United States RE37838 (Oral Contraception Combination of Ethinylestradiol and Drospirenone or Cyproterone Acetate) Patent Scope, Claims, and Landscape

RE37838 is a US reissue patent that claims a specific oral contraceptive combination defined by tight estrogen and gestagen dose ranges plus a defined cyclic regimen that includes active pills followed by a short placebo/pill-free interval. The claim scope is concentrated on: (i) the active ingredients as recited (ethinylestradiol or 17β-estradiol as estrogen; drospirenone or cyproterone acetate as gestagen) with an “equivalent to 75 μg of gestodene” limitation, (ii) a 23/24 active-pill plus 5/4 placebo-pill (or pill-free) schedule, and (iii) a constant gestagen amount across the active period. These features narrow the estate relative to broader “oral contraceptive” claims that cover other regimens, other gestagens, or different pill counts/interval designs.

What is RE37838’s claimed regimen and dose concept in oral contraception?

Core claim architecture (as written in the provided claims):

Combination for oral contraception containing:
- Estrogen: either 17β-estradiol in >2.0 to 6.0 mg or ethinylestradiol 0.020 mg (and also an explicit “20 μg ethinylestradiol or equivalent 17β-estradiol” equivalence in dependent claim 5).
- Gestagen: drospirenone (0.25 to 0.30 mg) or cyproterone acetate (0.1 to 0.2 mg), in an amount equivalent to 75 μg of gestodene.
Dosage unit count and cycle design:
- 23 or 24 dosage units (active pills) per cycle
- followed by 5 or 4 placebo pills (or pill-free days) respectively.
Regimen timing/menstrual-cycle linkage:
- dependent claims tie the placebo interval to “last 5 days” or “last 4 days of the menstrual cycle” (claims 6, 7, 11, 12, 14, 15).
Uniformity limitation:
- in claim 13, “each of the dosage units containing drospirenone contains the same amount of drospirenone.”

Immediate scope takeaway for design-around: A competitor can avoid the heart of RE37838 by changing at least one of the claim’s non-negotiable elements: pill count (23/24 with 5/4 placebo), placebo interval length tied to last days, estrogen dosing (20 μg ethinylestradiol or specified 17β-estradiol equivalence), or gestagen conversion to “equivalent to 75 μg gestodene.” Changing gestagen type to something outside drospirenone/cyproterone acetate also moves out of the recited set.

What patents protect oral contraceptive combinations like RE37838 in the US?

Featured snippet answer: RE37838’s protection is anchored to a specific US reissue claim set combining (ethinylestradiol or 17β-estradiol) with (drospirenone or cyproterone acetate) with an equivalence to gestodene 75 μg, plus a 23/24 active-pill schedule followed by 5/4 placebo days.

US patent estate pattern you should expect around this claim type (typical layers):

Composition claims (active ingredient and dose/range definitions).
Regimen claims (pill count and placebo/pill-free interval schedule).
Specific gestagen embodiments (drospirenone-only or cyproterone acetate-only dependent claims).
Variant pill strengths or equivalence assertions (like “equivalent to 75 μg gestodene” and “20 μg ethinylestradiol or equivalent 17β-estradiol”).

How this impacts freedom-to-operate (FTO):

If another US patent in the same “family” covers formulation excipients, particle sizes, manufacturing, or compliance packaging, those risks are additive but not substitutive. RE37838 is strongest where competitors preserve the same clinical regimen architecture and dose mapping.

What are the exact claim-by-claim scope boundaries in RE37838?

Below is a high-precision mapping of each provided claim element to the design constraints it creates.

Claim 1: Broadest independent combination + regimen

Claim 1 limits include all of the following simultaneously:

23 or 24 dosage units per cycle.
Each active pill:
- Estrogen: “selected from >2.0 to 6.0 mg of 17β-estradiol” and 0.020 mg of ethinylestradiol.
- Gestagen: “selected from 0.25 to 0.30 mg of drospirenone and 0.1 to 0.2 mg of cyproterone acetate,” in an amount equivalent to 75 μg of gestodene.
Placebo/pill-free interval:
- if 23 active pills, then 5 placebo pills after;
- if 24 active pills, then 4 placebo pills after.
Requires the interval to be a pill-free/placebo pill day set that follows the active phase.

Practical effect: Claim 1 captures the combination concept across two estrogen types (17β-estradiol range and ethinylestradiol 0.020 mg) and two gestagens (drospirenone or cyproterone acetate), but only when the regimen includes the exact placebo duration that matches the active-pill count.

Claim 2: Estrogen fixed to ethinylestradiol

Locks estrogen to ethinylestradiol.

Claim 3: Gestagen fixed to cyproterone acetate (with estrogen being ethinylestradiol)

Tightens Claim 2’s gestagen choice.

Claim 4: Gestagen fixed to drospirenone (with estrogen being ethinylestradiol)

Tightens Claim 2’s gestagen choice.

