List of Excipients in Branded Drug RALTEGRAVIR

Generic Drugs Containing RALTEGRAVIR

Company	Ingredient	NDC	Excipient
Camber Pharmaceuticals Inc	raltegravir	31722-584	LACTOSE MONOHYDRATE
Camber Pharmaceuticals Inc	raltegravir	31722-584	MAGNESIUM STEARATE
Camber Pharmaceuticals Inc	raltegravir	31722-584	MICROCRYSTALLINE CELLULOSE 102

What are the Most Frequently-Used Excipients in RALTEGRAVIR?

# Of NDCs	Excipient
1	LACTOSE MONOHYDRATE
1	MAGNESIUM STEARATE
1	MICROCRYSTALLINE CELLULOSE 102

Raltegravir Excipient Strategy and Commercial Opportunities

Last updated: August 6, 2026

Raltegravir has a mature active-ingredient patent position, but its commercial value remains relevant in generic HIV treatment, pediatric formulations, fixed-dose combinations, and differentiated oral delivery. The strongest excipient opportunities are in taste masking, rapid-dispersion products, moisture control, tablet robustness, and lower-cost manufacturing. Raltegravir is not a biologic, so biosimilar pathways do not apply. Commercial entrants must instead manage Abbreviated New Drug Application requirements, Orange Book patents, bioequivalence, formulation performance, and HIV-treatment substitution dynamics.

What formulations and excipients protect raltegravir products?

Raltegravir is marketed by Merck as Isentress and Isentress HD. The products contain raltegravir potassium and are available as film-coated tablets, chewable tablets, and oral suspension granules.

Product	Strength	Dosage form	Primary commercial use
Isentress	400 mg	Film-coated tablet	Twice-daily treatment
Isentress HD	600 mg	Film-coated tablet	Once-daily treatment in eligible patients
Isentress	25 mg and 100 mg	Chewable tablet	Pediatric dosing
Isentress	100 mg per packet	Oral suspension	Pediatric and weight-based dosing

The reference-product labels identify different excipient systems for each dosage form. The precise quantitative composition is not generally disclosed in the FDA label, which limits direct reverse engineering of the reference formulation.

Film-coated tablet excipients

The 400 mg and 600 mg tablets use conventional solid-dose excipients, including:

• Microcrystalline cellulose
• Lactose monohydrate or related diluent systems
• Dibasic calcium phosphate
• Hypromellose
• Poloxamer 407
• Sodium stearyl fumarate
• Film-coating components based on polyvinyl alcohol, polyethylene glycol, talc, and titanium dioxide

The formulation has a conventional direct-compression or dry-processing profile. Microcrystalline cellulose and dibasic calcium phosphate support tablet hardness and dimensional stability. Poloxamer 407 improves wetting and dissolution of the poorly water-soluble active moiety. Sodium stearyl fumarate provides lubrication with less hydrophobic impact than high levels of magnesium stearate.

Chewable-tablet excipients

The chewable formulation uses excipients that address palatability, mouthfeel, tablet dispersion, and pediatric acceptability. The label identifies components including:

• Mannitol
• Microcrystalline cellulose
• Hypromellose
• Crospovidone
• Sodium stearyl fumarate
• Sucralose
• Flavoring agents
• Coloring agents

Mannitol provides cooling mouthfeel and a relatively favorable pediatric sensory profile. Crospovidone supports rapid breakup. Sucralose and flavor systems help offset the bitter or medicinal taste associated with raltegravir potassium.

Oral-suspension excipients

The oral suspension uses a powder-for-reconstitution approach. Label-listed excipients include:

• Sucrose
• Microcrystalline cellulose
• Hypromellose
• Poloxamer 407
• Sodium citrate
• Citric acid
• Sodium saccharin
• Flavoring agents

This design combines a suspending system with pH control, sweetening, wetting, and flavor masking. The powder format reduces the stability burden associated with a ready-to-use aqueous suspension.

What excipient strategy is most commercially attractive for raltegravir?

The highest-value strategy is a platform that improves pediatric acceptability without changing the active ingredient, dose, or administration route.

Taste masking

Raltegravir pediatric products create the clearest excipient opportunity. Potential approaches include:

• Polymer coating of raltegravir particles
• Ion-exchange resin complexes
• Lipid-based barriers
• Cyclodextrin complexes
• Multiparticulate granules
• Flavor systems designed for short oral residence time
• Effervescent or rapidly dispersible systems that reduce bitterness exposure

A formulation must preserve dissolution after gastric transit. Strong taste masking can delay release or reduce apparent bioavailability, creating a bioequivalence problem.

