United States Patent 5,814,342: Scope, Claims Architecture, and U.S. Patent Landscape for LH-RH Analog Zero-Order Microcapsules

United States Patent 5,814,342 is directed to microcapsules that deliver a luteinizing hormone-releasing hormone (LH-RH) analog with zero-order release kinetics for extended periods (at least two months; at least three months in a dependent claim). The claimed formulation centers on a specific water-in-oil emulsion architecture and a tightly bounded poly(lactic acid) (PLA) / poly(lactic-co-glycolic acid) (PLGA) outer-wall polymer specification, including molecular weight and molecular-weight dispersity. The claimed manufacturing routes cover microencapsulation from the water-in-oil emulsion and, in the process claims, in-water drying and phase separation.

This patent is primarily a formulation-and-process monopoly around: (i) inner aqueous drug loading (35–60% w/w LH-RH analog, with “no drug retaining substance” in the inner phase), (ii) outer-wall polymer selection and polymer quality window (PLA or PLGA with lactic/glycolic ratio and molecular weight/dispersity bounds), and (iii) manufacturing steps that create the microcapsule from the specified emulsion.

What is the core inventive concept in US 5,814,342?

The claims define an LH-RH analog microcapsule engineered for sustained, “zero order” release by controlling polymer matrix properties and microencapsulation method. The outer wall is formed from a homopolymer of lactic acid (PLA) or a copolymer of lactic acid and glycolic acid (PLGA), constrained to a narrow polymer-characterization window:

Polymer type
- PLA homopolymer, or
- PLGA copolymer (lactic/glycolic ratio 100/0 to 90/10)
Polymer composition window
- lactic acid/glycolic acid = 100/0 to 90/10
Polymer molecular weight window
- weight-average molecular weight (Mw) = 13,800 to 19,000
Polymer dispersity window
- dispersity = 1.5 to 2.5, defined as Mw / number-average molecular weight (Mn)

The drug resides in an inner aqueous phase free from a drug retaining substance, with 35–60% (w/w) LH-RH analog.

The formulation is then converted into microcapsules by microencapsulation (claim 1) or by emulsion-to-solid conversion via in-water drying or phase separation (claim 5 and dependents).

How do the claims map into enforceable claim scope (independent vs dependent)?

Independent claims

Claim 1 (product, microcapsule)

Zero-order release of an LH-RH analog for at least 2 months
Produced by:
1. water-in-oil emulsion with:
  - inner aqueous phase: 35–60% w/w LH-RH analog, free from drug retaining substance
  - oil phase: polymer for outer wall:
    - PLA homopolymer OR PLGA (lactic/glycolic 100/0 to 90/10)
    - polymer Mw 13,800–19,000
    - dispersity 1.5–2.5
2. subjecting the water-in-oil emulsion to microencapsulation

Claim 5 (process)

Prepares a zero-order release microcapsule for at least 2 months
Uses the same emulsion composition and polymer specification as claim 1
Solidification routes:
- subjecting water-in-oil emulsion to in-water drying or phase separation

Dependent claims (product)

Claim 2

zero-order release for at least 3 months

Claim 3

polymer concentration in oil phase: 2–60% w/w

Claim 4

LH-RH analog is water-soluble and MW ≥ 1,000

Claims 10–13

specify polymer type and tighter polymer ranges:
- claim 10: oil phase contains homopolymer of lactic acid
- claim 11: PLA Mw 14,100–18,200 OR PLGA lactic/glycolic 100/0–90/10 with Mw 13,800–19,000
- claim 12: PLGA ratio 100/0–90/10
- claim 13: PLGA ratio 100/0–90/10 with Mw 13,800–19,000

Dependent claim 1-level composition controls are the main “hinge” Because claim 1 is written as:

a microcapsule defined by performance (“zero order release at least two months”), and
a production recipe with specific emulsion and polymer specs, the practical scope concentrates on combinations that satisfy both the performance and the defined formulation parameters.

Dependent claims (process)

Claims 6–9

claim 6: water-in-oil emulsion dispersed in aqueous phase; resulting water/oil/water ternary emulsion subjected to in-water drying
claim 7: aqueous dispersion contains polyvinyl alcohol as emulsifying agent
claim 8: LH-RH analog water-soluble, MW ≥ 1,000
claim 9: LH-RH analog is specifically (pyr)Glu-His-Trp-Ser-Tyr-D-Leu-Leu-Arg-ProNHC2H5

Claims 14–17

specify polymer type, Mw windows, and composition ratio for the oil phase in the process:
- claim 14: oil phase contains PLA
- claim 15: PLA Mw 14,100–18,200 OR PLGA with ratio 100/0–90/10 and Mw 13,800–19,000
- claim 16: PLGA ratio 100/0–90/10
- claim 17: PLGA ratio 100/0–90/10 with Mw 13,800–19,000

What is the claim-critical parameter set (the “design-around” map)?

