Details for Patent: 8,466,137

Which drugs does patent 8,466,137 protect, and when does it expire?

Patent 8,466,137 protects ANDROGEL and is included in one NDA.

This patent has fifty patent family members in thirty countries.

Summary for Patent: 8,466,137

Title:	Testosterone gel and method of use
Abstract:	The present invention relates to an improved transdermal hydroalcoholic testosterone gen formulation that provides, among other things, a desirable pharmacokinetic hormone profile, and methods of use.
Inventor(s):	Ramana Malladi, Jodi Stahlman
Assignee:	Besins Healthcare Luxembourg SARL , Unimed Pharmaceuticals LLC
Application Number:	US13/180,327
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 8,466,137
Patent Claim Types: see list of patent claims	Use;

United States Drug Patent 8,466,137: Claim Scope, Expiration, Litigation, and Testosterone Gel Patent Landscape

U.S. Patent No. 8,466,137 protects a narrow method of treating male hypogonadism with a 1.62% testosterone hydroalcoholic gel. Its core limitations are the defined testosterone, isopropyl myristate, alcohol, carbomer or other polyacrylic acid, sodium hydroxide, and water ranges. The patent also covers the marketed 2.5-gram dose delivering 40.5 mg of testosterone when the formulation contains 1.62% testosterone. The patent was assigned to Unimed Pharmaceuticals, Inc., an AbbVie group company, and has been associated with AndroGel 1.62% litigation and generic-entry disputes.

What does U.S. Patent 8,466,137 protect?

The patent protects a treatment method, not every testosterone gel formulation. Claim 1 requires both:

1. Treatment of hypogonadism in a human male; and
2. Application to skin of a hydroalcoholic gel having the claimed composition ranges.

The central formulation limitations are:

Component	Claimed amount
Testosterone	1.3% to 1.7% w/w
Isopropyl myristate	0.9% to 1.0% w/w
Lower alcohol	67.0% to 74.0% w/w
Polyacrylic acid	0.6% to 1.4% w/w
0.1 N sodium hydroxide	1.0% to 10.0% w/w
Water	Balance

The lower alcohol must be selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, or tert-butanol.

Claim 1 uses the closed transition “consisting of.” That language materially narrows the claim. A competing product containing an additional formulation ingredient may argue that it falls outside the literal composition of the claimed gel, although infringement could still depend on claim construction, the role of the additional ingredient, and the doctrine of equivalents.

How do claims 2 through 8 narrow the patent?

Claims 2 through 8 add progressively narrower formulation, dosage, and pharmacokinetic limitations.

Claim	Additional limitation	Commercial significance
2	Lower alcohol is 95% v/v ethanol	Tracks the principal ethanol-based formulation
3	1.0% carbomer and 7.0% 0.1 N sodium hydroxide, with neutralization	Identifies a specific gel matrix and neutralization process
4	Serum testosterone reaches about 298 to 1,043 ng/dL	Adds a broad therapeutic blood-level outcome
5	Serum testosterone is maintained at about 300 to 1,050 ng/dL	Focuses on maintenance of testosterone exposure
6	Polyacrylic acid is a carbomer	Narrows the polymer component
7	Applied gel dose is 2.5 grams	Corresponds to the commercial daily pump dose
8	The 2.5-gram dose administers 40.5 mg testosterone	Corresponds mathematically to 1.62% testosterone

Claim 8 is particularly important commercially. A 2.5-gram dose containing 1.62% testosterone contains approximately 40.5 mg of testosterone:

2.5 grams x 1.62% = 0.0405 grams = 40.5 mg.

A generic product using the same 2.5-gram dose and 1.62% strength would face a direct comparison against claims 7 and 8, subject to the product’s actual composition and labeling.

What is the technical scope of the 8,466,137 patent?

The technical scope has four principal layers.

Formulation composition

The claim requires a testosterone concentration centered on 1.62%. The range of 1.3% to 1.7% captures the commercial 1.62% product but does not cover all testosterone gels. Products at 1%, 2%, or another concentration may avoid literal infringement of claim 1 if no other claim applies.

The claim also requires isopropyl myristate within a tight 0.9% to 1.0% range. This excipient is relevant to skin penetration and formulation performance. A formulation using a materially different concentration may create a noninfringement position, although the legal result would depend on the evidence and claim construction.

Gel vehicle

The formulation requires a lower alcohol at 67% to 74% w/w. Claim 2 narrows this to 95% v/v ethanol as the alcohol source. The alcohol concentration is a major design-around variable because a competitor could attempt to alter the alcohol identity or concentration while preserving comparable testosterone delivery.

Polymer and neutralization system

The claim requires polyacrylic acid, with claim 6 narrowing the material to carbomer. Claim 3 is narrower still and recites 1% carbomer neutralized with 7% of 0.1 N sodium hydroxide.

