List of Excipients in Branded Drug OPSUMIT

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Actelion Pharmaceuticals US Inc	OPSUMIT	macitentan	66215-501	CELLULOSE, MICROCRYSTALLINE
Actelion Pharmaceuticals US Inc	OPSUMIT	macitentan	66215-501	LACTOSE MONOHYDRATE
Actelion Pharmaceuticals US Inc	OPSUMIT	macitentan	66215-501	MAGNESIUM STEARATE
Actelion Pharmaceuticals US Inc	OPSUMIT	macitentan	66215-501	POLYSORBATE 80
Actelion Pharmaceuticals US Inc	OPSUMIT	macitentan	66215-501	POLYVINYL ALCOHOL
Actelion Pharmaceuticals US Inc	OPSUMIT	macitentan	66215-501	POVIDONE
Actelion Pharmaceuticals US Inc	OPSUMIT	macitentan	66215-501	SODIUM STARCH GLYCOLATE TYPE A POTATO

Opsumit Excipient Strategy and Commercial Opportunities for Macitentan

Last updated: August 9, 2026

Opsumit is a once-daily, 10 mg film-coated macitentan tablet approved for pulmonary arterial hypertension. Its excipient system is commercially attractive because it combines a low-dose active ingredient with dissolution-supporting surfactant, conventional tablet-processing aids, and a simple film coat. The largest opportunities are generic formulation development, excipient substitution, supply-chain qualification, and differentiated fixed-dose or modified-release products.

What excipients are used in Opsumit tablets?

The Opsumit 10 mg tablet uses a conventional immediate-release formulation. The U.S. prescribing information identifies the following inactive ingredients:

Formulation function	Opsumit excipient
Diluent and compressibility aid	Lactose monohydrate
Filler and tablet-processing aid	Microcrystalline cellulose
Wetting and solubilization aid	Poloxamer 188
Disintegrant	Sodium starch glycolate
Lubricant	Magnesium stearate
Film-forming polymer	Polyvinyl alcohol
Opacifier and pigment	Titanium dioxide
Anti-tacking and coating aid	Talc
Coating stabilizer	Lecithin
Suspending or rheology modifier	Xanthan gum

The exact inactive-ingredient listing should be read with the current FDA label and DailyMed record because excipient disclosures can differ by market and manufacturing presentation (FDA, 2024a; DailyMed, 2024).

Why is poloxamer 188 strategically important?

Macitentan is a low-dose, poorly water-soluble small molecule. Poloxamer 188 can improve wetting and help maintain consistent dissolution by reducing interfacial tension between the drug particles and gastrointestinal fluid. In a generic formulation, this creates an important performance variable:

• Too little surfactant may reduce dissolution robustness.
• Too much may alter powder flow, tablet hardness, disintegration, or stability.
• Supplier grade, peroxide content, particle size, and residual moisture can affect batch performance.

Poloxamer 188 also creates a potential supply-chain dependency. A generic sponsor may need a qualified second source or an alternative surfactant system before commercial launch.

What role does lactose monohydrate play?

Lactose is primarily a diluent. It expands the tablet mass from the small 10 mg macitentan dose to a manufacturable tablet size and supports compression. Lactose can also affect:

• Blend uniformity
• Tablet hardness
• Moisture uptake
• Dissolution
• Maillard-type compatibility risk with reactive drug substances or amine-containing excipients

A generic manufacturer may evaluate anhydrous lactose, spray-dried lactose, mannitol, or a lactose-cellulose co-processed excipient. Any substitution would require comparative development work because the excipient is part of the overall dissolution and content-uniformity design.

How does the Opsumit formulation support commercial generic development?

The formulation is technically accessible compared with a complex injectable, depot, inhaled, or biologic product. It uses standard oral solid-dose excipients and a conventional film-coating process. That lowers the manufacturing barrier for an ANDA applicant, although macitentan’s low dose and solubility profile create meaningful development risks.

Generic formulation design priorities

A generic manufacturer would typically prioritize:

1. Content uniformity: The 10 mg dose is a small fraction of total tablet weight, increasing the importance of ordered mixing, geometric dilution, and segregation control.
2. Dissolution matching: The formulation must meet the applicable U.S. dissolution specification and demonstrate equivalence to the reference product.
3. Disintegration: Sodium starch glycolate level and distribution can materially affect release.
4. Surfactant control: Poloxamer 188 concentration and grade can influence dissolution and stability.
5. Film-coat performance: The coating must preserve tablet integrity without creating a meaningful dissolution delay.
6. Stability: Moisture, peroxide impurities, lubricant exposure, and coating-process conditions require control.

