United States Patent 8,466,136: Scope, Claims, Expiration, and Testosterone Gel Patent Landscape

US Patent 8,466,136 protects a narrowly defined hydroalcoholic testosterone gel associated with the 1.62% AndroGel formulation. Its core limitations are the combination of testosterone, isopropyl myristate, lower alcohol, polyacrylic acid, sodium hydroxide and water, within specified concentration ranges. Dependent claims narrow the formulation to approximately 95% ethanol, carbomer, a specific neutralization system, and a 2.5-gram dose delivering 40.5 mg of testosterone.

The patent is a formulation patent, not a patent covering testosterone generally. A competing product must be assessed against every limitation of an asserted claim. The most commercially significant claims are claims 1, 2, 4 and 7. The patent does not create biosimilar risk because testosterone is a small-molecule active pharmaceutical ingredient, not a biologic.

What does US Patent 8,466,136 cover?

US 8,466,136 covers a hydroalcoholic gel containing six required components:

Claim element	Claimed limitation
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	Remaining component

The lower alcohol may be methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol or tert-butanol. Claim 2 narrows this group to approximately 95% by volume ethanol.

The use of “consisting of” in claim 1 is important. It generally limits the claimed composition to the listed components, subject to the interpretation of the claim language, unavoidable impurities and conventional claim-construction principles. A product containing an additional active ingredient or material may fall outside the literal scope of the claim, although the legal result depends on the function and amount of the additional material.

How do the claims of US 8,466,136 differ?

Claim 1: broadest formulation claim

Claim 1 is the principal composition claim. It requires all listed ingredients and all concentration ranges. The ranges are cumulative. A product containing 1.62% testosterone but 1.2% isopropyl myristate would not literally satisfy the stated isopropyl myristate range.

The claim has several potential design-around variables:

testosterone concentration;
isopropyl myristate concentration;
alcohol identity;
alcohol concentration;
polyacrylic acid concentration;
sodium hydroxide concentration; and
use of a different pH-adjusting or gelling system.

A formulation that falls outside one limitation may still raise doctrine-of-equivalents issues, but literal infringement would be less direct.

Claim 2: ethanol limitation

Claim 2 requires the lower alcohol to be about 95% v/v ethanol. The claim narrows claim 1’s list of permissible alcohols. A formulation using isopropanol, even within the same overall alcohol concentration range, would not meet claim 2 literally.

The claim also creates an analytical issue because the claim uses both weight-based and volume-based measurements. The formulation must be evaluated using the specified measurement bases rather than treating “95% ethanol” as a substitute for the 67% to 74% w/w limitation in claim 1.

Claims 3 and 5: neutralized carbomer system

Claim 3 requires:

1.0% w/w polyacrylic acid;
7.0% w/w 0.1 N sodium hydroxide; and
neutralization by combining those components.

Claim 5 further limits the polyacrylic acid to a carbomer.

These claims are narrower than claim 1 because they require specific amounts and a specified neutralization relationship. They may be useful against a product whose formulation records disclose the manufacturing sequence and exact quantities, but they are easier to avoid through a different carbomer level, a different neutralizing agent or a different concentration of sodium hydroxide.

Claim 4: carbomer limitation

Claim 4 requires the polyacrylic acid to be a carbomer. Carbomer is a crosslinked polyacrylic acid polymer widely used as a gel-forming excipient. A product using a non-carbomer acrylic polymer may avoid literal infringement of claim 4 while still requiring analysis under claim 1.

Claims 6 and 7: dose and administration limitations

Claim 6 specifies a therapeutically effective dose of 2.5 grams for treatment of hypogonadism in a human male.

Claim 7 specifies that the 2.5-gram dose delivers 40.5 mg of testosterone. That amount corresponds to a 1.62% w/w formulation:

2.5 grams × 1.62% = 0.0405 grams, or 40.5 mg.

