US Patent 6,667,050: Scope, Claims, Expiration, and Oral Contraceptive Patent Landscape

US Patent 6,667,050 covers chewable, palatable oral contraceptive tablets and related administration regimens. Its independent claims target three categories: the tablet itself, human contraception using the tablet, and improved compliance through a chewable contraceptive regimen. The patent is expired, so its claims no longer create a current U.S. exclusionary right. Its commercial importance was concentrated in chewable norethindrone/ethinyl estradiol products, including Femcon Fe-type formulations.

What does US Patent 6,667,050 protect?

The patent protects a chewable oral contraceptive dosage form with four central elements:

An oral contraceptive agent.
A chewable carrier suitable for human consumption.
A tablet that is chewable and palatable.
No ferrocene compound.

The claims extend across estrogen-only, progestin-only, and combination estrogen/progestin products. They also cover specific excipients, tablet dimensions, hardness, flavors, sweeteners, colors, blister packaging, and contraceptive dosing regimens. The patent specification and issued claims identify the commercial formulation of norethindrone and ethinyl estradiol as a particularly narrow embodiment. (U.S. Patent No. 6,667,050, 2003)

Patent identification and legal status

Item	Detail
Patent	US 6,667,050
Title	Chewable oral contraceptive
Technology	Chewable hormonal contraceptive tablets
Grant date	December 23, 2003
Patent term	Generally 20 years from the applicable nonprovisional filing date
Nominal expiration	Approximately May 2020
Current enforceability	Expired
Claim categories	Product, contraception method, compliance method
Principal active ingredients	Estrogens and progestins
Key commercial embodiment	Norethindrone plus ethinyl estradiol
Key negative limitation	No ferrocene compound

The patent’s term is governed by the filing and priority history, any applicable patent-term adjustment, and statutory patent-term rules. The patent is no longer an enforceable U.S. exclusionary right under ordinary term calculations. (35 U.S.C. §§ 154, 156)

How are the 60 claims structured?

The claims are highly repetitive. They form three parallel claim groups.

Claims	Claim type	Core subject matter
1-18	Product claims	Chewable oral contraceptive tablet
19-36	Contraception method claims	Administering the tablet to a human female
37-60	Compliance method claims	Using chewable tablets to enhance adherence

Claims 2-17, 20-35, and 38-53 add progressively narrower limitations to the respective independent claims. Claims 18, 36, and 54 are the narrow formulation claims. Claims 55-60 define daily dosing, regimen design, blister packaging, and placebo tablets.

Independent claim 1: chewable contraceptive tablet

Claim 1 is the principal composition claim. It requires a tablet that is:

Oral;
Contraceptive;
Chewable;
Palatable;
Made with a chewable human-consumable carrier; and
Free of a ferrocene compound.

The claim is not limited to a particular hormone, dose, excipient, tablet weight, or contraceptive schedule. Its breadth is therefore driven by the interpretation of “oral contraceptive agent,” “chewable,” “palatable,” and “ferrocene compound.”

The claim does not require both an estrogen and a progestin. A product containing only a covered estrogen or only a covered progestin could fall within claim 1 if the other limitations were satisfied.

Independent claim 19: contraception method

Claim 19 covers a method of human female contraception involving:

A contraceptively effective amount of an oral contraceptive agent;
A chewable, palatable tablet;
A chewable carrier;
No ferrocene compound; and
Administration to a human female.

This is a method-of-use claim rather than a product claim. It requires actual administration or performance of the claimed contraceptive method. A tablet manufacturer could face a different infringement analysis from a healthcare provider or end user because direct, induced, and contributory infringement standards differ under 35 U.S.C. §§ 271(a)-(c).

Independent claim 37: compliance-enhancement method

Claim 37 is directed to improving compliance with an oral contraceptive regimen. It requires:

Chewable, palatable oral contraceptive tablets;
A contraceptively effective amount of an oral contraceptive agent;
A chewable carrier;
No ferrocene compound; and
Administration in accordance with the regimen.

This claim adds a functional objective: enhanced compliance. The claim does not merely require that the product be chewable. It requires use in a manner connected to adherence with the contraceptive regimen.

What formulations are protected by US 6,667,050?

The patent claims broad classes of excipients and a specific norethindrone/ethinyl estradiol formulation.

