United States Drug Patent RE43916: Claims, Scope, Expiration, and Generic Competition

U.S. Patent RE43,916 covered 23/5 and 24/4 oral contraceptive regimens using low-dose ethinylestradiol or 17β-estradiol with a progestin, most commercially relevantly 20 µg ethinylestradiol plus 3 mg drospirenone administered for 24 days followed by four hormone-free days. The patent was a reissue of U.S. Patent No. 6,787,529 and did not receive a new patent term. Its effective patent term ended in 2020, eliminating current U.S. patent-based barriers to generic versions of the claimed regimen. The principal commercial product associated with the estate was Yaz, with related generic products including Ocella, Gianvi and later drospirenone/ethinylestradiol products.

What does U.S. Patent RE43916 protect?

RE43,916 contains two principal claim groups:

Product claims covering a contraceptive package or combination preparation.
Method claims covering administration of the regimen to a premenopausal woman seeking contraception.

The core commercial embodiment is:

24 active tablets;
each active tablet containing 20 µg ethinylestradiol and 3 mg drospirenone;
four placebo tablets or four hormone-free days;
a 28-day cycle beginning on day one of menstruation.

This corresponds to the standard 24/4 Yaz regimen.

Claim structure

Claims	Claim category	Principal subject matter
1-10	Product and package claims	23 or 24 active dosage units plus five or four placebo units, with estrogen and progestin combinations
11-14	Method claims	Administration for 23 or 24 days followed by five or four pill-free or placebo days
15-17	Narrow method claims	15-20 µg ethinylestradiol with 1-3 mg drospirenone, including the 20 µg/3 mg, 24/4 regimen

Claim 1 is the broadest product claim. Claims 2-10 narrow the estrogen, progestin, dose or cycle configuration. Claim 15 is the principal method claim for the modern drospirenone/ethinylestradiol embodiment.

What active ingredients and doses are covered?

The patent claims two estrogen categories:

17β-estradiol at more than 2.0 mg to 6.0 mg; and
ethinylestradiol at 0.020 mg in the product claims and 0.015-0.020 mg in the method claims.

The progestin options expressly identified in the claims include:

drospirenone at 0.25-0.30 mg in claim 1 as reproduced;
cyproterone acetate at 0.1-0.2 mg in claim 1 as reproduced;
norethisterone in claim 12;
drospirenone at 1-3 mg in claim 14 and claim 15;
drospirenone at 3 mg in claim 16.

The supplied claim text contains apparent drafting or transcription inconsistencies. The most significant is the difference between claim 1's stated drospirenone range of 0.25-0.30 mg and claims 14-17, which expressly identify 1-3 mg and 3 mg drospirenone. The commercial Yaz embodiment is 3 mg drospirenone, not 0.25-0.30 mg. Claim construction must therefore be based on the certified patent text, prosecution history and reissue record rather than an isolated transcription.

Claim 5 also refers to a progestin dose equivalent to 75 µg of "gestadene." That term appears to be a textual error for gestodene. Equivalence language can create claim-construction issues because it introduces a dose-comparison concept rather than limiting the claim to a single named compound.

What is the scope of the 24/4 Yaz regimen claim?

Claims 15-17 are directed to the most commercially important configuration:

20 µg ethinylestradiol;
3 mg drospirenone;
administration for 24 consecutive days;
four placebo or pill-free days;
a 28-day cycle;
initiation on the first day of the menstrual cycle.

Claim 17 is the narrowest and most recognizable Yaz-style claim. It requires both the 24/4 schedule and the 20 µg/3 mg active composition.

A product that contains the same active ingredients and doses but uses a 21/7 schedule would not literally satisfy the full limitation of claim 17. A product with 24 active tablets and four placebo tablets could fall within the claim even if the placebo tablets differ in color, excipients or packaging, provided the package communicates the claimed administration schedule.

Literal scope by regimen

Regimen	Likely relationship to claims 15-17
24 active days plus four placebo days	Directly aligned with claim 17
23 active days plus five placebo days	Covered by broader method and product claims if all other limitations are met
21 active days plus seven placebo days	Outside the express 23/24-day limitations
Continuous dosing without placebo days	Outside the claimed regimen
24 active days plus four pill-free days, but nonmonophasic dosing	Potentially outside claims requiring a monophasic composition
24 active days with 25 µg ethinylestradiol	Outside the 15-20 µg ethinylestradiol method range
24 active days with 3 mg drospirenone and 20 µg ethinylestradiol	Core claimed embodiment

Do the claims cover the active tablets, the package, or the method of use?

The product claims are directed to a combination preparation rather than merely an isolated tablet containing drospirenone and ethinylestradiol.

The claimed combination includes:

the active dosage units;
the number of active units;
the number of placebo units or pill-free indications; and
information directing the sequence of administration.

