List of Excipients in Branded Drug GLUMETZA

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Depomed Inc	GLUMETZA	metformin hydrochloride	13913-002	CELLULOSE, MICROCRYSTALLINE
Depomed Inc	GLUMETZA	metformin hydrochloride	13913-002	HYPROMELLOSES
Depomed Inc	GLUMETZA	metformin hydrochloride	13913-002	MAGNESIUM STEARATE
Depomed Inc	GLUMETZA	metformin hydrochloride	13913-002	POLYETHYLENE GLYCOL

Last updated: August 18, 2026

Executive summary: GLUMETZA is an extended-release metformin hydrochloride product whose commercial differentiation depends on controlled drug release, gastrointestinal tolerability, and once-daily dosing rather than on the active ingredient. Its excipient strategy uses a hydrophilic polymer matrix, osmotic and structural excipients, lubricants, and a film coat to control hydration, swelling, tablet integrity, and metformin diffusion. The original formulation patents have largely expired or lost practical exclusivity, leaving opportunities in generic supply, excipient optimization, alternative modified-release systems, contract manufacturing, and patient-specific metformin products.

GLUMETZA Excipient Strategy, Patent Position, and Commercial Opportunities

What is GLUMETZA and how does its formulation work?

GLUMETZA is an extended-release tablet containing metformin hydrochloride, an oral biguanide used with diet and exercise to treat type 2 diabetes. The product was commercialized through Depomed technology and later marketed by Santarus, Salix Pharmaceuticals, and affiliated companies. Its FDA regulatory product is associated with NDA 021748. [1]

GLUMETZA uses a modified-release platform rather than immediate-release metformin. The formulation is designed to:

• Release metformin over an extended period.
• Support once-daily administration.
• Reduce peak gastrointestinal exposure compared with some immediate-release regimens.
• Maintain tablet integrity as the dosage form hydrates.
• Control diffusion and erosion in the gastrointestinal tract.

Metformin is highly water soluble. That creates a formulation challenge: without a release-controlling matrix, the active ingredient can dissolve and diffuse rapidly. A successful formulation must therefore manage water penetration and drug movement without compromising dose delivery.

The commercial value is tied to the dosage form, not to chemical novelty in metformin hydrochloride. Generic manufacturers can obtain the active ingredient from multiple suppliers, but they must reproduce the required extended-release performance and demonstrate bioequivalence under FDA standards.

What excipients are used in GLUMETZA?

The FDA labeling identifies inactive ingredients including hypromellose, povidone, colloidal silicon dioxide, magnesium stearate, sodium chloride, and other tableting or coating materials. The precise function of each excipient can be inferred from conventional pharmaceutical use, although the proprietary manufacturing sequence and quantitative formula are not fully disclosed in the public label. [1]

Excipient category	Publicly identified or representative material	Primary formulation function
Release-controlling polymer	Hypromellose	Hydration, gel formation, diffusion control, matrix integrity
Osmotic or ionic excipient	Sodium chloride	Promotes water movement into the matrix and affects release kinetics
Binder and processing aid	Povidone	Granule binding and mechanical strength
Glidant	Colloidal silicon dioxide	Powder flow and content uniformity
Lubricant	Magnesium stearate	Reduces sticking and ejection force
Core structural excipient	Microcrystalline cellulose or comparable filler, where used	Tablet strength, compressibility, and bulk
Film-coating materials	Hypromellose, polyethylene glycol, titanium dioxide, talc, or equivalent materials	Protection, appearance, swallowability, and coating performance

The critical excipient combination is the polymer-osmogent system. Hypromellose forms a hydrated gel barrier around the metformin-containing matrix. Sodium chloride can modify hydration and internal osmotic pressure. Povidone, silica, and magnesium stearate influence manufacturability and tablet robustness.

A generic manufacturer does not necessarily need to copy every inactive ingredient. It must meet the applicable pharmaceutical equivalence, bioequivalence, quality, and performance requirements. FDA guidance allows some excipient differences when they do not affect safety, efficacy, or performance. [2]

How does the GLUMETZA excipient system control drug release?

GLUMETZA’s release mechanism is best understood as a polymeric controlled-release matrix with excipient-assisted hydration and diffusion control.

When the tablet contacts gastrointestinal fluid, the polymer hydrates and forms a viscous barrier. Water penetrates the matrix, metformin dissolves, and the drug diffuses through the hydrated polymer. The rate depends on:

1. Polymer viscosity grade.
2. Polymer concentration.
3. Particle size and distribution of metformin.
4. Sodium chloride level and distribution.
5. Tablet hardness and porosity.
6. Compression force.
7. Granulation method.
8. Lubrication time and lubricant concentration.
9. Coating permeability.
10. Dissolution conditions across pH and agitation states.

