List of Excipients in Branded Drug REMODULIN

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
United Therapeutics Corporation	REMODULIN	treprostinil	66302-101	HYDROCHLORIC ACID
United Therapeutics Corporation	REMODULIN	treprostinil	66302-101	METACRESOL
United Therapeutics Corporation	REMODULIN	treprostinil	66302-101	SODIUM CHLORIDE
United Therapeutics Corporation	REMODULIN	treprostinil	66302-101	SODIUM HYDROXIDE
United Therapeutics Corporation	REMODULIN	treprostinil	66302-101	TRISODIUM CITRATE DIHYDRATE
United Therapeutics Corporation	REMODULIN	treprostinil	66302-101	WATER
United Therapeutics Corporation	REMODULIN	treprostinil	66302-111	HYDROCHLORIC ACID

Remodulin Excipient Strategy and Commercial Opportunities for Treprostinil Injection

Last updated: August 16, 2026

Remodulin is a parenteral treprostinil sodium product for pulmonary arterial hypertension. Its formulation uses a small excipient system: metacresol as preservative, sodium chloride for tonicity, water for injection, and pH adjustment with acid or base. The main commercial opportunities are preservative-free presentations, ready-to-use containers, higher-concentration products, less painful administration, extended in-use stability, and device-compatible delivery systems.

What excipients are used in Remodulin injection?

The Remodulin formulation contains treprostinil sodium, metacresol, sodium chloride, and water for injection. The commercial product is supplied in multiple concentrations for subcutaneous or intravenous infusion.

Formulation attribute	Remodulin position
Active ingredient	Treprostinil sodium
Therapeutic category	Prostacyclin-class vasodilator
FDA indication	Pulmonary arterial hypertension
Administration	Continuous subcutaneous or intravenous infusion
Commercial strengths	1 mg/mL, 2.5 mg/mL, 5 mg/mL, and 10 mg/mL
Preservative	Metacresol
Tonicity agent	Sodium chloride
Vehicle	Water for injection
pH control	Hydrochloric acid and/or sodium hydroxide
Dosage form	Multidose sterile injection
Original NDA	NDA 21-272
FDA approval	2002
Sponsor	United Therapeutics Corporation

The formulation is designed for multidose use during continuous infusion. Metacresol supports antimicrobial preservation after vial entry, while sodium chloride helps control tonicity. The formulation does not require a complex surfactant, lipid, polymer, or co-solvent system, which reduces formulation complexity but leaves room for differentiated products based on tolerability and administration convenience [1].

Why is metacresol commercially important in Remodulin?

Metacresol enables multidose vial use but creates a potential differentiation point. Patients receiving subcutaneous treprostinil commonly experience infusion-site pain, and formulation-related local tolerability is one factor that can influence adherence, titration, and product selection.

Metacresol is not necessarily the sole cause of infusion-site pain. Treprostinil concentration, solution pH, osmolality, infusion rate, catheter or cannula characteristics, tissue exposure, and individual patient sensitivity also affect tolerability. A commercial product that removes or reduces metacresol would therefore need clinical evidence showing a meaningful improvement in local tolerability rather than relying on excipient substitution alone.

A preservative-free formulation could create value in several settings:

• Patients with repeated subcutaneous site reactions.
• Patients requiring long-term continuous infusion.
• Hospital or specialty-pharmacy protocols favoring single-use containers.
• Patients with sensitivity to phenolic preservatives.
• Device systems using prefilled cartridges or closed reservoirs.
• High-concentration products where the preservative burden per delivered dose becomes commercially relevant.

The tradeoff is that removing metacresol can reduce multidose flexibility. A preservative-free product may require single-use vials, prefilled syringes, cartridges, or validated closed-system containers. Those formats increase packaging, manufacturing, and device-development requirements.

What formulation opportunities exist for Remodulin and treprostinil?

The strongest formulation opportunities involve delivery convenience rather than basic solubility enhancement. Treprostinil is sufficiently water-compatible in the marketed injectable formulation, so commercial development is more likely to focus on container closure, excipient tolerability, concentration, and device integration.