Covered active ingredients

The estrogen group includes:

Ethinyl estradiol;
Estradiol;
Estradiol valerate; and
Estradiol acetate.

The progestin group includes:

Norethindrone;
Norethindrone acetate;
Desogestrel;
Levonorgestrel;
Ethynodiol diacetate;
Norgestrel;
Norgestimate;
Gestodene;
Drospirenone;
Trimegestone;
Levodesogestrel;
Gestodyne; and
Nesterone.

The claims cover products containing an estrogen, a progestin, or both. Claims 11-13 and 29-31 are directed to combination products.

Covered carrier and excipient systems

Claims 3, 4, 7, 10, 13, 21, 22, 25, 28, 31, 39, 40, 43, 46, and 49 identify the following carrier materials:

Dicalcium phosphate;
Lactose;
Corn starch;
Microcrystalline cellulose;
Maltodextrin;
Dextrose;
Mannitol;
Sorbitol;
Xylitol;
Fructose;
Sucrose; and
Calcium carbonate.

Claims 14, 32, and 50 add flavor agents, sweeteners, and color agents. The claims do not require a particular flavor or sweetener, although claim 18 identifies sucralose and a flavor agent in the narrower formulation.

Narrow claim 18 formulation

Claim 18 requires:

Norethindrone;
Ethinyl estradiol;
Dicalcium phosphate;
Lactose monohydrate;
Maltodextrin;
Sucralose;
A flavor agent;
Sodium starch glycolate;
Povidone; and
Magnesium stearate.

Claims 36 and 54 replicate this formulation limitation in the method and compliance-method groups.

A product that omits one of these specifically required components would not literally satisfy the narrow formulation claims, although it could still implicate broader claims if it remained chewable, palatable, contraceptive, and free of a ferrocene compound.

How do the tablet physical-property claims affect scope?

Claims 15-17 and 33-35 address physical characteristics.

Limitation	Claim coverage
Tablet weight	About 50 to about 300 mg
Packaging property	Hardness sufficient for blister packaging
Hardness range	About 5 to about 15 kiloponds

Claims 51-53 repeat the same limitations for the compliance regimen. These limitations narrow the claims but create potential construction issues.

“About” introduces ordinary patent-tolerance questions. The relevant range may not be treated as a rigid mathematical boundary. The meaning of “hardness sufficient for blister packaging” depends on the technical disclosure, packaging system, test method, and evidence concerning the claimed function.

The hardness limitation is important commercially because chewable tablets must balance two competing requirements: sufficient mechanical strength for manufacture and packaging, while remaining easy to chew. A tablet that is swallowable but not intended to be chewed would present a materially different infringement and regulatory profile.

What is the significance of the ferrocene exclusion?

The phrase “does not contain a ferrocene compound” is a negative claim limitation. Ferrocene is an organometallic compound containing iron. The exclusion appears designed to distinguish the claimed tablets from formulations containing an iron-containing ferrocene compound, such as a ferrocene-based active or inactive component.

The limitation has two effects:

A product containing a ferrocene compound should fall outside the literal scope of the claims.
The exclusion may narrow the patent’s ability to capture alternative formulations that otherwise satisfy the chewable-tablet requirements.

The exclusion is present in the principal product and method claims. It is not merely a specification preference. A prosecution-history analysis would be necessary to determine whether the limitation was added to overcome prior art and whether prosecution disclaimer limits any doctrine-of-equivalents argument.

What contraceptive regimens are covered?

Claims 55-60 create a regimen and packaging sub-portfolio.

Daily-dose regimen

Claim 55 requires each tablet to contain a daily dosage of the oral contraceptive agent.

Claim 56 narrows the active-tablet portion to approximately 21 to 25 tablets. Claim 57 adds approximately 3 to 7 placebo tablets. This structure covers common 28-day oral contraceptive packages.

Uniphasic and multiphasic products

Claim 58 covers a uniphasic regimen in which the active agent is present in the same amount in each active tablet.

Claim 59 covers a multiphasic regimen in which the amount of active agent varies among tablets.

These claims address regimen architecture rather than only tablet composition. A product could potentially avoid one regimen claim while remaining within a broader product claim.

Blister packaging

Claim 60 requires the tablets to be provided in a blister package. The packaging limitation is narrower than the core tablet claims and applies only within the compliance-method claim chain.