These variables create a high formulation-development burden. A manufacturer can use the same named excipients and still produce a materially different release profile if it changes polymer grade, granule architecture, compression, or coating.

The principal technical risk is dose dumping or excessive early release. A second risk is incomplete release, which can reduce exposure. A third is sensitivity to food, gastrointestinal transit, or manufacturing variability.

What formulation patents protected GLUMETZA?

The original patent estate focused on controlled-release dosage forms and the delivery architecture rather than on metformin chemistry. Public patent records and litigation materials have associated GLUMETZA and related Depomed controlled-release technology with patents including U.S. Patent Nos. 6,340,475 and 6,488,962. Related patents and continuations addressed controlled-release compositions, dosage-form structures, and manufacturing or use features. [3][4]

Patent category	Protected subject matter	Commercial relevance
Controlled-release composition	Polymer matrix and drug-release architecture	Limited design-around flexibility during term
Dosage-form structure	Tablet configuration, swelling, hydration, or retention characteristics	Potential barrier to near-copy products
Method of treatment	Once-daily or controlled-release use of metformin	Supports method-of-use enforcement
Manufacturing process	Granulation, compression, coating, or release-control steps	Can raise technical and process-development costs
Continuation or related claims	Narrower formulations or use claims	May extend litigation leverage beyond the core patent

Patent expiry did not eliminate all technical barriers. A generic entrant still must satisfy FDA bioequivalence requirements, establish commercial-scale manufacturing, and avoid any unexpired claim that is listed or enforceable against the proposed product.

The practical value of formulation patents declines when:

• The core patents expire.
• The active ingredient is inexpensive and widely available.
• Multiple manufacturers develop acceptable release systems.
• The brand loses prescribing and reimbursement leverage.
• A generic product receives FDA approval without a protracted launch delay.

When did GLUMETZA lose meaningful exclusivity?

GLUMETZA’s commercial exclusivity was reduced in stages rather than at a single date. New chemical entity exclusivity did not apply because metformin was already an established active ingredient. The commercial protection came from formulation patents, regulatory exclusivity associated with the original approval, and the practical difficulty of reproducing the extended-release profile.

The principal controlled-release patents associated with the product were filed in the 1990s and early 2000s. Their terms therefore reached expiration during the 2020s or earlier, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and the specific claims at issue. FDA’s Orange Book remains the controlling source for current listed patents and exclusivity status. [5]

GLUMETZA’s loss of exclusivity should be analyzed through four separate dates:

Exclusivity element	What it controls
FDA regulatory exclusivity	When an ANDA or 505(b)(2) application can be submitted or approved
Orange Book patent term	Whether an ANDA applicant must certify to a listed patent
Paragraph IV litigation	Whether approval can be delayed by patent litigation
Commercial launch timing	When an approved generic can enter under settlement or independent launch rights

A patent expiration date alone does not establish the first possible generic launch date. FDA approval timing, pediatric exclusivity, litigation stays, settlements, and manufacturing readiness can change the outcome.

What is the Orange Book status of GLUMETZA?

GLUMETZA has been associated with an FDA-approved extended-release metformin product under NDA 021748. Orange Book entries must be reviewed by strength and dosage form because patent listings and therapeutic-equivalence determinations can differ between products. [5]

The relevant commercial questions are:

• Whether the brand NDA is listed as marketed or discontinued.
• Whether patent listings remain active.
• Whether any unexpired patent is subject to a 30-month stay.
• Whether approved ANDAs have therapeutic-equivalence ratings.
• Whether an authorized generic is available.
• Whether the reference listed drug has changed status for future ANDA submissions.

If the reference product is discontinued but FDA determines that discontinuation was not for safety or efficacy reasons, ANDA applicants may continue to rely on the discontinued reference product under applicable FDA procedures. This distinction matters for generic metformin ER products because the brand’s commercial availability and its regulatory reference-product status are separate issues. [6]

Which companies are challenging or competing with GLUMETZA?

The competitive field includes several groups:

Generic metformin ER manufacturers

Generic companies compete on:

• FDA-approved extended-release tablets.
• Wholesale acquisition cost.
• Pharmacy benefit manager access.
• Supply reliability.
• Multiple strengths and bottle configurations.
• Ability to substitute at the pharmacy.

The main generic risk is price erosion. Metformin is a mature, low-cost active ingredient, so a successful generic release system can move rapidly from premium pricing to commodity economics.

Authorized generic suppliers

An authorized generic can preserve some brand-linked economics while reducing the market share available to independent ANDA products. The commercial effect depends on launch timing, pricing, distribution, and payer contracting.

505(b)(2) developers

A 505(b)(2) applicant could pursue a differentiated metformin product with:

• A new release profile.
• A new dosage form.
• Improved gastrointestinal tolerability.
• Alternative dosing frequency.
• A sprinkle, liquid, multiparticulate, or orally disintegrating format.
• A product for patients who cannot swallow conventional tablets.

