Details for Patent: 8,580,298

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Which drugs does patent 8,580,298 protect, and when does it expire?

Patent 8,580,298 protects QSYMIA and is included in one NDA.

This patent has forty patent family members in seventeen countries.

Summary for Patent: 8,580,298

Title:	Low dose topiramate/phentermine composition and methods of use thereof
Abstract:	A method for effecting weight loss by administering a combination of topiramate and phentermine is provided. The phentermine is generally administered in immediate release form, in a daily dose in the range of 2 mg to 8 mg, in combination with a daily dose of topiramate selected to prevent the loss of effectiveness of phentermine alone. Methods for treating obesity, conditions associated with obesity, and other indications are also provided, as are compositions and dosage forms containing low doses of phentermine and topiramate, e.g., 3.75 mg phentermine and 23 mg topiramate.
Inventor(s):	Thomas Najaraian, Peter Y. Tam, Leland F. Wilson
Assignee:	Vivus LLC
Application Number:	US12/481,540
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 8,580,298
Patent Claim Types: see list of patent claims	Composition; Formulation; Compound; Dosage form;

United States Patent 8,580,298: Claim Scope, Qsymia Patent Estate, and Generic Entry Risk

U.S. Patent No. 8,580,298 protects selected once-daily oral combinations of immediate-release phentermine and controlled-release topiramate for obesity treatment. Its strongest coverage is directed to the Qsymia-type combination, particularly the 3.75 mg/23 mg and 7.5 mg/46 mg strengths, delayed-release topiramate beads, specified plasma-release behavior, and multipart dosage forms. The patent does not broadly cover every phentermine-topiramate combination or every obesity treatment.

The claims are product and packaged-product claims, not method-of-treatment claims. A competing product would generally need to satisfy every limitation of an asserted claim, including the dose relationship, release characteristics, and, for narrower claims, the bead or coating composition.

What does U.S. Patent 8,580,298 cover?

U.S. Patent 8,580,298 covers a unit dosage form combining:

• Immediate-release phentermine;
• Controlled-release topiramate;
• Phentermine at 2 mg to 8 mg per unit dose;
• Topiramate at 15 mg to 50 mg per unit dose;
• A phentermine daily dose equal to approximately 16% of the topiramate daily dose;
• Controlled-release topiramate with a Tmax of approximately 6 to 10 hours;
• Lower topiramate Cmax than non-controlled-release topiramate;
• No reduction in total exposure measured by AUC; and
• Use for weight loss in patients with a BMI of at least 30 kg/m² and an obesity-associated condition.

The patent therefore combines pharmaceutical composition limitations with pharmacokinetic limitations. A product may avoid literal infringement if it contains the same active ingredients but fails the claimed release profile, dose ratio, dosage-form structure, or other limitation.

Core claim elements

Claim element	Scope
Therapeutic population	Patient with BMI of at least 30 kg/m² and an obesity-associated condition
Active ingredients	Phentermine and topiramate
Phentermine release	Immediate release
Topiramate release	Controlled release
Phentermine unit dose	2 mg to 8 mg
Topiramate unit dose	15 mg to 50 mg
Dose relationship	Phentermine mg/day approximately 16% of topiramate mg/day
Topiramate Tmax	Approximately 6 to 10 hours; narrower claims recite 8 to 10 hours
Cmax	Lower than non-controlled-release topiramate
AUC	No decrease in total exposure
Dosage form	Capsule, beads, or tablet with discrete segments, depending on claim
Commercial embodiments	3.75 mg/23 mg and 7.5 mg/46 mg combinations

The claims are built around the pharmacokinetic rationale for reducing concentration-dependent topiramate side effects without sacrificing efficacy.

Which claims are independent in U.S. Patent 8,580,298?

Claims 1, 21, 22, 23, 24, and 25 are independent claims based on the claim set supplied.

Claim 1: broad combination dosage form

Claim 1 is the broadest substantive dosage-form claim. It requires the active-ingredient combination, dose ranges, dose ratio, obesity-related patient limitation, and controlled-release pharmacokinetic profile.

