Details for Patent: 4,390,531

Summary for Patent: 4,390,531

Title:	Method of contraception using peak progestogen dosage
Abstract:	A method of contraception and a pharmaceutical package for effecting the method are disclosed. The method comprises a three phase sequence of estrogen/progestogen administration which is a daily sequence of unit dosages over a repeating cycle, which dosage sequence comprises, for one cycle: (a) administering, as phase one, about 20-40 mu g of ethinyl estradiol, (or of other estrogen in an amount sufficient to result in an equivalent effect) and about 0.3-0.8 mg of norethindrone (or of other progestogen in an amount sufficient to result in an equivalent effect) each day for 5-8 days, followed by; (b) administering, as phase two, the same dosage of estrogen and twice the dosage of progestogen each day as was administered each day in phase one, for 7-11 days, followed by; (c) administering, as phase three, the same dosage of estrogen and the same dosage of progestogen each day as was administered each day in phase one, for 3-7 days, followed by; (d) administering, as phase four, no therapeutically active dosage, i.e. either no treatment or a placebo each day for 6-8 days, with the proviso that the total number of days in phases one through three is 21.
Inventor(s):	Richard A. Edgren
Assignee:	Actavis Laboratories UT Inc
Application Number:	US06/291,533
Patent Claim Types: see list of patent claims	Use;

# United States Drug Patent 4,390,531: Claim Scope, Expiration, Litigation Risk, and Patent Landscape

US Patent 4,390,531 covers a phased oral-contraceptive dosing regimen, not a particular tablet composition alone. The core claim requires a 28-day repeating cycle with three active-hormone phases followed by a placebo or treatment-free phase. The patent’s practical exclusivity has ended because the patent issued in 1983 under the former 17-year patent term and is no longer enforceable. The claims remain relevant as prior art and as a model for analyzing later contraceptive regimen patents, but they do not create current blocking rights. [1][2]

What does US Patent 4,390,531 claim?

The patent claims a method of contraception in a human female using a four-phase regimen:

Phase	Duration in claim 1	Estrogen	Progestogen	Required relationship
Phase one	5-8 days	About 20-40 micrograms ethinyl estradiol equivalent	About 0.3-0.8 mg norethindrone equivalent	Baseline dose
Phase two	7-11 days	Same estrogen dose as phase one	Twice the phase-one progestogen dose	Increased progestogen
Phase three	3-7 days	Same estrogen dose	Same progestogen dose as phase one	Returns to baseline
Phase four	6-8 days	None	None	Placebo or no treatment

The first three phases must total 21 days. Phase four therefore produces a nominal 28-day cycle when the most common seven-day phase structure is used.

The claim is a regimen claim. It does not require a specific tablet shape, package, excipient, manufacturing process, brand name, or commercial label. It reaches the administration of the active ingredients according to the claimed sequence.

How is claim 1 of US 4,390,531 constructed?

Claim 1 has several cumulative limitations. A potentially infringing regimen would need to satisfy all of them or an applicable doctrine-of-equivalents theory.

Required contraceptive use

The method must be used for contraception in a female human. The claim is not directed to treatment of acne, endometriosis, dysmenorrhea, hormone replacement, or other noncontraceptive indications.

The phrase “subject in need of, or desiring, such an effect” broadens the intended patient population. It does not remove the requirement that the method be used to produce a contraceptive effect.

Daily unit-dose administration

The claim requires a “daily sequence of unit dosages.” This language points toward daily administration of discrete dosage units, such as tablets, although the claim does not expressly limit the dosage form to tablets.

A regimen administered intermittently, continuously, or without identifiable daily units would face a stronger noninfringement argument. A 28-day blister pack containing active and placebo tablets would fall within the ordinary commercial implementation of the claim if the hormone sequence also matched the claim.

Estrogen and progestogen activity ranges

The claim does not require that the active ingredients literally be ethinyl estradiol and norethindrone in every case. It defines the dose by biological activity equivalent to:

• About 20-40 micrograms of ethinyl estradiol; and
• About 0.3-0.8 mg of norethindrone.

This creates two scope categories:

1. Literal embodiments using ethinyl estradiol and norethindrone.
2. Alternative estrogen-progestogen combinations that allegedly provide equivalent estrogenic and progestogenic activity.

Claims 7-9 narrow the scope to the named ingredients. Claim 9 is the most commercially direct species claim because it requires ethinyl estradiol and norethindrone together.