How strong is the patent estate for chewable oral contraceptives?

The patent estate was commercially meaningful but structurally narrow in several respects.

Strengths

The independent product claim reaches multiple estrogens, progestins, and combinations.
The claim covers chewable and palatable dosage forms rather than only one branded formulation.
The negative ferrocene limitation may have helped distinguish the invention from known iron-containing or ferrocene-containing compositions.
The patent includes product, administration, compliance, regimen, and packaging claims.
Claim 18 identifies a commercially recognizable norethindrone/ethinyl estradiol formulation.

Weaknesses

“Chewable” and “palatable” can require fact-intensive proof.
“Oral contraceptive agent” is broad but may be limited by the listed active classes in dependent claims.
The carrier list is closed in the dependent claims. An alternative excipient may avoid those dependent claims.
“Hardness sufficient for blister packaging” may be difficult to apply without a defined testing protocol.
The claims do not generally require a particular dose of hormone.
The patent is expired, eliminating current exclusionary value.

The patent’s present value is therefore historical, freedom-to-operate, and landscape-related rather than enforcement-based.

When did US Patent 6,667,050 lose exclusivity?

The patent reached the end of its ordinary U.S. patent term around May 2020, based on the applicable filing history and the 20-year term rule. The patent is no longer a current barrier to generic or branded development of chewable oral contraceptives.

Patent expiration does not eliminate other potential barriers, including:

Separate formulation patents;
Manufacturing-process patents;
Trademark rights;
Regulatory exclusivity;
Trade secrets;
Clinical-data protection; and
Patent rights covering a specific active ingredient or delivery technology.

For this patent itself, however, a new product launched after expiration would not need a patent license from the patent owner.

What is the Orange Book status of US 6,667,050?

US Patent 6,667,050 is not a current enforceable Orange Book barrier. The Orange Book lists patents submitted by NDA sponsors for approved drug products, but a patent’s existence does not establish that it was listed for a particular NDA. Orange Book status must be assessed at the NDA-product level, including the product’s active ingredient, dosage form, strength, formulation, and method of use. (U.S. Food and Drug Administration, 2025a)

The patent’s claims resemble a dosage-form and regimen patent rather than a patent directed to a novel active ingredient. Such patents may be listed against a specific approved product if they meet FDA listing criteria and were submitted by the NDA holder. The patent number alone does not establish a current Orange Book listing.

For an ANDA applicant, the relevant analysis would include:

Whether the reference listed drug is a chewable contraceptive;
Whether the patent was listed for that reference product;
Whether the patent has expired;
Whether any later-issued patents remain listed;
Whether a Paragraph IV certification was previously filed; and
Whether the proposed product uses the same dosage form, formulation, or method of use.

Which companies challenged or competed with the patented technology?

The commercial field included branded oral contraceptive manufacturers and generic manufacturers developing chewable or orally dissolving hormonal products. The most relevant commercial product category was chewable norethindrone/ethinyl estradiol contraception associated with Warner-Lambert, Warner Chilcott, and later Actavis/Allergan product portfolios.

The principal competitive paths were:

Competitive path	Patent relevance
Conventional swallowable tablets	Usually outside the chewable limitation
Chewable hormonal tablets	Closest technical and claim overlap
Oral contraceptive tablets with iron placebo tablets	Potentially relevant to the ferrocene exclusion and regimen claims
Alternative sweetener and carrier systems	May avoid dependent formulation claims
Different active ingredients	May avoid narrow active-ingredient claims but not necessarily claim 1
Non-tablet delivery systems	May avoid tablet claims
Transdermal, vaginal, injectable, and implant products	Outside the claimed oral chewable tablet format

No current Paragraph IV threat arises from this patent because the patent has expired. Any present generic-launch risk would come from separate patents associated with the relevant reference listed drug, not from US 6,667,050.

Does the patent create biosimilar risk?

No. Biosimilar law is not relevant to this patent. The claimed products are small-molecule oral contraceptive tablets, not biologics. The relevant regulatory pathway is generally an ANDA under section 505(j) of the Federal Food, Drug, and Cosmetic Act, or, depending on the product and circumstances, an NDA or supplemental NDA pathway. (21 U.S.C. § 355)

The principal regulatory risks are formulation equivalence, bioequivalence, labeling, manufacturing controls, and any separately listed patents.