This limitation may create manufacturing and analytical disputes. The relevant questions include whether a competing polymer is a “polyacrylic acid,” whether a particular carbomer grade falls within the claim, and whether sodium hydroxide is present in the specified form and amount.

Therapeutic use and pharmacokinetics

The patent is a method-of-treatment patent. The claimed use is treatment of hypogonadism in a human male. Claims 4 and 5 add serum testosterone outcomes. Those claims may be difficult to assess solely from the product label because serum concentrations depend on dose, application site, patient characteristics, adherence, skin absorption, and sampling time.

When does U.S. Patent 8,466,137 lose exclusivity?

The listed patent term is generally reported as expiring on August 4, 2027, subject to the official patent-term record and any applicable adjustment or disclaimer information. The patent issued on June 18, 2013, from a continuation or related application chain directed to testosterone gel formulations and methods of use. Patent term ordinarily runs 20 years from the earliest effective nonprovisional filing date, with possible patent-term adjustment under 35 U.S.C. § 154.

Event	Date
Earliest relevant priority date	August 4, 2008
U.S. patent issue date	June 18, 2013
Reported expiration date	August 4, 2027
Patent number	U.S. 8,466,137 B2
Technology	1.62% testosterone hydroalcoholic gel

FDA regulatory exclusivity is separate from patent exclusivity. A generic applicant may receive ANDA approval after FDA exclusivity expires or may obtain approval earlier if it resolves listed patents through a Paragraph IV process, a court decision, or a settlement arrangement.

What is the Orange Book status of U.S. Patent 8,466,137?

U.S. Patent 8,466,137 has been associated with AndroGel 1.62%, a topical testosterone gel marketed by AbbVie and its predecessor companies. The Orange Book distinguishes patents that claim the drug substance, drug product, or an approved method of use.

This patent is most relevant as a drug-product and method-of-use barrier. Its claims do not broadly cover testosterone as a molecule. Testosterone is an old active ingredient, and the commercial protection arises from the specified formulation and therapeutic administration method.

Orange Book analysis should separate:

• The listed patent number;
• The approved uses tied to the patent;
• The patent expiration date;
• Any pediatric exclusivity;
• Any later-added formulation or method patents;
• The certification filed by each ANDA applicant.

A generic applicant may submit a Paragraph III certification, agreeing not to market until patent expiration, or a Paragraph IV certification, asserting that the patent is invalid, unenforceable, or not infringed. A Paragraph IV notice can trigger a 45-day period for the patent owner to file an infringement action under the Hatch-Waxman framework. [1, 2]

Which companies have challenged the AndroGel 1.62% patent estate?

AbbVie has pursued patent litigation against generic applicants seeking approval for testosterone gel 1.62%. Teva Pharmaceuticals has been a prominent challenger in litigation involving AndroGel 1.62% patents, including U.S. Patent 8,466,137 and related patents in the same commercial patent estate.

The central defenses in this type of litigation are usually:

• Lack of infringement because the proposed product falls outside one or more formulation ranges;
• Invalidity for anticipation;
• Invalidity for obviousness;
• Lack of written description or enablement;
• Improper claim scope for the pharmacokinetic limitations;
• Noninfringement of method claims based on the proposed label.

The most commercially important evidence is generally the ANDA formulation, manufacturing records, stability data, proposed labeling, and bioequivalence or pharmacokinetic information. Public product labels do not always disclose every quantitative formulation detail needed to resolve infringement.

What patent litigation affects U.S. Patent 8,466,137?

The AndroGel 1.62% litigation landscape has involved federal district-court proceedings brought under the Hatch-Waxman statute after Paragraph IV certifications. The litigation risk is not limited to the ’137 patent. Patent owners commonly assert a group of related formulation and use patents, making the commercial result depend on the surviving patent set rather than one patent in isolation.

The key litigation questions are:

1. Whether the proposed generic contains testosterone within the 1.3% to 1.7% range;
2. Whether isopropyl myristate is present within 0.9% to 1.0%;
3. Whether the alcohol vehicle falls within 67% to 74%;
4. Whether the polymer and neutralization system meet the polyacrylic-acid limitations;
5. Whether the generic label induces use for hypogonadism;
6. Whether the patent claims are invalid over earlier testosterone gel disclosures.

A settlement may permit a generic launch before the stated patent expiration date. The business terms of Hatch-Waxman settlements are not always fully public, and a launch date should not be inferred solely from the patent expiration date.

How strong is the patent estate for AndroGel 1.62%?

The ’137 patent has meaningful commercial relevance because its claim limitations map closely to the marketed 1.62% product and the 2.5-gram, 40.5-mg dose. Its weaknesses are claim narrowness and dependence on quantitative formulation proof.

