US Patent 9,173,859: Linagliptin-Metformin Claim Scope, Expiration, Litigation and Generic Entry Risk
US Patent 9,173,859 covers methods of treating type 2 diabetes with linagliptin and metformin, including fixed-dose tablets and capsules. Its commercial relevance is concentrated in Jentadueto and Jentadueto XR, which combine linagliptin with immediate-release or extended-release metformin. The strongest claim set targets the combination regimen, particularly linagliptin 5 mg once daily with metformin. Claim 14 is broader and covers an oral tablet containing 2.5 mg or 5 mg of linagliptin, with metformin included optionally.
The patent does not cover linagliptin as a chemical entity. It is a combination, dosage, formulation and method-of-treatment patent.
What drug does US Patent 9,173,859 protect?
The compound identified in the claims is linagliptin, a DPP-4 inhibitor marketed by Boehringer Ingelheim under the Tradjenta brand and in combination with metformin under the Jentadueto brands.
| Patent subject |
Covered by US 9,173,859? |
| Linagliptin chemical structure itself |
No |
| Linagliptin treatment of type 2 diabetes with no metformin |
Limited, primarily claim 14 formulation language |
| Linagliptin plus metformin therapy |
Yes |
| Fixed-dose linagliptin-metformin combination |
Yes |
| Immediate-release metformin combinations |
Yes |
| Extended-release or delayed-release metformin combinations |
Yes |
| Oral tablets |
Yes |
| Capsules |
Yes under claim 3 |
| Injectable products |
No |
| Other DPP-4 inhibitors |
No |
| Diabetes indications other than type 2 diabetes |
Not expressly claimed |
The claims use the chemical name for linagliptin rather than the International Nonproprietary Name. The structural limitation is specific to linagliptin and does not extend to sitagliptin, saxagliptin, alogliptin, vildagliptin or other DPP-4 inhibitors.
How many claims does US 9,173,859 have?
The patent has 22 claims. The claim architecture contains four principal coverage groups.
| Claim group |
Claims |
Main subject |
| Combination treatment |
1-13 |
Linagliptin plus metformin for type 2 diabetes |
| Fixed-dose oral products |
2-7, 9-12 |
Tablets or capsules containing both agents |
| Oral tablet formulation |
14-15 |
Linagliptin tablet, optionally with metformin |
| Narrow dosing regimens |
16-22 |
Specific 5 mg, 2.5 mg, once-daily or twice-daily regimens |
Claims 1, 13 and 16-18 are independent method claims. Claim 14 is an independent formulation claim.
What are the broadest claims in US Patent 9,173,859?
Claim 1 is the principal combination-treatment claim. It requires:
- A patient with type 2 diabetes;
- Oral administration of linagliptin at 2.5 mg or 5 mg; and
- Administration of metformin within one of several specified dose ranges.
The claim does not require a single tablet. Separate administration of linagliptin and metformin can fall within the claim if the dosing conditions are met. Claim 2 narrows the method to a fixed combination.
Claim 14 is the principal formulation claim. It covers:
- An oral tablet;
- Linagliptin in an amount of 2.5 mg or 5 mg;
- A pharmaceutically acceptable carrier or diluent; and
- Optional metformin.
The phrase "optionally in combination with metformin" creates a materially broader formulation claim than claims 1-13. On its face, claim 14 can reach a linagliptin-only tablet, provided the product contains the claimed linagliptin amount and pharmaceutical excipients. Claim 15 narrows the product to 500 mg to 1000 mg of metformin.
Which marketed products are most directly exposed?