The activity-equivalence language is commercially important but legally imprecise. Determining whether another progestogen is equivalent would require attention to the patent’s specification, testing methodology, accepted pharmacologic conversion standards, and the meaning of “about” in the relevant technical field.

What do claims 2 through 6 protect?

Claims 2 and 3 identify two specific 28-day schedules.

Claim	Phase one	Phase two	Phase three	Phase four
Claim 2	7 days	7 days	7 days	7 days
Claim 3	7 days	9 days	5 days	7 days

Claim 2 covers the conventional 7-7-7-7 pattern. Claim 3 covers a 7-9-5 active-phase sequence followed by seven placebo or treatment-free days.

Claims 4, 5, and 6 narrow the baseline daily dose to activity corresponding to approximately 35 micrograms of ethinyl estradiol and 0.50 mg of norethindrone:

• Claim 4 depends directly on claim 1.
• Claim 5 depends on claim 2.
• Claim 6 depends on claim 3.

Claims 7, 8, and 9 separately narrow claim 1 by specifying ethinyl estradiol, norethindrone, or both. Claim 9 combines the active ingredients but leaves the phase durations and dosage ranges of claim 1 intact.

What is the strongest commercial scope of the patent?

The commercially strongest combination is claims 5, 6, and 9, depending on the product configuration.

A product using 35 micrograms of ethinyl estradiol activity and 0.50 mg of norethindrone activity could implicate claims 4-6. If the product uses the named compounds directly, claims 7-9 provide narrower but more chemically certain coverage.

The broadest commercial implementation would be:

• Ethinyl estradiol plus norethindrone;
• Seven days of baseline dosing;
• Seven or nine days of doubled norethindrone;
• Five or seven days of baseline dosing; and
• Seven placebo or treatment-free days.

A product with a different progestogen could still be relevant to claim 1 if its progestogenic activity were shown to be equivalent to norethindrone. It would not automatically fall within claims 8 or 9.

What formulations are protected by US 4,390,531?

The patent primarily protects use of the dosing sequence rather than a formulation platform.

Potentially covered commercial forms include:

• Monophasic tablets packaged for phased administration;
• Blister packs containing tablets with different progestogen doses;
• Packs containing active tablets and placebo tablets;
• Separate estrogen and progestogen units administered together;
• Products using alternative estrogen or progestogen compounds with the claimed activity equivalents.

The claim does not expressly require:

• A particular excipient;
• A particular tablet coating;
• Extended release;
• Immediate release;
• A fixed-dose combination tablet;
• A specific packaging configuration; or
• A particular manufacturing process.

A product could therefore practice the claimed method even if its tablet formulation, packaging, and manufacturing process differed from the disclosed embodiments.

Does US 4,390,531 cover method-of-use rights or product rights?

It covers method-of-use rights. It does not claim the chemical compounds ethinyl estradiol or norethindrone as new molecules. It also does not, on the claim language supplied, claim a pharmaceutical composition independently of administration according to the sequence.

This distinction matters under the Hatch-Waxman framework. A generic applicant could address a listed method-of-use patent through a Section viii statement when the generic label carves out the patented indication or regimen, or through a Paragraph IV certification if the applicant challenges patent validity or noninfringement. [3][4]

When did US Patent 4,390,531 lose exclusivity?

The patent issued in 1983. Under the pre-Uruguay Round patent term applicable to this patent, the term generally ran for 17 years from issuance rather than 20 years from the earliest nonprovisional filing date. On that basis, the patent expired in 2000, subject to any term adjustment or extension reflected in the official record. [1][5]

Event	Approximate date or status
US patent issuance	June 1983
Original statutory term	17 years from issuance
Expected basic expiration	June 2000
Current status	Expired
Current enforceability	No enforceable exclusionary right from this patent
Current relevance	Prior art, historical patent landscape, and claim-construction reference

Patent term extension under 35 U.S.C. § 156 is generally directed to regulatory review delays for eligible products. A regimen patent of this age would not ordinarily create a current commercial barrier through an unexpired term. [6]

What is the Orange Book status of US Patent 4,390,531?

US Patent 4,390,531 should not be treated as a current Orange Book blocking patent solely because it concerns an FDA-regulated contraceptive regimen.