Claim 1 does not require beads, a capsule, a tablet, or a particular excipient system. A capsule, tablet, multiparticulate system, or other oral unit dosage form could fall within claim 1 if it satisfies the functional and quantitative limitations.

Claim 21: narrower controlled-release composition

Claim 21 adds the following structural limitations to the claim 1 combination:

• Controlled-release topiramate beads;
• A matrix core;
• Topiramate, a binder, and a polymeric filler in the matrix core;
• A delayed-release coating;
• Ethyl cellulose and polyvinyl pyrrolidone in the coating.

Claim 21 is materially narrower than claim 1 because it requires a particular multiparticulate formulation architecture. It creates a more defensible infringement position against products using the claimed coating and matrix system, but it is easier to design around with a different controlled-release technology.

Claims 22 through 25: packaged pharmaceutical preparations

Claims 22 to 25 cover packaged products containing multiple dosage forms and instructions for oral administration to produce weight loss.

Claims 22 and 24 use a sealed container. Claims 23 and 25 require each dosage form to be housed in a discrete sealed housing. Claims 22 and 23 depend from claim 1, while claims 24 and 25 depend from claim 21.

These claims may be relevant to finished commercial products, blister packs, bottles, and other marketed presentations. They do not independently broaden the active pharmaceutical composition beyond the incorporated dosage-form claims.

How do claims 2 through 20 narrow the patent scope?

The dependent claims divide into formulation, dosage, pharmacokinetic, and presentation limitations.

Claims	Limitation added
2	Immediate-release phentermine on beads with inactive cores
3	Capsule containing phentermine beads and topiramate beads
4	Substantially constant topiramate blood level for about 4 to 12 hours
5	Substantially constant blood level for about 6 to 10 hours
6	Topiramate Tmax of about 8 to 10 hours
7	Topiramate matrix beads with binder, polymeric filler, ethyl cellulose, and polyvinyl pyrrolidone
8	Polymeric filler is microcrystalline cellulose
9	Binder is methylcellulose
10	Phentermine unit dose is 2 mg to 5 mg
11	Topiramate unit dose is 15 mg to 25 mg
12	Topiramate unit dose is 17 mg to 23 mg
13	Combined narrower phentermine and topiramate ranges
14	Combined ranges narrowed to 17 mg to 23 mg topiramate
15	3.75 mg phentermine and 23 mg topiramate
16	3.75 mg phentermine provided as 4.92 mg phentermine hydrochloride
17	7.5 mg phentermine and 46 mg topiramate
18	7.5 mg phentermine provided as 9.84 mg phentermine hydrochloride
19	Ethyl cellulose to polyvinyl pyrrolidone ratio of approximately 2.3:1
20	Tablet with at least two discrete segments for the two formulations

Claims 15 and 17 are commercially important because they correspond to the principal Qsymia dose strengths. The claimed ratios are mathematically consistent:

• 3.75 mg phentermine / 23 mg topiramate = approximately 16.3%;
• 7.5 mg phentermine / 46 mg topiramate = approximately 16.3%.

The hydrochloride claims address the distinction between the active phentermine amount and the salt amount used in manufacture.

What formulations are protected by U.S. Patent 8,580,298?

The patent protects several formulation configurations.

Multiparticulate capsule

The most technically specific embodiment is a capsule containing separate bead populations:

1. Immediate-release phentermine beads; and
2. Controlled-release topiramate beads.

The topiramate beads include a matrix core containing the drug, binder, and polymeric filler. The core is coated with ethyl cellulose and polyvinyl pyrrolidone. Claims 7 through 9 and 19 identify the formulation components with increasing specificity.

This structure permits phentermine to become available rapidly while delaying and smoothing topiramate exposure.

Multisegment tablet

Claim 20 covers a tablet with at least two discrete segments. One segment contains immediate-release phentermine and another contains controlled-release topiramate.

This claim is important for design-around analysis because it is directed to a tablet architecture rather than a capsule containing separate beads. A single homogeneous tablet may present a different infringement question, depending on whether it includes the claimed discrete segments and satisfies claim 1.