For freedom-to-operate analysis, US 5,814,342 is best treated as a set of hard boundaries. The product claim 1 (and process claim 5) require all of the following simultaneously:

A. Drug and inner aqueous phase

LH-RH analog
Inner aqueous phase contains 35–60% (w/w) LH-RH analog
Inner aqueous phase is free from a “drug retaining substance”
- This “free from” limitation is a major narrowing element.

B. Outer-wall polymer in oil phase

Outer wall polymer is either:
- PLA homopolymer, or
- PLGA copolymer with lactic acid/glycolic acid = 100/0 to 90/10
Polymer material properties:
- Mw = 13,800 to 19,000
- Dispersity (Mw/Mn) = 1.5 to 2.5

C. Microencapsulation / solidification method

For product claim 1:
- water-in-oil emulsion is subjected to microencapsulation
For process claim 5:
- water-in-oil emulsion is subjected to in-water drying or phase separation
Dependent claims further narrow process:
- water/oil/water ternary emulsion via aqueous dispersion
- PVA emulsifier for the aqueous phase
- specific LH-RH analog sequence (claim 9)

D. Release performance requirement

Zero-order release for at least two months (claims 1 and 5)
At least three months is a dependent product improvement (claim 2)

Practical enforcement posture

If a competitor’s microcapsule uses a materially different polymer Mw/dispersity window, the literal “polymer quality” limitations can fall away.
If drug is loaded outside 35–60% w/w, or if the inner phase includes any “drug retaining substance,” the claims are harder to meet.
If solidification is not via the claimed in-water drying/phase separation routes, process claim 5 may weaken, but product claim 1 can still apply depending on whether a court reads the “produced by” language as requiring those exact steps for infringement.

How narrow is the polymer specification, and where are the likely infringement fault lines?

US 5,814,342 narrows outer-wall polymer using four coupled parameters:

Copolymer ratio: lactic acid/glycolic acid from 100/0 to 90/10
- This covers PLA (100/0) through low-glycolic PLGA (down to 90/10).
Mw: 13,800 to 19,000
- Notably centered around ~16k-17k.
Dispersity: 1.5 to 2.5
- Excludes very narrow “low-dispersity” materials and broad distributions.
Polymer identity:
- Either PLA or PLGA with the above characteristics.

Likely fault lines in practice

Mw mismatch: Many commercial PLGA lots target different Mw grades (e.g., 20k, 30k, 50k, 75k). Even if the ratio is correct, Mw outside 13,800–19,000 can avoid literal scope.
Dispersity mismatch: Dispersity is rarely advertised consistently; it can become a litigation battleground via polymer characterization.
Emulsion and inner-phase compositional mismatch: “Free from a drug retaining substance” can be engineered around by avoiding excipients or components that a patentee might argue are “drug retaining.”
Drug loading mismatch: 35–60% w/w is high. Formulations using substantially lower drug loading (common in some depot systems for solubility/viscosity reasons) risk non-infringement.

What does the patent family and prosecution posture imply for the U.S. landscape?

Based on the claim text alone, US 5,814,342 sits in a predictable technical neighborhood:

controlled-release LH-RH analog depot microcapsules
polymer-driven zero-order release control using PLGA/PLA
emulsion-based microencapsulation and in-water drying/phase separation
inner aqueous high drug loading without drug-retaining additives

However, producing a complete U.S. “patent landscape” (overlapping claims, expiry dates, active/inactive status, and citations forward/backward) requires identifying the patent’s full bibliographic record and then mapping all U.S. related applications and citing/cited patents. The provided information includes only claim text; no publication/application numbers, assignee, priority dates, prosecution history, or cited references are included. Under strict requirements for complete and accurate response, a full landscape cannot be constructed here without those missing bibliographic anchors.

Accordingly, the landscape discussion below is limited to in-scope scope mapping that is grounded in the claims provided, not a complete U.S. citation graph.

How would a competitor attempt a literal claim avoidance strategy? (Claim-based, not speculative)

1) Change polymer molecular weight and/or dispersity

To avoid claim 1/5 literal polymer window:

use PLA/PLGA outside Mw 13,800–19,000 or dispersity outside 1.5–2.5
keep the lactic/glycolic ratio outside the 100/0 to 90/10 band if using a PLGA with higher glycolic content

This is the most direct “parameter surgery,” since it is explicitly recited in the claims.

2) Alter inner aqueous phase composition and/or remove “drug retaining substance” logic

To avoid the “inner aqueous phase free from a drug retaining substance” limitation:

ensure the inner phase includes no component that can be characterized as “drug retaining substance” under the claim’s wording; conversely, a competitor can also design the inner phase so it cannot be argued to contain such a substance.

To avoid the drug load window:

formulate so LH-RH analog is outside 35–60% w/w in the inner aqueous phase.

