United States Patent 12,090,231 (Drospirenone, estrogen-free, 24/4 contraception): Scope, claim architecture, and landscape impact
United States Patent 12,090,231 claims a specific estrogen-free oral drospirenone contraception regimen and a drug product performance profile under fasting conditions, with hard numerical boundaries on PK exposure and dissolution behavior. The claim set is structured to cover (1) the 24-consecutive-day dosing with 4-day hormone-free interval, (2) an allowance for up to two skipped doses on non-consecutive days, and (3) an oral formulation that yields a constrained drospirenone PK window (Tmax, Cmax, AUC) plus measurable dissolution criteria using USP apparatus and paddle method.
What is the core claim scope (independent claim 1)?
Claim 1 is the independent, capture-all protection layer. It requires all of the following elements:
A. Regimen structure
- 28-day daily dosing regimen to provide contraception in a female patient.
- Daily dose administered orally for 24 consecutive days
- Followed by 4 consecutive days without administering a daily dose
- Within the 24 consecutive days, up to two daily doses may be skipped provided they are non-consecutive.
B. Formulation composition constraints
- Drospirenone dose: 2 mg to 6 mg
- No estrogen: the pharmaceutical composition does not comprise estrogen
- The formulation must be designed so that, when one daily dose is given orally under fasting conditions, it produces a drospirenone PK profile with these constraints:
C. Fasting PK profile constraints (quantified)
- Mean Tmax: 2.2 hours to 6 hours
- Mean Cmax: less than 30 ng/mL
- Mean AUC0h-tlast: *at least 300 ngh/mL**
Claim 1 therefore is not just a “24/4 schedule” patent. It ties the regimen to a specific estrogen-free drospirenone exposure target that is measurable in human fasting dosing.
How do dependent claims narrow and diversify coverage?
Dependent claims add tighter thresholds, formulation specs, and regimen operational details.
Dissolution and formulation performance
- Claim 2 (early dissolution ceiling):
- Using USP XXIII Paddle Method, 900 mL water at 37°C (±0.5°C), apparatus 2, 50 rpm
- No more than 50% of drospirenone dissolves within 30 minutes
- Claim 3 (later dissolution floor):
- Under the same USP paddle conditions
- At least 55% dissolves within 4 hours
These two claims bracket dissolution: slow early release but sufficient overall dissolution.
PK refinement
- Claim 4 (tighter Tmax range): mean Tmax 3 to 4 hours
- Claim 5 (tighter Cmax range): mean Cmax 15 ng/mL to less than 30 ng/mL
- Claim 6 (higher AUC threshold): *AUC0h-tlast at least 350 ngh/mL**
Fixed drospirenone strengths
- Claim 7: 3.5 mg drospirenone
- Claim 8: 4.0 mg drospirenone
- Claim 9: 3.0 mg to 4.5 mg
- Claim 10: 3.0 mg to 3.5 mg
- Claim 11: 3.5 mg to 4.5 mg
These claims create protection for specific dosage strengths and strength ranges within the broader 2 to 6 mg band of claim 1.
Skip-dose operational variants
- Claim 12: two daily doses skipped
- Claim 13: one daily dose skipped
- Claim 14: zero daily doses skipped
- Claim 15: a daily dose administered within 24 hours of a skipped dose
- Claim 16: two daily doses administered within 24 hours of a skipped dose
Hormone-free interval handling
- Claim 17: a daily placebo administered during the 4 consecutive days
This matters because claim 1 defines “not administering a daily dose,” and claim 17 covers the implementation where the 4-day interval uses placebo tablets rather than no dosing.
Where does the patent land in the “28-day oral contraception” space?
The claim set targets a combination of three differentiators that, together, make design-around harder:
- Estrogen-free drospirenone
- 24/4 regimen with defined contraception-day structure and skip-dose rules
- Quantitative fasting PK profile (Tmax, Cmax, AUC) tied to the formulation
- Quantitative dissolution behavior (USP paddle method thresholds at 30 minutes and 4 hours)
The practical implication: an infringing product needs to satisfy both use (regimen) and product performance (PK/dissolution). Many “dose schedule” patents do not force product-level performance criteria like Cmax/AUC thresholds; this one does.
What would constitute infringement risk (claim-matching logic)?
A. Regimen match requirements
A product would need to be marketed/used as:
- 24 consecutive days of daily drospirenone dosing
- then 4 consecutive days off or placebo
- skip-dose pattern allows up to two non-consecutive missed daily doses during the 24-day window
B. Product match requirements
The daily dose must be:
- Oral
- Estrogen-free
- Contains drospirenone 2 mg to 6 mg per daily dose
- Produces drospirenone PK under fasting dosing with:
- mean Tmax 2.2 to 6 hours
- mean Cmax < 30 ng/mL
- mean *AUC0h-tlast ≥ 300 ngh/mL**
And the formulation must meet dissolution:
- ≤50% dissolved at 30 minutes
- ≥55% dissolved at 4 hours
C. Tight subrange hooks
Even if a developer hits claim 1 broadly, the dependent claims define narrower “fall-through” positions:
- Tmax 3-4 hours
- Cmax 15 to <30 ng/mL
- AUC *≥350 ngh/mL**
- specific strengths like 3.5 mg or 4.0 mg
Patent landscape: what this claim set implies about likely prior-art pressure
Even without a full prosecution history or citation list in the text provided, the claim construction shows the likely landscape battlefields:
1. Estrogen-free drospirenone contraceptive regimens
Claim 1 requires “does not comprise estrogen.” This positions the patent against:
- combined oral contraceptives containing ethinyl estradiol or other estrogens
- drospirenone regimens where estrogen is a necessary component
2. Drospirenone exposure tuning
The patent is PK-bound. That typically follows years of formulation work to shape absorption:
- Cmax control often drives risk of cross-over with prior formulations that are faster or higher exposure
- AUC floors indicate the regimen is not merely low exposure; it must reach systemic exposure levels
3. Dissolution engineering
The USP paddle dissolution windows are narrow enough to:
- distinguish from immediate-release products that dissolve quickly
- distinguish from products that might be too slow (failing the 4-hour dissolution floor)
This suggests prior art likely includes:
- drospirenone formulations with different dissolution curves
- PK profiles not matching the claimed fasting targets
4. Compliance mechanics and missed-dose instructions
Skip-dose logic is explicitly claimed:
- two missed non-consecutive doses allowed within the 24-day dosing window
- “within 24 hours” catch-up dosing logic is claimed
This resembles label-based differentiators that patent owners often embed into method-of-use or regimen patents. Competitors can sometimes avoid by altering the missed-dose logic, but here it is explicitly part of claim scope.
