List of Excipients in Branded Drug ACTHAR

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Mallinckrodt ARD LLC	ACTHAR	repository corticotropin	63004-8710	ACETIC ACID
Mallinckrodt ARD LLC	ACTHAR	repository corticotropin	63004-8710	CYSTEINE
Mallinckrodt ARD LLC	ACTHAR	repository corticotropin	63004-8710	GELATIN
Mallinckrodt ARD LLC	ACTHAR	repository corticotropin	63004-8710	PHENOL
Mallinckrodt ARD LLC	ACTHAR	repository corticotropin	63004-8710	SODIUM HYDROXIDE

Acthar Excipient Strategy and Commercial Opportunities

Last updated: August 9, 2026

H.P. Acthar Gel is a repository corticotropin injection whose commercial differentiation depends heavily on its gelatin-based depot formulation. The product contains repository corticotropin in a 16% gelatin matrix, with phenol as a preservative and water for injection. The main commercial opportunities are differentiated depot systems, preservative-free presentations, improved injection usability, lower-cost manufacturing, and potential follow-on products using the 505(b)(2) pathway. The principal barriers are clinical bridging, manufacturing comparability, regulatory exclusivity, formulation know-how, and Acthar’s established reimbursement and specialty-pharmacy infrastructure.

What is the Acthar formulation and which excipients does it contain?

The marketed product is H.P. Acthar Gel, also known as repository corticotropin injection. It is supplied at 80 USP units/mL in a multidose vial. The FDA prescribing information identifies the formulation as containing gelatin, phenol, and water for injection. The product is refrigerated and administered by intramuscular or subcutaneous injection.[1]

Component	Function in Acthar Gel	Commercial relevance
Repository corticotropin	Active pharmaceutical ingredient	Porcine-derived ACTH-related peptide mixture
Gelatin, 16%	Depot-forming excipient and viscosity-building matrix	Central to sustained-release behavior and product identity
Phenol, 0.5%	Antimicrobial preservative	Supports multidose-vial use but creates tolerability and formulation constraints
Water for injection	Vehicle	Standard parenteral solvent
Hydrochloric acid or sodium hydroxide	pH adjustment, where applicable	Supports formulation control

The gelatin matrix is the key excipient strategy. It creates a viscous injectable depot rather than a conventional aqueous peptide solution. This design supports the product’s repository profile and differentiates Acthar from immediate-release corticotropin preparations.

How does gelatin function in Acthar Gel?

Gelatin is not merely a bulking agent. At the concentration used in Acthar Gel, it contributes to viscosity, local depot formation, and release behavior after injection. It also imposes manufacturing requirements involving gelatin source, molecular-weight distribution, bloom strength, microbial control, sterilization, and batch-to-batch consistency.

A follow-on manufacturer would need to demonstrate that changes in gelatin grade, concentration, source, or processing do not materially change:

• Peptide distribution within the gel
• Injection force and syringeability
• In vivo release
• Local tolerability
• Storage stability
• Preservative effectiveness
• Delivered dose per actuation or vial withdrawal

This makes the excipient system a potential barrier to substitution even when the active ingredient is chemically characterized.

What excipient strategy creates the strongest commercial opportunity?

The strongest opportunity is a next-generation repository corticotropin product that retains depot performance while improving administration, safety, or manufacturing economics.

Preservative-free single-dose presentation

Acthar Gel is supplied in a multidose vial and contains phenol. A preservative-free, single-dose vial or prefilled syringe could target patients with sensitivity to phenolic preservatives, reduce repeated vial puncture, and improve home-administration controls.

The commercial tradeoff is higher packaging cost and lower doses per container. A single-dose product would need a validated container-closure system, sterility assurance strategy, extractables and leachables program, and stability package.

Lower-viscosity depot formulation

A lower-viscosity formulation could reduce injection force and improve usability for subcutaneous administration. Potential approaches include:

• Lower gelatin concentration
• Alternative gelatin grades
• Modified gelatin molecular-weight distribution
• Combination of gelatin with a second biocompatible polymer
• Controlled pH and ionic-strength adjustment
• Device-assisted delivery

The product must preserve repository pharmacology. Reducing viscosity may accelerate release and undermine the clinical profile.