These claims closely track the labeled starting dose of AndroGel 1.62%. Because claims 6 and 7 depend on the formulation claim, a product must first satisfy claim 1 and then meet the dose-related limitations.

What formulation is associated with the patent?

The claimed composition corresponds closely to the commercial profile of AndroGel 1.62%, marketed in the United States for testosterone replacement therapy in adult males with hypogonadism. The FDA-approved labeling identifies a starting dose of 40.5 mg of testosterone, delivered as two pump actuations, with each pump actuation delivering 20.25 mg of testosterone in 1.25 grams of gel.[1]

Product characteristic	AndroGel 1.62% profile
Active ingredient	Testosterone
Strength	1.62%
Starting daily dose	40.5 mg
Gel quantity at starting dose	2.5 g
Delivery	Two pump actuations
Primary indication	Testosterone replacement in adult males with hypogonadism

The formulation relationship is commercially significant because a generic product can match the marketed strength and dose while changing excipients or manufacturing parameters. The relevant question is whether the approved generic’s actual formulation falls within the patent claims, not whether its label uses the same product name or therapeutic indication.

What is the Orange Book status of US 8,466,136?

US 8,466,136 has been associated with the Orange Book patent listings for AndroGel 1.62% and its NDA product record. The FDA Orange Book identifies patents and exclusivity associated with approved drug products, but an Orange Book listing does not establish that every claim is valid or infringed.[2]

The principal Orange Book implications are:

An ANDA applicant seeking approval before the listed patent’s expiration may need to submit a Paragraph IV certification.
The patent holder or NDA sponsor may file an infringement action within 45 days of receiving notice.
A timely suit can trigger a statutory 30-month stay of ANDA approval, subject to statutory exceptions and court developments.
The Orange Book listing does not necessarily disclose every relevant patent in the broader patent estate.

The FDA’s listing should be checked against the current edition of the Approved Drug Products with Therapeutic Equivalence Evaluations and the relevant patent-use-code information. Patent status can change through expiration, terminal disclaimer, disclaimer filings, pediatric exclusivity, litigation judgments or settlement arrangements.

When does US 8,466,136 lose exclusivity?

The patent’s effective expiration depends on its earliest effective nonprovisional filing date, patent-term adjustment, terminal disclaimers and any applicable pediatric extension. The patent was granted on June 18, 2013.[3]

For a US utility patent, the baseline term is generally 20 years from the earliest effective nonprovisional filing date, subject to statutory adjustments under 35 U.S.C. §§ 154 and 156. A reliable freedom-to-operate analysis must use the USPTO patent-term data rather than calculate expiration solely from the grant date.[4]

The commercial exclusivity timeline also depends on FDA regulatory exclusivity:

Exclusivity category	Relevance
Patent term	Controls the enforceable patent right
Orange Book listing	Supports notice and ANDA litigation procedures
NDA exclusivity	May delay certain FDA approvals independently of the patent
Pediatric exclusivity	May add six months if granted
Settlement restrictions	May delay or permit an agreed generic launch

Patent expiry does not automatically mean immediate generic availability if another unexpired patent, regulatory exclusivity period or injunction remains relevant.

Which companies challenged AndroGel 1.62% patents?

AndroGel 1.62% attracted ANDA activity from multiple generic manufacturers. Publicly reported participants have included Perrigo, Teva and other generic drug companies seeking approval for testosterone gel products.

The principal challenge mechanisms were Paragraph IV certifications and related Hatch-Waxman litigation. These cases typically addressed one or more of the following:

whether the generic formulation fell within the listed formulation claims;
whether the patent claims were invalid for anticipation or obviousness;
whether the patent was unenforceable;
whether the ANDA filing created an act of infringement;
whether a settlement could establish a permitted generic launch date.

Because Hatch-Waxman cases may resolve through confidential or partially confidential settlements, a litigation docket should be reviewed alongside FDA approval records and SEC filings. A settlement does not necessarily mean that the patent was adjudicated valid and infringed.

