US Patent 5,898,032: What is claimed in female contraception and how broad is the method scope?
What does US 5,898,032 claim, in plain claim-scope terms?
US 5,898,032 claims a method for female contraception based on a cyclic regimen of combined estrogen-progestin dosing in a monophasic formulation with a defined cycle length and withdrawal interval. The core structure is:
1) Monophasic administration of an estrogen plus a progestin to a pre-menopausal female
2) Given as 60 to 110 consecutive days of continuous administration
3) Where daily doses are defined by equivalence to ethinyl estradiol (estrogen) and norethindrone acetate (progestin) within stated ranges
4) Then non-administration for 3 to 10 days (a withdrawal interval)
Claim 1 is the anchor
Claim 1 defines the full regimen geometry (continuous on-period length + off-period length) and the dosage equivalence ranges.
Claim 1 (independent):
- Method of female contraception
- Monophasic administration to pre-menopausal female
- On-period: 60 to 110 consecutive days
- Daily amounts equivalent to:
- Estrogen: about 5 to 35 mcg ethinyl estradiol
- Progestin: about 0.025 to 10 mg norethindrone acetate
- Off-period: non-administration for 3 to 10 days
This is a combined regimen claim: it is not a composition claim; it is a use method with hard dosing ranges and time windows.
How do the dependent claims narrow the scope?
The dependent claims add dose narrowing and specific identity limitations (ethinyl estradiol and norethindrone acetate) and minimum duration thresholds.
Claim 2 narrows estrogen dose
- Daily estrogen equivalent to 10 to 20 mcg ethinyl estradiol
Claim 3 narrows progestin dose
- Daily progestin equivalent to 0.25 to 1.5 mg norethindrone acetate
Claim 4 sets a minimum on-period
- Combination administered for at least 80 consecutive days
Claims 5 and 6 set drug identities
- Claim 5: estrogen is ethinyl estradiol
- Claim 6: progestin is norethindrone acetate
Claims 7–10 are duplicative refinements
They restate narrower subsets already covered by Claims 3, 4, 5, 6:
- Claim 7: progestin 0.25–1.5 mg (norethindrone acetate equivalent)
- Claim 8: combination at least 80 consecutive days
- Claim 9: estrogen is ethinyl estradiol
- Claim 10: progestin is norethindrone acetate
Claim 11 narrows upper estrogen
- Daily estrogen equivalent to up to 30 mcg ethinyl estradiol
(Note: “up to 30” sits within Claim 1’s 5 to 35 mcg band, and overlaps Claim 2’s 10 to 20 mcg.)
How broad is the infringement-relevant scope?
What is the outer boundary of Claim 1?
Claim 1’s breadth comes from three axes:
1) Population: pre-menopausal female (not post-menopausal; not male; not pregnancy-specific language)
2) Regimen timing:
- On: 60–110 consecutive days
- Off: 3–10 days
3) Dose equivalence ranges:
- Estrogen: 5–35 mcg ethinyl estradiol equivalents per day
- Progestin: 0.025–10 mg norethindrone acetate equivalents per day
That combination yields a wide design space. Many real-world combined hormonal contraception (CHC) products use lower estrogen and a limited set of progestin dose levels; the patent’s range is broad enough to cover multiple dose points, as long as the regimen cycle timing matches.
What is the likely “design-around” pressure point?
The tightest operational pressure is the windowing of time:
- If a competitor uses a different continuous-on interval outside 60–110 days, Claim 1 misses on timing.
- If a competitor uses an off interval outside 3–10 days, Claim 1 misses on withdrawal window.
- If a competitor uses a different progestin whose dosing is not measured/equated to norethindrone acetate in the claim construction, it may avoid. But Claim 1 explicitly frames progestin daily amounts as “equivalent to… norethindrone acetate,” which suggests equivalence is central to claim interpretation.
Dose design-around is harder because Claim 1 covers broad bands and later claims still leave room for overlapping ranges.
Scope map: regimen and dose ranges at a glance
What exact dosing and scheduling ranges are claimed?
| Claim |
Estrogen (daily) equivalence |
Progestin (daily) equivalence |
On-period (consecutive days) |
Off-period (days) |
Identity constraints |
| 1 |
5–35 mcg ethinyl estradiol |
0.025–10 mg norethindrone acetate |
60–110 |
3–10 |
None (equivalence framing) |
| 2 |
10–20 mcg ethinyl estradiol |
Same as claim 1 |
60–110 |
3–10 |
None (still equivalence) |
| 3 |
Same as claim 2 or claim 1 (depends on dependency chain) |
0.25–1.5 mg norethindrone acetate |
60–110 |
3–10 |
None (equivalence framing) |
| 4 |
Same as claim 1 |
Same as claim 1 |
≥80 |
3–10 |
None |
| 5 |
ethinyl estradiol |
Same as claim 1 |
60–110 |
3–10 |
Estrogen fixed |
| 6 |
Same as claim 1 |
norethindrone acetate |
60–110 |
3–10 |
Progestin fixed |
| 7 |
Same as claim 1 |
0.25–1.5 mg norethindrone acetate |
60–110 |
3–10 |
Progestin fixed by range |
| 8 |
Same as claim 1 |
Same as claim 1 |
≥80 |
3–10 |
Minimum duration |
| 9 |
ethinyl estradiol |
Same as claim 1 |
60–110 |
3–10 |
Estrogen fixed |
| 10 |
Same as claim 1 |
norethindrone acetate |
60–110 |
3–10 |
Progestin fixed |
| 11 |
up to 30 mcg ethinyl estradiol |
Same as claim 1 |
60–110 |
3–10 |
Upper estrogen limit |
Patent landscape implications for competitors
What space does this patent likely cover versus mainstream CHC regimens?