Jentadueto and Jentadueto XR are the products most directly aligned with the patent claims.
| Product |
Active ingredients |
Relevant claim exposure |
| Tradjenta |
Linagliptin |
Potential exposure under claim 14, depending on product presentation and claim construction |
| Jentadueto |
Linagliptin plus immediate-release metformin |
Claims 1-15 and 16-22 |
| Jentadueto XR |
Linagliptin plus extended-release metformin |
Claims expressly addressing delayed-release metformin, including claims 1, 7, 8 and 16-18 |
| Generic linagliptin alone |
Linagliptin |
Claim 14 may be relevant |
| Generic linagliptin-metformin fixed combination |
Linagliptin plus metformin |
Broadest infringement exposure |
The principal commercial regimen is linagliptin 5 mg once daily with metformin. That regimen is expressly covered by claims 16-20 and 22, subject to the metformin dose and fixed-combination limitations in each claim.
What formulations are protected by US 9,173,859?
The formulation claims cover oral solid dosage forms rather than a particular excipient system, manufacturing process or release mechanism.
Fixed-dose tablet and capsule claims
Claims 2 and 3 cover a fixed combination administered as a tablet or capsule. Claim 4 limits the product to a tablet. Claims 5 and 6 specify the linagliptin strength:
Claims 7-12 specify metformin quantities ranging from 100 mg to 1000 mg in particular administration schedules. Claim 8 also addresses total daily metformin exposure up to 2850 mg and delayed-release strengths of 500 mg, 1000 mg, 1500 mg and 2000 mg.
Extended-release metformin
The claims use "delayed-release" language rather than limiting the invention to one named extended-release technology. This creates potential coverage for several controlled-release metformin designs if the product also satisfies the linagliptin strength and dosing requirements.
The patent does not, based on the supplied claims, require:
- A specific polymer;
- A particular dissolution profile;
- A defined tablet layer structure;
- A particular granulation process;
- A specific particle size;
- A particular salt of metformin; or
- A named excipient.
That makes the product claims potentially relevant to design-arounds that change the excipient system but retain the claimed active ingredients, strengths and dosage form.
What method-of-use claims are protected?
The method claims require treatment of type 2 diabetes. They do not expressly recite:
- A particular baseline HbA1c;
- Failure of metformin monotherapy;
- A patient subgroup;
- Renal impairment;
- Cardiovascular disease;
- A specific treatment duration;
- A reduction in hypoglycemia; or
- A particular sequencing of the two drugs.
The claims are therefore regimen-driven rather than biomarker-driven. A generic applicant using the same active ingredients, strengths and fixed-dose presentation would face a direct infringement theory based on the product label and intended use.
Claims 13 and 21 are especially narrow. They require linagliptin 2.5 mg administered twice daily with metformin in an amount of 500 mg to 1000 mg. Claims 19, 20 and 22 focus on 5 mg daily administration. These claims provide fallback positions if broader claims are invalidated or narrowed.
When does US Patent 9,173,859 lose exclusivity?
The patent issued on November 3, 2015. Its term is governed by the 20-year term rules under 35 U.S.C. §154, measured from the relevant nonprovisional or international filing date, subject to patent-term adjustment, patent-term extension and terminal disclaimers.
The patent family is generally associated with combination protection for linagliptin and metformin extending into the late 2020s. The expected unadjusted term is approximately 2027, but the controlling expiration date must be taken from the USPTO patent record and any FDA Orange Book listing because continuation practice, terminal disclaimers and patent-term adjustment can change the operative date.
The base linagliptin compound patent and the combination patent should be analyzed separately. Expiration of a chemical-entity patent does not automatically eliminate later method, formulation or combination claims.
| Exclusivity layer |
Commercial relevance |
| Linagliptin compound patent |
Protects the active pharmaceutical ingredient |
| Linagliptin formulation patents |
May restrict particular tablet compositions or solid forms |
| Linagliptin-metformin combination patent |
Targets Jentadueto and Jentadueto XR |
| FDA regulatory exclusivity |
Separate from patent protection |
| Pediatric exclusivity, if awarded |
Could add six months to eligible patents |
What is the Orange Book status of US 9,173,859?
