RIOMET ER Drug Patent Profile

When do Riomet Er patents expire, and what generic alternatives are available?

Riomet Er is a drug marketed by Sun Pharm and is included in one NDA. There is one patent protecting this drug.

This drug has twenty-nine patent family members in eight countries.

The generic ingredient in RIOMET ER is metformin hydrochloride. There are forty-nine drug master file entries for this compound. Eighty-one suppliers are listed for this compound. Additional details are available on the metformin hydrochloride profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Riomet Er

A generic version of RIOMET ER was approved as metformin hydrochloride by CHARTWELL on January 24^th, 2002.

Summary for RIOMET ER

International Patents:	29
US Patents:	1
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	164
Clinical Trials:	41
Patent Applications:	38
DailyMed Link:	RIOMET ER at DailyMed

Recent Clinical Trials for RIOMET ER

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)	Early Phase 1
Washington State University	Early Phase 1
National Institutes of Health (NIH)	Early Phase 1

See all RIOMET ER clinical trials

US Patents and Regulatory Information for RIOMET ER

RIOMET ER is protected by one US patents.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Sun Pharm	RIOMET ER	metformin hydrochloride	FOR SUSPENSION, EXTENDED RELEASE;ORAL	212595-001	Aug 29, 2019		DISCN	Yes	No			Y

International Patents for RIOMET ER

See the table below for patents covering RIOMET ER around the world.

Country	Patent Number	Title	Estimated Expiration
Australia	2015254875
Australia	2015294912
Australia	2017254908
Australia	2018250470
Brazil	112017001968
Canada	2947528
Canada	2956902

Supplementary Protection Certificates for RIOMET ER

Patent Number	Supplementary Protection Certificate	SPC Country	SPC Expiration	SPC Description
0861666	07C0006	France		PRODUCT NAME: PIOGLITAZONE/METFORMINE ET LEURS SELS PHARMACEUTIQUEMENT ACCEPTABLES; REGISTRATION NO/DATE IN FRANCE: EU/1/06/354/001 DU 20060728; REGISTRATION NO/DATE AT EEC: EU/1/06/354/001 DU 20060728
1412357	CA 2008 00035	Denmark		PRODUCT NAME: SITAGLIPTIN VALGFRIT I FORM AF ET FARMACEUTISK ACCEPTABELT SALT, ISAER MONOPHOSPHAT, METFORMIN VALGFRIT I FORM AF ET FARMACEUTISK ACCEPTABELT SALT, ISAER HYDROCHLORID
1412357	PA2008013	Lithuania		PRODUCT NAME: SITAGLIPTINUM PHOSPHAS MONOHYDRICUS, METFORMINI HYDROCHLORIDUM; REG. NO/DATE: EU/1/08/455/001-014 20080716
1412357	PA2008013,C1412357	Lithuania		PRODUCT NAME: SITAGLIPTINUM PHOSPHAS MONOHYDRICUS, METFORMINI HYDROCHLORIDUM; REGISTRATION NO/DATE: EU/1/08/455/001 - EU/1/08/455/014 20080716
1412357	77 5006-2008	Slovakia		PRODUCT NAME: SITAGLIPTIN A METFORMIN; NAT. REG.NO/DATE: EU/1/08/455/001-014, EU/1/08/456/001-014, EU/1/08/457/001-014 20080716; FIRST REG.:CH 58450 01-03 20080408
1412357	SPC/GB08/040	United Kingdom		PRODUCT NAME: SITAGLIPTIN OPTIONALLY IN THE FORM OF A PHARMACEUTICALLY ACCEPTABLE SALT, IN PARTICULAR THE MONOPHOSPHATE, PLUS METFORMIN OPTIONALLY IN THE FORM OF A PHARMACEUTICALLY ACCEPTABLE SALT, IN PARTICULAR THE HYDROCHLORIDE.; REGISTERED: CH 58450 01-03 20080408; UK EU/1/08/455/001 20080716; UK EU/1/08/455/002 20080716; UK EU/1/08/455/003 20080716; UK EU/1/08/455/004 20080716; UK EU/1/08/455/005 20080716; UK EU/1/08/455/006 20080716; UK EU/1/08/455/007 20080716; UK EU/1/08/455/008 20080716; UK EU/1/08/455/009 20080716; UK EU/1/08/455/010 20080716; UK EU/1/08/455/011 20080716; UK EU/1/08/455/012 20080716; UK EU/1/08/455/013 20080716; UK EU/1/08/455/014 20080716
1412357	C300357	Netherlands		PRODUCT NAME: SITAGLIPTINE, DESGEWENST IN DE VORM VAN EEN FARMACEUTISCH AANVA ARDBAAR ZOUT, IN HET BIJZONDER HET MONOFOSFAAT, EN METFORMINE DESGEWENST IN DE VORM VAN EEN FARMACEUTISCH AANVAARDBAAR ZOUT, IN HET BIJZONDER HET HYDROCHLORIDE; REGISTRATION NO/DATE: EU/1/08/455/001-014 20080716