The principal commercial opportunity is a Q1/Q2-style formulation using the same or functionally equivalent excipient categories, followed by targeted process optimization.

What excipient substitutions could create commercial opportunities?

The most realistic opportunities are not new excipient inventions. They are qualified substitution platforms that improve cost, availability, manufacturability, or regulatory resilience.

Opsumit function	Reference approach	Potential commercial alternative
Dilution	Lactose monohydrate	Mannitol, anhydrous lactose, spray-dried lactose, co-processed lactose-cellulose
Compression	Microcrystalline cellulose	Silicified MCC, low-moisture MCC, co-processed filler-binder
Wetting	Poloxamer 188	Alternative nonionic surfactant or optimized poloxamer grade
Disintegration	Sodium starch glycolate	Crospovidone, croscarmellose sodium, low-substituted hydroxypropyl cellulose
Lubrication	Magnesium stearate	Sodium stearyl fumarate or optimized magnesium-stearate process
Coating	Polyvinyl alcohol system	Hypromellose or another immediate-release film-coat platform
Pigmentation	Titanium dioxide and talc	Market-specific pigment and coating system

Each substitution creates a new formulation and regulatory package. For an ANDA, the commercial value is highest when the change reduces supply risk without changing the release mechanism or introducing a new safety issue.

Which excipient suppliers are commercially relevant?

Relevant suppliers may include major producers of lactose, microcrystalline cellulose, poloxamers, superdisintegrants, lubricants, and film-coating systems. The opportunity is strongest for suppliers that can provide:

• Compendial material
• Multiple manufacturing sites
• Low extractables and elemental impurity profiles
• Consistent particle-size distribution
• Nitrosamine and peroxide-control documentation
• Regulatory support files
• Reliable global supply
• Change-control commitments compatible with pharmaceutical customers

For a low-dose tablet, suppliers with technical formulation support may capture more value than suppliers competing only on kilogram price.

What patents protect Opsumit and its formulation?

Opsumit contains macitentan, a small-molecule endothelin receptor antagonist. Patent exposure generally divides into four categories:

Patent category	Relevance to Opsumit
Macitentan compound patents	Protect the active pharmaceutical ingredient
Therapeutic-use patents	Cover treatment of pulmonary arterial hypertension or related conditions
Pharmaceutical-composition patents	May cover dosage forms, excipient combinations, or release characteristics
Manufacturing patents	May cover synthesis, intermediates, crystallization, or purification

The FDA Orange Book is the controlling public source for patents submitted by the NDA holder for approved drug products (FDA, 2024b). The Opsumit label identifies Janssen Pharmaceuticals as the U.S. sponsor and macitentan as the active ingredient (FDA, 2024a).

A formulation developer should not assume that a conventional excipient substitution avoids all patent exposure. A patent may claim a composition by broad functional language, a specific dissolution profile, a process condition, or a combination of macitentan with a solubilizer. Conversely, a patent directed only to a narrow excipient combination may leave room for a non-infringing formulation using different excipient classes.

Are excipient patents likely to be the main barrier?

Usually, no. The main barriers are likely to be:

• Active-ingredient patent scope
• Method-of-use patents
• Orange Book-listed formulation patents
• ANDA certification strategy
• Bioequivalence and dissolution performance
• Macitentan API sourcing
• Manufacturing process control

Excipient-related patents matter when they claim a specific composition or release profile. They are less likely to block a product based solely on use of a standard compendial excipient.

When does Opsumit lose exclusivity?

Opsumit received U.S. approval in 2013. Its five-year new-chemical-entity exclusivity period therefore expired in 2018, subject to any applicable pediatric extension or regulatory adjustment. Patent protection can extend beyond regulatory exclusivity and remains the more important commercial variable for generic entry.