The Orange Book lists patents submitted by applicants for approved drug products and identifies the patent type and expiration information. A patent can be absent from the Orange Book, listed historically, or listed with an expiration date that has already passed. Current regulatory impact must be assessed against the relevant approved product, FDA patent listing, and expiration status rather than the patent number alone. [2]

Because this patent is expired, it cannot presently delay ANDA approval through a live patent term. A historical listing would not restore enforceability.

What Paragraph IV challenges could affect this patent?

A Paragraph IV certification could have been used before expiration to allege that the patent was invalid, unenforceable, or not infringed. The principal challenge theories would have included:

Noninfringement

A generic product could avoid the claims by changing one required element, such as:

• Using a regimen without the three specified active phases;
• Keeping progestogen constant rather than doubling it in phase two;
• Using a total active period other than 21 days;
• Omitting the placebo or treatment-free phase;
• Using a noncontraceptive label, where legally and commercially appropriate; or
• Using doses outside the claimed activity ranges.

Invalidity for anticipation

A challenger would search earlier oral-contraceptive regimen patents and publications for the same sequence, dose relationships, and 21-day structure. Anticipation requires a single prior-art reference to disclose every claim element arranged as claimed. [7]

Obviousness

The most substantial historical validity issue would likely be obviousness. The claim combines known oral-contraceptive components with a dose-escalation sequence. A challenger would assess whether earlier references taught:

• Triphasic hormone administration;
• A mid-cycle increase in progestogen;
• A 21-day active regimen;
• A seven-day hormone-free interval; and
• The claimed estrogen and progestogen dose equivalents.

Under U.S. law, predictable combinations of known elements can be invalid if a skilled person would have had a reason to combine them with a reasonable expectation of success. [8]

Indefiniteness and enablement

The terms “about,” “correspond in estrogenic activity,” and “correspond in progestogenic activity” could be challenged if the specification failed to provide a workable boundary or reliable conversion method. The strength of that argument would depend on the patent disclosure and the state of pharmacologic testing at filing.

The claim also requires a contraceptive effect but does not specify a clinical endpoint. That language is likely understood as a method-purpose limitation, not as a requirement to prove pregnancy prevention in every individual patient.

Which companies challenged or licensed rights under this patent?

No reliable conclusion about historical Paragraph IV filers, litigation defendants, or licensing counterparties should be inferred from the claims alone. The patent number and claim text do not establish a complete prosecution, litigation, assignment, or licensing record.

The principal commercial parties potentially relevant to this technology class would include manufacturers of oral contraceptives containing ethinyl estradiol and norethindrone, including brand owners, generic manufacturers, and product licensors. A current competitive analysis must distinguish this expired patent from later patents covering specific products, hormone combinations, packaging systems, and labeling.

How strong is the patent estate for this technology?

The estate represented by the supplied claims has limited current strength because the patent is expired. Its historical claim strength can be summarized as follows:

Factor	Assessment
Claim type	Method of contraception
Chemical specificity	Moderate in claim 1; high in claims 7-9
Regimen specificity	High
Formulation coverage	Limited
Manufacturing coverage	None apparent from the supplied claims
Geographic coverage	United States only
Current enforceability	None after expiration
Design-around difficulty	Moderate
Prior-art exposure	Potentially significant because phased contraceptive dosing was an established technology area
Biosimilar relevance	None; this is a small-molecule contraceptive regimen patent

The patent does not create biosimilar risk because ethinyl estradiol and norethindrone are small molecules, not biologics. The relevant competitive threats are generic oral contraceptives and later branded or generic regimen patents.

How does this patent compare with later contraceptive patent strategies?

US 4,390,531 uses a regimen-centered strategy. Later patent portfolios in hormonal contraception commonly add one or more of the following:

• Specific active ingredients;
• Specific dose strengths;
• Low-estrogen formulations;
• Extended-cycle or continuous administration;
• Reduced hormone-free intervals;
• Transdermal, vaginal, injectable, or implantable delivery;
• Controlled-release formulations;
• Packaging and calendar systems;
• Manufacturing controls; and
• Treatment of additional hormone-sensitive conditions.

A later product may avoid this patent while still facing separate rights covering its composition, delivery system, indication, or package. Conversely, a product could fall within this patent’s historical method scope without infringing a later composition patent.

What generic entry risks existed before expiration?

Before expiration, a generic entrant using the same active ingredients and the same 7-7-7-7 or 7-9-5-7 pattern would have faced the clearest risk under claims 2, 3, 5, 6, and 9.

