United States Patent 5,543,150: Scope, Claim Construction, and US Landscape

US Patent 5,543,150 claims a vaginal progesterone delivery method that produces endometrial secretory transformation while keeping serum progesterone below 6.0 ng/mL for at least 48 hours, using a vaginal drug delivery system that includes cross-linked polycarboxylic polymer + progesterone (with polycarbophil explicitly called out). The claim set narrows the permissible formulation and performance outcomes via (i) dose range (10 to 200 mg), (ii) serum target range (1 to 4 or 1 to <5 or 1 to 6 ng/mL), (iii) time-at-level (at least 48 hours), and (iv) delivery device composition parameters, including cross-link density expressed as weight percent cross-linking agent (0.1 to 6.0 wt%).

Core independent claim logic (Claim 1)

Claim 1 is the foundation. It requires all of the following limitations:

Indication/endpoint: “secretory transformation of the endometrium”
Route: progesterone is delivered via a drug delivery system inserted into the vagina
Dose-to-exposure constraint: progesterone must maintain serum levels below 6.0 ng/mL
Duration: continuous period of at least 48 hours

Claims 2-7, 12-23 then layer additional narrowing limitations around dose, serum window, polymer identity, cross-linking, adjuvants, and estradiol priming.

What is the claim scope, element-by-element?

How are the method claims defined?

The claims are method claims tied to a clinical/physiological outcome plus pharmacokinetic control plus a specific delivery platform.

Key elements that bound infringement:

Treatment is performed on women by delivering progesterone intravaginally.
The progesterone delivery device/system must be inserted into the vagina (not oral, not implant in uterus, not intramuscular).
Endometrial secretory transformation must occur as the physiological result.
Serum progesterone is controlled: below 6.0 ng/mL in Claim 1; and narrower ranges in dependent claims.
Time: continuous at least 48 hours (Claim 1 and the underlying system concept).
Composition: cross-linked polycarboxylic polymer + progesterone in the system (Claims 6-7, 8-10, 13-20, 23).
Polymer identity and cross-linking: polycarbophil is called out; cross-linker wt% ranges are specified (Claims 7, 10, 16, 19, 23).
Optional modifiers: adjuvants and estradiol priming are included in multiple dependent claims (Claims 4-5, 11, 18).

What serum constraints do the claims impose?

The claim set creates overlapping serum windows that are likely to be used to distinguish prior art and to target specific PK profiles.

Claim(s)	Serum progesterone requirement (ng/mL)	Placement in claim chain
1	< 6.0	Independent (base)
3	1 to 4	Dependent on claim 1
12	1 to < 5	Dependent on claim 1
13	1 to 6	Dependent on claim 12 + cross-linked polymer delivery
15	1 to 4	Dependent on claim 13
20	1 to 4	Dependent on claim 12
21	1 to 2	Dependent on claim 20

Practical reading: infringement is easiest where an accused regimen produces measurable serum progesterone in the claimed band and uses the claimed vaginal delivery system.

What progesterone dose constraints are claimed?

The claims repeatedly lock in a dose range.

Claim(s)	Progesterone amount inserted (mg)
2	10-200 mg (with serum <6.0 under Claim 1 framing)
14	10-200 mg (with Claim 13 serum range)
8-9	8 requires 10-200 mg as part of endometrium-targeting scheme; 9 requires serum 1-4 as part of that scheme

No claim in the provided set specifies dose as “mg/kg” or other scaling. The scope is tied to absolute mass inserted intravaginally.

What polymer and cross-linking constraints are claimed?

The claims use a “cross-linked polycarboxylic polymer” architecture and specify polycarbophil plus cross-link wt%.