Preservative-free treprostinil injection

A preservative-free product could use sterile single-dose vials, prefilled syringes, cartridges, or sealed infusion reservoirs. The development questions would include:

• Sterility maintenance after container opening.
• Adsorption to syringe, cartridge, or tubing materials.
• Chemical stability over the proposed shelf life.
• Compatibility with ambulatory infusion pumps.
• In-use stability after connection to the delivery system.
• Extractables and leachables from elastomers and plastics.
• Particulate control and container closure integrity.

A preservative-free product would not automatically be therapeutically superior. Its commercial value would depend on a clear reduction in local reactions, better device compatibility, lower handling burden, or improved patient persistence.

Higher-concentration formulations

Higher strengths can reduce infusion volume and may support lower pump rates. This can improve portability and reduce reservoir changes. Remodulin is already marketed in 1, 2.5, 5, and 10 mg/mL strengths, creating a concentration ladder that covers different dose requirements [1].

A future product could seek value through:

• Concentrations above the existing commercial range.
• Lower pump flow rates.
• Smaller reservoirs.
• Longer intervals between cartridge changes.
• Reduced exposure to infusion-site volume.
• Compatibility with wearable or patch-based pumps.

The technical risk is that increasing drug concentration can change pH, osmolality, viscosity, precipitation risk, and local tissue tolerability. Higher strength can also increase the impact of small dosing or pump-delivery errors.

Ready-to-use infusion systems

Ready-to-use presentations may be more commercially defensible than a new vial. Potential formats include:

• Prefilled syringes for pump filling.
• Prefilled cartridges.
• Single-use reservoirs.
• Closed-transfer containers.
• Device-specific treprostinil cassettes.

These formats can reduce preparation steps and contamination risk. They can also create device and combination-product barriers that are harder for a conventional injectable competitor to replicate.

Excipient substitution

Possible alternatives to metacresol include other preservatives or preservative-free systems. Each alternative introduces a separate safety and compatibility assessment. A substitute must preserve microbiological quality without increasing irritation, extractables, adsorption, or degradation.

For a chronic infusion product, an excipient with an established parenteral safety history is commercially preferable. Novel excipients can lengthen regulatory review and require additional toxicology work.

How does Remodulin compare with other treprostinil products?

Treprostinil competes across injectable, inhaled, and oral delivery routes. Excipient strategy differs sharply by route.

Product	Active ingredient	Route	Excipient opportunity
Remodulin	Treprostinil	Subcutaneous or intravenous infusion	Preservative tolerance, concentration, pump compatibility
Treprostinil injection generics	Treprostinil	Subcutaneous or intravenous infusion	Price, equivalent formulation, supply reliability
Tyvaso	Treprostinil	Inhalation	Aerosol performance, device compatibility, inhalation tolerability
Orenitram	Treprostinil diolamine	Oral extended release	Matrix technology, release control, food effects

Remodulin has a route-specific advantage for patients who need continuous parenteral prostacyclin therapy. Its commercial disadvantages are infusion-site burden, pump dependence, preparation requirements, and administration complexity.

Tyvaso and Orenitram compete through different convenience profiles rather than direct excipient similarity. A new injectable formulation would need to improve the infusion experience without sacrificing the predictable exposure associated with continuous delivery.

When did Remodulin lose regulatory exclusivity?

Remodulin received orphan-drug approval in 2002. The standard seven-year U.S. orphan-drug exclusivity period therefore expired in 2009, assuming no later orphan designation for a separate indication extended protection. Orphan exclusivity is separate from patent protection and does not prevent all forms of competing development after expiration.

The core treprostinil molecule is no longer the principal source of commercial exclusivity. Current competitive protection is more likely to depend on:

• Listed formulation patents.
• Method-of-use patents.
• Manufacturing and impurity-control processes.
• Device and cartridge design.
• Regulatory complexity for continuous infusion products.
• Supplier qualification and commercial scale.
• Physician and specialty-pharmacy relationships.

What is the Orange Book and patent status of Remodulin?

