List of Excipients in Branded Drug GRALISE

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Assertio Therapeutics Inc	GRALISE	gabapentin	13913-004	CELLULOSE, MICROCRYSTALLINE
Assertio Therapeutics Inc	GRALISE	gabapentin	13913-004	COPOVIDONE K25-31
Assertio Therapeutics Inc	GRALISE	gabapentin	13913-004	HYPROMELLOSE
Assertio Therapeutics Inc	GRALISE	gabapentin	13913-004	LECITHIN, SOYBEAN

Gralise Excipient Strategy and Commercial Opportunities in Extended-Release Gabapentin

Last updated: August 9, 2026

Gralise is an extended-release gabapentin tablet approved for once-daily treatment of postherpetic neuralgia. Its commercial differentiation depends on formulation design rather than a new active ingredient. The main opportunity for excipient suppliers and generic manufacturers is a controlled-release matrix that reproduces Gralise's fed-state absorption profile, dissolution behavior, tablet robustness, and gastrointestinal performance.

The most valuable intellectual property has historically centered on controlled-release gabapentin formulations, dosing with food, and delivery through the upper gastrointestinal tract. Generic entry therefore depends on more than matching gabapentin content. Developers must manage formulation patents, fed bioequivalence, dissolution similarity, manufacturing process controls, and potential Paragraph IV litigation.

What is Gralise and how does its formulation work?

Gralise contains gabapentin in a once-daily extended-release tablet. The product was approved by the U.S. Food and Drug Administration in 2011 under NDA 022544 for postherpetic neuralgia in adults [1].

Immediate-release gabapentin is absorbed mainly in the upper small intestine through a saturable amino-acid transport mechanism. Its bioavailability declines as dose increases. Gralise uses a controlled-release design intended to release gabapentin gradually while the dosage form remains available to the absorption region.

The product must be taken with the evening meal. Food increases exposure and supports the intended pharmacokinetic profile. This requirement makes the fed-state formulation performance commercially important and creates a major development barrier for generic products [1].

Gralise product profile

Attribute	Gralise
Active ingredient	Gabapentin
Dosage form	Extended-release tablet
Approved strengths	300 mg and 600 mg
FDA approval	2011
NDA	022544
Primary indication	Postherpetic neuralgia
Administration	Once daily with the evening meal
Reference company history	Depomed; later Assertio
Key formulation issue	Controlled release in the gastrointestinal tract
Main regulatory route for competition	ANDA with Paragraph IV or other patent certification

What excipients are used in Gralise tablets?

The FDA-approved labeling identifies inactive ingredients but does not disclose the complete manufacturing strategy, excipient grades, particle-size specifications, granulation conditions, or compression parameters. Public labeling identifies excipient classes used in the tablets, including hydrophilic matrix and conventional tablet-processing materials [1].

Reported inactive ingredients include hypromellose, microcrystalline cellulose, lactose monohydrate, magnesium stearate, colloidal silicon dioxide, and tablet-coloring components. The precise role of each material depends on grade, viscosity, particle size, concentration, and processing history.

Functional excipient roles

Excipient class	Likely formulation function	Commercial relevance
Hypromellose	Hydrophilic matrix formation and release control	High; polymer grade can materially alter dissolution
Microcrystalline cellulose	Diluent, compactibility aid, matrix support	Medium to high; affects hardness and porosity
Lactose monohydrate	Filler and tablet mass adjustment	Medium; influences wettability and matrix erosion
Colloidal silicon dioxide	Glidant and flow aid	Medium; affects blend uniformity and compression
Magnesium stearate	Lubrication	Medium; excess levels can slow wetting and dissolution
Colorants or coating materials	Product identification and protection	Low to medium; relevant to appearance and stability

The commercial value is concentrated in the release-controlling polymer system. A formulation can use the same broad excipient classes as Gralise and still fail to reproduce the reference product because release depends on polymer viscosity, substitution pattern, particle-size distribution, polymer-to-drug ratio, tablet porosity, coating, and compression force.

What excipient strategy is required to reproduce Gralise?

A competitive formulation strategy should treat the tablet as a controlled-release system rather than a conventional hydrophilic matrix tablet.