This pathway would require a stronger clinical and regulatory rationale than a conventional ANDA but could support a higher price if the product solves a clear adherence or tolerability problem. [7]

Competing branded diabetes therapies

GLUMETZA also competes indirectly with immediate-release metformin, other metformin ER products, fixed-dose combinations, and newer type 2 diabetes products such as SGLT2 inhibitors and GLP-1 receptor agonists. These products reduce the addressable market for premium metformin formulations, even when metformin remains a standard first-line therapy.

What commercial opportunities exist in GLUMETZA excipients?

1. Generic excipient systems

The most direct opportunity is supply of high-quality hypromellose and associated excipients to generic manufacturers. Suppliers can compete through:

• Controlled viscosity grades.
• Narrow particle-size distributions.
• Low-moisture grades.
• Improved flow and compressibility.
• Consistent hydration behavior.
• Regulatory support packages.
• Dual-source qualification.

The highest value is not the raw excipient alone. It is the excipient grade supported by dissolution data, process knowledge, and regulatory documentation.

2. Polymer and osmogent optimization

A supplier or CDMO could develop a platform using hypromellose, polyethylene oxide, carbomer, or other release-controlling polymers. The objective would be to match the target dissolution profile while improving process robustness.

Potential development advantages include:

• Lower tablet weight.
• Better dose uniformity.
• Reduced sensitivity to compression force.
• Lower variability between manufacturing sites.
• Improved performance under fed and fasted conditions.
• Easier scale-up from pilot to commercial equipment.

The main commercial barrier is that a technically superior formulation may still be difficult to differentiate in a generic market unless it lowers cost or solves a regulatory problem.

3. Alternative modified-release technology

An entrant could develop a non-infringing formulation using a different release mechanism, such as:

• Multiparticulate coated beads.
• Ion-exchange resin complexes.
• Osmotic delivery.
• Gastroretentive systems.
• Dual-layer tablets.
• High-density matrix tablets.
• Delayed-release or site-specific systems.

These technologies may create new intellectual property but also increase development cost, manufacturing complexity, and regulatory burden.

4. Patient-centered dosage forms

Metformin tablets have a known tolerability and swallowing burden. Commercial opportunities include lower-swallowing-burden products, provided the formulation maintains appropriate exposure and does not create unacceptable gastrointestinal effects.

Potential products include:

• Smaller high-load tablets.
• Once-daily multiparticulates.
• Sprinkle formulations.
• Liquid or reconstitutable extended-release products.
• Pediatric or geriatric presentations.
• Combination products with other diabetes medicines.

A new dosage form may support a 505(b)(2) strategy, but the product must offer a clinically relevant benefit rather than only a reformulated presentation.

5. Manufacturing and analytical services

CDMOs can support GLUMETZA-related products through:

• High-shear wet granulation.
• Roller compaction.
• Matrix-tablet compression.
• Functional film coating.
• Dissolution method development.
• IVIVC and food-effect studies.
• Scale-up and process validation.
• Stability testing.
• ANDA CMC documentation.

Analytical capability is important because metformin ER products can show similar single-point dissolution results while differing materially across the full release curve.

What manufacturing and intellectual-property barriers remain?

The primary barrier is formulation reproducibility. Metformin hydrochloride is inexpensive, but controlled-release performance is sensitive to process variables. A manufacturer must control:

• API particle size.
• Blend uniformity.
• Polymer hydration.
• Granule density.
• Compression force.
• Tablet porosity.
• Coating weight gain.
• Dissolution across multiple media.
• Stability under humidity and temperature stress.

Patent risk remains relevant where a company uses a claimed formulation architecture, process, or method of treatment. A design-around analysis should review issued claims, continuations, terminal disclaimers, prosecution history, and litigation outcomes rather than relying solely on the patent title.

A second barrier is regulatory comparability. FDA approval of one generic metformin ER product does not guarantee approval of a different matrix design. The sponsor must demonstrate that its formulation delivers comparable exposure and meets product-quality requirements.

What paragraph IV and litigation risks affect generic GLUMETZA?

A generic applicant that believes a listed patent is invalid, unenforceable, or not infringed can submit a Paragraph IV certification. The certification may trigger litigation by the patent holder and a statutory approval stay under the Hatch-Waxman framework. [8]

For GLUMETZA, relevant litigation analysis should examine:

• The patents listed against the reference product at ANDA submission.
• The specific claims asserted against each applicant.
• Whether the dispute concerned composition, dosage form, method of use, or process.
• Whether the court found infringement.
• Whether claims were invalidated or narrowed.
• Whether the parties entered a launch settlement.
• Whether the settlement included an authorized generic or license.

The greatest business risk is usually timing, not permanent exclusion. A settlement can establish a licensed launch date that determines market value for both the brand and the generic applicant.