Jentadueto and related linagliptin products are FDA-approved prescription drugs. The FDA Orange Book is the controlling source for current patent listings, use codes, expiration dates and any withdrawn or delisted patents.[2]
For an abbreviated new drug application, an applicant must address each listed patent through one of four certifications:
- Paragraph I: no patent information is listed;
- Paragraph II: the patent has expired;
- Paragraph III: the applicant will wait until patent expiration;
- Paragraph IV: the patent is invalid, unenforceable or will not be infringed.
A Paragraph IV certification against US 9,173,859 would create litigation risk if the patent is listed for the relevant Jentadueto product and the proposed generic falls within the listed use or product scope. Under the Hatch-Waxman framework, timely patent litigation can trigger a 30-month stay of FDA approval, subject to statutory exceptions.[3]
The patent's practical significance depends on the current Orange Book listing, the listed drug reference product, the use code and whether the generic applicant seeks approval for all labeled strengths or uses.
What Paragraph IV challenges and litigation risks exist?
The highest-risk target would be a generic fixed-dose linagliptin-metformin product that reproduces:
- Linagliptin 5 mg;
- Metformin 500 mg, 850 mg or 1000 mg;
- Oral tablet dosage form;
- Once-daily administration;
- Type 2 diabetes labeling; and
- Immediate-release or extended-release metformin, depending on the reference product.
A generic linagliptin-only product presents a different issue. Claims 1-13 and 16-22 require metformin, so they would not read on a linagliptin-only product. Claim 14 is the principal potential obstacle because it covers an oral tablet containing 2.5 mg or 5 mg of linagliptin, optionally with metformin.
Potential Paragraph IV defenses would likely focus on:
- Claim construction of "optionally in combination with metformin";
- Written-description and enablement support for the full range of claimed metformin doses;
- Obviousness of combining linagliptin with the long-established diabetes therapy metformin;
- Anticipation by earlier linagliptin or linagliptin-metformin disclosures;
- Lack of infringement based on dosing instructions or product formulation; and
- Terminal-disclaimer or patent-term issues.
A generic applicant could also pursue a section viii statement for an unpatented use if the FDA-approved labeling allows a legally effective carve-out. That strategy is less useful where the claims cover the core combination product rather than a distinct secondary indication.
How strong is the patent estate?
The estate is strongest against a product that copies the commercial fixed-dose combination and weakest against a product that changes the active ingredients, excludes metformin or avoids the claimed dosage form.
| Risk category |
Assessment |
| Fixed-dose linagliptin-metformin tablet |
High |
| Jentadueto-like 5 mg/500 mg tablet |
High |
| Jentadueto-like 5 mg/850 mg or 5 mg/1000 mg tablet |
High |
| Extended-release metformin combination |
High to moderate, depending on release design and listing |
| Linagliptin-only tablet |
Moderate, principally due to claim 14 |
| Separate co-packaged products |
Moderate to high under method claims |
| Nonoral formulation |
Low under supplied claims |
| Different DPP-4 inhibitor |
None under these claims |
| Metformin-only product |
None |
The patent has substantial claim redundancy. Claims 13-22 provide narrower dosing and administration positions. That redundancy improves litigation flexibility but does not eliminate validity risk. The broadest formulation language in claim 14 may attract the most serious written-description, enablement and obviousness challenges.
What manufacturing and intellectual-property barriers remain?
A generic manufacturer must address more than the active ingredients. It must assess:
- Linagliptin polymorph and salt selection;
- Particle size and flow properties;
- Low-dose content uniformity for 2.5 mg and 5 mg tablets;
- Compatibility between linagliptin and metformin;
- Immediate-release versus extended-release metformin;
- Tablet compression and coating;
- Dissolution and bioequivalence;
- Stability of the fixed combination;
- Manufacturing-site qualification; and
- Patent claims covering crystal forms, processes or excipient systems outside US 9,173,859.
