List of Excipients in Branded Drug DELSTRIGO

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Merck Sharp & Dohme LLC	DELSTRIGO	doravirine, lamivudine, and tenofovir disoproxil fumarate	0006-5007	CARNAUBA WAX	2036-11-29
Merck Sharp & Dohme LLC	DELSTRIGO	doravirine, lamivudine, and tenofovir disoproxil fumarate	0006-5007	CELLULOSE, MICROCRYSTALLINE	2036-11-29
Merck Sharp & Dohme LLC	DELSTRIGO	doravirine, lamivudine, and tenofovir disoproxil fumarate	0006-5007	CROSCARMELLOSE SODIUM	2036-11-29
Merck Sharp & Dohme LLC	DELSTRIGO	doravirine, lamivudine, and tenofovir disoproxil fumarate	0006-5007	FERRIC OXIDE YELLOW	2036-11-29
Merck Sharp & Dohme LLC	DELSTRIGO	doravirine, lamivudine, and tenofovir disoproxil fumarate	0006-5007	HYPROMELLOSE	2036-11-29
Merck Sharp & Dohme LLC	DELSTRIGO	doravirine, lamivudine, and tenofovir disoproxil fumarate	0006-5007	HYPROMELLOSE ACETATE SUCCINATE 06081224	2036-11-29

DELSTRIGO Excipient Strategy and Commercial Opportunities

Last updated: August 3, 2026

Delstrigo is a fixed-dose, once-daily tablet combining doravirine, lamivudine, and tenofovir disoproxil fumarate, marketed by Merck as an oral HIV-1 treatment. Its excipient system uses established pharmaceutical ingredients rather than a novel delivery technology. The commercial opportunity is therefore concentrated in generic formulation development, bioequivalence execution, supply-chain control, and differentiated lifecycle products rather than in proprietary excipient claims.

The largest technical challenge is combining three active pharmaceutical ingredients with different dose levels, physicochemical properties, and stability requirements in one film-coated tablet. A successful competitor must reproduce the reference product's performance without necessarily copying its qualitative or quantitative excipient composition.

What is Delstrigo and how is it formulated?

Delstrigo contains 100 mg of doravirine, 300 mg of lamivudine, and 300 mg of tenofovir disoproxil fumarate per tablet. The FDA approved Delstrigo on August 30, 2018, for the treatment of HIV-1 infection in adults and pediatric patients weighing at least 35 kg who have no prior antiretroviral treatment history or are replacing an existing antiretroviral regimen under specified conditions.[1]

What are the active ingredients in Delstrigo?

Component	Amount per tablet	Role
Doravirine	100 mg	Non-nucleoside reverse transcriptase inhibitor
Lamivudine	300 mg	Nucleoside reverse transcriptase inhibitor
Tenofovir disoproxil fumarate	300 mg	Nucleotide reverse transcriptase inhibitor

The total active load is 700 mg before accounting for excipients and coating. That load creates a meaningful tablet-size constraint, particularly because the product must remain suitable for once-daily administration and commercial high-volume manufacturing.

What excipients are used in Delstrigo?

The FDA prescribing information identifies the following inactive ingredients for Delstrigo tablets:

• Colloidal silicon dioxide
• Croscarmellose sodium
• Hypromellose
• Lactose monohydrate
• Magnesium stearate
• Microcrystalline cellulose
• Sodium lauryl sulfate
• Titanium dioxide
• Triacetin
• Iron oxide yellow

The exact quantitative composition and manufacturing process are not disclosed in the public prescribing information. The listed materials indicate a conventional immediate-release tablet architecture with a compression aid, superdisintegrant, lubricant, glidant, surfactant, polymeric film former, plasticizer, and colorants.[1]

How does the Delstrigo excipient system work?

The formulation appears designed to manage high active loading, rapid disintegration, powder flow, lubrication, and film-coating performance in a single tablet.

Why is microcrystalline cellulose used?

Microcrystalline cellulose is likely a principal diluent and compression aid. It improves tablet mechanical strength and supports direct compression or a related low-complexity tableting process. In a three-drug formulation, it can help offset differences in particle size, density, and compressibility among the active ingredients.

Microcrystalline cellulose also permits adjustment of tablet weight without adding a pharmacologically active component. That flexibility is valuable when optimizing hardness, friability, disintegration, and dissolution.