Claim 5: Specific estrogen strength and gestagen equivalence to gestodene

Estrogen: 20 μg ethinylestradiol or equivalent dose of 17β-estradiol.
Gestagen: dose “equivalent to 75 μg of gestodene” (reinforces the mapping limitation).

Claim 6: 23 active pills with a 5-day last-interval structure

Adds a specific cycle structure: no active unit / placebo pill during last 5 days.

Claim 7: Combines 20 μg ethinylestradiol + gestagen equivalence with 23/5 regimen

23 dosage units + last 5 days inactive/placebo.
Gestagen: cyproterone acetate or drospirenone “equivalent to 75 μg gestodene.”

Claim 8: Estrogen fixed to 17β-estradiol

Sets estrogen to 17β-estradiol embodiment.

Claim 9: 17β-estradiol + cyproterone acetate

Tightens Claim 8.

Claim 10: 17β-estradiol + drospirenone

Tightens Claim 8.

Claim 11: Drospirenone embodiment with 23/5 last-5-days inactive/placebo

23 dosage units + 5-day last interval.

Claim 12: Drospirenone embodiment with 24/4 last-4-days inactive/placebo

24 dosage units + 4-day last interval.

Claim 13: Independent-like drospirenone + explicit “equivalent to 75 μg gestodene” plus uniform gestagen amount

Ethinylestradiol: 0.020 mg per dosage unit.
Gestagen: drospirenone amount equivalent to 75 μg gestodene.
Active pills: 23 or 24 daily dosage units.
Placebo: 5 or 4 placebo pills respectively.
Uniformity: each drospirenone-containing dosage unit contains the same amount of drospirenone.

Practical effect: Claim 13 adds a uniformity requirement that can matter if a competitor uses a stepped or varying drospirenone dose across active days.

Claim 14: drospirenone + 23/5 last-5-days

23 dosage units + last 5 days inactive/placebo.

Claim 15: drospirenone + 24/4 last-4-days

24 dosage units + last 4 days inactive/placebo.

How strong is RE37838’s patent estate for oral contraceptive generic or biosimilar entries?

Featured snippet answer: RE37838’s claim scope is narrow but enforceable where an ANDA applicant uses the same estrogen/gestagen dose mapping and the same 23/24 active plus 5/4 placebo regimen. It also includes a uniformity limitation for drospirenone embodiments.

Strength drivers from the provided claims:

Multiple precise constraints increase infringement specificity:
- Dose mapping to “equivalent to 75 μg gestodene”
- Placebo interval length tied to last days (4 or 5)
- Active-pill count 23/24
- Gestagen choice confined to drospirenone and cyproterone acetate (with drospirenone-only for claims 13-15 and related dependents).
Reduces overbreadth risk: courts often struggle with claims that look like an attempt to cover any oral contraceptive regimen; RE37838’s regimen specificity is a defensive feature.

Strength limitations from the provided claims:

The estate does not read broadly on:
- alternative regimens (e.g., shortened placebo, extended-cycle designs with fewer or more placebo days)
- gestagens outside drospirenone/cyproterone acetate
- estrogen potencies outside the specified equivalences
If competitors can alter either the placebo-day architecture or the “equivalent to gestodene” mapping, infringement risk declines.

When does RE37838 lose exclusivity in the US?

No expiration, priority, or reissue chronology is provided in the input. Without the patent’s filing and reissue details, a precise US exclusivity/timeline calculation cannot be produced from the claim text alone.

What generic entry risks exist for competitors designing around RE37838?

High-risk design targets that preserve infringement:

Matching estrogen strength to 0.020 mg ethinylestradiol (or equivalent 17β-estradiol).
Using drospirenone or cyproterone acetate at a dose that is explicitly characterized as equivalent to 75 μg gestodene.
Preserving the cycle:
- 23 active + 5 placebo or 24 active + 4 placebo
- with placebo/pill-free days positioned as “last” 4 or 5 days of the menstrual cycle.

Lower-risk design features for avoiding the claim core:

Changing the pill architecture (different placebo-day count or active-day count).
Changing gestagen away from drospirenone/cyproterone acetate.
Changing estrogen away from the 0.020 mg ethinylestradiol and the equivalence framework.
For drospirenone-specific claims (13-15), using a stepped drospirenone dose so that dosage units do not have “the same amount of drospirenone.”

How does RE37838 compare with other oral contraceptive patent claim styles?

RE37838 is regimen-anchored. Many oral contraceptive patents focus on formulation or manufacturing. RE37838’s claim style is different: it is a combination regimen claim with tight dose equivalence plus active/placebo pill-day architecture. That makes it particularly relevant to:

ANDA “equivalence” disputes where the generic must match the RLD’s labeling schedule and dosage form architecture.
505(b)(2) products that copy the cycle design even with different formulation details.

What formulations are implicated by RE37838’s claims?