Rapid dispersion and reconstitution

For pediatric products, reconstitution time, sedimentation, dose uniformity, and syringe withdrawal accuracy are commercial differentiators. A suspension platform with controlled particle size, high redispersibility, and low foaming can support:

• More consistent weight-based dosing
• Reduced caregiver handling
• Lower dosing error
• Improved use in low-resource settings
• Better compatibility with oral syringes

Co-processed cellulose systems, xanthan gum, hypromellose, or alternative suspending agents may provide opportunities if they meet regulatory and microbiological requirements.

Moisture and solid-state control

Raltegravir potassium formulation work should evaluate:

• Hygroscopicity
• Polymorphic or solid-state conversion risk
• Water activity
• Compression behavior
• Dissolution after accelerated storage
• Interaction with lactose, phosphate salts, and polymeric excipients

Alu-Alu blister packaging, high-barrier bottles, desiccants, or moisture-scavenging closures can complement excipient selection. Packaging patents can create additional differentiation even where the tablet composition is conventional.

Direct compression and cost reduction

A generic manufacturer can pursue lower-cost processing by optimizing:

• Co-processed microcrystalline cellulose
• Spray-dried lactose
• Dibasic calcium phosphate grades
• Low-level sodium stearyl fumarate lubrication
• Continuous blending
• Roller compaction where flow or segregation requires improvement
• Lower coating weight with equivalent protection

The commercial benefit is greatest in high-volume 400 mg and 600 mg tablets, where modest reductions in cycle time, tooling wear, rejects, and coating burden can affect gross margin.

What patents protect raltegravir formulations and methods?

The principal historical patent covering raltegravir and related integrase-inhibitor chemistry was U.S. Patent No. 7,169,780, assigned to Merck. The patent covered raltegravir-related compounds and had a listed term extending into 2022, subject to patent-term adjustment and pediatric exclusivity considerations.[1][2]

The commercial exclusivity position for the original Isentress product has largely expired. Formulation, manufacturing, pediatric, and method-of-use patents must be assessed separately because expiry of the core compound patent does not automatically eliminate every potential barrier.

IP category	Relevance to raltegravir	Commercial impact
Compound patent	Covers raltegravir or related chemical genus	Historically the main barrier; largely expired in the U.S.
Salt or solid-state patent	May cover raltegravir potassium, crystal form, or stability attributes	Can affect formulation design and ANDA certification
Tablet-composition patent	May claim specific excipient ratios or release characteristics	Potential barrier to a formulation-specific generic
Pediatric formulation patent	May cover chewable or suspension technology	Relevant to pediatric competition
Method-of-use patent	May cover dosing, treatment population, or combination use	Possible Paragraph IV or section viii issue
Manufacturing patent	May cover synthesis, purification, granulation, or coating	Can restrict API sourcing or process selection
Packaging patent	May cover moisture protection or reconstitution systems	Usually a secondary barrier unless narrowly drafted

An excipient is not automatically protected merely because it appears in the reference-product label. Patent protection depends on claim language, filing date, enforceability, and whether the proposed product practices the claims.

What is the Orange Book status of raltegravir?

The FDA Orange Book identifies approved drug products, patent listings, and regulatory exclusivity. Generic developers should review the current listing for:

• Isentress 25 mg, 100 mg, 400 mg, and 600 mg products
• Isentress oral suspension
• Listed patents and use codes
• Patent expiration dates
• Whether a listed patent applies to a particular strength or dosage form
• Whether an approved generic has been designated therapeutically equivalent

The original 400 mg product and later 600 mg product have different approval histories and may have different listed patents. A commercial assessment should not rely on the core compound patent alone. Orange Book data must be checked against the specific reference listed drug and dosage form.[2]

When did raltegravir lose exclusivity?

Raltegravir’s principal U.S. compound patent protection ended in the early 2020s. Pediatric exclusivity can add six months to qualifying patent or exclusivity periods, but it does not create a new long-term compound monopoly.[1][2]

Milestone	Approximate timing
Isentress U.S. approval	2007
Isentress chewable and oral suspension approvals	2013
Isentress HD approval	2017
Core U.S. patent term	Expired in the early 2020s
Generic competition	Expanded after core patent expiry
Current opportunity	Formulation, supply, pediatric, and market-access differentiation

The timing of individual generic launches depends on ANDA approval, Paragraph IV litigation, settlements, manufacturing readiness, and commercial strategy.

Which companies are challenging raltegravir exclusivity?

Generic competition has developed through ANDA applicants targeting raltegravir tablets and, depending on the product, pediatric dosage forms. The relevant competitive set can include large multisource manufacturers, specialty generic companies, and vertically integrated API suppliers.