What is the role of lactose monohydrate?

Lactose monohydrate is a common filler and can improve powder handling and tablet mass balance. Its use creates several development considerations:

• Lactose is a reducing sugar and must be evaluated for compatibility with susceptible active ingredients or impurities.
• Moisture content and grade selection can affect flow and dissolution.
• Supplier changes can alter particle-size distribution and compaction behavior.
• Lactose intolerance concerns generally do not prevent use at the low excipient quantities found in tablets, but labeling and market positioning may still matter.

Why are croscarmellose sodium and sodium lauryl sulfate included?

Croscarmellose sodium is a superdisintegrant. It promotes rapid tablet breakup after administration, which supports immediate-release dissolution.

Sodium lauryl sulfate is a surfactant and wetting agent. It can improve liquid penetration and support dissolution of poorly wettable components. Its presence is especially relevant in a multidrug formulation where one or more actives may have different wettability or dissolution behavior.

A generic developer could attempt to replace sodium lauryl sulfate with another surfactant, but any substitution would require comparative dissolution and bioequivalence risk assessment. Surfactant changes can alter wetting, particle dispersion, gastrointestinal dissolution, and the release profile of all three actives.

What are the roles of magnesium stearate and colloidal silicon dioxide?

Magnesium stearate is a lubricant that reduces adhesion to punches and dies. Excessive lubrication can weaken tablets or slow dissolution, so blending time and lubricant concentration are critical process variables.

Colloidal silicon dioxide improves powder flow and can reduce segregation in a formulation containing multiple active ingredients and excipient grades. It may also help manage low-dose doravirine distribution relative to the higher-dose lamivudine and tenofovir disoproxil fumarate components.

Why does Delstrigo use a film coat?

Hypromellose provides the principal film-forming polymer. Triacetin acts as a plasticizer, improving coating flexibility and reducing cracking. Titanium dioxide and iron oxide yellow provide opacity and color.

The film coat can support:

• Product identification
• Swallowability
• Protection from abrasion
• Visual differentiation from other antiretroviral products
• Limited protection against light and handling exposure

The coating is unlikely to provide a meaningful controlled-release function. Delstrigo is an immediate-release, once-daily tablet.

What formulation barriers face a Delstrigo generic?

The main barriers are technical rather than based on novel excipient exclusivity.

Three active ingredients create content-uniformity risk

Doravirine is present at 100 mg, while lamivudine and tenofovir disoproxil fumarate are each present at 300 mg. The lower dose of doravirine increases the risk of segregation and content-uniformity failures during blending and compression.

A generic manufacturer may need:

• Controlled particle-size distributions
• Ordered mixing or preblending
• Granulation of selected components
• Segregation studies during hopper discharge
• In-process weight and assay controls
• Dedicated sampling plans for doravirine distribution

The formulation cannot be evaluated only on total tablet assay. Uniformity of each active ingredient is critical.

Dissolution must be controlled across three actives

A generic tablet may match the reference product's total dissolution while showing different release behavior for individual active ingredients. Development teams should compare dissolution profiles for doravirine, lamivudine, and tenofovir disoproxil fumarate across relevant pH conditions and agitation settings.

The most commercially efficient formulation is usually the one that achieves reference-like dissolution without relying on complex granulation or unusually expensive excipient grades.

Lubrication and compression are potential failure points

High active loading can require stronger compaction. Excess magnesium stearate or prolonged lubrication may reduce tablet strength or delay dissolution. Insufficient lubrication can produce sticking, picking, and manufacturing downtime.

The commercial formulation target is a narrow process window that preserves:

• Tablet hardness
• Low friability
• Rapid disintegration
• Consistent dissolution
• Stable long-term performance

What generic opportunities exist for Delstrigo?

The principal opportunity is an ANDA for the same strength and dosage form. Delstrigo is a small-molecule product, so it is subject to the abbreviated new drug application pathway rather than the biosimilar pathway.

Does Delstrigo face biosimilar risk?

No. Delstrigo is not a biologic. Biosimilar regulation under section 351(k) of the Public Health Service Act does not apply. A competitor would generally pursue an ANDA under section 505(j) of the Federal Food, Drug, and Cosmetic Act if it can demonstrate pharmaceutical equivalence and bioequivalence.[2]

What is the regulatory status of Delstrigo?