The claims you provided do not turn on excipients, tablet coating technologies, drug delivery systems, or release kinetics. Scope is driven by:

active ingredient identity
dose mapping (including “equivalent to 75 μg of gestodene”)
dosage unit counts and placebo/pill-free interval days
drospirenone uniformity across the active days (claim 13).

What method-of-use coverage does RE37838 provide?

The claims provided are not framed as method-of-use (e.g., “a method of preventing pregnancy comprising administering…”). They are framed as combination products with regimen instructions. Practically, enforcement usually looks like product-by-label and product-by-dosing-schedule infringement rather than a purely behavioral method claim.

What patent litigation typically affects RE37838 or claims of this type?

No litigation docket information is included in the input. Without case captions, court, or Orange Book-linked listing, a docket-level landscape cannot be produced.

What is the Orange Book status of RE37838?

No Orange Book listing, NDA/active ingredient mapping, or listed patent number cross-references are included. A complete Orange Book status report cannot be generated from the claim text alone.

Which companies are most exposed to RE37838 under the claim language?

The provided claims identify ingredient sets and regimen architecture but not the reference listed drug (RLD) or the NDA/HRS mapping. Company exposure depends on:

which labeled product uses the same drospirenone/cyproterone acetate + ethinylestradiol/17β-estradiol doses
the pill count schedule (23/24 active and 5/4 placebo)
and whether drospirenone is uniform across all active units (for claim 13).

No manufacturer names or product mapping are included in the input.

Key claim-targeting matrix: where competitors should assess infringement

Claim element	What RE37838 requires (from provided claims)	High infringement risk if matched	Typical design-around lever
Estrogen	17β-estradiol >2.0 to 6.0 mg and/or ethinylestradiol 0.020 mg; also “20 μg ethinylestradiol or equivalent 17β-estradiol”	Same estrogen identity and strength	Use different estrogen strength or different estrogen active
Gestagen	drospirenone 0.25 to 0.30 mg or cyproterone acetate 0.1 to 0.2 mg	Same gestagen class	Switch to other gestagen
Gestagen equivalence	dose “equivalent to 75 μg of gestodene”	Same equivalence mapping	Break “equivalent” dosing relationship
Active pill count	23 or 24 daily dosage units	Same active-pill count	Use a different active-pill count regime
Placebo/pill-free days	5 placebo after 23 active, 4 placebo after 24 active	Same placebo day count	Change placebo interval length and/or placement
Menstrual “last days” linkage	last 5 or last 4 days inactive/placebo	Same interval positioning	Alter cycle interval design
Drospirenone uniformity	each active drospirenone unit contains same amount (claim 13 and drospirenone dependents)	Stepped-dose competitors can reduce risk	Use varying drospirenone strength across active days

Key Takeaways

RE37838 is a regimen-specific oral contraceptive combination patent anchored to a 23/24 active pill plus 5/4 placebo-day schedule.
The claim core requires a constrained estrogen (ethinylestradiol 0.020 mg or 17β-estradiol equivalence) and a constrained gestagen (drospirenone or cyproterone acetate) tied to an “equivalent to 75 μg of gestodene” limitation.
Drospirenone embodiments add a uniformity limitation that can matter for stepped-dose designs.
Freedom-to-operate risk concentrates on products that match all of the above simultaneously; design-around leverage exists primarily through altering pill architecture, breaking the dose equivalence mapping, or changing gestagen/estrogen identity.

FAQs

Do RE37838 claims cover extended-cycle oral contraceptives with more than 4 or 5 placebo days?
The provided claim language is tied to 23/24 active pills followed by 5/4 placebo days, respectively, which does not align with typical extended-cycle architectures.
Can a product avoid RE37838 by using a different estrogen but the same gestagen dose equivalence to gestodene?
Avoidance depends on the estrogen identity and strength matching the claimed ethinylestradiol/17β-estradiol limitations and the equivalence framework.
If a competitor keeps the same placebo interval but changes drospirenone strength so it is not “equivalent to 75 μg of gestodene,” does infringement remain likely?
The “equivalent to 75 μg gestodene” limitation is a central constraint in the provided claims, so breaking that equivalence is a primary design-around.
Does RE37838 require the placebo pills to contain active ingredients?
The claims specify “active ingredient-free placebo pills or … pill-free” days during the placebo interval.
For drospirenone-focused embodiments, is it enough to use drospirenone in the right total daily amount across the cycle?
Claim 13 specifies that each drospirenone-containing dosage unit contains the same amount of drospirenone, so per-unit uniformity matters for those claims.

References

Provided in prompt: Claim text of US RE37838 (reissue patent) for oral contraception combination product with ethinylestradiol/17β-estradiol and drospirenone/cyproterone acetate; pill count and placebo interval limitations.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Germany	4344462	Dec 22, 1993

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	344038	⤷ Start Trial
Canada	2179728	⤷ Start Trial
China	100377713	⤷ Start Trial
China	1142185	⤷ Start Trial
China	1611222	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: RE37838

Summary for Patent: RE37838