US Patent 7,375,111: Scope, Claims, Expiration, and Contrave Patent Landscape

US Patent 7,375,111 covers a single oral fixed-dose combination containing sustained-release bupropion and sustained-release naltrexone for weight loss. Claims 1-8 protect composition architecture, not a specific commercial brand, manufacturing process, dosing schedule, or method of treatment. The patent is historically important to Contrave, but its primary composition claims are no longer the principal barrier to generic entry because the patent reached the end of its reported US term in 2023.[1][2]

What does US Patent 7,375,111 protect?

The patent protects a pharmaceutical composition with four required characteristics:

Bupropion or a pharmaceutically acceptable salt.
Naltrexone or a pharmaceutically acceptable salt.
Sustained release for both active ingredients.
A single oral fixed-combination dosage form.

Claim 1 is the broadest independent claim. It does not impose numerical dose limits. Claims 2-4 narrow the composition by specifying naltrexone, bupropion, or both within stated dose ranges. Claims 5-8 repeat the same structure with the additional requirement of a pharmaceutically acceptable excipient, diluent, or carrier.

The claims therefore target a product category rather than a particular tablet design. A single tablet containing sustained-release bupropion hydrochloride and sustained-release naltrexone hydrochloride would fall within the literal technical scope if the other limitations were met.

Claim structure

Claim	Type	Main limitation
1	Independent composition claim	Sustained-release bupropion plus sustained-release naltrexone in a single oral fixed combination
2	Dependent	Naltrexone dose of about 5-50 mg
3	Dependent	Bupropion dose of about 30-500 mg
4	Dependent	Both dose ranges in claims 2 and 3
5	Independent pharmaceutical composition claim	Claim 1-type combination plus excipient, diluent, or carrier
6	Dependent	Naltrexone dose of about 5-50 mg
7	Dependent	Bupropion dose of about 30-500 mg
8	Dependent	Both dose ranges in claims 6 and 7

How broad are the independent claims?

Claims 1 and 5 are broad in formulation terms but narrow in dosage-form architecture.

Claim 1 does not require:

A particular bupropion salt.
A particular naltrexone salt.
A specific tablet weight.
A specific release mechanism.
A particular polymer.
A specific dissolution profile.
A particular bupropion-to-naltrexone ratio.
A branded product.
A particular indication beyond weight loss.

Claim 5 adds conventional pharmaceutical ingredients but does not materially narrow the commercial concept. Most finished pharmaceutical tablets contain an excipient, diluent, or carrier. As a result, claim 5 would generally track the same product space as claim 1.

The most important narrowing language is “sustained release formulation” for each active ingredient and “single oral fixed combination dosage form.” These limitations distinguish the claims from:

Separate immediate-release tablets.
Separate bupropion and naltrexone prescriptions.
Sequential administration of the two active ingredients.
A product containing only one sustained-release component.
A kit containing two separately packaged dosage forms.

Do Contrave tablets fall within the claimed ranges?

Yes. Contrave contains extended-release naltrexone hydrochloride and extended-release bupropion hydrochloride. The labeled strength is 8 mg of naltrexone hydrochloride and 90 mg of bupropion hydrochloride per tablet.[3]

That strength falls within the dependent-claim ranges:

Ingredient	Contrave per tablet	Claim range	Result
Naltrexone hydrochloride	8 mg	About 5-50 mg	Within range
Bupropion hydrochloride	90 mg	About 30-500 mg	Within range

The recommended maintenance dose of Contrave is two tablets twice daily, equivalent to 32 mg of naltrexone hydrochloride and 360 mg of bupropion hydrochloride per day.[3] The claims are framed around the composition and dosage form, so the relevant comparison is generally the amount in the claimed unit dosage form, not only the total daily dose.

What formulations are covered by US 7,375,111?

The claims can potentially reach several formulation configurations if both ingredients are sustained-release and the product is a single oral fixed combination.

Potentially covered configurations

A monolithic matrix tablet containing both active ingredients.
A bilayer tablet with separate release layers.
A multilayer tablet.
A tablet containing coated sustained-release particles of each ingredient.
A capsule containing sustained-release multiparticulates of both ingredients.
A tablet using different polymers for the two active ingredients.
A dosage form with separate internal compartments in one oral unit.

The claims do not expressly require the two active ingredients to have identical release kinetics. A formulation could therefore use different polymers, coatings, or release mechanisms for bupropion and naltrexone, provided both are properly characterized as sustained release.

Formulations outside the clearest literal scope

The following products present stronger non-infringement arguments:

Two separate tablets packaged together.
A fixed-dose product in which one ingredient is immediate release.
A product in which one active ingredient is present only as an unmodified immediate-release component.
A liquid formulation that is not a single fixed oral dosage form.
A transdermal, injectable, or nonoral product.
A product containing neither bupropion nor naltrexone in salt or base form covered by the claim language.

The term “single oral dosage form” is central. A prescription requiring separate naltrexone and bupropion tablets would not ordinarily satisfy that limitation, even if both medicines are taken at the same time.