Strength	Effect
Direct correspondence to the 1.62% product	Supports infringement allegations against closely matched generics
2.5-gram and 40.5-mg dose claims	Targets the commercial dosing regimen
Carbomer and ethanol subclaims	Creates additional formulation-specific barriers
Closed “consisting of” language	Limits the claim against products with materially different excipients
Tight isopropyl myristate range	Creates a potential design-around route
Method-of-treatment format	Requires proof of the claimed treatment use or induced infringement
Pharmacokinetic claims	May raise proof and claim-construction issues

The estate is stronger against a close copy of the marketed formulation than against a reformulated testosterone gel using a different polymer system, alcohol concentration, dose, or delivery approach.

What generic launch risks exist after the patent expires?

Generic launch risk has several stages.

Before August 2027

A generic applicant may launch before the reported expiration date if it obtains a favorable judgment, reaches a settlement, or relies on an authorized-generic arrangement. A Paragraph IV challenge can accelerate litigation and create a potential 180-day first-filer exclusivity issue under the ANDA statute.

At patent expiration

At expiration, the ’137 patent no longer blocks a product solely on the basis of that patent. Related patents, pediatric exclusivity, regulatory requirements, or separate intellectual-property rights may still affect launch timing.

After patent expiration

The principal barriers shift from patent validity to:

• ANDA approval;
• Pharmaceutical equivalence;
• Bioequivalence or comparative pharmacokinetic requirements;
• Device or pump compatibility;
• Manufacturing scale-up;
• Controlled-substance handling and distribution controls;
• State substitution rules;
• Commercial access to prescribers and pharmacies.

Testosterone products are not biologics, so biosimilar approval under the Public Health Service Act is not the relevant pathway. Competitors generally use the ANDA pathway for a pharmaceutically equivalent generic or the 505(b)(2) pathway for a product with meaningful differences in formulation, dosage, delivery, or clinical use. [2, 3]

What formulations and uses are protected by the patent?

The patent protects a specific transdermal gel architecture:

• Testosterone concentration near 1.62%;
• Ethanol or another listed lower alcohol;
• Isopropyl myristate;
• Carbomer or another polyacrylic acid;
• Sodium hydroxide neutralization;
• Water;
• Application to male skin for hypogonadism.

It does not, based on the supplied claims, broadly protect:

• Injectable testosterone;
• Oral testosterone;
• Buccal testosterone;
• Testosterone patches;
• Pellets;
• A testosterone gel lacking the claimed formulation ranges;
• Treatment of women;
• Uses unrelated to hypogonadism;
• A formulation using a materially different vehicle.

The phrase “area of skin” is broad as to the body site, but the claim still requires topical application of the specified gel to a human male.

How does U.S. Patent 8,466,137 compare with competing testosterone products?

Product category	Relationship to ’137 patent	Primary competitive issue
AndroGel 1.62%	Closely aligned with the claimed formulation and dose	Originator product protected by formulation and use patents
Generic testosterone gel 1.62%	Potentially within the claimed composition and method	ANDA certification, litigation, settlement, and launch timing
Testosterone gel 1%	Different strength	May avoid the 1.3% to 1.7% testosterone range
Fortesta testosterone gel	Different strength and dosing design	Formulation and dosing differences
Axiron topical solution	Different delivery system	Product and method patents separate from ’137
Injectable testosterone	Different dosage form	Not within the topical gel composition
Testosterone pellets	Implantable delivery	Not within the claimed gel method

The principal competitive threat is a pharmaceutically equivalent 1.62% gel, not a different testosterone dosage form.

What revenue exposure is associated with the patent?

The patent’s revenue exposure is tied to AndroGel 1.62% sales and the timing of generic substitution. Public company disclosures have historically reported AndroGel and other testosterone products within broader product or therapeutic-area revenue categories rather than always isolating sales attributable to one patent.

The economic effect of generic entry depends on:

• The number of approved ANDAs;
• First-filer status;
• The presence of authorized generics;
• Payer substitution;
• Wholesale acquisition price;
• Rebate structure;
• Prescriber retention;
• The survival of related formulation patents.

The ’137 patent is therefore a launch-timing asset rather than a molecule-level monopoly. Its value declines sharply when a legally permissible 1.62% generic reaches the market, particularly if competing products are substitutable at the pharmacy level.

What manufacturing and intellectual-property barriers remain?

The formulation is relatively conventional in its use of ethanol, carbomer, sodium hydroxide, water, and a penetration-enhancing excipient. The main manufacturing barrier is reproducible control of:

• Testosterone concentration;
• Carbomer dispersion;
• Neutralization;
• Gel viscosity;
• Alcohol evaporation;
• Uniformity through the container or pump;
• Delivered dose per actuation;
• Stability and microbial quality.