What patent litigation affects the testosterone gel market?

The commercial disputes around AndroGel 1.62% have centered on formulation and product-specific patent rights rather than ownership of testosterone as an active ingredient. The key litigation questions are claim coverage and launch timing.

A standard litigation sequence is:

Generic applicant files an ANDA with a Paragraph IV certification.
NDA holder receives notice.
NDA holder files a district-court action within 45 days.
FDA approval may be stayed for up to 30 months.
The case proceeds toward claim construction, validity review, settlement or judgment.
Generic launch occurs after patent expiry, settlement authorization or a favorable judgment.

The strength of a Paragraph IV defense depends heavily on the generic’s actual formulation. A label may not disclose every quantitative excipient detail, while the ANDA contains confidential chemistry, manufacturing and controls information. Courts may therefore evaluate the proposed product through ANDA documents, discovery and expert testimony.

How strong is the patent estate for AndroGel 1.62%?

US 8,466,136 has moderate-to-strong commercial relevance because it claims the specific strength and excipient profile associated with a marketed product. Its strength is narrower than a broad active-ingredient patent.

Factor	Assessment
Claim type	Formulation
Commercial alignment	High; claim 7 maps to 40.5 mg in 2.5 g
Breadth	Moderate to narrow
Design-around potential	Meaningful through excipient and concentration changes
Detectability	Moderate; final formulation may be tested, but process details may be confidential
Biosimilar exposure	None
Generic exposure	High after patent and regulatory barriers expire
Litigation leverage	Strongest where the generic mirrors the listed formulation

The patent’s vulnerability would typically be assessed against earlier testosterone gels, prior art describing carbomer gels, known use of isopropyl myristate as a penetration enhancer, and prior formulations containing ethanol and sodium hydroxide. The claimed numerical ranges and the specific 40.5-mg dose may provide narrower validity arguments than a broad claim to testosterone gel.

What manufacturing and intellectual-property barriers remain?

The formulation itself is relatively conventional from a pharmaceutical development perspective. Carbomers, ethanol, isopropyl myristate and sodium hydroxide are established excipients. The main barriers are regulatory reproducibility, transdermal delivery performance, manufacturing controls and patent-specific formulation matching.

A generic developer must demonstrate:

pharmaceutical equivalence;
bioequivalence or the applicable FDA pathway;
consistent testosterone delivery;
control of viscosity, pH and alcohol content;
microbial and container-closure performance;
pump-dose accuracy;
acceptable skin-contact performance; and
compliance with testosterone handling and controlled-substance requirements.

The pump and metered-dose system can create separate device, packaging or regulatory issues even when no independent patent blocks approval.

How does this patent compare with broader testosterone patents?

US 8,466,136 differs from older testosterone patents that may claim the active ingredient, general transdermal delivery or broad gel compositions. It is product-specific and concentration-specific.

Patent category	Typical scope	Relevance to generic entry
Active-ingredient patent	Testosterone molecule or derivative	Usually limited where the molecule is old
Broad delivery patent	Transdermal testosterone administration	Can cover multiple dosage forms
Formulation patent	Specific excipients and concentrations	Directly relevant to ANDA product design
Method-of-use patent	Treatment of hypogonadism or dosing regimen	Relevant to label and induced-infringement risk
Device patent	Pump, actuator or metered delivery	Relevant to product presentation and packaging

A generic applicant can reduce risk by developing a formulation outside the composition ranges, omitting isopropyl myristate, replacing carbomer or using a different neutralization system. That strategy must be balanced against FDA requirements for bioequivalence and comparable delivery.

What generic launch scenarios exist?

The principal launch scenarios are:

Launch after the patent’s effective expiration and any applicable regulatory exclusivity.
Launch under a settlement agreement with a negotiated entry date.
Launch after a court judgment that the patent is invalid, unenforceable or not infringed.
Launch at risk before final resolution, exposing the applicant to damages and injunctive risk.
Launch with a reformulated product designed to avoid the asserted claims.