The claims describe a prolonged active dosing period followed by a short withdrawal period. This sits in the broader universe of “extended cycle” combined hormonal contraception.
From a landscape perspective, the most salient takeaway is that the patent is not tied to:
- a specific tablet color, imprint, or pack design
- a specific formulation manufacturer
- a specific total number of active tablets per cycle
- a specific daily dose outside the defined bands
Instead, it is tied to:
- continuous duration (60–110 days and at least 80 days)
- withdrawal/non-administration duration (3–10 days)
- monophasic equivalence to ethinyl estradiol and norethindrone acetate
That makes it a potentially relevant barrier for any competitor designing an extended-cycle CHC regimen that hits those time windows with matching daily dose equivalences.
Where are the likely claim “hot zones” for litigation risk?
The highest-risk implementations are those that satisfy all of:
- Monophasic combined estrogen-progestin administration
- Continuous administration for 60–110 consecutive days
- 3–10 day non-administration window
- Daily dosing within the ethinyl estradiol 5–35 mcg and norethindrone acetate 0.025–10 mg equivalence bands
- Use of ethinyl estradiol and norethindrone acetate where identity claims (5,6,9,10) matter
In practice, products with:
- ethinyl estradiol as estrogen component
- norethindrone acetate as progestin component
- prolonged active cycles with a short break
are the most likely to map cleanly to the claim structure.
How to read dependent claims as coverage layering
The dependent claims do two things:
1) Increase certainty of coverage by locking key components:
- estrogen identity: ethinyl estradiol (Claims 5,9)
- progestin identity: norethindrone acetate (Claims 6,10)
2) Increase coverage for narrower dose and duration embodiments:
- estrogen narrow band: 10–20 mcg (Claim 2)
- progestin narrow band: 0.25–1.5 mg (Claim 3 and 7)
- minimum continuous interval: at least 80 days (Claim 4 and 8)
- estrogen upper constraint: up to 30 mcg (Claim 11)
This structure means enforcement can target broader Claim 1 first, then use dependent claims for fallback positions when accused regimens are close but not identical.
Scope construction: key claim elements that drive interpretation
Even without parsing the full specification, the claims themselves identify the interpretive drivers that matter for freedom-to-operate and invalidity analysis:
“Monophasicly administering”
“Monophasicly” limits the regimen to a single combination strength during the on-period. If an accused product varies estrogen or progestin strength across the active interval (true biphasic or multiphasic schedules), that is a logical attack surface against “monophasic” mapping.
“Daily amounts… equivalent to about…”
Equivalence language implies the claim does not strictly require identical numerical mg or mcg, but rather equivalence to:
- ethinyl estradiol for estrogen
- norethindrone acetate for progestin
That can broaden enforcement to products that use compounds considered equivalent for pharmacological or dosing equivalence determinations, depending on claim construction.
“Following by non-administration”
The claim uses “non-administration” rather than “administration of placebo” or “withdrawal bleeding triggering.” That pushes the critical question toward what happens in the off window: the method requires a period of no administration of the combination.
Business-use implications for R&D and investment
What does this mean for next-generation regimen design?
A competitor seeking to avoid this claim’s method coverage would need to move at least one of the following out of range:
- continuous active interval (leave 60–110 consecutive days; or ensure not at least 80 days if aiming to avoid dependent claims as well)
- withdrawal/non-administration window (leave 3–10 days)
- daily dose equivalence bands
Moving estrogen/progestin components away from ethinyl estradiol and norethindrone acetate can also matter because the dependent identity claims reduce argument room for those embodiments.
Key Takeaways
- US 5,898,032 claims a method of female contraception built around an extended continuous “on” interval (60–110 days) plus a short “off” interval (3–10 days).
- Claim 1 is broad on dosing: estrogen is equivalent to 5–35 mcg ethinyl estradiol/day and progestin is equivalent to 0.025–10 mg norethindrone acetate/day, during monophasic administration.
- Dependent claims layer narrower protection for common subsets: 10–20 mcg ethinyl estradiol (Claim 2), 0.25–1.5 mg norethindrone acetate (Claims 3 and 7), and minimum ≥80 consecutive on-days (Claims 4 and 8), plus identity locking of both hormones (Claims 5, 6, 9, 10).
- Landscape risk concentrates on extended-cycle monophasic CHC regimens that use ethinyl estradiol + norethindrone acetate and maintain timing within the specified active and off windows.
FAQs
1) Is US 5,898,032 claiming a drug product or a dosing method?
It claims a method of contraception, not a standalone composition. The infringement event is the performance of the regimen on a pre-menopausal female with the specified timing and dosing relationships.
2) What scheduling parameters are the hardest boundaries in the claims?
The regimen timing: 60–110 consecutive days of administration followed by 3–10 days of non-administration. These time windows define the core inventive structure.
3) Do dependent claims mainly add dose ranges or hormone identity?
Both. They add narrower dose bands (Claims 2, 3, 7, 11), add a minimum duration (Claims 4, 8), and lock identities for estrogen and progestin (Claims 5, 6, 9, 10).
4) Can a regimen outside Claim 1 still fall under some dependent claims?
If the regimen violates Claim 1’s base structure (monophasic administration, pre-menopausal female, on/off timing, or the equivalence dose ranges), dependent claims do not save it because they depend on Claim 1.
5) What is the most direct design-around lever?
Moving at least one of the required elements outside the claimed ranges, especially the on-period length and off-period length, since the dependent claims still preserve those base timing constraints while narrowing dose or minimum duration.
References
[1] US Patent 5,898,032. “Method of female contraception.”