The central risks for an entrant are:

1. A Paragraph IV notice against a remaining Orange Book patent.
2. A 30-month stay triggered by patent litigation.
3. Failure to demonstrate bioequivalence for a modified excipient system.
4. Supply interruption involving raltegravir potassium or a key excipient.
5. Price erosion after several ANDA approvals.
6. Limited formulary access despite regulatory approval.

Because generic HIV products are often evaluated by government and managed-care purchasers on price, supply reliability, and therapeutic equivalence, an excipient strategy must produce a measurable operational or patient-use advantage.

What Paragraph IV and litigation risks affect raltegravir?

Paragraph IV risk is product-specific. An applicant may certify that a listed patent is invalid, unenforceable, or not infringed. If the patent holder files suit within the statutory period, FDA approval may be delayed by a 30-month stay unless the litigation is resolved earlier or the stay is otherwise terminated.[3]

For raltegravir, the key litigation questions are:

• Whether the patent claims the active ingredient or only a specific formulation
• Whether the proposed product uses the same salt or a non-infringing alternative
• Whether a chewable or suspension product practices pediatric formulation claims
• Whether the use code covers the proposed label
• Whether the applicant has a section viii statement carving out a patented indication
• Whether settlement terms permit an agreed launch date

Public patent litigation records should be reviewed through PACER, FDA Paragraph IV notices where available, and Orange Book updates. A complete litigation conclusion cannot be drawn from the existence of an Orange Book patent alone.

How strong is the raltegravir patent estate?

The historical compound estate was strong because it controlled the active pharmaceutical ingredient used in Isentress. Its current strength is materially lower because the principal compound term has expired or reached the end of its effective commercial life in the United States.

The residual estate is more fragmented:

• Core chemical protection: low current blocking value after expiry
• Specific formulation protection: potentially moderate, depending on claim scope
• Pediatric dosage-form protection: potentially meaningful for chewables and suspension
• Manufacturing protection: relevant where alternative processes are difficult to qualify
• International protection: varies by country and patent-family member
• Trade secrets: potentially important for process parameters and supplier qualification

The strongest remaining commercial moat is likely operational rather than purely patent-based: reliable API supply, validated pediatric products, stable reconstitution performance, and access to government HIV procurement channels.

What licensing deals and partnerships matter for raltegravir?

Raltegravir was developed and commercialized by Merck. The main commercial partnership structure has involved Merck’s product operations, regional licensing and distribution arrangements, and public-health procurement channels rather than a widely disclosed excipient-specific licensing program.[4]

Excipient companies can pursue several partnership models:

Co-development with generic manufacturers

A supplier can provide a differentiated excipient platform for:

• Chewable raltegravir
• Oral suspension granules
• Taste-masked multiparticulates
• Direct-compression tablets
• High-barrier moisture-stable products

The strongest proposition includes development data, regulatory support, and a qualified second source.

Licensing of formulation technology

Licensable technologies may include:

• Taste-masking polymers
• Co-processed suspending agents
• Controlled-release or rapid-release granules
• Ready-to-use suspension systems
• Pediatric flavor platforms
• Low-moisture dry granulation systems

Claims should focus on measurable performance, such as dissolution, bitterness reduction, reconstitution time, sedimentation, or storage stability.

Supply agreements

A supplier can secure value through long-term contracts for:

• Poloxamer 407
• High-purity microcrystalline cellulose
• Specialty coating polymers
• Pediatric flavors
• Co-processed excipients
• Packaging-compatible desiccant systems

Supply reliability can be more valuable than a narrow composition patent once multiple generic manufacturers enter.

What FDA regulatory pathway applies to raltegravir products?

A conventional generic raltegravir tablet generally proceeds through an ANDA under section 505(j) of the Federal Food, Drug, and Cosmetic Act. The applicant must demonstrate pharmaceutical equivalence and bioequivalence to the reference listed drug.[3]

A formulation that materially changes the dosage form, route, release profile, or clinical performance may require a 505(b)(2) application rather than a conventional ANDA. This is especially relevant for:

• Long-acting delivery systems
• Novel pediatric suspensions
• Modified-release products
• Alternative salt or complexed forms
• Products with clinically meaningful administration differences

Excipient changes are usually acceptable in an ANDA when they do not alter the product’s critical quality attributes or clinical performance. The applicant must still address impurity profiles, dissolution, stability, microbial quality, content uniformity, and bioequivalence.

What generic launch scenarios exist for raltegravir?

Low-cost multisource launch

A manufacturer uses conventional excipients and closely matches the reference product. This approach has the lowest development risk but usually produces rapid price competition.

Pediatric differentiation

A manufacturer launches a better-tasting chewable tablet or suspension. This strategy can support hospital, pediatric, and public-health procurement, especially if dosing accuracy and reconstitution performance improve.