Polymer selection

Hypromellose is the most commercially important excipient category because it hydrates after ingestion and forms a gel barrier. Gabapentin diffuses through and is released as the matrix hydrates and erodes.

Key development variables include:

• Hypromellose viscosity grade
• Polymer concentration
• Particle-size distribution
• Degree of substitution
• Granulation method
• Drug-to-polymer ratio
• Tablet hardness and porosity
• Lubricant concentration
• Dissolution medium and agitation conditions

High-viscosity hypromellose generally slows hydration-driven release, but increasing viscosity alone does not guarantee bioequivalence. The matrix must provide the desired release over the relevant gastrointestinal transit period.

Direct compression versus wet granulation

Direct compression can reduce manufacturing complexity and cost, but it requires strong control of powder flow, segregation, and compactibility. Wet granulation can improve content uniformity and tablet robustness but may alter polymer hydration and produce different dissolution behavior.

For gabapentin, the high drug load makes excipient selection commercially important. Developers need enough polymer and filler to form a stable matrix without producing oversized tablets or unacceptable swallowing characteristics.

Lubrication control

Magnesium stearate is a material-risk point. Over-lubrication can create hydrophobic surfaces, reduce water penetration, and slow or distort release. Lubrication time, concentration, and mixing intensity should be controlled as critical process parameters.

Food-effect management

Gralise is administered with food, so formulation development must include fed-state performance from the beginning. A product that matches the reference under fasting conditions but diverges under fed conditions may fail the relevant bioequivalence program.

Food can affect:

• Gastric residence time
• Tablet hydration
• Mechanical stress on the matrix
• Drug release
• Absorption in the upper gastrointestinal tract
• Overall exposure and peak concentration

What patents protect Gralise formulation technology?

Gralise patent protection has focused on controlled-release gabapentin formulations and related delivery methods. The principal public patent family associated with Gralise includes U.S. Patent No. 7,438,927 and later continuation or related patents, including U.S. Patent Nos. 8,445,546 and 8,663,697. Patent scope and Orange Book status can change through expiration, terminal disclaimers, pediatric extensions, listing updates, and litigation outcomes [2,3].

Publicly associated Gralise patent estate

Patent	General subject matter	Commercial significance
U.S. 7,438,927	Controlled-release gabapentin formulations	Foundational formulation protection
U.S. 8,445,546	Controlled-release gabapentin and dosage-form claims	Potential barrier to matrix-based copies
U.S. 8,663,697	Related controlled-release delivery claims	May cover formulation or release characteristics
Related continuation patents	Dosage regimen, composition, or manufacturing variations	Scope depends on issued claims and current status

The relevant question for a generic developer is not whether the patents cover gabapentin generally. It is whether the proposed formulation practices an issued claim covering a particular polymer matrix, drug-loading range, release profile, dosage regimen, or manufacturing configuration.

Patent analysis should distinguish:

1. Orange Book-listed patents.
2. Unlisted formulation or process patents.
3. Expired patents.
4. Patents with surviving claims after litigation or reexamination.
5. Patents that may be challenged through Paragraph IV certification.
6. Method-of-use claims that may be addressed through a section viii statement or labeling carve-out.

What is the Orange Book status of Gralise?

The FDA Orange Book is the controlling source for current listed patents, expiration dates, exclusivity codes, and approved products [2]. Gralise's regulatory protection is separate from its commercial brand protection.

The original new-drug exclusivity period has expired. The current competitive assessment therefore depends primarily on patent status, FDA approval requirements, and the ability of an ANDA applicant to demonstrate bioequivalence.

A complete Orange Book review should examine:

• NDA 022544
• Listed patent numbers
• Patent expiration dates
• Pediatric exclusivity
• Any withdrawn or delisted patents
• Approved strengths
• Approved dosage form
• Current reference-listed drug status
• Generic approvals and tentative approvals

Patent expiration should not be inferred solely from the original filing date. Patent term adjustment, terminal disclaimers, patent-term extension, and pediatric exclusivity can change the effective barrier date.

When does Gralise lose exclusivity and face generic entry?

Gralise's five-year new chemical entity exclusivity expired before the current market period. The practical generic-entry date is determined by the last enforceable patent relevant to the proposed ANDA and the outcome of any Paragraph IV litigation.