Remodulin is an FDA-approved small-molecule drug, not a biologic. Biosimilar rules therefore do not apply. Competing products would generally pursue an abbreviated new drug application or another applicable abbreviated pathway, subject to FDA requirements for pharmaceutical equivalence, bioequivalence, labeling, and manufacturing controls [2].

Orange Book patent listings, if any remain active for a specific Remodulin presentation, should be evaluated by patent type rather than counted as a single exclusivity block. The relevant categories are:

Patent category	Commercial relevance
Active ingredient	Low if core compound protection has expired
Formulation	Potentially significant for preservative, concentration, pH, or stability claims
Method of use	May cover pulmonary arterial hypertension dosing or patient subgroups
Device or container	Relevant to cartridges, pumps, reservoirs, and delivery systems
Manufacturing	Relevant to impurity profile, polymorph, salt, or process control
Labeling	May create litigation exposure if use claims are listed

A Paragraph IV challenge to an Orange Book-listed patent could accelerate litigation even where the underlying drug is chemically old. The practical value of a formulation patent depends on claim breadth, written-description support, enablement, prosecution history, and whether a competitor can design around the claimed excipient or container system.

Which companies are challenging or competing with Remodulin?

Competition is divided into three groups:

1. Generic treprostinil injection manufacturers.
2. Alternative treprostinil products from United Therapeutics.
3. Other pulmonary arterial hypertension companies offering prostacyclin-pathway therapies.

Generic competition is most likely to begin with conventional multidose injection presentations. A generic entrant can compete on price and supply but may not match proprietary cartridges, pump integration, specialty-pharmacy services, or patient-support programs.

The most credible differentiated competitors would offer:

• Preservative-free treprostinil.
• A higher-concentration product.
• A smaller-volume infusion system.
• A prefilled, ready-to-connect device.
• A formulation with improved subcutaneous-site tolerability.
• A product supported by longer in-use stability.

What patent and manufacturing barriers affect an excipient-based competitor?

Excipient changes can create a new product profile but do not eliminate regulatory and manufacturing barriers. The major barriers include:

Sterile manufacturing

Continuous-infusion products require consistent control of sterility, endotoxin, particulate matter, fill volume, container closure, and extractables. A small-volume injectable with a multidose presentation also requires validated preservative effectiveness and microbiological controls.

Stability and compatibility

Treprostinil products must be evaluated under long-term, accelerated, freeze-thaw, transport, and in-use conditions. Compatibility must be established with the intended pump, tubing, catheter, syringe, reservoir, and cartridge.

Device integration

A prefilled cartridge can become a combination product. Changes in flow rate, reservoir materials, dosing software, occlusion response, and pump accuracy may affect the regulatory submission and the patent landscape.

Process patents

Process protection may cover impurity removal, salt formation, concentration control, sterilization, or filling operations. Even if a formulation is outside a composition claim, a competitor may face process patent risk during commercial manufacture.

How strong is the commercial opportunity for a new Remodulin excipient strategy?

The opportunity is strongest where excipient innovation solves a measurable administration problem. A new formulation is less attractive if it only changes the preservative without improving patient outcomes, handling, or cost.

Opportunity	Commercial attractiveness	Main barrier
Preservative-free single-dose vial	Medium	Higher packaging cost and reduced multidose convenience
Prefilled syringe	High	Device compatibility and combination-product requirements
Prefilled cartridge	High	Pump integration and proprietary-device access
Higher concentration	Medium to high	Local tolerability and dosing-error risk
Alternative preservative	Medium	Need to prove safety and improved tolerability
Extended in-use stability	Medium	Stability evidence and labeling support
Low-cost conventional generic	High volume potential	Price competition and manufacturing scale
Novel excipient platform	Low to medium	Safety, regulatory, and patent uncertainty

The highest-value strategy is likely a ready-to-use, preservative-free or low-preservative cartridge with validated pump compatibility and a credible reduction in preparation and infusion-site burden.

What generic launch risks exist for Remodulin?

Generic launch risk is greatest for conventional injectable presentations once applicable patent and regulatory barriers no longer block approval. A generic can enter with a formulation close to the reference product and compete primarily on price.