Functional controlled-release formulation

The claims also cover controlled-release topiramate defined by performance characteristics rather than only by ingredients. The relevant properties include:

• Tmax approximately 6 to 10 hours;
• In narrower claims, Tmax approximately 8 to 10 hours;
• Lower Cmax than non-controlled-release topiramate; and
• Maintained AUC.

A generic sponsor cannot assess risk solely by comparing excipient lists. Comparative pharmacokinetic data may be required to determine whether the product meets the claimed Cmax, Tmax, and AUC limitations.

What is the strongest claim coverage in the patent?

Claims 15 and 17 are likely the most commercially significant dosage claims because they track the two principal fixed-dose strengths:

Commercial strength	Claimed active amounts	Claimed phentermine hydrochloride amount
Low dose	3.75 mg phentermine / 23 mg topiramate	4.92 mg phentermine hydrochloride
High dose	7.5 mg phentermine / 46 mg topiramate	9.84 mg phentermine hydrochloride

Claim 1 is broader in dosage-form structure but has more functional limitations. Claim 21 is narrower structurally but may provide a more targeted claim against products using the claimed bead and coating system.

The patent’s practical strength depends on how courts construe:

• “About”;
• “Approximately”;
• “Substantially constant”;
• “Lower Cmax”;
• “Without decreasing” AUC; and
• “About 16%.”

Those terms may create infringement and validity disputes. They can support reasonable claim scope around the disclosed embodiments, but they may also invite indefiniteness, written-description, enablement, or anticipation challenges if the specification and prosecution history do not provide adequate boundaries.

When does U.S. Patent 8,580,298 lose exclusivity?

The patent issued on November 12, 2013. Public patent records identify a March 30, 2007 priority date for the underlying U.S. patent family. The nominal patent term is therefore tied to the applicable earliest nonprovisional or international filing date, not simply the issue date. The actual expiration date must account for patent-term adjustment, terminal disclaimers, and any applicable patent-term extension.

The patent’s expiration should be assessed together with the other patents listed for Qsymia in the FDA Orange Book. A generic sponsor may challenge one or more listed patents through an ANDA Paragraph IV certification rather than waiting for every patent in the estate to expire.

Patent term and regulatory exclusivity are separate:

Protection	Relevance
Patent term	Can block commercial manufacture, use, or sale of infringing products
New-drug exclusivity	Restricts certain FDA approval actions for a defined period
Orphan exclusivity	Not generally applicable to Qsymia
Pediatric exclusivity	May extend applicable listed patent or exclusivity periods if awarded
Controlled-substance regulation	Adds DEA and distribution requirements but is not patent exclusivity

FDA approved Qsymia, containing phentermine hydrochloride and extended-release topiramate, on July 17, 2012, under NDA 022580. The approval was for chronic weight management in adults with obesity or overweight adults with at least one weight-related condition, together with a reduced-calorie diet and increased physical activity (FDA, 2012).

What is the Orange Book status of Qsymia and U.S. Patent 8,580,298?

Qsymia is an FDA-approved small-molecule drug product. Its relevant Orange Book analysis concerns listed patents and ANDA certifications, not biosimilar interchangeability.

The Orange Book can list patents for:

• Drug substance;
• Drug product or formulation;
• Method of use; and
• Other patent categories recognized under FDA listing regulations.

U.S. Patent 8,580,298 is relevant to the drug product and formulation strategy because its claims cover the combined dosage form and controlled-release topiramate technology. The claims supplied do not themselves establish whether the patent is currently listed, delisted, expired, or subject to a statutory stay. That status is determined from FDA Orange Book entries, USPTO records, court dockets, and any patent-listing updates.

A business assessment should distinguish between:

1. Patent claims that technically read on a product;
2. Patents listed in the Orange Book;
3. Patents asserted in litigation; and
4. Patents that remain enforceable after prosecution and term adjustments.

These categories overlap but are not identical.

Which companies are challenging Qsymia patents?