3) Use a different emulsion-to-solid route

claim 5 covers “in-water drying or phase separation.” A competitor using alternative solidification routes not falling under these terms can weaken process claim 5.
product claim 1 is harder to avoid because it is a microcapsule defined by its production recipe plus performance.

4) Avoid prolonged “zero order” performance targets

claim 1 requires zero-order release for at least two months
claim 2 requires at least three months

A competitor can target shorter release duration or different release kinetics; whether that avoids infringement depends on measurement standards and how “zero order” is defined in litigation evidence.

Where do the dependent claims concentrate additional enforcement leverage?

Dependent claims can become high-value for enforcement if a competitor’s formulation tracks claim 1 tightly:

Longer release (claim 2): if a product achieves at least three months zero-order release under the same polymer and inner phase constraints.
Polymer concentration (claim 3): oil phase polymer concentration of 2–60% w/w.
Specific LH-RH analog (claim 9): (pyr)Glu-His-Trp-Ser-Tyr-D-Leu-Leu-Arg-ProNHC2H5, which narrows to a specific analog.
PVA emulsifier (claim 7): if the manufacture uses PVA in the aqueous phase.

These dependent layers do not typically broaden the invention; they narrow it. For a product that already matches claim 1, dependent claims provide additional “fit points” to capture manufacturing details and performance extensions.

US 5,814,342: Claim chart style summary of scope coverage

Claim element	What it requires	Main scope impact
Zero-order release duration	≥2 months (claim 1/5), ≥3 months (claim 2)	Performance gate for infringement
Inner aqueous phase	35–60% w/w LH-RH analog; free from “drug retaining substance”	Narrows formulation and excipient freedom
Oil phase polymer identity	PLA homopolymer or PLGA with lactic/glycolic 100/0–90/10	Narrows polymer choice
Polymer Mw	13,800–19,000	Narrows polymer grade
Polymer dispersity	1.5–2.5 (Mw/Mn)	Narrows polymer quality window
Microcapsule formation	microencapsulation (claim 1)	Product production route gate
Process route	in-water drying or phase separation (claim 5)	Narrows manufacturing method
Optional manufacturing detail	aqueous ternary emulsion + in-water drying (claim 6); PVA emulsifier (claim 7)	Adds dependent specificity
Optional analog specificity	specific LH-RH analog sequence (claim 9)	Captures only certain analogs

Key takeaways

US 5,814,342’s literal scope concentrates on a specific emulsion architecture: high drug loading (35–60% w/w) in an inner aqueous phase “free from a drug retaining substance,” paired with PLA/PLGA outer-wall polymers defined by both composition and polymer quality (lactic/glycolic 100/0 to 90/10; Mw 13,800–19,000; dispersity 1.5–2.5).
The strongest enforceability lever is the coupled polymer specification. Shifting polymer Mw or dispersity outside the stated windows is the clearest claim-avoidance path.
Dependent claims extend coverage for longer zero-order release (≥3 months), specific polymer concentrations, specific LH-RH analog sequence, and specific manufacturing details like PVA emulsifier use.
A complete U.S. “patent landscape” (overlaps across assignees, citation graph, and active status) is not reconstructible from the provided dataset because critical bibliographic identifiers (assignee, priority, application/publication numbers, family members, and cited references) are not supplied.

FAQs

1) Does US 5,814,342 cover any LH-RH analog?

Claim 1 requires an LH-RH analog meeting the claim’s definition; dependent claim 4 restricts to water-soluble analogs with MW ≥ 1,000, and dependent claim 9 further specifies one particular analog sequence.

2) Is the polymer composition limited to PLGA only?

No. Claim 1 includes PLA homopolymer and PLGA with lactic/glycolic ratio 100/0 to 90/10.

3) What is the biggest numerical limitation in claim 1?

The outer-wall polymer Mw (13,800–19,000) and dispersity (1.5–2.5) are the tightest coupled numeric constraints, alongside the inner aqueous drug loading 35–60% w/w.

4) Can a process differ and still infringe the product claim?

Claim 1 is a product claim defined by “produced by” steps. A different process can avoid process claims, but product infringement can still be asserted if the microcapsule itself satisfies the claim’s structural/production limitations and performance.

5) What additional coverage do the dependent claims add?

They narrow the invention to higher performance duration (≥3 months), specify polymer concentration, and capture particular analog identities and manufacturing details like PVA emulsifier use.

References (APA)

[1] United States Patent 5,814,342. (Claim text provided).

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Japan	2-33133	Feb 13, 1990

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	123413	⤷ Start Trial
Australia	645108	⤷ Start Trial
Australia	8179491	⤷ Start Trial
Brazil	9103553	⤷ Start Trial
Canada	2036089	⤷ Start Trial
Canada	2316159	⤷ Start Trial
China	1054009	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,814,342

Summary for Patent: 5,814,342