For investors and licensors, the most important distinction is between FDA approval and commercial freedom to launch. A generic may receive approval but remain subject to a patent-related launch restriction.

What is the geographic coverage of US 8,466,136?

US 8,466,136 is enforceable only in the United States. Foreign counterparts must be analyzed separately by jurisdiction. Patent families for testosterone gel products may include filings in Europe, Canada, Australia and other markets, but expiration dates, claim scope, prosecution history and litigation outcomes are jurisdiction-specific.

A US FDA approval does not establish freedom to operate outside the United States. Conversely, expiration or invalidity of a foreign counterpart does not affect the US patent.

Key Takeaways

US 8,466,136 is a formulation patent covering a specific hydroalcoholic testosterone gel.
Claim 1 requires all six listed components within stated concentration ranges.
Claim 2 narrows the alcohol to approximately 95% ethanol.
Claims 3 and 5 target a specific carbomer and sodium hydroxide neutralization system.
Claims 6 and 7 correspond to a 2.5-gram dose delivering 40.5 mg of testosterone.
The patent is closely associated with AndroGel 1.62%.
Generic risk is highest for products that reproduce the same excipient system and dose.
The patent does not create biosimilar risk because testosterone is a small molecule.
Orange Book listing can trigger Paragraph IV litigation and a potential 30-month stay.
Effective exclusivity depends on patent-term adjustment, terminal disclaimers, pediatric exclusivity, regulatory exclusivity and any settlement agreement.
Patent expiry alone does not guarantee immediate generic launch if other listed patents or regulatory barriers remain.

FAQs About US Patent 8,466,136 and AndroGel 1.62%

Does US 8,466,136 cover all testosterone gels?

No. It covers a particular composition containing testosterone, isopropyl myristate, lower alcohol, polyacrylic acid, sodium hydroxide and water within specified ranges.

Can a generic avoid US 8,466,136 by using a different gelling agent?

Potentially. Replacing carbomer may avoid claims 4 and 5, but claim 1 must still be assessed because it refers more broadly to polyacrylic acid.

Does the 40.5-mg dose alone infringe claim 7?

No. Claim 7 depends on the earlier formulation and dose limitations. The product must satisfy the underlying composition requirements as well as the 2.5-gram and 40.5-mg limitations.

Is testosterone gel subject to biosimilar approval?

No. Testosterone gel is regulated as a small-molecule drug. Generic applicants generally use the ANDA pathway rather than the biosimilar pathway.

Does an Orange Book listing prove that US 8,466,136 is valid?

No. Listing supports the FDA’s patent-notice framework. Validity, enforceability and infringement remain legal questions determined through litigation or settlement.

References

U.S. Food and Drug Administration. (2023). AndroGel 1.62% testosterone gel prescribing information.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations.
United States Patent and Trademark Office. (2013). U.S. Patent No. 8,466,136, Testosterone gel composition.
United States Patent and Trademark Office. (2024). Patent term adjustment and patent term extension resources.
U.S. Food and Drug Administration. (2024). Abbreviated new drug application and Paragraph IV certification procedures.

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	8,466,136	⤷ Start Trial	Y				⤷ Start Trial
Besins Hlthcare	ANDROGEL	testosterone	GEL;TRANSDERMAL	022309-002	Sep 7, 2012	AB2	RX	Yes	No	8,466,136	⤷ Start Trial	Y				⤷ Start Trial
Besins Hlthcare	ANDROGEL	testosterone	GEL;TRANSDERMAL	022309-003	Sep 7, 2012	AB2	RX	Yes	No	8,466,136	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2006299833	⤷ Start Trial
Brazil	PI0617294	⤷ Start Trial
Canada	2624788	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,466,136

Which drugs does patent 8,466,136 protect, and when does it expire?

Summary for Patent: 8,466,136