Qsymia has faced generic competition efforts, including ANDA activity by Teva Pharmaceuticals. The principal legal mechanism is a Paragraph IV certification asserting that listed patents are invalid, unenforceable, or not infringed.

A Paragraph IV filing can trigger patent litigation under the Hatch-Waxman Act. If the NDA holder sues within the statutory period, FDA approval may be subject to a 30-month stay, subject to court action and statutory exceptions (21 U.S.C. § 355).

Public reports have described patent litigation and settlement activity involving Qsymia and generic applicants. The commercial effect of a settlement depends on:

• The agreed generic launch date;
• Whether the agreement permits an authorized generic;
• Whether the settlement covers all listed patents;
• Whether later-issued continuation patents remain enforceable;
• Whether the generic product uses a formulation outside the asserted claims; and
• Whether the generic applicant obtains approval before the agreed launch date.

A settlement does not establish that the patent claims are valid or infringed. It establishes the parties’ agreed allocation of launch and litigation risk.

What patent litigation affects U.S. Patent 8,580,298?

The relevant litigation questions are claim-specific. A generic applicant may challenge the patent on several grounds:

Infringement

A product-by-product analysis would examine:

• Phentermine and topiramate strengths;
• Immediate-release versus extended-release phentermine;
• Controlled-release topiramate technology;
• Pharmacokinetic test results;
• Capsule, tablet, or other dosage form;
• Bead construction;
• Coating composition;
• Excipient identity;
• Coating ratios; and
• Package configuration.

Anticipation and obviousness

Potential prior-art issues include:

• Earlier phentermine-topiramate combinations;
• Topiramate controlled-release formulations;
• Obesity-treatment dosage regimens;
• Multiparticulate bead systems;
• Delayed-release coatings using ethyl cellulose and polyvinyl pyrrolidone; and
• Prior pharmacokinetic data showing reduced Cmax with maintained AUC.

The inventive contribution may be assessed as a combination of known active ingredients, dose selection, release timing, and side-effect management. The central obviousness question would be whether a skilled person would have had a reason and reasonable expectation of success in combining immediate-release phentermine with controlled-release topiramate at the claimed ratio and exposure profile.

Indefiniteness

The most vulnerable language is functional and approximate language. “About 16%,” “about 6 to about 10 hours,” “lower Cmax,” and “without decreasing” AUC require a baseline and measurement methodology. The specification and prosecution history would be important in defining those boundaries.

Enablement and written description

The claims cover ranges broader than the two commercial strengths. A challenge could ask whether the specification supports and enables the full dose and formulation ranges, especially across different patients, analytical methods, bead structures, and pharmacokinetic conditions.

How does the patent estate compare with competing obesity drugs?

Qsymia is a small-molecule combination product with a formulation-centered patent profile. Its competitive products have materially different risk structures.

Product	Active ingredient(s)	Product type	Principal generic or biosimilar issue
Qsymia	Phentermine/topiramate ER	Small-molecule combination	ANDA and Paragraph IV risk
Contrave	Naltrexone/bupropion ER	Small-molecule combination	ANDA patent challenges
Wegovy	Semaglutide	Peptide biologic-like injectable	Biosimilar or follow-on competition, subject to applicable pathway
Saxenda	Liraglutide	Peptide injectable	Follow-on injectable competition
Zepbound	Tirzepatide	Peptide injectable	Later patent and regulatory exclusivity exposure
Phentermine	Phentermine	Generic small molecule	Established generic competition
Topiramate	Topiramate	Generic small molecule	Established generic competition

Qsymia’s commercial differentiation depends on the combination, dosing, and release profile. The individual active ingredients are old and widely available in generic form. The principal barrier is therefore the fixed-dose controlled-release product, not ownership of novel chemical entities.

Is biosimilar risk relevant to U.S. Patent 8,580,298?

No. Biosimilar risk is not the primary pathway for Qsymia because Qsymia is an approved small-molecule drug product, not a reference biologic. Competition would ordinarily proceed through an ANDA, including Paragraph III or Paragraph IV certifications against listed patents.

