 includes:

somatostatin or a somatostatin analog

Claim 4 includes:

a soluble LHRH analog (luteinizing hormone-releasing hormone analog)

Claim 5 includes:

GRF, PTH, PTHrp, calcitonin
plus soluble biologically active analogs of those

Composition claims 19 and 22 repeat this peptide set and also include a qualifier in at least one spot:

“soluble, hydrophobic LHRH analog” appears in claim 19 and 22

Claim 22’s peptide list is otherwise consistent with claims 3-5 and 19’s list.

8) Release duration extension: at least 14 days

Claim 9 specifies a performance extension:

Gel releases peptide continuously for at least 14 days

This is a dependent-claim uplift that can matter for commercial product positioning and for freedom-to-operate around shorter-release competitors.

How do the independent and dependent claims layer protection? (Claim map)

A. Method claims

Independent method claim 1 (solid composition)

Requires all of the following:

One injection
Continuous peptide release for at least 3 days
Obtain a solid pharmaceutical composition
- consisting essentially of:
- soluble, gelable peptide salt
- up to 30 wt% soluble monomeric carrier (optional)
- peptide salt and carrier soluble in aqueous liquids
Parenteral administration
Automatically forms a gel after interaction with bodily fluids
Gel releases peptide continuously for ≥ 3 days

Dependent method claim set

Claim 2: route (IM, SC, or intradermal)
Claim 3: peptide = somatostatin/analog
Claim 4: peptide = soluble LHRH analog
Claim 5: peptide = GRF/PTH/PTHrp/calcitonin and soluble biologically active analogs
Claim 6: no carrier
Claim 7: carrier selection (mannitol/sorbitol/lactose)
Claim 8: solid in cylindrical form, diameter < 3 mm
Claim 9: release ≥ 14 days

Independent method claim 10 (semisolid suspension)

Adds a solvent-threshold definition:

Semisolid suspension includes:
1. solid soluble gelable peptide salt + up to 30 wt% soluble monomeric carrier (both soluble in aqueous solvents)
2. aqueous solvent in an amount < 50% of the amount required to dissolve peptide salt and provide semisolid consistency
One injection, parenteral administration
Automatically gels in vivo
Continuous release ≥ 3 days

Dependent method claims 11-15

Claims 11-13: peptide identities (same set as solid)
Claim 14: solvent amount < 10%
Claim 15: shifts to “sustained-release gel formed within a patient” (product-by-process style within method claim set, but effectively composition-of-gel coverage)

B. Gel claim

Claim 15 (gel in vivo)

Defines an in situ gel composition:

Gel comprises:
- composition consisting essentially of:
- soluble gelable peptide salt
- up to 30 wt% soluble monomeric carrier
- plus contact with one or more bodily fluids
Peptide salt automatically gels after bodily fluid interaction
Gel releases peptide continuously for ≥ 3 days after formation

This claim creates direct coverage for the gel phase, independent of whether the pre-injection dosage was solid or semisolid (as long as the gel composition meets the stated “consisting essentially” elements).

C. Composition claims

Claim 18 (solid, non-particulate, sustained-release composition)

Defines a solid dosage form:

A “solid, non-particulate” composition for parenteral administration:
- consists essentially of:
  1. soluble gelable peptide salt
  2. up to 30 wt% pharmaceutically acceptable monomeric soluble carrier
Compounded into a solid cylindrical form
Peptide salt and carrier soluble in aqueous liquids
Automatically forms a gel in patient
Gel releases peptide continuously ≥ 3 days

Claim 19 (peptide species for claim 18)

Specifies peptide from the list:

somatostatin/analog
“soluble, hydrophobic LHRH analog”
GRF
PTH
PTHrp
calcitonin
soluble biologically active analogs of GRF/PTH/PTHrp/calcitonin

Claim 20 (semisolid suspension composition)

Defines a semisolid sustained-release suspension:

consists essentially of:
1. soluble gelable peptide salt + up to 30 wt% soluble monomeric carrier
2. aqueous solvent amount < 50% of the amount required to dissolve peptide salt and provide semisolid consistency
Automatically forms a gel after bodily fluids
Gel releases peptide continuously ≥ 3 days

Claim 21 and 22 (solvent tightening and peptide species)

Claim 21: solvent amount < 10%
Claim 22: peptide species list (including “soluble, hydrophobic LHRH analog”)

Where are the “hard” boundaries in scope? (Design-around map)

The claims contain several elements that function as clear inclusion boundaries:

Claim element	Hard limit in patent text	Scope impact
Release duration	Continuous release ≥ 3 days	Products releasing <3 days avoid this coverage; products showing gel release duration require mapping
Gel trigger	“Automatically forms a gel” after interaction with bodily fluids	Competitors using pre-formed depots or non-gelling systems likely fall outside
Carrier amount	Up to 30 wt%	Formulations with higher carrier content do not meet “consisting essentially of ... up to 30%”
Carrier type	“soluble, monomeric carrier”	Polymeric carriers or insoluble excipients are at risk of falling outside the defined class
Carrier identity	mannitol/sorbitol/lactose (dependent)	If a product uses a different carrier, it may avoid dependent coverage but still risk independent claims if “monomeric soluble carrier” is satisfied
Solvent limits (semisolid)	Aqueous solvent < 50% (and dependent < 10%) of dissolution/consistency threshold	High-solvent semisolids and fully dissolved systems present a potential carve-out
Geometry (solid)	Solid cylindrical form, diameter < 3 mm (dependent claim 8)	If a solid device is not cylindrical or exceeds diameter, it can avoid that dependent layer; independent claims 18 still require “solid cylindrical form” but not the <3 mm dependent feature

Two key legal takeaways from the text:

The patent is not just about “a gel” but about a specific formulation constellation that yields in vivo gelation and continuous release.
Multiple claim tiers exist for the same invention across solid dosage, semisolid suspension, and in situ gel composition.