RIOMET ER (metformin hydrochloride extended-release): market dynamics and financial trajectory

Last updated: June 22, 2026

RIOMET ER is a branded extended-release metformin product positioned in the large U.S. diabetes market dominated by generic metformin. Financial trajectory is constrained by (i) deep generic penetration of metformin ER tablets, (ii) limited remaining patent and exclusivity leverage typical of long-circulating metformin incumbents, and (iii) payer-driven price erosion for oral antidiabetics. Commercial performance therefore tracks broadly with managed-care formularies, gross-to-net pressure, and unit volume rather than brand differentiation.

What is RIOMET ER and who markets it in the U.S.?

RIOMET ER is an extended-release oral formulation of metformin hydrochloride for type 2 diabetes. Like other metformin ER products, it competes in the same pharmacologic class where interchangeability with generic metformin ER tablets drives pricing pressure.

Key commercial context

• Therapeutic class: oral biguanide for type 2 diabetes
• Formulation type: extended-release metformin hydrochloride
• Competitive set: generic metformin ER tablets and authorized generics; branded alternatives if any in-market at the time; patient-specific selection based on dosing convenience and payer coverage

How big is the addressable market for RIOMET ER in type 2 diabetes?

The addressable market is the U.S. oral antidiabetic class led by metformin, where most new prescriptions and many ongoing refills are metformin-based. Extended-release metformin is a dominant subsegment because it supports once-daily or twice-daily regimens and is commonly used after tolerability issues with immediate-release dosing.

Market dynamic that matters for RIOMET ER

• In metformin, brand life is typically driven less by differentiated efficacy and more by formulary access and net price after rebates and discounts.
• The segment is structurally exposed to rapid generics and formulary substitution, which compresses launch-to-peak trajectories even when brands enter at meaningful volumes.

What drives demand for metformin ER products like RIOMET ER?

Demand is mostly mechanical, tied to type 2 diabetes prevalence, prescribing patterns, and payer preferences for low-cost metformin.

Primary demand drivers

• Formulary placement (preferred vs non-preferred)
• Net pricing and rebates affecting PBM incentives
• Adherence influenced by dose schedule and tolerability
• Step therapy policies requiring coverage of specific metformin formulations
• Interchangeability with generic equivalents reducing willingness to pay for branded SKUs

What do financial trajectories for metformin ER brands typically look like?

For branded metformin ER products, the common financial shape is:

• Early growth after formulary establishment or substitution lag
• Mid-term plateau once generics dominate
• Sustained gross-to-net pressure as payers use competitive bidding and therapeutic substitution

Implication for RIOMET ER

• Financial results are likely to depend on how well RIOMET ER maintains:
  • net price,
  • formulary coverage,
  • and persistence against generic metformin ER.

How does payer economics shape RIOMET ER gross-to-net and margin?

In oral diabetes, payers and PBMs compress net revenue through rebates and formulary mechanisms.

Margin pressure mechanisms

• Therapeutic class rebates that scale with market share
• Laddering and plan switches that move patients from non-preferred to preferred generics
• Price resets during pharmacy benefit re-contracting cycles

Financial outcome

• Net sales can remain stable for a time even as list price erodes, but operating margin typically declines if sales don’t grow faster than gross-to-net ratios.

What is the generic competition and how does it impact RIOMET ER unit share?

Metformin ER faces intense generic competition. Even when branded products retain some market segment, they usually compete against:

• multi-source generic metformin ER tablets,
• combination metformin products that can shift prescribing away from standalone ER formulations.

Competitive impact

• Brands often lose share when a plan design favors lowest-cost generics.
• Any differentiation in patient convenience can help, but typically not enough to overcome payer-driven substitution.

Which markets and formulary systems decide RIOMET ER uptake?

Commercial uptake is concentrated in plans with:

• broad generic coverage,
• structured preferred drug lists for oral diabetes.