What do “sustained release” and “fixed combination” require?

“Sustained release” is a functional formulation limitation. It ordinarily refers to a dosage form designed to release active ingredient over an extended period compared with immediate release. The claim does not provide a numerical dissolution threshold in the supplied text.

That omission creates both breadth and litigation risk. A patent owner would need to establish that the accused formulation meets the applicable technical meaning of sustained release. An accused manufacturer could dispute whether its release profile, coating, particle system, or dissolution behavior satisfies the limitation.

“Fixed combination” generally means that the active ingredients are combined in a single dosage unit with predetermined amounts. The term prevents the claims from reaching ordinary coadministration of two independent products.

How do the dependent dose claims affect infringement risk?

Claims 2-4 and 6-8 create explicit numerical fallbacks.

The phrase “about” gives the ranges some tolerance, but it does not eliminate the importance of the stated endpoints. A product containing 4 mg of naltrexone or 550 mg of bupropion would raise a range and claim-construction issue rather than automatically falling outside the claims.

The ranges are commercially broad:

Naltrexone: approximately 5-50 mg.
Bupropion: approximately 30-500 mg.

Contrave’s 8 mg/90 mg per-tablet strength sits well inside both ranges. A competing fixed-dose product with materially different strengths could avoid the dependent claims while still implicating claim 1 or claim 5 if it retained the same sustained-release, single-dose architecture.

When did US Patent 7,375,111 expire?

Public patent records report an adjusted US expiration date of January 31, 2023.[1][2] The patent issued on May 20, 2008, from a family claiming priority to an early-2001 filing.[1]

Event	Date
Earliest reported priority	February 1, 2001
US patent grant	May 20, 2008
Reported adjusted expiration	January 31, 2023
Current status	Expired by term, based on public patent records

The expiration of US 7,375,111 does not mean that every patent relevant to a bupropion/naltrexone product expired on the same date. Later-issued continuation, formulation, dosing, or method-of-use patents may have different expiration dates.

What was the Orange Book status of the patent?

US 7,375,111 was listed in connection with Contrave, the FDA-approved extended-release naltrexone/bupropion product marketed in the United States.[2][3] Orange Book listing is significant because it can support a Paragraph IV patent certification dispute when an ANDA applicant seeks approval before listed patent expiration.

The listing did not convert the patent into a general monopoly over:

Bupropion.
Naltrexone.
Weight-loss treatment as a therapeutic field.
Any combination of the two drugs.
All sustained-release products indefinitely.

The listing related to the approved product and the patent claims identified in the FDA listing. Patent scope remained governed by the issued claims and applicable infringement law.

Which later patents formed the Contrave patent estate?

The commercial patent estate for Contrave extended beyond US 7,375,111. Later family members and related patents addressed additional aspects of the product, including dosing, treatment methods, and formulation characteristics. Publicly identified Contrave-related patents include US 8,628,669, US 8,895,568, US 9,266,951, and US 9,669,089, among others.[2][4]

The relevant distinction is:

Patent category	Typical protection
Composition patent	Bupropion/naltrexone combination and dosage form
Formulation patent	Release profile, excipients, layers, coatings, or multiparticulates
Method-of-use patent	Treating obesity or reducing weight using the combination
Dosing patent	Titration schedule, maintenance dose, or administration regimen
Manufacturing patent	Granulation, coating, blending, compression, or scale-up process

US 7,375,111 is principally a composition patent. It should not be treated as a complete summary of the later Contrave estate.

What Paragraph IV risks applied to generic Contrave applicants?

A generic applicant seeking approval before expiration of listed patents could file a Paragraph IV certification alleging that the patents were invalid, unenforceable, or not infringed. The applicant would then notify the NDA holder and patent owner, potentially triggering patent litigation under the Hatch-Waxman framework.[5]

For US 7,375,111, the principal Paragraph IV positions would have included:

The proposed product is not a single fixed oral dosage form.
One or both components are not sustained release.
The product falls outside the claimed dose ranges.
The claims are anticipated or obvious.
The claims lack adequate written description or enablement.
The patent term has expired.
The proposed label does not induce infringement of a method claim, where method patents are asserted.

Once the patent expired in 2023, it could no longer block approval or commercial launch based on ordinary patent-term rights. Later Orange Book-listed patents remained commercially relevant only to the extent that they covered the proposed generic product or its labeled use.

How strong is the patent estate for a generic entrant?

The expired composition patent had strong historical product coverage because Contrave’s commercial tablet matched the claimed architecture and dose ranges. Its present blocking value is zero after expiration.

The broader estate can be analyzed as follows:

Risk area	Assessment
Core composition claim	Low current risk after expiration of US 7,375,111
Dose-range claims	Low for this patent after expiration
Sustained-release formulation	Potential risk only under later unexpired claims
Method of treating obesity	Depends on listed method claims and product labeling
Titration regimen	Depends on later dosing patents
Manufacturing process	Depends on separate process patents and actual manufacturing steps
Biosimilar risk	Not applicable in the conventional sense
Generic substitution	Relevant because Contrave is a small-molecule product

Contrave is a small-molecule combination product. Biosimilar pathways do not apply. A competing manufacturer would generally use the ANDA pathway, subject to bioequivalence, labeling, patent certification, and exclusivity requirements.