What is the likely patent landscape structure around this filing?

The claims are written broadly enough to cover a range of “peptide salt + limited soluble monomeric carrier” vehicles that self-gel in vivo. In a typical landscape sense, that pushes competitors into three avoidance strategies:

Avoid in situ gel formation from a soluble gelable peptide salt
- Use different release technologies (e.g., polymer depots that release by diffusion/erosion without “automatic gel formation after bodily fluid interaction” of a gelable peptide salt system).
Break the formulation boundaries
- Exceed 30 wt% carrier.
- Use a carrier that is not a “monomeric soluble carrier.”
- Use solvent levels in semisolids at or above the claimed dissolution/consistency thresholds.
Use different peptide salt architectures
- If the peptide form is not a “soluble, gelable peptide salt,” it can avoid the core claim element. (Whether it still gels via some other component depends on the exact “consisting essentially” and “automatic gel” requirements.)

Because the claim set explicitly targets several well-known peptide hormone systems (somatostatin analogs, LHRH analogs, GRF, PTH/PTHrp, calcitonin), product launches for these categories using in situ gel-forming salt-based depots are the most exposed.

Practical scope summary by claim family

Solid family (claims 1, 2, 6-9, 18-19)

Solid, non-particulate sustained-release composition
Soluble, gelable peptide salt with up to 30 wt% soluble monomeric carrier
Automatically gels in vivo
Continuous release ≥ 3 days
Specific route (dependent)
Cylindrical form (independent) and diameter <3 mm (dependent)

Semisolid family (claims 10, 14, 20-22)

Semisolid suspension with reduced solvent
Salt + up to 30 wt% carrier
Aqueous solvent amount <50% (or <10% dependent) of what would be needed to dissolve salt and reach semisolid consistency
Automatically gels in vivo
Continuous release ≥ 3 days
Peptide identity species explicitly listed

Gel family (claim 15)

In situ gel composition itself
Includes “one or more bodily fluids” interacting with the formulation elements
Continuous release ≥ 3 days after formation

Key Takeaways

Claim center is an in vivo, automatic gel-forming system driven by a soluble, gelable peptide salt, optionally combined with a soluble monomeric carrier up to 30 wt%.
The patent covers one-injection parenteral delivery with continuous peptide release for at least 3 days, plus a dependent upgrade to ≥ 14 days.
Coverage spans solid cylindrical, semisolid suspension, and the in situ gel itself.
The strongest numeric boundaries are carrier cap (30 wt%) and solvent limits (<50% / <10%) for semisolids, and geometry (<3 mm diameter) for a dependent solid claim.
The peptide scope explicitly targets somatostatin/analogs, soluble LHRH analogs, and GRF/PTH/PTHrp/calcitonin and soluble biologically active analogs, creating high relevance for sustained-release hormone/peptide therapeutics.

FAQs

1) Does the patent require a specific gel mechanism?

No. It requires that the preparation “automatically forms a gel after interaction with the patient’s bodily fluids” and that the gel releases peptide continuously for the claimed duration.

2) Are carrier excipients limited to mannitol, sorbitol, and lactose?

Not in the independent claims. Those appear in a dependent claim (claim 7). Independent claims require a “soluble, monomeric carrier” up to 30 wt%, which can include other carriers if they meet that defined class.

3) Can a competitor avoid the patent by using a peptide that is not a “gelable peptide salt”?

Yes, if the peptide form is not a soluble, gelable peptide salt that leads to the claimed “automatic gel” behavior after bodily fluid interaction, it can miss the core claim element.

4) What is the key numeric boundary for semisolid formulations?

The aqueous solvent amount must be less than 50% of the amount required to dissolve the peptide salt and provide semisolid consistency; dependent coverage tightens this to less than 10%.

5) Is the solid form required to be under 3 mm diameter?

Only for dependent claim 8. The independent composition claim (claim 18) requires a solid cylindrical form, while the diameter threshold is specified in the dependent layer.

References

[1] US Patent No. 5,595,760, “Method and composition for sustained release of peptides via in situ gel formation,” claims (provided by user).

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0779805	⤷ Start Trial	CA 2002 00032	Denmark	⤷ Start Trial
European Patent Office	0779805	⤷ Start Trial	91037	Luxembourg	⤷ Start Trial
Austria	188615	⤷ Start Trial
Austria	210424	⤷ Start Trial
Austria	230977	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 5,595,760