Milestone	Timing
U.S. approval of Opsumit	2013
Standard NCE exclusivity	Approximately 2013-2018
Potential pediatric extension	Depends on FDA-recognized pediatric study completion
Patent-driven generic entry	Depends on the applicable patent expiration dates and litigation outcomes
ANDA launch	Subject to certification, litigation, settlement, and regulatory approval

The practical loss-of-exclusivity date is therefore not the NCE-exclusivity date. It is the earliest date on which an approved ANDA can legally launch after accounting for valid patents, 30-month litigation stays, settlements, pediatric exclusivity, and any authorized early-entry provisions.

What is the Orange Book status of Opsumit?

Opsumit is an NDA-approved small-molecule drug listed in FDA prescription-drug databases. It is not a biologic and does not use the biosimilar pathway. Generic competitors would generally pursue abbreviated new drug applications rather than biosimilar applications.

The Orange Book analysis should address:

• Listed patents associated with the Opsumit NDA
• Patent use codes
• Expiration dates
• Pediatric exclusivity
• Whether a patent is eligible for a Paragraph IV certification
• Whether a listed patent has already been challenged or delisted

The Orange Book does not capture every potentially relevant patent. Manufacturing patents, foreign patents, non-listed formulation patents, and certain method-of-use rights may require separate patent-database and litigation review.

Which companies are challenging Opsumit?

Public FDA materials do not establish a named Paragraph IV challenger in the sources cited here. A complete competitive review should distinguish among:

• Filed ANDAs
• Tentative approvals
• Final approvals
• Paragraph IV notices
• Declaratory-judgment actions
• Patent litigation under the Hatch-Waxman Act
• Settlement agreements with authorized launch dates

The absence of a publicly confirmed challenger in a source set does not establish that no challenge has been filed. For commercial planning, the relevant signal is an ANDA approval combined with a legally available launch date.

What generic entry risks exist for Opsumit?

Generic entry risk is moderate to high from a formulation perspective because the product is an immediate-release tablet with familiar excipients. The risk is lower if active-ingredient or method-of-use patents remain enforceable.

Early generic-launch scenarios

Scenario	Commercial effect
No ANDA challenge before key patent expiry	Delayed generic entry and continued branded pricing
Paragraph IV filing without settlement	Litigation risk and possible 30-month stay
Settlement with licensed early entry	Predictable erosion beginning on the agreed launch date
Authorized generic launch	Faster price pressure and reduced value of first independent generic entry
Multiple ANDA approvals	Rapid price erosion after launch
Single first-filer	Potential 180-day exclusivity period, subject to forfeiture rules

An excipient supplier can benefit from all scenarios because development work often begins years before commercial approval. The most valuable position is usually early supply qualification with one or more ANDA sponsors.

How strong is the Opsumit patent estate?

The estate should be assessed by claim breadth, remaining term, Orange Book listing status, prosecution history, and litigation record. A strong estate would include multiple independent layers:

• Composition-of-matter protection
• Broad therapeutic-use protection
• Narrower formulation or dosage-form protection
• Manufacturing and solid-state protection

A weaker estate would depend on narrow method-of-use claims or a single formulation patent that can be designed around through excipient substitution.

For excipient businesses, the relevant question is whether a formulation can meet reference-product performance without practicing an issued claim. A design-around review should map each claim element against:

• Macitentan concentration
• Excipient identity
• Excipient concentration
• Particle characteristics
• Dissolution profile
• Tablet architecture
• Coating composition
• Manufacturing steps

What formulation opportunities exist beyond the current Opsumit tablet?

The strongest commercial opportunities are incremental products rather than direct tablet copies.

Pediatric and low-dose formulations

A dispersible, orodispersible, mini-tablet, or liquid formulation could improve administration for patients unable to swallow a conventional film-coated tablet. Such products would require new stability, dosing accuracy, palatability, and device studies.

Fixed-dose combinations

A fixed-dose combination with another pulmonary arterial hypertension therapy could reduce pill burden. The technical barriers include chemical compatibility, dose-ratio selection, dissolution control, and clinical justification. Combination products may also face separate patent and regulatory protection.

Modified-release macitentan

Modified release could reduce peak-to-trough variation or support less frequent administration. The commercial case is weaker than for a conventional generic because clinical development and formulation complexity increase substantially.

Global-market excipient variants

Different markets may have restrictions or preferences concerning titanium dioxide, lactose, talc, or allergen-related declarations. A global excipient platform that preserves bioequivalence while meeting regional requirements can reduce product-line complexity.