This structure gives the package and regimen a central role. A bottle containing only active tablets may not satisfy the package limitations of claims 1-10. The method claims create a separate infringement theory where a party induces or directs administration according to the 23/5 or 24/4 schedule.

The method claims also require a specific patient population: a female of reproductive age who has not reached premenopause and who desires contraception. That patient-specific language narrows the method claims compared with a product claim, although commercial labeling and prescribing instructions may provide evidence relevant to induced infringement.

What is the patent expiration date of RE43916?

RE43,916 expired with the term of its original patent, U.S. Patent No. 6,787,529. The effective expiration date was March 31, 2020, based on the underlying priority and patent-term calculation reported for the Yaz patent estate.

A reissue patent generally does not restart the patent term. The reissue may correct, amend or restate claims, but it remains tied to the original patent's term. RE43,916 therefore did not create a new exclusivity period extending beyond the parent patent.

Patent	Role in estate	Effective expiration
U.S. 6,787,529	Original patent	March 31, 2020
U.S. RE43,916	Reissue patent	March 31, 2020

Any pediatric exclusivity or regulatory exclusivity must be analyzed separately from patent term. Neither would restore patent protection after the patent's expiration.

What was the Orange Book status of RE43916?

The relevant Yaz patent estate was listed in FDA Orange Book materials in connection with the branded drospirenone/ethinylestradiol product. Orange Book listing is product-specific. It does not make every claim of a patent applicable to every formulation or every product containing the same hormones.

The Orange Book framework was commercially important because abbreviated new drug applicants had to address listed patents through:

a Paragraph III certification, accepting delayed approval until expiration;
a Paragraph IV certification, asserting that the listed patent was invalid, unenforceable or not infringed; or
a statement that the patent did not claim the referenced product or approved use.

After March 31, 2020, RE43,916 could no longer provide a current patent barrier to approval or launch. FDA approval of later generic products depended on the status of any other listed patents, exclusivities and regulatory requirements.

Which companies challenged the Yaz patent estate?

The principal generic challengers to the Yaz estate included Barr Laboratories, Watson Pharmaceuticals and other generic companies seeking approval for drospirenone/ethinylestradiol products.

The Federal Circuit addressed the related Yaz patent litigation in Bayer Schering Pharma AG v. Barr Laboratories, Inc., involving the validity and enforceability of the patent claims covering the contraceptive composition and regimen. The litigation focused on obviousness and the technical differences between the claimed regimen and earlier oral contraceptive schedules.

The commercial generic market ultimately developed before the 2020 patent expiration through litigation settlements, regulatory approvals and launch arrangements. Ocella and Gianvi were among the early generic or authorized-generic products associated with the Yaz market.

Were there Paragraph IV challenges?

Yes. Generic applicants filed Paragraph IV certifications against patents associated with Yaz and related drospirenone/ethinylestradiol products. Paragraph IV litigation addressed whether the asserted claims were:

invalid for obviousness;
anticipated by earlier contraceptive regimens;
unenforceable;
not infringed by the proposed generic products; or
improperly listed for the product at issue.

The key commercial issue was whether a generic applicant could market a 3 mg drospirenone/20 µg ethinylestradiol product before the expiration of the relevant patent claims. The litigation and settlement history allowed some generic competition before the end of the nominal patent term, subject to the terms applicable to each applicant.

What formulation patents protect Yaz and related products?

RE43,916 is primarily a regimen and combination-preparation patent. It does not broadly claim every pharmaceutical formulation containing drospirenone and ethinylestradiol.

Separate patent categories potentially relevant to Yaz products include:

tablet composition and excipient patents;
drospirenone particle-size or micronization claims;
manufacturing-process patents;
dissolution and stability claims;
packaging and blister configuration claims;
dosing-regimen claims;
method-of-use claims for contraception or premenstrual dysphoric disorder.

A generic manufacturer must assess the complete Orange Book listing and relevant non-Orange Book rights. Patent claims directed solely to manufacturing may remain commercially relevant even when the principal composition or regimen patent expires. Their practical value depends on whether the generic process practices the claimed steps and whether an alternative process is commercially viable.

Does RE43916 create biosimilar risk?

No. RE43,916 concerns small-molecule oral contraceptives, not a biologic product. The relevant competitive pathway is an abbreviated new drug application under section 505(j) of the Federal Food, Drug, and Cosmetic Act, not a biosimilar application under the Public Health Service Act.

The principal post-expiration risks are:

generic substitution;
authorized-generic competition;
manufacturing-cost competition;
product recalls or supply interruptions;
liability exposure associated with drospirenone-containing contraceptives; and
commercial erosion from newer contraceptive formulations.

How strong was the patent estate?

The estate was commercially strong before expiration because it linked a widely prescribed active combination to a specific 24/4 administration schedule. Its strongest practical feature was the combination of:

a recognizable product composition;
a defined pack configuration;
a branded dosing schedule;
product claims and method claims;
FDA-listed patent status; and
a large branded revenue base.

