Details for Patent: 6,379,703

Scope, Claims, and US Patent Landscape: US 6,379,703 (Microparticles with Controlled Release via Intermediate Drying)

What is US 6,379,703 claiming in plain scope terms?

US 6,379,703 centers on a process for making polymeric microparticles (and the resulting microencapsulated active agents) whose drug release profile is tuned by how much “intermediate drying” is performed between solvent extraction and final drying. The independent methods set out an emulsion-based solvent extraction route, then make the drying strategy the release-shaping control variable.

Core independent claim structure (Methods)

The patent includes two method categories:

1) Method for preparing microparticles with a selected release profile

• Preparing an emulsion (first phase: drug + polymer + polymer solvent; second phase: immiscible phase for emulsification)
• Extracting solvent from the emulsion to form drug-loaded microparticles
• Selecting a degree of intermediate drying to achieve a selected release profile
• Final drying

2) Method for controlling a release profile (short-form control abstraction)

• Form microparticles containing active agent
• Select degree of drying whose effect is known to modulate release
• Perform the selected drying

Key dependent claim mechanics (the “release-shaping” levers)

The claims define at least two end-member drying strategies:

• No intermediate drying: yields initial burst and substantially linear release (Claims 2, 9, 12)
• Substantially complete intermediate drying: yields initial lag and substantially sigmoidal release (Claims 3, 10, 13)

The claims further tie “substantially complete” to a measurable endpoint:

• Moisture content < about 0.2% after intermediate drying (Claims 5, 15)

Other process refinements appear as dependent limitations:

• After selection of intermediate drying, perform the selected degree (Claim 4, and Claim 14 in the microencapsulated-agent set)
• Washing microparticles (Claim 6)
• Extraction uses a quench liquid (Claim 7)
• Microparticles prepared by certain method claims (Claims 16-18)

Product-by-process coverage

The patent includes product claims framed around the process:

• Microencapsulated active agent having a selected release profile prepared by the defined emulsion + extraction + intermediate drying + final drying sequence (Claims 11-15)

This creates both:

• Direct process infringement risk (if others make via the described sequence) and
• Product-by-process argument space (if others sell a microencapsulated agent made through the claimed sequence, or if the product is characterized by process-defined attributes).

What exactly is the claim scope around “intermediate drying”?

“Intermediate drying” is not just a timing detail. In the claim set, it is the control step that determines whether the resulting release curve shows:

• an immediate burst with linear release (when intermediate drying is omitted), or
• an initial lag followed by a sigmoidal release shape (when intermediate drying is substantially complete)

End-member drying outcomes (explicitly claimed)

Moisture endpoint binding the “substantially complete” concept

Enforcement-relevant reading

From a scope standpoint, competitors do not avoid the claims by simply using “some drying.” The claims require a selected degree of intermediate drying tied to achieving the selected release profile. The presence or absence of intermediate drying is one explicitly claimed binary; the “substantially complete” category is the other. The moisture threshold appears in dependent claims, but it reinforces the patent’s view of what “substantially complete” means.

How broad are the independent concepts given the claim language?

Independent method breadth

Both independent methods are drafted at a relatively high level of abstraction:

• Emulsion formation + solvent for polymer + extraction of solvent to form microparticles
• Then selection and performance of intermediate drying degree plus final drying
• And, in Claim 8, the drying selection is expressed functionally as affecting the release profile

There are no explicit drug identity constraints or polymer identity constraints in the claim text you provided. As written, the method reads on microparticle release control across a range of polymer-drug systems that fit the emulsion + solvent extraction framework.

What the independent claims do NOT require (based on the text provided)

The claims, as provided, do not explicitly require:

• a particular polymer chemistry (e.g., PLGA vs. other polyesters)
• a particular microparticle size range
• a particular quench liquid composition (only appears in dependent Claim 7)
• a specific emulsification technique (only “preparing an emulsion” is required)
• a defined numeric release curve metric (it uses qualitative descriptors: burst, linear, lag, sigmoidal)

This means the patent’s enforceable distinction rests primarily on the drying strategy and its linkage to release shape.

What is the scope of the dependent claims and where do they narrow?

Binary drying strategy (narrower, but high signal)

• Claims 2 and 9: no intermediate drying
• Claims 3 and 10: substantially complete intermediate drying

These are narrow because they effectively require the process to be configured to achieve a specific release shape. In litigation or licensing discussions, these are often the easiest target for noninfringement because competitors may change drying strategy, not just drying equipment.

Moisture endpoint (narrower)

• Claims 5 and 15 require < about 0.2% moisture content after intermediate drying.
  Even if a competitor argues they “substantially complete” the drying, this dependent limitation provides an objective metric to anchor infringement and validity arguments.

Washing (narrower)

• Claim 6 adds washing after the drying selection step (c).