What manufacturing and intellectual-property barriers remain?

The expired patent does not prevent manufacture of the claimed chewable tablet. Commercial barriers may still include:

Taste masking of estrogen and progestin ingredients;
Uniform distribution of low-dose hormones;
Blend segregation control;
Tablet compression without dose loss;
Mechanical strength sufficient for blister packaging;
Rapid disintegration after chewing;
Stability of hormones and excipients;
Moisture protection;
Flavor and sweetener compatibility;
Content uniformity;
Bioequivalence; and
Manufacturing validation.

The specific excipient combination in claim 18 is no longer patent-blocked by this patent. A developer must still review later patents, manufacturing know-how, trademarks, and regulatory requirements.

What generic launch scenarios exist?

Scenario 1: Conventional swallowable generic

A conventional swallowable tablet generally avoids the chewable-tablet limitation. It may still be subject to separate patents covering the active ingredient, dosage, regimen, or indication.

Scenario 2: Chewable generic after patent expiration

A chewable norethindrone/ethinyl estradiol product can now practice the expired claim set without infringing US 6,667,050. The applicant would still need to address any live patents listed against the reference product.

Scenario 3: Alternative excipient chewable product

A product using a different carrier may avoid the dependent carrier claims. It may still fall within claim 1 if it remains chewable, palatable, contraceptive, and free of ferrocene.

Scenario 4: Different regimen or packaging

A product outside the 21-25 active tablet and 3-7 placebo tablet structure may avoid claims 56-60, but those claims are narrower than the principal product claim and would not be necessary to establish infringement of claim 1.

Key Takeaways

US Patent 6,667,050 covers chewable, palatable oral contraceptive tablets and related contraception and compliance methods.
The broadest claim requires an oral contraceptive agent, a chewable human-consumable carrier, chewability, palatability, and no ferrocene compound.
The patent covers estrogen-only, progestin-only, and combination products.
Dependent claims identify specific hormones, carriers, flavors, tablet weights, hardness ranges, blister packaging, and 21-28-day regimens.
Claim 18 is directed to a narrow norethindrone/ethinyl estradiol formulation with dicalcium phosphate, lactose monohydrate, maltodextrin, sucralose, flavoring, sodium starch glycolate, povidone, and magnesium stearate.
The patent expired around May 2020 under the applicable 20-year term.
It presents no current Paragraph IV or biosimilar barrier.
Current commercial risk must be assessed against later patents, Orange Book listings, trademarks, regulatory exclusivity, and manufacturing know-how.
The patent remains relevant as prior art and as a historical map of chewable oral contraceptive formulation strategy.

FAQs

Can a company make a chewable norethindrone and ethinyl estradiol tablet today?

Yes, US Patent 6,667,050 is expired. The company must still evaluate later patents, Orange Book listings, regulatory requirements, and product-specific exclusivity.

Does using a different sweetener avoid the patent?

It may avoid narrow claims requiring particular dependent formulations, but a different sweetener does not automatically avoid claim 1. The product would still need to be assessed against the chewable, palatable, carrier, contraceptive-agent, and ferrocene limitations.

Does a tablet have to contain both estrogen and progestin?

No. Claim 1 is broad enough to cover a tablet containing an oral contraceptive agent generally. Dependent claims separately address estrogen-only, progestin-only, and combination products.

Are placebo tablets protected by the patent?

Claims 56 and 57 cover regimens containing approximately 21-25 active tablets and approximately 3-7 placebo tablets. The placebo tablets are relevant to the regimen claims, not necessarily to the broad product claim.

Is the patent relevant to contraceptive patches or vaginal rings?

Generally no. The claims are directed to oral chewable tablets and administration regimens using those tablets. Non-tablet delivery systems fall outside the claimed dosage form.

References

U.S. Patent No. 6,667,050. (2003). Chewable oral contraceptive. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2025a). Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services.
U.S. Food and Drug Administration. (2025b). Orange Book: Questions and answers. U.S. Department of Health and Human Services.
21 U.S.C. § 355. New drugs.
35 U.S.C. § 154. Contents and term of patent; provisional rights.
35 U.S.C. § 156. Extension of patent term.
35 U.S.C. § 271. Infringement of patent.

Summary for Patent: 6,667,050