The risk is lower for differentiated delivery systems because the competitor must address additional requirements:

• Device-specific performance.
• Container closure and extractables.
• In-use stability.
• Pump accuracy.
• Human factors.
• Patient training.
• Specialty-pharmacy distribution.
• Potential device or formulation patents.

A generic launch could reduce pricing for standard vial presentations while leaving a premium segment for proprietary cartridges, prefilled systems, or higher-concentration products.

What licensing deals could support a Remodulin formulation opportunity?

A formulation developer would typically need multiple commercial relationships:

• A treprostinil active-pharmaceutical-ingredient supplier.
• A sterile injectable contract development and manufacturing organization.
• A pump or cartridge manufacturer.
• A specialty-pharmacy distributor.
• A device company with ambulatory infusion expertise.
• A sponsor with FDA combination-product and pulmonary hypertension experience.

The most valuable licensing asset would be a formulation-device package with clinical or human-factors evidence. An excipient patent without a validated delivery system would have lower partnering value.

What is the revenue exposure from Remodulin competition?

Revenue exposure depends on the share of sales generated by conventional vials versus differentiated delivery formats. A low-cost generic is more likely to pressure standard injection pricing than to displace a proprietary device ecosystem immediately.

Key commercial variables include:

• Number of patients receiving continuous parenteral treprostinil.
• Average daily dose and concentration.
• Vial or cartridge consumption.
• Reimbursement for drug and pump separately.
• Switching friction at specialty centers.
• Availability of hospital and home-infusion channels.
• Patient persistence with subcutaneous therapy.
• Product-specific support services.

An excipient-led product that reduces site pain or preparation complexity could command a premium if it improves persistence or lowers total care burden. Without such evidence, the market will likely treat the product as an interchangeable injectable and apply generic pricing pressure.

Key Takeaways

• Remodulin uses a relatively simple injectable formulation containing treprostinil sodium, metacresol, sodium chloride, and water for injection.
• Metacresol is the clearest excipient-based differentiation point because it supports multidose use but may be relevant to local tolerability.
• The strongest commercial opportunity is a ready-to-use preservative-free or low-preservative cartridge, syringe, or reservoir.
• Higher-concentration products can reduce infusion volume and pump burden but require careful control of osmolality, pH, local tolerability, and dosing risk.
• Remodulin is a small-molecule product, so biosimilar competition is irrelevant. Generic injectable competition is the relevant regulatory pathway.
• Future protection is more likely to come from formulation, device, manufacturing, and combination-product claims than from the original treprostinil molecule.
• Generic competition should pressure conventional vial pricing more than integrated pump and cartridge systems.
• The commercial value of a new excipient strategy depends on demonstrated patient, handling, or device benefits.

FAQs

Can metacresol be removed from Remodulin?

Yes, a preservative-free treprostinil product could be developed in a single-dose vial, prefilled syringe, cartridge, or sealed reservoir. The product would require new stability, sterility, container-closure, and in-use data.

Would a preservative-free treprostinil product reduce infusion-site pain?

It could, but metacresol is only one potential contributor. Clinical evidence would need to separate preservative effects from drug concentration, pH, osmolality, flow rate, and patient-specific factors.

Is Remodulin eligible for biosimilar competition?

No. Treprostinil is a small molecule. Competitive products would generally be evaluated under generic-drug or other abbreviated FDA pathways rather than the biosimilar framework.

Can a higher-concentration treprostinil product obtain separate patent protection?

Potentially. Protection could cover concentration ranges, excipient ratios, pH, stability, container systems, pump compatibility, or methods of reducing infusion volume. Patent strength would depend on claim scope and the supporting data.

What is the best commercial format for a new treprostinil product?

A prefilled, ready-to-connect cartridge or syringe with validated pump compatibility, low preservative burden, long in-use stability, and demonstrated tolerability would offer the strongest differentiation from a conventional multidose vial.

References

1. United Therapeutics Corporation. (2023). Remodulin (treprostinil) injection prescribing information. U.S. Food and Drug Administration.

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/approved-drug-products-therapeutic-equivalence-evaluations-orange-book