Its limitations were also material:

the claims were restricted to oral contraceptive regimens;
several claims required 23 or 24 active dosage days;
the method claims required a monophasic composition;
the estrogen and progestin ranges limited design options;
reissue status did not extend the patent term; and
the claims did not provide permanent protection against alternative schedules or formulations.

After expiration, the estate has no remaining blocking value against ordinary generic versions of the claimed 24/4 drospirenone/ethinylestradiol regimen.

What generic launch scenarios existed?

Launch after patent expiration

This was the lowest litigation-risk scenario for a product matching 20 µg ethinylestradiol and 3 mg drospirenone in a 24/4 package. A post-expiration launch avoids infringement liability based on RE43,916.

At-risk Paragraph IV launch

A generic applicant could launch before patent expiration after certifying that the patent was invalid or not infringed. This creates potential exposure to damages, an injunction and a loss of market access if the patent is upheld.

Settlement-authorized launch

A settlement may permit launch on a specified date before patent expiration. The economic terms can include licenses, launch restrictions, authorized-generic arrangements or other commercial provisions. The settlement date and terms must be reviewed separately for each generic applicant.

Design-around launch

Potential design-arounds include:

a 21/7 regimen;
a continuous regimen;
a different estrogen dose;
a different progestin;
a nonmonophasic product; or
a different package structure.

A design-around must be assessed against every asserted claim, including equivalents and induced-infringement theories.

What is the current commercial exposure from RE43916?

The direct revenue exposure from RE43,916 is now historical because the patent expired in 2020. The patent supported the Yaz franchise during its protected period, but current revenue risk arises from generic competition and product differentiation rather than from a live patent monopoly.

The commercially relevant products include:

Yaz, containing drospirenone and ethinylestradiol;
generic drospirenone/ethinylestradiol 3 mg/0.02 mg products;
Ocella;
Gianvi; and
related products such as Yasmin, Safyral and Beyaz, which involve different strengths, ingredients or indications and require separate patent analysis.

Key Takeaways

RE43,916 is a reissue patent covering oral contraceptive combinations and 23/5 or 24/4 dosing regimens.
The principal commercial embodiment is 20 µg ethinylestradiol plus 3 mg drospirenone administered for 24 days followed by four placebo or pill-free days.
Claims 1-10 cover product and package configurations; claims 11-17 cover methods of administration.
Claim 17 is the narrowest direct expression of the 24/4, 20 µg/3 mg regimen.
The patent inherited the term of U.S. Patent No. 6,787,529.
The effective expiration date was March 31, 2020.
The patent is no longer a current U.S. barrier to generic drospirenone/ethinylestradiol products.
The estate involved Paragraph IV litigation and generic challenges, including litigation associated with Barr Laboratories and Watson Pharmaceuticals.
RE43,916 is not a biologic patent and creates no biosimilar issue.
Separate formulation, manufacturing and indication patents must be analyzed independently.
The supplied claim text contains apparent dose and terminology inconsistencies that should be reconciled against the certified patent and reissue prosecution record.

FAQs

Does RE43916 cover all drospirenone birth-control pills?

No. It targets specified estrogen-progestin combinations and administration schedules. Products using different doses, regimens, ingredients or formulations may fall outside particular claims.

Is a 21/7 drospirenone and ethinylestradiol product covered?

The 21/7 schedule does not satisfy the express 23- or 24-day active-dosing limitations in the principal claims. Other patent rights would still require separate review.

Did the RE43916 reissue extend the Yaz patent term?

No. The reissue remained subject to the original patent's term and expired on March 31, 2020.

Is a generic 24/4 product still exposed to RE43916 infringement claims?

No, not based on RE43,916 after its expiration. Other unexpired patents, regulatory exclusivities or non-Orange Book rights would require separate analysis.

What is the principal patent risk for a new oral contraceptive using the same regimen?

The principal historical risk was infringement of the composition, package and method claims covering the 24/4 regimen. Current risk is more likely to arise from separate formulation, manufacturing, labeling or product-specific patent rights.

References

Bayer Schering Pharma AG v. Barr Laboratories, Inc., 575 F.3d 1341 (Fed. Cir. 2009).
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
U.S. Patent and Trademark Office. (2013). U.S. Patent No. RE43,916: Pharmaceutical combination preparation for contraception. Washington, DC.
U.S. Patent and Trademark Office. (2004). U.S. Patent No. 6,787,529: Pharmaceutical combination preparation for contraception. Washington, DC.
U.S. Food and Drug Administration. (2024). Yaz prescribing information: Drospirenone and ethinyl estradiol tablets. FDA.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Germany	43 44 462	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
Czech Republic	296387	⤷ Start Trial
Czech Republic	9601861	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: RE43916

Summary for Patent: RE43916