Prefilled syringe or autoinjector

A device-enabled Acthar presentation could reduce preparation steps and improve dosing consistency. The principal technical issue is compatibility between the viscous gel and the delivery device. Relevant testing would include injection-force curves, dose accuracy, needle gauge, hold-up volume, cold-temperature performance, and container closure.

An autoinjector may be commercially attractive for specialty indications but could increase development cost. The device would also require human-factors validation and combination-product review.

Alternative depot polymers

A polymeric depot based on poloxamers, hyaluronic acid, polycaprolactone, or other injectable materials could provide greater control over release than gelatin. These systems may support smaller injection volumes or extended dosing intervals.

The regulatory risk is high. A new polymer could change local tissue exposure, immunogenicity, pharmacokinetics, and product classification. It would likely require substantial nonclinical and clinical bridging rather than a simple excipient substitution.

What formulation patents protect Acthar Gel?

Public product-label and regulatory sources identify the formulation components but do not, by themselves, establish a complete list of enforceable formulation patents. Patent protection must be evaluated separately through the FDA Orange Book, USPTO records, assignment data, prosecution histories, and litigation dockets.

For Acthar, the commercially relevant protection is likely to involve a combination of:

1. Composition and repository-formulation claims
2. Methods of treating corticosteroid-responsive or inflammatory diseases
3. Manufacturing and purification processes for porcine-derived corticotropin
4. Stability and storage claims
5. Dosing regimens and administration schedules
6. Device or container-closure claims for improved delivery

An excipient-focused competitor should not assume that the absence of a broad gelatin patent eliminates infringement risk. A product can face claims directed to the active-excipient combination, defined concentration ranges, release characteristics, treatment methods, or manufacturing steps.

What is the Orange Book status of Acthar?

Acthar is approved under NDA 009488. The product’s regulatory status is distinct from a conventional small-molecule generic because repository corticotropin is a complex biological-derived peptide product and the dosage form is a viscous depot injection.[1]

A potential applicant would need to determine whether an ANDA is available for the proposed product or whether a 505(b)(2) application is more appropriate. A materially different excipient system, delivery device, strength, route, or release profile would increase the likelihood of a 505(b)(2) strategy.

The FDA’s Orange Book remains the controlling source for listed patents and regulatory exclusivity. Patent listings and expiry dates should be verified against the current electronic Orange Book before making a launch or litigation decision.[2]

When does Acthar lose exclusivity?

Acthar’s commercial protection does not depend on one expiry date. The relevant barriers include statutory exclusivity, listed patents, formulation know-how, regulatory requirements, reimbursement controls, and physician adoption.

Protection category	Relevance to Acthar follow-on entry
NDA exclusivity	Can delay certain FDA approvals, depending on the approved application and product history
Listed patents	May trigger Paragraph IV certification and patent litigation
Method-of-use patents	Can affect labeled indications and commercial launch strategy
Formulation know-how	May remain difficult to reproduce even after patent expiry
Manufacturing controls	Porcine-source control and depot consistency can increase development time
Market-access infrastructure	Specialty distribution and payer authorization can delay uptake

How do Paragraph IV challenges apply?

If an eligible patent is listed for Acthar, an ANDA applicant could submit a Paragraph IV certification asserting that the patent is invalid, unenforceable, or not infringed. The NDA holder could then file patent litigation, potentially triggering a 30-month stay under the Hatch-Waxman framework.[3]

A 505(b)(2) applicant may also face patent certifications, depending on the reference product and the proposed labeling. A formulation change that avoids one patent may still leave method-of-use or manufacturing claims in force.

For a complex depot injection, the most practical launch pathway may involve a narrow label, a non-infringing formulation, a negotiated license, or a launch after a court ruling rather than a conventional first-to-file generic strategy.

Which companies are challenging Acthar?