How competitors might try to design around (and why the patent narrows exits)
A. Change the regimen
Potential approaches:
- alter the cycle length or dosing structure (break the “24 consecutive days then 4 days off/placebo” framework)
- remove “up to two non-consecutive skipped doses” language by changing instructions such that no missed-dose scenario is handled under the claimed structure
- change the placebo/off handling for the final interval
But claim 1 also forces the regimen to tie to the PK/dissolution constrained product, so regimen-only changes may still face product-performance capture if the product PK matches and the competitor’s real-world instructions are close.
B. Use estrogen
Avoid claim 1’s “does not comprise estrogen” by using an estrogen component. That moves outside this patent’s composition restriction.
C. Shift PK outside the claimed window
If a competitor can keep mean:
- Cmax ≥ 30 ng/mL or Tmax < 2.2 hours or Tmax > 6 hours or *AUC0h-tlast < 300 ngh/mL**
then claim 1 can fail. Claim 4 to 6 further compress the safe zone.
This strategy is formulation-intensive because changing dissolution can rebound into absorption elsewhere.
D. Shift dissolution behavior
Claim 2 and claim 3 create a dual constraint:
- early dissolution must be limited (≤50% at 30 minutes)
- later dissolution must still be adequate (≥55% at 4 hours)
A competitor can target one boundary, but typically doing so risks failing the other unless the formulation is redesigned in a controlled way.
Actionable take for business decisions (how to use this for freedom-to-operate)
1. Treat claim 1 as a combined regimen-and-performance gate
No infringement assessment based solely on schedule or product strength will be decisive. A valid infringement opinion requires:
- regimen dosing pattern and missed-dose mechanics
- estrogen-free composition
- fasting PK showing mean Tmax/Cmax/AUC within claimed limits
- dissolution test results under the specified USP XXIII paddle conditions
2. Dependent claims increase strike probability
Even if a competitor aims to fall outside claim 1’s broader ranges, narrower dependent claims provide additional “landing pads” once they match the regimen and product category:
- Tmax 3-4 hours
- Cmax 15 to <30 ng/mL
- AUC ≥350 ng*h/mL
3. Strength-specific versions likely matter for portfolio strategy
Claim 7 to 11 show that product variants at 3.5 mg and 4.0 mg are central. If a development program targets these strengths (common in drospirenone products), claim coverage is structurally reinforced.
4. Labeling and instructions can be risk drivers
Claim 15 and claim 16 tie to catch-up dosing after missed doses within a 24-hour window. If a competitor’s SmPC or consumer instructions align, it heightens method-use exposure even if the core formulation is comparable.
Key Takeaways
- US 12,090,231 covers an estrogen-free oral drospirenone contraception regimen: 24 consecutive dosing days + 4 consecutive days off/placebo, allowing up to two non-consecutive skipped doses during the 24-day window.
- Claim 1 is performance-bounded: fasting drospirenone mean Tmax 2.2 to 6 hours, mean Cmax < 30 ng/mL, and *mean AUC0h-tlast ≥ 300 ngh/mL**.
- The formulation is also bounded by dissolution under USP paddle conditions: ≤50% dissolved at 30 minutes and ≥55% dissolved at 4 hours.
- Dependent claims tighten the PK and dissolution thresholds and lock in key drospirenone strengths (notably 3.5 mg and 4.0 mg), while also capturing missed-dose timing mechanics and placebo use during the 4-day interval.
- In freedom-to-operate terms, the patent is best analyzed as a combined regimen + estrogen-free composition + fasting PK + dissolution profile gate, not as a simple schedule patent.
FAQs
1. Does US 12,090,231 cover combined oral contraceptives with estrogen?
No. Claim 1 requires the composition does not comprise estrogen.
2. What are the fasting PK boundaries in claim 1?
Mean Tmax 2.2 to 6 hours, mean Cmax < 30 ng/mL, and mean *AUC0h-tlast ≥ 300 ngh/mL**.
3. Are dissolution characteristics part of the infringement analysis?
Yes. Claims 2 and 3 impose quantitative dissolution limits using USP XXIII paddle method, 900 mL at 37°C (±0.5°C), apparatus 2, 50 rpm.
4. How many missed doses are allowed under the regimen?
Up to two daily doses may be skipped on non-consecutive days within the 24 consecutive dosing days (claim 1), with additional dependent claims addressing zero, one, or two skipped doses and catch-up timing.
5. Does the patent cover placebo administration during the 4-day interval?
Yes. Claim 17 covers administering a daily placebo during the 4 consecutive days.
References
[1] United States Patent 12,090,231 (claims as provided in prompt).