The more relevant risks are:

• Generic fixed-dose combination products;
• Separate phentermine and topiramate products prescribed together;
• Formulation design-arounds;
• Alternative dosing schedules;
• Products with different topiramate release profiles; and
• FDA approval of competing obesity therapies.

Separate generic administration may not automatically infringe the product claims, but commercial substitution, prescribing practices, and inducement theories can create separate legal issues.

What generic launch scenarios exist for Qsymia?

Three principal scenarios are commercially relevant.

Launch after patent expiry

A generic applicant accepts the listed patents and waits until the relevant patents expire. This reduces litigation exposure but delays market entry.

Paragraph IV challenge

The applicant certifies that one or more listed patents are invalid, unenforceable, or not infringed. Litigation can produce:

• Early approval after a favorable judgment;
• Delayed approval after an adverse judgment;
• A settlement with a fixed launch date; or
• Approval limited by formulation or labeling differences.

Formulation design-around

A sponsor may develop a product that avoids one or more limitations, such as:

• A different phentermine-to-topiramate ratio;
• A topiramate Tmax outside the claimed range;
• A different controlled-release polymer system;
• A non-bead matrix;
• A single-layer tablet;
• A different coating composition; or
• Separate products rather than a unitary combination.

A design-around must account for the broader claim 1 limitations, not merely the narrower bead claims.

How geographically broad is the patent protection?

U.S. Patent 8,580,298 provides rights in the United States only. Corresponding foreign applications may exist in the same international family, but foreign protection requires separate analysis of:

• National-phase filings;
• Granted claims;
• Local prosecution amendments;
• Patent-term adjustments or supplementary protection certificates;
• Maintenance fees;
• Opposition proceedings;
• Patent litigation; and
• Country-specific claim construction.

A U.S. claim directed to a dosage form does not establish protection in Canada, Europe, Japan, China, Australia, or other markets. Foreign claims may be narrower, abandoned, revoked, or subject to different expiration dates.

How strong is the patent estate for Qsymia?

The estate has practical strength where a competing product reproduces the commercial formulation and dose strengths. The strongest risk combination is likely:

1. A 3.75 mg/23 mg or 7.5 mg/46 mg product;
2. Immediate-release phentermine;
3. Controlled-release topiramate;
4. Tmax in the claimed 6-to-10-hour range;
5. Lower Cmax with maintained AUC; and
6. A bead or multiparticulate dosage form using the claimed excipients.

The estate is weaker against products that alter the release mechanism, dose ratio, dosage-form architecture, or pharmacokinetic profile. The breadth of claim 1 creates a potentially meaningful barrier, but its functional limitations may increase the burden of proving infringement and defending validity.

Manufacturing and intellectual-property barriers

The manufacturing barrier is not limited to active-ingredient supply. A competing sponsor would need to reproduce or replace:

• Controlled-release topiramate processing;
• Bead-size and coating uniformity;
• Delayed-release coating performance;
• Dose segregation;
• Content uniformity;
• Dissolution profile;
• Stability performance;
• Cmax and Tmax behavior; and
• Commercial-scale encapsulation or tableting.

These technical requirements can delay entry even when the active ingredients are generic.

What is the commercial exposure from Qsymia patent risk?

Qsymia competes in a large obesity market but has faced competition from GLP-1 and incretin-based therapies with greater weight-loss efficacy in many clinical settings. Its commercial value is linked to:

• Prescription volume;
• Net price;
• Insurance coverage;
• Patient tolerance;
• Prior authorization requirements;
• Controlled-substance distribution rules for phentermine;
• Physician familiarity; and
• The timing of generic fixed-dose entry.

Generic entry could reduce price and market share rapidly because both active ingredients are already available separately. The degree of erosion would depend on whether the generic matches the branded dosage strengths, receives substitutable approval, and enters before newer obesity products further shift prescribing patterns.