Publicly documented competitive pressure has historically centered on corticosteroids, immunosuppressants, biologics, and alternative therapies rather than a mature field of approved Acthar-equivalent depot injections. Relevant competitors include:

• Generic and branded corticosteroids
• Intravenous immunoglobulin
• Biologic immunomodulators
• Disease-specific therapies for infantile spasms, nephrotic syndrome, multiple sclerosis exacerbations, and rheumatologic disease
• Potential synthetic ACTH or repository corticotropin products

The threat differs by indication. In infantile spasms, hormonal therapies and vigabatrin are key comparators. In nephrotic syndrome, corticosteroids, calcineurin inhibitors, and biologics can compete. In multiple sclerosis exacerbations, high-dose corticosteroids are the main practical alternative.

A true excipient-enabled follow-on would compete on total treatment cost, injection convenience, payer acceptance, and evidence of comparable clinical performance.

What manufacturing and intellectual-property barriers affect Acthar?

Acthar’s manufacturing barriers are more significant than the ingredient list suggests.

Porcine-derived active ingredient

Repository corticotropin is a complex porcine-derived product rather than a single, simple synthetic molecule. Source-animal controls, extraction, purification, characterization, viral and microbial controls, and lot consistency create barriers to entry.

Gelatin variability

Gelatin is a naturally derived material with variability in source, hydrolysis, molecular weight, viscosity, and impurity profile. A manufacturer must control the excipient as a critical material, not treat it as a generic commodity.

Sterility and multidose control

Phenol-containing multidose packaging requires preservative-effectiveness testing and repeated-use stability. A preservative-free product could simplify some tolerability concerns but would require a different sterile manufacturing and packaging strategy.

Cold-chain and viscosity

The label requires refrigerated storage at 2°C to 8°C and protection from freezing.[1] Viscosity can change with temperature, creating implications for shipping, administration, dose withdrawal, and device performance.

What is the commercial opportunity for Acthar excipient suppliers?

Excipient companies can pursue Acthar-related opportunities without developing a competing drug. The most attractive areas are:

Opportunity	Potential customer need	Development barrier
Pharmaceutical-grade gelatin	Consistent depot performance	Source qualification and lot variability
Low-endotoxin gelatin	Parenteral safety and process control	Cost and supply assurance
Synthetic or recombinant gelatin	Reduced animal-origin concerns	Regulatory qualification and performance matching
Injectable polymer systems	Longer or more controlled release	New safety and bridging requirements
Preservative alternatives	Reduced phenol exposure	Antimicrobial effectiveness and compatibility
Device-compatible gel systems	Prefilled syringe or autoinjector use	Injection-force and stability testing
Single-dose packaging	Home-use and sterility improvements	Higher packaging and manufacturing cost

The best near-term opportunity is likely a high-purity, tightly specified gelatin system with better rheological control and device compatibility. A completely new polymer depot has greater upside but substantially higher regulatory risk.

How does Acthar compare with potential follow-on products?

Attribute	Acthar Gel	Lower-viscosity follow-on	Alternative polymer depot
Depot mechanism	16% gelatin matrix	Modified gelatin or reduced concentration	Synthetic or semi-synthetic polymer
Preservative	Phenol	Could retain or remove phenol	Could be preservative-free
Administration	IM or SC injection	Potentially improved SC usability	May support extended dosing
Regulatory path	Existing NDA	Likely 505(b)(2) or complex generic analysis	Likely 505(b)(2)
Main advantage	Established clinical and commercial position	Easier administration and possible cost reduction	Differentiated release profile
Main risk	Existing product cost and access	Clinical comparability	New local safety and PK requirements

A follow-on product does not need to replicate every aspect of Acthar to create value. A narrower product could target one indication, one route of administration, or one patient segment with a simpler presentation.

What revenue exposure and launch scenarios matter?

Acthar has historically generated annual sales above $1 billion for its commercial owner, making it a material specialty-pharmaceutical asset. Its value has been concentrated in a limited number of indications and depends on reimbursement, prior authorization, specialty distribution, and the absence of clinically accepted substitutes at the point of treatment.[4]

Three launch scenarios are commercially relevant:

1. Low-price complex generic: Competes primarily on acquisition cost and may face substantial patent and manufacturing challenges.
2. 505(b)(2) reformulation: Charges a premium for lower injection force, single-dose packaging, improved tolerability, or device delivery.
3. Indication-focused product: Uses a narrower clinical and commercial strategy, reducing trial cost while targeting a high-value disease segment.