Claim(s)	Polymer definition	Cross-link parameter
6	cross-linked polycarboxylic polymer + progesterone	not quantified in claim 6
7	polymer is polycarbophil	not quantified in claim 7
8, 10	cross-linked carboxylic polymer + progesterone (endometrium targeting)	not quantified in claim 8/10
13	cross-linked polycarboxylic polymer + progesterone	not quantified in claim 13
16	polymer is polycarbophil	not quantified in claim 16
19	polymer is cross-linked with 0.1 to 6.0 wt% cross-linking agent	explicit range
23	polymer is cross-linked with 0.1 to 6.0 wt% cross-linking agent	explicit range (separate dependent)

Practical reading: a product with a different polymer chemistry (not polycarboxylic/carboxylic polymer, not cross-linked) will fall outside key dependent coverage; a cross-linking profile outside 0.1-6.0 wt% is a potential design-around if other elements are not enough to reach literal coverage.

What optional features expand the scope in dependent claims?

These are “add-on” limitations that can narrow infringement to specific combinations:

Adjuvants inserted (Claims 4 and 11 and 17)
Vagina primed with estradiol (Claim 5 and 18)
Drug delivery device inserted into vagina (Claims 22, 1 already requires this; 22 restates as a structural device delivery context for claims 12/20/21)

Note that adjuvants and estradiol priming appear in multiple places as dependent claims. They matter for infringement only if the accused protocol includes those additional steps/components.

Claim-by-claim scope map (what must be true to infringe)

Independent claim coverage

Claim 1: vaginal delivery system + progesterone + endometrial secretory transformation + serum < 6.0 ng/mL for ≥48 hours.

Dependent claim narrowing coverage

Claims 2-5: add progesterone dose range, narrower serum window (1-4), optional adjuvants, and estradiol priming.
Claims 6-7: require cross-linked polycarboxylic polymer; then polymer identity as polycarbophil.
Claims 8-10: create a “targeting” formulation path: cross-linked carboxylic polymer + progesterone, with 10-200 mg and serum 1-4; then polycarbophil.
Claims 11: adds adjuvant requirement in the targeting path.
Claims 12-21: lock physiological endpoint with serum windows (1 to <5; 1 to 6) and progressively narrow to 1-4 and 1-2; include cross-linked polycarboxylic polymer delivery as the serum-band mechanism.
Claims 17-18: add adjuvants and estradiol priming in the cross-linked-polymer anchored serum-band claims.
Claims 19 and 23: define cross-linking agent wt% between 0.1 and 6.0.

Net effect: The patent’s strongest “center of gravity” coverage is for vaginal progesterone delivery using cross-linked polycarboxylic polymer systems (polycarbophil emphasized) that deliver progesterone into the 1-4 ng/mL zone (with additional options for 1 to <5 or up to 6), sustaining effect over at least 48 hours, and producing endometrial secretory transformation.

How does claim language constrain design-around strategies?

Route and endpoint are hard constraints

To avoid Claim 1, a party would need to avoid at least one of:

vaginal insertion delivery system
“secretory transformation of the endometrium” outcome
continuous duration of at least 48 hours with serum control
serum progesterone staying below the defined thresholds

If an alternative route is used (oral, injectable, intrauterine), Claim 1 and most dependent claims are largely neutralized by route mismatch.

Polymer class and cross-linking ranges are the main formulation pressure points

Using a non-polycarboxylic polymer (or non-cross-linked system) aims to avoid Claims 6, 8, 13, 19, 23.
If a cross-linking chemistry remains but cross-link density falls outside 0.1 to 6.0 wt%, Claims 19 and 23 are avoidable, though other claims without that numeric cross-linking limitation may still be asserted (Claims 6-7, 8-10, 13-16).

Serum window tailoring is also a lever

Because the dependent claims define specific serum ranges, product development that targets higher serum levels (above 6 ng/mL) or lower than 1 ng/mL would aim to exit those bands. Claim 1 remains “< 6.0,” so pushing above 6 mL would attempt to avoid the baseline.

Where does the landscape likely cluster around this patent’s theory of invention?