The principal launch paths would have been:

1. A Paragraph IV challenge against validity or infringement.
2. A label carve-out excluding the patented contraceptive regimen, if the FDA-approved labeling permitted a legally effective carve-out.
3. A redesigned dosing schedule outside the claimed phase durations or dose relationship.
4. A product using ingredients or dose equivalents outside the claim boundaries.
5. Launch after patent expiration.

The current launch risk from US 4,390,531 itself is zero because an expired patent cannot support an injunction or statutory patent damages for post-expiration conduct.

What is the geographic coverage of the patent?

The patent covers the United States only. It does not establish rights in Canada, Europe, Japan, Australia, or other jurisdictions. Parallel foreign applications, national-phase filings, continuations, or related patents would require separate review.

The expiration of the U.S. patent also says nothing about the status of related foreign rights. Geographic freedom to operate must be assessed country by country.

What manufacturing and intellectual-property barriers remain?

The supplied claims disclose no independent manufacturing barrier. A manufacturer could face separate rights involving:

• Synthesis of ethinyl estradiol or norethindrone;
• Tablet compression and coating;
• Dose uniformity;
• Stability and packaging;
• Calendar blister packs;
• Combination-tablet technology;
• Regulatory labeling; and
• Trademark or trade-dress rights.

Those rights are separate from the regimen claims and cannot be attributed to US 4,390,531 without reviewing related patents and regulatory records.

Key Takeaways

• US 4,390,531 claims a phased contraceptive dosing method with three active phases and a placebo or treatment-free phase.
• Claim 1 requires phase durations of 5-8, 7-11, 3-7, and 6-8 days, with the first three phases totaling 21 days.
• Claims 2 and 3 specifically cover 7-7-7-7 and 7-9-5-7 schedules.
• Claims 4-6 focus on approximately 35 micrograms of ethinyl estradiol activity and 0.50 mg of norethindrone activity.
• Claims 7-9 narrow the invention to ethinyl estradiol, norethindrone, or both.
• The patent is expired and does not create a current U.S. blocking right.
• The patent is a method-of-use patent, not a composition-of-matter or manufacturing patent.
• Paragraph IV challenges would historically have focused on anticipation, obviousness, noninfringement, indefiniteness, and enablement.
• Biosimilar exposure is irrelevant because the claimed products are small-molecule contraceptives.
• Current freedom to operate depends on later patents, Orange Book listings, regulatory labeling, and foreign rights, not on this expired patent alone.

FAQs

Did US Patent 4,390,531 cover the birth-control pill itself?

No. It covered administration of hormonal contraceptive doses in a specified sequence. It did not claim ethinyl estradiol or norethindrone as chemical compounds generally.

Could a current generic contraceptive infringe US 4,390,531?

No current infringement claim can be based on an expired patent. The claim language may still help identify historical scope and prior art, but the patent cannot impose present exclusionary rights.

Does a seven-day placebo interval fall within the patent?

Yes, when the active phases satisfy the other limitations. Claims 2, 3, 5, and 6 expressly use a seven-day phase-four interval.

Does doubling the progestogen require doubling the tablet strength?

Not necessarily. The claim is directed to the administered daily dosage. A manufacturer could use one tablet, multiple tablets, or different dosage units, provided the administered amount satisfies the claim.

Are later oral-contraceptive products automatically covered because they use ethinyl estradiol?

No. Ethinyl estradiol alone is insufficient. The product would also need to satisfy the progestogen, dose-equivalence, phase-duration, 21-day active-phase, and placebo or treatment-free limitations.

References

1. United States Patent and Trademark Office. (1983). United States Patent No. 4,390,531.
2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
3. Drug Price Competition and Patent Term Restoration Act, 21 U.S.C. § 355(j).
4. U.S. Food and Drug Administration. (2015). Approved drug products with therapeutic equivalence evaluations: Guidance for industry.
5. Uruguay Round Agreements Act, Pub. L. No. 103-465, § 532, 108 Stat. 4809 (1994).
6. Patent Act, 35 U.S.C. § 156.
7. Patent Act, 35 U.S.C. § 102.
8. Patent Act, 35 U.S.C. § 103.

Drugs Protected by US Patent 4,390,531

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

International Family Members for US Patent 4,390,531

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	560922
Australia	8697682
Canada	1198057
Germany	3229612
United Kingdom	2104779
Hong Kong	26087
Malaysia	8700596