The second scenario offers the clearest excipient-led differentiation. It can preserve specialty pricing if the reformulation produces a measurable benefit and secures payer recognition.

What licensing deals could accelerate entry?

Licensing opportunities may involve:

• Gelatin or polymer excipient rights
• Repository peptide manufacturing
• Drug-device combination technology
• Preservative-free multidose or single-dose packaging
• Indication-specific commercialization
• Regional rights outside the United States
• Manufacturing partnerships with qualified sterile injectable facilities

A licensee should seek rights covering formulation, manufacturing process, analytical methods, regulatory filings, and device integration. A formulation-only license may leave critical freedom-to-operate gaps.

How strong is the Acthar patent estate?

The estate should be assessed as a layered protection system rather than by patent count alone. Strong protection would require surviving claims that cover the proposed formulation, manufacturing process, treatment indication, or delivery system. A competitor that changes the excipient concentration may avoid a composition claim but still face method-of-use or process claims.

The most durable barriers are likely to be:

• Complex active-ingredient characterization
• Manufacturing know-how
• Clinical evidence linked to the repository formulation
• Specialty reimbursement controls
• Patient and prescriber familiarity

Patent strength should be scored claim by claim against the proposed formulation, not inferred from the existence of Acthar’s brand franchise.

Key Takeaways

• Acthar Gel’s principal excipient is 16% gelatin, which creates the repository depot and contributes to viscosity and release.
• Phenol supports multidose-vial preservation but creates an opportunity for preservative-free reformulation.
• The most credible near-term commercial opportunity is a lower-viscosity, device-compatible, single-dose or prefilled presentation.
• A materially different depot polymer could offer stronger differentiation but would carry greater clinical and regulatory risk.
• Acthar follow-on entry may require a 505(b)(2) strategy rather than a conventional small-molecule ANDA.
• Patent analysis must cover composition, formulation, treatment methods, manufacturing, stability, and device claims.
• Manufacturing know-how involving porcine-derived corticotropin and gelatin consistency may remain a barrier after patent expiry.
• The commercial case depends on a measurable administration, safety, dosing, or cost advantage over Acthar Gel and corticosteroid alternatives.

FAQs

Can gelatin in Acthar Gel be replaced with another depot excipient?

Yes, but replacing gelatin would likely change release, viscosity, local tolerability, and regulatory comparability. A new polymer system would generally require substantial formulation and clinical bridging.

Would a preservative-free Acthar formulation qualify as a generic?

Not automatically. A preservative-free product could require an ANDA or 505(b)(2) application depending on the formulation, labeling, dosage form, and FDA determination of therapeutic equivalence.

Is phenol in Acthar Gel a major commercial weakness?

It is a potential differentiation point rather than an established clinical defect. A preservative-free product could target patients, caregivers, and prescribers seeking reduced preservative exposure, but it would face higher packaging and sterile manufacturing costs.

Can Acthar be delivered through an autoinjector?

Potentially, but the gel’s viscosity, refrigeration requirements, syringeability, dose accuracy, and device compatibility would require extensive testing. Human-factors and combination-product requirements would also apply.

Are synthetic ACTH products direct substitutes for Acthar Gel?

They may compete pharmacologically but are not automatically substitutable. The repository gelatin formulation, dosing profile, approved indications, clinical evidence, and regulatory status would determine the practical level of competition.

References

1. U.S. Food and Drug Administration. (2024). H.P. Acthar Gel (repository corticotropin injection) prescribing information. Mallinckrodt Pharmaceuticals.
2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Electronic Orange Book.
3. U.S. Food and Drug Administration. (2024). Abbreviated new drug application approvals and patent certifications.
4. Mallinckrodt plc. (2024). Annual report and Form 10-K.