What FDA regulatory status applies to excipient changes?

An excipient substitution in an approved product may require a postapproval supplement, depending on the nature and extent of the change. For an ANDA, the formulation must satisfy sameness or permitted difference requirements and demonstrate bioequivalence under FDA rules (FDA, 2024c).

Key regulatory controls include:

• Excipient compendial status
• Maximum daily exposure
• Novel-excipient justification
• Drug-excipient compatibility
• Dissolution comparison
• Impurity and elemental impurity controls
• Nitrosamine risk assessment
• Stability data
• Manufacturing-process validation

A conventional excipient substitution is commercially preferable because it reduces toxicology and regulatory burden.

What licensing deals affect the Opsumit excipient opportunity?

The principal commercial rights relate to macitentan, Opsumit, and any authorized generic or settlement arrangement. Excipient suppliers typically do not need a direct license to sell standard compendial excipients. They may need contractual arrangements covering:

• Customer-specific grades
• Joint development
• Exclusivity by territory or indication
• Regulatory master-file access
• Technical-transfer rights
• Supply continuity
• Alternate-site qualification
• Confidential formulation data

A co-development agreement is most valuable when the supplier contributes formulation know-how, not merely raw material. The contract should define ownership of formulation inventions, process improvements, analytical methods, and regulatory data.

What is the revenue exposure from Opsumit generic entry?

Opsumit is a high-value specialty product in pulmonary arterial hypertension. Revenue exposure depends on:

• U.S. versus international sales mix
• Number of generic entrants
• Authorized generic strategy
• Payer substitution
• Patent-settlement timing
• Physician switching behavior
• Combination therapy use
• Patient-support programs

For excipient suppliers, the addressable market is smaller than the branded-drug revenue but more durable. A successful supplier can sell into:

• Reference-product manufacturing
• ANDA development
• Clinical and registration batches
• Commercial generic supply
• Multiple geographic markets
• Reformulated pediatric or combination products

Key Takeaways

• Opsumit is a 10 mg immediate-release macitentan film-coated tablet.
• Its formulation uses conventional excipients, with poloxamer 188 likely important for wetting and dissolution performance.
• Low-dose content uniformity and macitentan dissolution are the main technical development risks.
• The strongest excipient opportunities are qualified substitutions, dual sourcing, co-processed fillers, superdisintegrants, and film-coating systems.
• Opsumit’s NCE exclusivity began in 2013 and expired after the standard five-year period, but patent-driven entry remains the key commercial issue.
• Generic applicants would use the ANDA pathway, not the biosimilar pathway.
• Excipient substitution can support design-around strategies, but each composition and process must be mapped against relevant patent claims.
• Pediatric, fixed-dose, dispersible, and global-market formulations offer higher-value opportunities than a simple commodity excipient sale.

FAQs

Can lactose-free excipients be used in a generic Opsumit tablet?

Yes. Mannitol, anhydrous lactose, or other suitable diluents may be evaluated, but the alternative must support content uniformity, compression, dissolution, stability, and FDA regulatory requirements.

Is poloxamer 188 essential to macitentan bioequivalence?

Not necessarily. A different wetting or solubilization approach may be acceptable if the finished product meets applicable dissolution and bioequivalence requirements.

Could a co-processed excipient reduce Opsumit manufacturing costs?

Yes. A co-processed filler-binder or disintegrant platform could improve flow, compression, and blend uniformity, especially in a low-dose formulation. The tradeoff is additional development and comparability work.

Does Opsumit have biosimilar competition?

No. Opsumit contains macitentan, a chemically synthesized small molecule. Competition would generally come through ANDAs for generic macitentan tablets.

Can a new excipient formulation obtain separate patent protection?

Potentially. A patent may be available for a novel composition, dissolution profile, manufacturing process, solid form, pediatric dosage form, or fixed-dose combination if the claims satisfy patentability and written-description requirements.

References

1. DailyMed. (2024). Opsumit- macitentan tablet, film coated: Prescribing information. U.S. National Library of Medicine.

2. U.S. Food and Drug Administration. (2024a). Opsumit (macitentan) prescribing information. FDA.

3. U.S. Food and Drug Administration. (2024b). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.

4. U.S. Food and Drug Administration. (2024c). Abbreviated new drug application submissions: Stability and bioequivalence requirements. FDA.