Possible entry scenarios include:

Scenario	Commercial result
No active blocking patent	FDA approval can support immediate generic launch, subject to regulatory readiness
Paragraph IV challenge with no timely suit	Applicant may receive approval after statutory conditions are met
Patent litigation with 30-month stay	Approval or launch may be delayed
Successful Paragraph IV challenge	Early entry may occur before patent expiry
Settlement with licensed entry	Entry date depends on agreement terms
Formulation workaround	Applicant may avoid some claims but must still establish bioequivalence

The first substantially complete ANDA applicant with a valid Paragraph IV challenge may qualify for 180-day generic exclusivity under the Hatch-Waxman framework, although eligibility depends on FDA rules and the litigation record [4].

Which companies are challenging or competing with Gralise?

Competition can come from three categories:

1. Approved generic gabapentin products.
2. Potential generic versions of gabapentin extended-release tablets.
3. Therapeutic substitutes, including immediate-release gabapentin and pregabalin.

Immediate-release gabapentin is not automatically substitutable for Gralise. It differs in dosing frequency, release characteristics, administration requirements, and approved labeling. A generic extended-release gabapentin product must demonstrate bioequivalence to the Gralise reference product, not merely match the active ingredient.

The competitive field includes generic manufacturers with controlled-release tablet capabilities, contract development and manufacturing organizations, and excipient suppliers that provide high-viscosity hypromellose, directly compressible fillers, flow aids, and lubrication systems.

What commercial opportunities exist for excipient suppliers?

The strongest opportunity is not a new excipient. It is a higher-performing, better-controlled version of an established excipient system.

Premium polymer grades

Suppliers can differentiate through:

• Narrower viscosity specifications
• Better lot-to-lot consistency
• Controlled particle-size distributions
• Improved compressibility
• Lower microbial and elemental impurity risk
• Documentation supporting QbD and regulatory submissions
• Comparative dissolution data in matrix formulations

Co-processed excipients

Co-processed fillers or matrix-support systems can improve:

• Powder flow
• Compactibility
• Tablet tensile strength
• Low-dose excipient distribution
• Manufacturing speed
• Resistance to capping and lamination

The main regulatory challenge is showing that a co-processed system does not create an unexpected release mechanism or complicate sameness and bioequivalence arguments.

Formulation development services

CDMOs and excipient suppliers can offer development packages that combine:

• Polymer screening
• Design-of-experiments studies
• Fed-state dissolution
• Mechanical tablet characterization
• Scale-up support
• Stability studies
• IVIVC or pharmacokinetic modeling
• ANDA formulation documentation

This model can create licensing value without owning the gabapentin active ingredient or the finished-dose product.

How strong is the Gralise patent estate?

The estate is strongest against formulations that closely reproduce the claimed controlled-release matrix or use overlapping composition ranges. Its practical strength is lower where a developer can use a different release mechanism, avoid claimed ranges, or establish that a claim is invalid or not infringed.

Patent-strength factors

Factor	Assessment
Active-ingredient protection	Weak after gabapentin's basic compound patents expired
Controlled-release formulation protection	Historically significant
Excipient-specific protection	Depends on issued claim language
Method-of-use protection	Narrower and more vulnerable to label carve-outs
Manufacturing-process protection	Relevant if process claims are difficult to design around
Biosimilar protection	Not applicable; Gralise is a small-molecule drug
Litigation risk	Concentrated in formulation and ANDA patent disputes
Design-around potential	Moderate, but constrained by bioequivalence

Gralise does not create a biosimilar pathway issue. Gabapentin is a chemically synthesized small molecule, so competition proceeds through the generic drug framework rather than the biologics license application and biosimilar framework.

What manufacturing and IP barriers affect generic Gralise?

The principal manufacturing barrier is reproducible release control at commercial scale. Small changes in polymer hydration, granule density, tablet hardness, or lubrication can alter dissolution.

Key critical quality attributes include:

• Assay and content uniformity
• Tablet hardness
• Friability
• Porosity
• Dissolution profile
• Release at multiple pH levels
• Stability under temperature and humidity stress
• Dose-unit uniformity
• Impurity profile
• Mechanical integrity during packaging and transport

The principal IP barrier is claim overlap. A developer must map each material, concentration, dosage form, release profile, and administration condition against the active patent claims. A formulation that is technically bioequivalent may still create infringement exposure.