How strong is the GLUMETZA patent estate today?

The estate is technically meaningful but commercially mature. Its strongest historical feature was the combination of a controlled-release formulation and difficult-to-reproduce dissolution behavior. Its current strength depends on the existence of unexpired, enforceable claims and the status of any remaining Orange Book listings.

Strength factor	Current commercial assessment
Metformin chemical composition	Weak protection because the active ingredient is old and widely available
Core extended-release concept	Limited after expiration of foundational patents
Specific polymer and dosage-form claims	Potentially relevant if unexpired and claim scope is narrow
Manufacturing know-how	Moderate value as trade secret and scale-up knowledge
Brand recognition	Declines as generic substitution expands
Regulatory exclusivity	Limited for a mature active ingredient
Excipient know-how	Valuable for speed, reproducibility, and cost control, but difficult to enforce broadly

The residual competitive advantage is more likely to reside in manufacturing knowledge, supplier relationships, dissolution control, and distribution than in broad composition exclusivity.

How does GLUMETZA compare with standard metformin ER products?

Factor	GLUMETZA	Conventional metformin ER
Active ingredient	Metformin hydrochloride	Metformin hydrochloride
Release strategy	Proprietary controlled-release matrix or related delivery architecture	Product-specific matrix or other ER system
Brand positioning	Premium extended-release metformin	Low-cost generic substitution
Main differentiation	Release performance, dosing convenience, tolerability claims	Price, availability, formulary status
Excipient value	High during formulation development	High for manufacturing efficiency and bioequivalence
Patent leverage	Historically formulation-based	Usually limited to each manufacturer’s own formulation
Commercial risk	Generic erosion and brand discontinuation	Price compression and supply competition

What are the key takeaways for investors and licensing teams?

• GLUMETZA’s value is formulation-driven, not API-driven.
• Hypromellose and sodium chloride are central to the likely release-control strategy, with povidone, silica, magnesium stearate, and coating materials supporting manufacture and performance.
• The original patent estate created historical entry barriers but is now mature.
• Current opportunity is concentrated in generic supply, excipient-grade differentiation, CDMO services, and new dosage forms.
• A new product needs a regulatory or clinical advantage to command a premium over low-cost metformin ER.
• Patent diligence must separate expired foundational patents from any remaining continuation, method-of-use, process, or formulation claims.
• Commercial diligence should prioritize FDA Orange Book records, Drugs@FDA approval history, ANDA competition, authorized-generic status, payer coverage, and current brand marketing status.

FAQs about GLUMETZA excipients and commercial strategy

Is hypromellose the most important GLUMETZA excipient?

It is likely the central release-controlling excipient because it hydrates and forms a diffusion-limiting gel matrix. Polymer grade, viscosity, concentration, and processing conditions can materially affect metformin release.

Can a generic manufacturer use different excipients from GLUMETZA?

Yes, subject to FDA requirements. The generic product must demonstrate pharmaceutical equivalence, bioequivalence, quality, and acceptable inactive-ingredient safety. A different excipient system may be used if it produces the required performance.

Does GLUMETZA have biologic or biosimilar competition?

No. GLUMETZA contains a small-molecule active ingredient, metformin hydrochloride. The relevant competitors are ANDA generics, authorized generics, other metformin ER products, and alternative diabetes therapies.

Can a new metformin extended-release product receive patent protection?

Yes. Patent protection could cover a novel composition, release profile, dosage form, manufacturing process, or therapeutic use. The claims must satisfy novelty, non-obviousness, written-description, enablement, and other applicable requirements.

Is the main commercial opportunity in GLUMETZA the excipient or the finished product?

The larger value generally lies in the finished product and its manufacturing platform. Excipient suppliers can capture value through specialized grades, technical support, and regulatory packages, but commodity excipient pricing limits returns unless the material improves bioequivalence, scale-up, or supply reliability.

References

1. U.S. Food and Drug Administration. (2016). GLUMETZA (metformin hydrochloride) extended-release tablets prescribing information.
2. U.S. Food and Drug Administration. (2018). Size, shape, and other physical attributes of generic tablets and capsules: Guidance for industry.
3. U.S. Patent No. 6,340,475. (2002). Controlled-release dosage forms. United States Patent and Trademark Office.
4. U.S. Patent No. 6,488,962. (2002). Controlled-release dosage forms. United States Patent and Trademark Office.
5. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, Orange Book.
6. U.S. Food and Drug Administration. (n.d.). Discontinued drug product list and reference listed drug procedures.
7. U.S. Food and Drug Administration. (2019). Applications covered by section 505(b)(2): Guidance for industry.
8. U.S. Congress. (1984). Drug Price Competition and Patent Term Restoration Act of 1984, 21 U.S.C. § 355(j).