Regulatory issue	Status
Product type	Small-molecule fixed-dose combination
Dosage form	Film-coated oral tablet
Strength	100 mg/300 mg/300 mg
FDA approval	August 30, 2018
Likely generic route	ANDA under section 505(j)
Biosimilar pathway	Not applicable
Reference product	Delstrigo tablets
FDA exclusivity category	New chemical entity exclusivity initially applied to doravirine-containing product

Doravirine's five-year new chemical entity exclusivity period began with the 2018 approval and would ordinarily have ended in 2023, subject to any applicable pediatric extension or other regulatory event. Patent protection, not NCE exclusivity, is the more relevant barrier for later generic entry.[1][3]

Can a generic use different excipients?

Yes. An ANDA applicant generally does not need to duplicate the reference product's inactive ingredients. The applicant must demonstrate that the proposed formulation is pharmaceutically equivalent, bioequivalent, adequately controlled, and acceptable from a quality and safety perspective.

A different excipient strategy can reduce cost or improve manufacturability, but it increases the need for:

• Comparative dissolution
• Excipient compatibility testing
• Stability studies
• Impurity monitoring
• Bioequivalence risk management
• Assessment of hypersensitivity or intolerance concerns

The strongest commercial strategy is usually a conservative excipient substitution plan, not wholesale reformulation.

What patents protect Delstrigo?

Delstrigo's patent protection is likely distributed across the active ingredient, combination, formulation, and method-of-use portfolios rather than a single excipient patent.

Public FDA Orange Book records are the controlling source for patents listed against the reference product. The Orange Book should be reviewed for:

• Delstrigo product listings
• Patent numbers
• Expiration dates
• Pediatric extensions
• Patent-use codes
• Any delisting or litigation-related changes

Excipient ingredients such as lactose, microcrystalline cellulose, magnesium stearate, and hypromellose are established materials and generally do not create an independent exclusivity barrier. The relevant IP risks are more likely to involve:

• Doravirine composition-of-matter rights
• Combination claims covering doravirine with nucleoside or nucleotide reverse transcriptase inhibitors
• Pharmaceutical composition claims
• Treatment methods for HIV-1 infection
• Solid-state, crystallinity, or manufacturing claims
• Specific formulation or dosage regimens

What patent claims are most relevant to an ANDA applicant?

An ANDA applicant must analyze each listed patent and determine whether to file:

• Paragraph I certification, if no patent information is listed
• Paragraph II certification, if the patent has expired
• Paragraph III certification, if the applicant will wait until expiration
• Paragraph IV certification, if the patent is invalid, unenforceable, or not infringed

A Paragraph IV filing can trigger patent litigation if the reference sponsor files suit within the statutory period. That litigation can delay approval through the statutory 30-month stay, subject to court decisions and regulatory events.[2]

Are formulation patents the principal Delstrigo risk?

Probably not. The public excipient profile is conventional, which reduces the likelihood that a generic developer would infringe merely by using similar inactive ingredients. The greater risk is an active-ingredient, combination, method-of-use, or manufacturing patent that captures the product or its use in HIV therapy.

A formulation workaround may still be needed if a patent claims a specific ratio, dosage form, release profile, solid form, or excipient combination. The practical value of such patents depends on claim breadth and whether the proposed ANDA formulation can avoid the claimed limitations.

When does Delstrigo lose exclusivity?

Delstrigo's regulatory exclusivity and patent exclusivity should be analyzed separately.

Exclusivity category	Commercial significance
NCE exclusivity	Initially blocked ANDA submission for five years, subject to statutory exceptions
Pediatric exclusivity	May add six months to qualifying regulatory or patent protections
Orange Book patents	Can delay approval or generate Paragraph IV litigation
Data exclusivity	Less important than patent barriers for a small-molecule product after NCE expiry
Formulation exclusivity	Depends on the existence and enforceability of listed or unlisted claims
Trademark protection	Does not block an ANDA but affects generic naming and market presentation

The end of NCE exclusivity does not establish the first possible commercial generic launch. The launch date depends on patent expiration, litigation outcomes, settlement terms, ANDA approval, tentative approval, and the applicant's commercial strategy.