Regional supply strategy

A company targets countries where raltegravir remains important for treatment-experienced patients, pediatric use, or public-health programs. Patent status and regulatory requirements must be assessed country by country.

Integrated API and finished-dose model

Vertical integration can lower supply risk and improve pricing. This model is attractive where API qualification, impurity control, or geopolitical sourcing creates barriers for finished-dose competitors.

How does raltegravir compare with competing HIV drugs?

Raltegravir competes with newer integrase strand transfer inhibitors, especially dolutegravir and bictegravir-based regimens.

Attribute	Raltegravir	Dolutegravir	Bictegravir
Integrase inhibitor class	Yes	Yes	Yes
Original commercial position	First-generation INSTI	Later-generation INSTI	Later-generation INSTI
Typical dosing burden	Historically twice daily; HD once daily for eligible patients	Often once daily	Once daily in combination product
Pediatric formulation opportunity	Chewable and suspension products	Strong pediatric opportunity	Primarily fixed-dose combination
Generic opportunity	Mature and expanding	More active lifecycle and combination competition	More concentrated around combination products
Excipient differentiation	Taste masking, suspension, tablet robustness	Fixed-dose compatibility and pediatric palatability	Multi-API stability and tablet compression

Raltegravir’s disadvantage is competitive displacement by once-daily, higher-barrier integrase inhibitors. Its advantage is a mature regulatory record, established pediatric dosage forms, and a broader opportunity for lower-cost generic supply.

What revenue exposure and commercial opportunity remain?

The branded revenue base faces structural erosion from generic entry and newer integrase inhibitors. The remaining commercial opportunity is concentrated in:

• Generic tablet volume
• Pediatric products
• Public-sector procurement
• Emerging-market access
• API and excipient supply
• Formulation licensing
• Contract development and manufacturing

For excipient suppliers, the addressable opportunity is unlikely to come from a single premium tablet technology. It is more likely to arise from repeat supply across several generic manufacturers or from a pediatric platform that can be reused for other bitter antiretroviral drugs.

Key Takeaways

• Raltegravir is a mature small-molecule HIV product with a largely expired core U.S. compound patent position.
• The most attractive excipient opportunities are pediatric taste masking, suspension performance, reconstitution, and moisture stability.
• Isentress and Isentress HD use conventional tablet excipients, including microcrystalline cellulose, phosphate salts, hypromellose, poloxamer 407, and sodium stearyl fumarate.
• Chewable and oral-suspension products offer more formulation differentiation than standard film-coated tablets.
• Generic applicants must assess current Orange Book listings, use codes, Paragraph IV exposure, and formulation-specific patents.
• Biosimilar risk does not apply because raltegravir is a small molecule.
• Commercial value is shifting from molecule-level exclusivity to manufacturing economics, pediatric usability, supply reliability, and public-health access.
• A 505(j) ANDA is the standard pathway for conventional generic products; materially novel delivery systems may require 505(b)(2).

FAQs About Raltegravir Excipient Commercialization

Can a generic manufacturer change the excipients in raltegravir tablets?

Yes. An ANDA applicant may use different inactive ingredients if the product remains pharmaceutically equivalent, bioequivalent, stable, and compliant with FDA requirements.

Which raltegravir dosage form offers the greatest excipient differentiation?

The chewable tablet and oral suspension offer the greatest opportunity because taste, redispersibility, dose uniformity, and pediatric acceptability are clinically relevant performance attributes.

Is poloxamer 407 essential to every raltegravir formulation?

No. Poloxamer 407 is used in the reference products, but a generic developer may evaluate alternative wetting or solubilizing excipients if dissolution and bioequivalence requirements are satisfied.

Can an excipient supplier obtain patent protection for a raltegravir formulation?

Yes. Patent protection may be available for a novel composition, taste-masking system, process, particle architecture, reconstitution system, or packaging combination. The claims must provide technical distinctions over the reference product and prior art.

Does raltegravir still have commercial value after patent expiry?

Yes. The opportunity is strongest in generic supply, pediatric dosage forms, emerging markets, government procurement, API integration, and formulation technologies that reduce manufacturing or administration problems.

References

1. U.S. Patent No. 7,169,780. (2007). 5-Hydroxypyrimidinone carboxamides and their use as integrase inhibitors. United States Patent and Trademark Office.

2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book

3. U.S. Food and Drug Administration. (2023). Code of Federal Regulations, Title 21, Part 314: Applications for FDA approval to market a new drug. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-D/part-314

4. Merck & Co., Inc. (2024). 2023 annual report. https://www.merck.com/investor-relations/annual-reports/