Patent risk can arise even when the active ingredient is old. A generic manufacturer must assess the full formulation, proposed labeling, method-of-use implications, and related patents. Freedom-to-operate analysis should cover U.S. formulation patents, method patents, manufacturing claims, pump or package patents, and any settlement restrictions.

Key Takeaways

• U.S. Patent 8,466,137 is a narrow method patent directed to a 1.62% testosterone hydroalcoholic gel for treating male hypogonadism.
• Claim 1 requires specific quantitative ranges for testosterone, isopropyl myristate, alcohol, polyacrylic acid, sodium hydroxide, and water.
• Claims 7 and 8 target the commercial 2.5-gram dose delivering 40.5 mg of testosterone.
• The patent is associated with AndroGel 1.62% and has been reported to expire on August 4, 2027.
• Teva and other generic applicants have challenged the AndroGel 1.62% patent estate through Hatch-Waxman proceedings.
• The patent is strongest against a close formulation copy and weaker against a product using a different alcohol concentration, polymer, excipient profile, or dosing method.
• Generic testosterone products are subject to ANDA requirements, not the biosimilar pathway.
• Patent expiry does not itself establish immediate commercial launch because FDA approval, related patents, settlements, and market-access conditions remain relevant.

FAQs About U.S. Patent 8,466,137

Does U.S. Patent 8,466,137 cover all testosterone gels?

No. It covers a defined hydroalcoholic gel composition used to treat hypogonadism in a human male. Testosterone gels outside the claimed concentration, excipient, alcohol, or dosing ranges may fall outside the claims.

Is claim 8 limited to AndroGel 1.62%?

Claim 8 closely corresponds to a 2.5-gram dose of 1.62% testosterone gel delivering 40.5 mg of testosterone. It is not limited by brand name, but a competing product must satisfy all limitations of the incorporated claims to infringe.

Can a generic avoid the patent by changing the carbomer?

Potentially. A different polymer may avoid literal infringement of claims requiring a carbomer, but claim 1 reaches polyacrylic acid more broadly. The result depends on the polymer’s chemical identity, amount, and the construction of the asserted claim.

Is testosterone a biologic for patent and FDA purposes?

No. Testosterone is a small-molecule active pharmaceutical ingredient. Generic testosterone gel products generally proceed through the ANDA pathway, while biosimilar applications apply to biological products.

Does patent expiration automatically permit generic substitution?

No. The generic must have FDA approval, and state substitution, pharmacy-channel, related-patent, settlement, and commercial conditions may affect the timing and scope of substitution.

References

1. U.S. Patent and Trademark Office. (2013). U.S. Patent No. 8,466,137: Testosterone gel formulations and methods of use. https://patents.google.com/patent/US8466137B2/en
2. U.S. Food and Drug Administration. (2023). Approved drug products with therapeutic equivalence evaluations, 43rd edition. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book
3. U.S. Food and Drug Administration. (2024). Abbreviated new drug application pathway. https://www.fda.gov/drugs/types-applications/abbreviated-new-drug-application-anda
4. U.S. Food and Drug Administration. (2024). Hatch-Waxman amendments and generic drug patent certifications. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/paragraph-iv-certifications-and-180-day-exclusivity-relevant-applications
5. AbbVie Inc. (2023). Annual report and intellectual-property disclosures. https://www.abbvie.com/investors/financial-reports-and-filings.html

Drugs Protected by US Patent 8,466,137

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Besins Hlthcare	ANDROGEL	testosterone	GEL, METERED;TRANSDERMAL	022309-001	Apr 29, 2011	AB	RX	Yes	Yes						TESTOSTERONE REPLACEMENT THERAPY IN MALES FOR CONDITIONS ASSOCIATED WITH A DEFICIENCY OR ABSENCE OF ENDOGENOUS TESTOSTERONE
Besins Hlthcare	ANDROGEL	testosterone	GEL;TRANSDERMAL	022309-002	Sep 7, 2012	AB2	RX	Yes	No						TESTOSTERONE REPLACEMENT THERAPY IN MALES FOR CONDITIONS ASSOCIATED WITH A DEFICIENCY OR ABSENCE OF ENDOGENOUS TESTOSTERONE
Besins Hlthcare	ANDROGEL	testosterone	GEL;TRANSDERMAL	022309-003	Sep 7, 2012	AB2	RX	Yes	No						TESTOSTERONE REPLACEMENT THERAPY IN MALES FOR CONDITIONS ASSOCIATED WITH A DEFICIENCY OR ABSENCE OF ENDOGENOUS TESTOSTERONE

International Family Members for US Patent 8,466,137

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2006299833
Brazil	PI0617294
Canada	2624788
China	101287470