Which companies are challenging Delstrigo?

A definitive list of active challengers requires current FDA Orange Book records, ANDA litigation dockets, and Paragraph IV notices. The relevant competitive set includes:

1. Generic manufacturers with ANDAs for doravirine/lamivudine/tenofovir disoproxil fumarate.
2. Companies developing separate doravirine, lamivudine, and tenofovir products for regimen substitution.
3. HIV-focused companies offering alternative single-tablet regimens.
4. Contract development and manufacturing organizations developing fixed-dose combinations for regional markets.

The existence of an ANDA does not establish approval, litigation settlement, or commercial launch. Those events must be tracked independently.

What commercial opportunities exist beyond a conventional generic?

Authorized generic opportunity

Merck could launch an authorized generic or license a third party to distribute a product equivalent to Delstrigo. An authorized generic can compete with Paragraph IV entrants while preserving supply-chain control and price segmentation.

Regional fixed-dose combination licensing

A local or regional manufacturer could seek rights to manufacture or commercialize the combination outside the United States. Opportunities may be stronger in markets where HIV treatment programs favor once-daily fixed-dose tablets and where procurement organizations prioritize regimen simplification.

Key licensing issues include:

• Territory
• Patent status by country
• Regulatory responsibility
• Active pharmaceutical ingredient sourcing
• Pharmacovigilance
• Government procurement pricing
• Technology-transfer obligations

Excipient and process optimization

A developer could pursue a lower-cost tablet using:

• Direct compression
• Co-processed excipients
• Lower-cost equivalent grades
• Reduced coating weight
• Improved powder-flow control
• Continuous manufacturing
• More efficient packaging

The commercial value must be balanced against bioequivalence and stability risk. A small reduction in excipient cost has limited value if it increases batch failure rates or requires additional clinical studies.

Alternative presentations

Potential lifecycle concepts include:

• Smaller tablets
• Sprinkle or dispersible formats
• Pediatric strengths
• Blister packaging
• Adherence-oriented packaging
• Fixed-dose combinations with other antiretroviral backbones

These concepts would require regulatory and clinical assessment. They also face commercial competition from established single-tablet HIV regimens.

How does Delstrigo compare with competing HIV fixed-dose combinations?

Delstrigo competes primarily on once-daily administration, three-drug consolidation, and doravirine's clinical positioning. It competes against products containing integrase strand transfer inhibitors, including bictegravir- and dolutegravir-based regimens, as well as other non-nucleoside reverse transcriptase inhibitor combinations.

Commercial factor	Delstrigo implication
Dosing	Once daily
Tablet burden	One tablet
Generic complexity	Higher than single-API products because of three active ingredients
Excipient complexity	Moderate, with conventional excipients
Differentiation	Doravirine-based regimen and fixed-dose convenience
Biosimilar exposure	None
Generic substitution	Potentially limited by clinical preference and formulary positioning
Procurement opportunity	Stronger where low-cost fixed-dose HIV regimens are prioritized

A Delstrigo generic must compete against both an eventual same-product generic and alternative regimens. Price alone may not determine market share. Prescriber familiarity, guideline positioning, drug-interaction considerations, payer formulary status, and procurement contracts will influence uptake.

What is the revenue exposure from Delstrigo generic entry?

Revenue exposure depends on the geographic mix of sales, the share of patients receiving Delstrigo rather than other Merck HIV products, the timing of generic entry, and the number of approved competitors.

A practical scenario framework is:

Scenario	Entry condition	Likely commercial effect
Delayed entry	Patent litigation or settlement delays approval	Longer branded revenue protection
Single generic	One approved entrant with limited supply	Moderate price erosion
Multi-generic entry	Several ANDAs launch near the same time	Rapid price and share erosion
Authorized generic	Sponsor-backed competitor launches	Earlier price segmentation
Regional erosion	Generic entry outside the United States precedes U.S. entry	Country-specific revenue pressure

The greatest price erosion risk arises when several manufacturers launch simultaneously after patent barriers fall. Manufacturing reliability and API access will determine whether nominally approved competitors can supply the market at scale.

What manufacturing and IP barriers matter most?

The highest-value barriers are process control and active-ingredient sourcing, not the basic excipients.