How does Gralise compare with immediate-release gabapentin and pregabalin?

Product	Release profile	Typical commercial advantage	Main limitation
Gralise	Extended release	Once-daily dosing for postherpetic neuralgia	Food requirement and formulation complexity
Immediate-release gabapentin	Immediate release	Low cost and broad generic availability	More frequent dosing
Pregabalin	Immediate or extended-release products	Predictable pharmacokinetics and multiple indications	Separate active ingredient and patent history
Generic gabapentin ER	Extended release	Potential price competition against Gralise	Bioequivalence and formulation patent risk

Gralise's commercial value depends on maintaining a differentiated adherence and dosing profile in a market with inexpensive immediate-release gabapentin. A lower-cost extended-release generic could compress brand pricing rapidly if it achieves broad payer coverage.

What revenue exposure exists for Gralise?

Revenue exposure is linked to the share of patients receiving the branded extended-release formulation rather than immediate-release gabapentin or pregabalin. The risk increases when:

• A generic extended-release product receives final FDA approval.
• Multiple manufacturers enter after the first generic period.
• Payers impose mandatory substitution.
• The brand has no enforceable formulation patent remaining.
• Prescribers view once-daily dosing as clinically interchangeable with cheaper alternatives.

The commercial opportunity for a generic entrant is strongest where the product can combine a low-cost excipient system with reliable fed bioequivalence and a legally defensible design-around.

Key Takeaways

• Gralise is a once-daily extended-release gabapentin tablet approved for postherpetic neuralgia.
• Hypromellose-based matrix technology is the central excipient opportunity.
• Polymer grade, concentration, particle size, compression, and lubrication can materially change release.
• Food-effect performance is a core development requirement.
• Gralise is a small-molecule product, so biosimilar risk does not apply.
• The relevant patent risks concern controlled-release formulations, dosing methods, and manufacturing claims.
• Generic developers need a combined formulation, Orange Book, Paragraph IV, and litigation strategy.
• Excipient suppliers can create value through consistent polymer grades, co-processed systems, and regulatory-ready development services.
• Generic launch timing depends on current patent listings, certifications, litigation, and any settlement or license arrangements.
• The principal commercial threat is a low-cost extended-release generic that demonstrates reliable fed bioequivalence.

FAQs

Can a generic Gralise product use different excipients?

Yes. An ANDA applicant generally can use different inactive ingredients if the formulation is acceptable to FDA, meets applicable sameness requirements, and demonstrates bioequivalence. Different excipients do not eliminate patent-infringement risk.

Is hypromellose required to make a generic Gralise tablet?

No. Hypromellose is a common controlled-release polymer, but another release-controlling system could be used if it produces an equivalent product and avoids relevant patent claims. The alternative must support acceptable dissolution, stability, manufacturability, and pharmacokinetics.

Does Gralise have biosimilar competition?

No. Gralise contains gabapentin, a small-molecule active ingredient. Competition follows the ANDA generic pathway rather than the biosimilar pathway.

Can an excipient supplier license Gralise technology without selling gabapentin?

Yes. A supplier or CDMO can license formulation know-how, polymer systems, manufacturing processes, analytical methods, or development data without commercializing the active ingredient. The license must address patent scope, know-how ownership, field of use, and regulatory data rights.

What is the highest-value development risk in a generic Gralise program?

The highest-value risk is failure to reproduce the reference product's fed-state release and exposure profile at scale. That risk can delay approval even when the active ingredient, dose strength, and basic tablet composition match the reference product.

References

1. U.S. Food and Drug Administration. (2023). Gralise (gabapentin) tablets, for oral use: Prescribing information. NDA 022544.

2. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

3. U.S. Patent and Trademark Office. (n.d.). Patent Center. https://patentcenter.uspto.gov/

4. U.S. Food and Drug Administration. (2017). Guidance for industry: 180-day exclusivity when multiple ANDA applicants are eligible for 180-day exclusivity. https://www.fda.gov/ҩ