Tactical commercial implication

• Brand performance is most sensitive to PBM formulary decisions and pharmacy channel incentives.
• Hospital or specialty centers matter less because metformin is largely outpatient chronic therapy.

When does RIOMET ER lose exclusivity or face generic launch risk?

For metformin ER brands with long market history, generic entry risk is usually already realized or becomes accelerated via:

• patent expiry,
• settlement agreements,
• ANDA approvals for generic versions,
• and Orange Book expirations triggering easy design-around paths.

Financial consequence

• Once multiple generics are on market, branded RIOMET ER typically experiences ongoing price and volume pressure, and revenue growth slows or reverses absent niche positioning.

What patents protect RIOMET ER and what is the patent estate strength?

This analysis requires Orange Book and patent listing details for RIOMET ER (application numbers, listed patents, expiration dates, and remaining exclusivity). Without those specific listings, it is not possible to state the patent estate, geographic scope, or remaining term with accuracy.

What is the Orange Book status of RIOMET ER?

This analysis requires RIOMET ER’s FDA Orange Book entry, including:

• NDA number,
• listed patent numbers,
• regulatory exclusivities (if any),
• and expiration dates tied to each listed patent.

Are there Paragraph IV challenges or ANDA litigation impacting RIOMET ER?

This requires confirmation of:

• ANDA applicants,
• Paragraph IV notices,
• district court filings or Federal Circuit records,
• and any settlement terms.

How does RIOMET ER compare with other metformin ER products commercially?

A useful comparison framework is:

• net price trajectory,
• time on formulary,
• share vs preferred generic SKUs,
• and dosing availability.

But without RIOMET ER’s specific competitive set and internal company financial disclosures, it is not possible to produce a precise side-by-side financial comparison.

What FDA status and regulatory milestones shape RIOMET ER commercialization?

For an already marketed extended-release metformin product, the key regulatory milestones are largely in the past. Current performance is typically shaped by:

• current label scope,
• any manufacturing changes affecting supply,
• and whether the product remains the same approved formulation.

A precise FDA status summary requires direct data from FDA and labeling records tied to RIOMET ER.

What manufacturing/IP barriers affect generic substitution for RIOMET ER?

Metformin ER’s substitution barriers are usually limited because:

• extended-release tablets and similar oral dosage forms are established technology,
• and generic manufacturers can design around formulation specifics if patents have expired.

Whether RIOMET ER has formulation-specific restrictions depends on the listed patents for RIOMET ER, which must be verified from the Orange Book and associated patent documents.

How strong is the settlement and licensing posture for RIOMET ER?

Settlement and licensing posture depends on:

• ANDA Paragraph IV settlements,
• co-marketing or authorized generic arrangements,
• and any brand protection strategy tied to exclusivity.

No settlement facts can be stated without sourced litigation and agreement records for RIOMET ER.

What generic entry risks exist for RIOMET ER in the next 24–48 months?

For metformin ER, next-interval risks are usually not about “new” generic entry but about:

• further erosion of net price via intensified competition,
• additional generic entrants in sub-conditions (dose strengths, package types, or labeling carve-outs),
• and payer renegotiation effects.

A concrete 24–48 month risk view requires RIOMET ER’s remaining patent and exclusivity calendar.

Key data required for a complete financial trajectory model

A full financial trajectory for RIOMET ER should be modeled using:

• annual U.S. net sales and prescription counts,
• gross-to-net ratio trends by year,
• formulary access metrics (preferred/non-preferred),
• and market share vs generic metformin ER.

Those data points are not provided here, and RIOMET ER-specific financials cannot be asserted without access to the underlying sources.

Key Takeaways

• RIOMET ER sits in a structurally price-pressured metformin ER segment where generic substitution and payer rebates dominate financial outcomes.
• The most material determinants of RIOMET ER revenue are formulary placement and gross-to-net compression, not product-level differentiation.
• A defensible, date-anchored exclusivity, litigation, and patent-risk view requires RIOMET ER’s FDA Orange Book listings and related patent entries, which are not included in the provided information.

FAQs

1. What PBM formulary dynamics typically determine net sales for metformin ER brands like RIOMET ER?
2. How do gross-to-net rebates in oral diabetes usually evolve after multiple generic metformin ER entrants?
3. What does a typical metformin ER brand share trajectory look like after patent expiry?
4. How does dosing convenience for extended-release metformin influence persistence versus tablet generics?
5. What Orange Book data fields should be checked to build a litigation and exclusivity calendar for RIOMET ER?

References

1. FDA Orange Book. U.S. Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book). (Accessed via FDA database).