Key Takeaways

• U.S. Patent 8,580,298 is directed to phentermine/topiramate unit dosage forms for obesity treatment.
• Claim 1 combines dose ranges, an approximately 16% dose ratio, immediate-release phentermine, controlled-release topiramate, and specified pharmacokinetic behavior.
• Claim 21 is narrower and requires topiramate beads with a matrix core and an ethyl cellulose/polyvinyl pyrrolidone coating.
• Claims 15 and 17 correspond to the commercially important 3.75 mg/23 mg and 7.5 mg/46 mg strengths.
• Claims 22 through 25 cover packaged preparations and instructions.
• The principal competitive pathway is ANDA litigation and Paragraph IV certification, not biosimilar litigation.
• The strongest infringement risk applies to products reproducing Qsymia-like strengths, release characteristics, and multiparticulate formulation.
• Design-around opportunities include changing the dose ratio, release technology, coating composition, bead architecture, or pharmacokinetic profile.
• Patent expiration, Orange Book listing, litigation status, and settlement effects must be assessed across the full Qsymia patent family rather than from Patent 8,580,298 alone.

FAQs About U.S. Patent 8,580,298

Does Patent 8,580,298 cover all phentermine and topiramate combinations?

No. The claims require specific dose ranges, an approximately 16% phentermine-to-topiramate daily-dose relationship, immediate-release phentermine, and controlled-release topiramate with defined pharmacokinetic characteristics.

Does the patent cover Qsymia’s 3.75 mg/23 mg strength?

Yes. Claim 15 expressly recites 3.75 mg phentermine and 23 mg topiramate. Claim 16 addresses the corresponding 4.92 mg phentermine hydrochloride amount.

Does the patent cover separate generic phentermine and topiramate prescriptions?

The claims are directed to unit dosage forms and packaged preparations. Separate products may raise different infringement questions from a combined dosage form, although inducement and other theories require separate analysis.

Is a product with a different coating automatically outside the patent?

No. A different coating may avoid narrower claims requiring ethyl cellulose, polyvinyl pyrrolidone, or a 2.3:1 ratio, but claim 1 does not expressly require that coating. The alternative product would still need to be tested against claim 1’s broader limitations.

Can a generic launch before every Qsymia patent expires?

Potentially, through a successful Paragraph IV challenge, a settlement with an agreed launch date, or a noninfringing product design. FDA approval timing and patent litigation outcomes control the practical launch date.

References

1. U.S. Food and Drug Administration. (2012, July 17). FDA approves weight-management drug Qsymia. https://www.fda.gov
2. U.S. Patent No. 8,580,298. (2013). Pharmaceutical compositions comprising phentermine and topiramate. United States Patent and Trademark Office. https://patents.google.com
3. United States Code, 21 U.S.C. § 355. New drug application approval and patent certifications.
4. United States Code, 35 U.S.C. §§ 154, 156. Patent term and patent-term extension.
5. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugsatfda
6. U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application approvals and patent certifications. https://www.fda.gov cand-offsetof

Drugs Protected by US Patent 8,580,298

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Vivus Llc	QSYMIA	phentermine hydrochloride; topiramate	CAPSULE, EXTENDED RELEASE;ORAL	022580-001	Jul 17, 2012	AB	RX	Yes	No	8,580,298		Y
Vivus Llc	QSYMIA	phentermine hydrochloride; topiramate	CAPSULE, EXTENDED RELEASE;ORAL	022580-002	Jul 17, 2012	AB	RX	Yes	No	8,580,298		Y
Vivus Llc	QSYMIA	phentermine hydrochloride; topiramate	CAPSULE, EXTENDED RELEASE;ORAL	022580-003	Jul 17, 2012	AB	RX	Yes	No	8,580,298		Y
Vivus Llc	QSYMIA	phentermine hydrochloride; topiramate	CAPSULE, EXTENDED RELEASE;ORAL	022580-004	Jul 17, 2012	AB	RX	Yes	Yes	8,580,298		Y

International Family Members for US Patent 8,580,298

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	2317997		CA 2021 00049	Denmark
European Patent Office	2317997		CR 2021 00049	Denmark
European Patent Office	2317997		2190050-1	Sweden
European Patent Office	2317997		833	Finland
Australia	2009257572
Australia	2009257573