The patent itself does not claim a specific manufacturing process in the supplied claims. Process and solid-form patents may create separate freedom-to-operate barriers.
How does US 9,173,859 compare with the broader linagliptin patent estate?
US 9,173,859 is narrower than a compound patent because it depends on a specific combination and therapeutic use. It is broader than a conventional formulation patent because several claims cover the treatment regimen without requiring a particular excipient or manufacturing method.
| Patent type |
Scope |
Typical challenge |
| Compound patent |
Linagliptin molecule and salts |
Invalidity, term expiration |
| Combination patent |
Linagliptin plus metformin |
Obviousness, anticipation, noninfringement |
| Formulation patent |
Tablet composition or release profile |
Design-around, claim construction |
| Method patent |
Diabetes treatment regimen |
Label carve-out, noninfringement |
| Process patent |
Manufacture of linagliptin or tablets |
Process modification |
Biosimilar risk is not relevant. Linagliptin and metformin are small molecules regulated through the ANDA pathway, not biologics regulated under the biosimilar provisions of the Public Health Service Act.[4]
What is the commercial exposure?
The commercial exposure centers on Boehringer Ingelheim's linagliptin franchise:
- Tradjenta for linagliptin monotherapy;
- Jentadueto for linagliptin plus immediate-release metformin; and
- Jentadueto XR for linagliptin plus extended-release metformin.
The combination patent is more commercially important for Jentadueto products than for Tradjenta. A successful generic fixed-dose combination could pressure branded volume and pricing even if separate linagliptin and metformin products remain subject to different patent positions.
Key Takeaways
- US 9,173,859 is a linagliptin-metformin combination, dosing and formulation patent.
- Claims 1-13 and 16-22 primarily target treatment with both agents.
- Claims 2-15 target fixed-dose oral products, especially tablets.
- Claim 14 is unusually important because it covers a linagliptin tablet with metformin included optionally.
- The core commercial regimen, linagliptin 5 mg once daily with metformin, is expressly covered by multiple claims.
- Jentadueto and Jentadueto XR are the principal branded products exposed to the patent.
- The patent is expected to remain relevant into the late 2020s, subject to the controlling USPTO and Orange Book expiration data.
- Paragraph IV challenges would likely focus on obviousness, anticipation, claim construction, written description and noninfringement.
- Biosimilar analysis is inapplicable because the products are small-molecule drugs.
- Separate solid-form, process and formulation patents may create additional entry barriers beyond US 9,173,859.
FAQs
Does US 9,173,859 cover Tradjenta alone?
Potentially, under claim 14, which recites an oral tablet containing 2.5 mg or 5 mg of linagliptin, optionally in combination with metformin. The combination-treatment claims require metformin.
Does the patent cover a generic that sells linagliptin and metformin separately?
The answer may be yes under the method claims if the product labeling directs the claimed combination and dosing regimen. A fixed-dose tablet is not required by claim 1.
Is linagliptin 5 mg once daily specifically claimed?
Yes. Claims 16-20 and 22 recite or depend on a 5 mg daily linagliptin regimen, with additional metformin and fixed-combination limitations in several claims.
Can a generic avoid the patent by using a different tablet coating?
Not necessarily. The supplied claims do not require a particular coating or excipient system. A coating change alone would not avoid claims that are satisfied by the active ingredients, dosage, dosage form and treatment regimen.
Does expiration of the linagliptin compound patent eliminate US 9,173,859?
No. Chemical-entity, combination, formulation and method-of-use patents are legally distinct. The combination patent remains relevant until its own enforceable term ends or the claims are invalidated or held unenforceable.
References
- United States Patent and Trademark Office. (2015). U.S. Patent No. 9,173,859, pharmaceutical composition comprising linagliptin and metformin.
- U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
- 35 U.S.C. § 355(j). Abbreviated applications for new drugs.
- U.S. Food and Drug Administration. (n.d.). Biosimilar and interchangeable biosimilar products.