Manufacturing barriers

A commercial developer must control:

• Doravirine distribution at the lower dose
• Blend uniformity across three APIs
• Compression behavior at high active loading
• Lubricant sensitivity
• Dissolution across all actives
• Film-coat uniformity
• Long-term stability and impurity growth
• API cost and supply continuity

Geographic coverage

Patent rights and regulatory exclusivity are territorial. A formulation cleared in the United States may still face patent restrictions in Europe, Japan, Canada, Latin America, or key procurement markets. Country-level analysis should distinguish:

• Composition-of-matter expiration
• Combination patents
• National patent-term adjustments
• Supplementary protection certificates
• Pediatric extensions
• Local registration requirements
• Government-use or public-health licensing mechanisms

How strong is the Delstrigo patent estate?

The estate's practical strength depends on whether enforceable claims cover the active combination and whether a generic can design around them. Conventional excipients reduce the likelihood of a broad, commercially decisive excipient barrier. Stronger protection would arise from claims that capture the combination itself, a necessary dosage regimen, or a manufacturing process that competitors cannot readily avoid.

For investment and licensing purposes, the decisive diligence points are:

1. Current Orange Book patent listings.
2. Patent expiration and pediatric-extension calculations.
3. Paragraph IV certifications and litigation status.
4. Settlement agreements and launch dates.
5. Patent claims covering doravirine and the fixed-dose combination.
6. Regulatory exclusivity for any later-approved strengths or populations.
7. Actual ANDA approval and launch capacity.

Key Takeaways

• Delstrigo is a 100 mg/300 mg/300 mg fixed-dose tablet containing doravirine, lamivudine, and tenofovir disoproxil fumarate.
• Its excipients are conventional and include microcrystalline cellulose, lactose monohydrate, croscarmellose sodium, magnesium stearate, colloidal silicon dioxide, sodium lauryl sulfate, hypromellose, triacetin, titanium dioxide, and iron oxide yellow.
• The principal formulation challenge is uniform delivery of three active ingredients with different dose levels and material properties.
• Delstrigo is a small-molecule product and faces ANDA, not biosimilar, competition.
• Excipient patents are unlikely to be the principal barrier. Active-ingredient, combination, method-of-use, formulation, and manufacturing claims are more relevant.
• The leading generic opportunity is a reference-like immediate-release tablet using a conservative excipient substitution strategy.
• Commercial upside also exists in authorized generic supply, regional licensing, adherence packaging, pediatric presentations, and process-cost reduction.
• Launch timing depends on Orange Book patents, Paragraph IV activity, litigation, settlements, and ANDA approval, not solely on expiration of NCE exclusivity.

FAQs

Can a generic Delstrigo use lactose-free excipients?

Yes. An ANDA applicant can generally replace lactose if the alternative formulation meets quality, stability, dissolution, and bioequivalence requirements. A lactose-free product could support selected patient or procurement preferences, but it would not by itself create a new regulatory exclusivity period.

Is Delstrigo suitable for direct-compression generic development?

It may be suitable, but the decision depends on API particle properties, flow, segregation behavior, compressibility, and dissolution. Doravirine's lower dose relative to the other two active ingredients makes blend uniformity a central development risk.

Could an excipient supplier obtain a patent around a Delstrigo generic?

Potentially, but a patent would need to claim a novel and non-obvious composition, process, or performance advantage. The use of established excipients alone is unlikely to provide meaningful blocking protection.

Does a Delstrigo generic need clinical efficacy trials?

A conventional ANDA generally relies on pharmaceutical equivalence, product quality, and bioequivalence rather than repeating full efficacy trials. The required evidence depends on FDA standards for the reference product and the proposed formulation.

What is the most commercially valuable differentiation for a Delstrigo generic?

The strongest differentiators are reliable supply, lower cost, regulatory timing, procurement access, and a formulation that reduces tablet weight or manufacturing complexity without increasing bioequivalence risk.

References

1. U.S. Food and Drug Administration. (2018). Delstrigo (doravirine, lamivudine, and tenofovir disoproxil fumarate) prescribing information. Merck Sharp & Dohme LLC.

2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, 44th ed.: Orange Book. U.S. Department of Health and Human Services.

3. U.S. Food and Drug Administration. (2024). Guidance for industry: Abbreviated new drug application submissions. U.S. Department of Health and Human Services.