Even without relying on a full bibliographic dossier, the claim architecture points to a landscape cluster in which competitors and generics must confront three value drivers simultaneously:

Intravaginal progesterone delivery using controlled-release systems
PK management to keep systemic levels within a narrow band while generating local uterine effects
Use of cross-linked mucoadhesive or polymeric vaginal matrices (polycarbophil is explicitly named)

Landscape categories implied by the claim set

Landscape bucket	How it intersects with 5,543,150
Vaginal progesterone gels or inserts with systemic exposure control	Potential direct overlap if serum falls under 6 ng/mL and endometrial transformation is claimed
Progesterone devices using polycarbophil-like cross-linked polycarboxylic polymers	Direct technical overlap with Claims 6-7, 8-10, 13-16
Vaginal progesterone systems using different polymer chemistry or non-cross-linked matrices	Risks are reduced versus the polymer-dependent claims but may still face Claim 1 if performance and endpoint requirements align
Protocols combining estradiol priming with progesterone	Potential to trigger dependent coverage (Claims 5, 18) if other limitations match
Systems with adjuvants inserted in the vagina	Potential dependent overlap (Claims 4, 11, 17)

Claim enforcement posture: which claims are most valuable in practice?

Most enforceable claim targets

Claim 1 because it is the broadest: it does not require polycarbophil or explicit cross-link wt%.
Claims 6 and 8 because they narrow to cross-linked polycarboxylic/carboxylic polymer platforms while still leaving cross-link density to other dependents.
Claims 7, 10, 16 because they pin polymer identity to polycarbophil.
Claims 12, 13, 20, 21 because they narrow to specific serum bands that are measurable and can be used for infringement by PK performance.
Claims 19 and 23 because they give a quantitative cross-linking design window (0.1 to 6.0 wt%), useful for both invalidity/design-around and for enforcement when formulation details are discoverable.

Potential claim validity and prior-art pressure points (based on claim structure)

The claims are strongly structured as a combination invention: (vaginal progesterone delivery + endometrial secretory transformation + serum PK below a threshold + sustained duration + a particular formulation platform). That means invalidity is most likely to be assessed as an overlap of prior art on:

intravaginal progesterone intended to induce endometrial changes
sustained release systems lasting 48+ hours
serum progesterone control to a threshold (below 6 ng/mL)
cross-linked polycarboxylic polymers used as vaginal delivery matrices

The most sensitive elements for novelty and non-obviousness are likely the serum thresholds and their relationship to endometrial transformation as a functional endpoint, plus the combination with specific polymer platform features.

Key Takeaways

US 5,543,150 covers vaginal progesterone delivery that achieves endometrial secretory transformation while maintaining serum progesterone < 6.0 ng/mL for at least 48 hours (Claim 1).
The strongest dependent claim “core” is cross-linked polycarboxylic polymer delivery, with polycarbophil explicitly claimed, and serum bands repeatedly narrowed to 1-4 ng/mL and 1-2 ng/mL.
The claim set contains clear numeric formulation constraints: 10-200 mg progesterone inserted and cross-linking agent 0.1 to 6.0 wt%.
Adjuvants and estradiol priming expand scope only in dependent claims, creating narrower infringement profiles tied to combined treatment protocols.
From a design-around perspective, the highest-leverage escape routes are: changing route, avoiding the serum band constraints, or using a delivery matrix that is not a cross-linked polycarboxylic/carboxylic polymer system, or avoids the specified 0.1-6.0 wt% cross-linking range.

FAQs

1) What serum level does the patent require in the broadest claim?

Claim 1 requires serum progesterone below 6.0 ng/mL.

2) Does the patent require sustained delivery for at least two days?

Yes. Claim 1 requires a continuous period of at least 48 hours while maintaining serum levels below the threshold.

3) What progesterone dose range is claimed for the vaginal insertion?

Several dependent claims require 10-200 mg progesterone inserted into the vagina.

4) Is polycarbophil mandatory for infringement?

No. Polycarbophil is explicitly required only in dependent claims (e.g., Claims 7, 10, 16). Claim 1 does not require polycarbophil.

5) Can estradiol priming and adjuvants be ignored?

They are not required for Claim 1. They appear as dependent limitations in Claims 5, 4, 11, 17, and 18, so they matter only if those dependent claims are asserted.

References

[1] United States Patent 5,543,150.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	174796	⤷ Start Trial
Australia	689133	⤷ Start Trial
Australia	7726194	⤷ Start Trial
Brazil	9407475	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,543,150

Summary for Patent: 5,543,150