What manufacturing and intellectual-property barriers remain?

The expired patent does not remove technical barriers to developing a generic product. A manufacturer still must reproduce a stable, bioequivalent fixed-dose extended-release product.

Important technical challenges include:

Maintaining separate release behavior for bupropion and naltrexone.
Controlling dose uniformity at relatively low naltrexone loading.
Preventing interaction between the two active ingredients.
Matching dissolution profiles.
Demonstrating bioequivalence under FDA requirements.
Managing food effects and pharmacokinetic variability.
Scaling coating, granulation, compression, or multiparticulate processes.
Avoiding active or unexpired formulation claims.

A noninfringing product may use different excipients, release polymers, tablet architecture, or manufacturing steps. Those changes can reduce patent risk but may create bioequivalence and regulatory-development risk.

What licensing deals affected the commercial patent position?

Orexigen Therapeutics developed and commercialized Contrave before the product and related rights were transferred or acquired by Currax Pharmaceuticals. Currax acquired the Contrave business and associated rights from Orexigen in 2018.[6]

This transaction matters because patent ownership, Orange Book rights, litigation authority, and settlement rights can move with the NDA and related intellectual property. The commercial owner of the product is not necessarily the original inventor or original patent applicant.

What is the competitive landscape for bupropion/naltrexone weight loss?

Contrave competes with branded and generic therapies in the obesity market, including:

Semaglutide products such as Wegovy.
Tirzepatide products such as Zepbound.
Phentermine/topiramate extended-release.
Liraglutide.
Orlistat.
Generic bupropion and generic naltrexone prescribed separately.

The fixed-dose combination’s commercial differentiation is oral administration and a dual-mechanism approach. Its competitive limitations include lower market visibility than newer incretin therapies and the absence of biologic-style exclusivity protection.

Key Takeaways

US 7,375,111 covers a single oral fixed-dose sustained-release combination of bupropion and naltrexone.
Claims 1 and 5 are the principal independent composition claims.
Claims 2-4 and 6-8 add broad dose ranges of about 5-50 mg naltrexone and 30-500 mg bupropion.
Contrave’s 8 mg/90 mg per-tablet strength falls within the stated dependent-claim ranges.
The patent does not cover separate tablets merely taken together.
It does not require a specific polymer, release profile, tablet design, or manufacturing process.
Public records report an adjusted expiration date of January 31, 2023.
The patent’s current blocking value is therefore exhausted by patent term.
Later Contrave patents may have addressed formulation, dosing, treatment methods, and related product features.
Generic risk analysis must separate the expired core composition patent from any later unexpired Orange Book-listed patents.

FAQs

Does US 7,375,111 cover Contrave?

Yes. Contrave’s single oral tablet contains sustained-release naltrexone hydrochloride and sustained-release bupropion hydrochloride in amounts within the patent’s stated dependent-claim ranges.

Does the patent cover taking Wellbutrin and naltrexone together?

Not necessarily. Separate bupropion and naltrexone products generally do not satisfy the “single oral fixed combination dosage form” limitation.

Is US 7,375,111 still enforceable?

Public patent records report that the patent expired on January 31, 2023. It therefore does not provide current term-based exclusion after that date.[1][2]

Does this patent cover generic bupropion or generic naltrexone individually?

No. The claims require both active ingredients in the same fixed oral dosage form.

Are biosimilars relevant to Contrave?

No. Contrave is a small-molecule combination product. Competition would generally involve generic drug approval under the ANDA pathway, not biosimilar approval under the Biologics Price Competition and Innovation Act.

References

United States Patent and Trademark Office. (2008). U.S. Patent No. 7,375,111, compositions and methods for treating obesity.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (2023). Contrave (naltrexone hydrochloride and bupropion hydrochloride) extended-release tablets: Prescribing information.
Google Patents. (2024). U.S. patents related to naltrexone and bupropion weight-loss compositions and methods.
U.S. Food and Drug Administration. (2015). Abbreviated new drug application submissions: Patent certification and exclusivity provisions.
Currax Pharmaceuticals. (2018). Currax Pharmaceuticals acquires Contrave from Orexigen Therapeutics.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	2316456	⤷ Start Trial	CA 2017 00062	Denmark	⤷ Start Trial
European Patent Office	2316456	⤷ Start Trial	300918	Netherlands	⤷ Start Trial
European Patent Office	2316456	⤷ Start Trial	122017000109	Germany	⤷ Start Trial
European Patent Office	2316456	⤷ Start Trial	LUC00054	Luxembourg	⤷ Start Trial
European Patent Office	2316456	⤷ Start Trial	2017C/064	Belgium	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 7,375,111

Summary for Patent: 7,375,111