Quench liquid extraction (narrower)

• Claim 7 requires solvent extraction “using a quench liquid.”

Product-by-process set (medium breadth on paper, practical limits in proof)

• Claims 11-15 define the microencapsulated active agent as having a selected release profile prepared via the process steps including intermediate drying degree selection. In practice, this often becomes an evidentiary contest about whether the product was made via the claimed process and whether it meets the release-profile-defined character.

Microparticle product claims (process-linked products)

• Claims 16-18 cover “microparticles prepared by” certain method claims, meaning infringement can track method practice as well as product properties.

Where does this sit in the patent landscape for controlled-release microparticles?

Landscape positioning

US 6,379,703 fits within the broader controlled-release microparticle space where common levers include:

• polymer selection
• drug loading
• emulsion formulation and phase ratios
• solvent extraction conditions
• drying conditions (which are here specifically split into intermediate vs. final)

The claim innovation, on its face, is not merely “drying affects release.” The patent explicitly claims intermediate drying degree selection as the release-shaping mechanism, generating distinct curve archetypes: burst/linear vs. lag/sigmoidal.

How competitors typically design around this type of claim

Given the claim structure, design-around pathways usually fall into two categories: 1) Change drying architecture (eliminate the claimed intermediate drying concept or avoid performing intermediate drying in the claimed sense)
2) Change the pathway/sequence so extraction and drying do not match the claimed “select intermediate drying degree then perform it” sequence

Because Claim 8 is broad and functionally tied to “degree of drying affects release profile,” a competitor must be careful: even if they treat drying as part of processing in a different order, if they still follow the “select degree of drying affecting release and perform it” logic, Claim 8 becomes harder to avoid.

Practical claim-to-activity mapping for R&D and filing decisions

Process map aligned to the claims

A workflow aligned to the patent’s claim steps (for either method category) looks like:

1. Emulsify:
   • first phase: active agent + polymer + solvent for the polymer
   • second phase: emulsifying medium
2. Solvent extraction to form microparticles
3. Intermediate drying:
   • either omit it (mapped to burst/linear claims) or drive it to “substantially complete” (mapped to lag/sigmoidal claims)
4. Final drying
5. Optional washing
6. Optional quench liquid extraction

Release-profile mapping (directly claimed)

Moisture compliance target if pursuing “substantially complete”

• Claims 5 and 15 anchor this to < about 0.2% moisture content after intermediate drying.

For developers seeking to reproduce the claimed “sigmoidal/lag” regime, the moisture target is the clearest quantitative anchor in the claim set you provided.

Patent landscape implications (freedom-to-operate lens)

Claim features most likely to be central in disputes

• Whether the accused process includes an intermediate drying step between solvent extraction and final drying in the way the claim contemplates
• Whether the drying degree selection is used to achieve the specific release-profile archetype asserted in the dependent claims
• Whether intermediate drying is “substantially complete” and whether moisture falls below the dependent threshold (<0.2%), if that dependent claim is implicated

Competitive risk focus

• Processes that follow emulsion + solvent extraction and use controlled drying staging to tune release curves create the highest conceptual overlap risk.
• Products marketed for reduced burst and longer initial lag, where developers disclose staged drying or moisture control between extraction and final drying, tend to cluster around the claimed design space.

Key Takeaways

• US 6,379,703’s enforceable center of gravity is intermediate drying degree selection to shift release behavior between burst/linear and lag/sigmoidal release profiles.
• The claims remain broad on material specifics in the text provided (no explicit drug/polymer identity constraints), and they rely on the process sequence and drying strategy.
• Dependent claims introduce high-friction constraints: substantially complete intermediate drying tied to moisture < about 0.2%, plus optional washing and use of quench liquid during extraction.
• Product-by-process claim coverage (microencapsulated active agent) is directly tied to the same drying-staging mechanism, raising both process and product proof issues in potential enforcement.

FAQs

1) Does US 6,379,703 require a specific active ingredient?

No. The claim language you provided describes “an active agent” without limiting identity.

2) Is “intermediate drying” a single fixed step?

No. The claims require selecting a degree of intermediate drying, with two explicitly claimed outcomes: none vs. substantially complete.

3) What is the objective moisture limit tied to “substantially complete” intermediate drying?

A moisture content less than about 0.2% after intermediate drying appears in dependent claims (Claims 5 and 15).

4) Can a process avoid infringement by changing final drying only?

The claims focus on intermediate drying selection. Changing only final drying does not address the claim’s requirement to select and perform intermediate drying degree to achieve the release profile.

5) What release shapes does the patent explicitly associate with drying choices?

It explicitly associates:

• No intermediate drying with initial burst and substantially linear release
• Substantially complete intermediate drying with initial lag and substantially sigmoidal release

References

[1] US Patent 6,379,703.