List of Excipients in Branded Drug DOFETILIDE

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Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Greenstone LLC	DOFETILIDE	dofetilide	59762-0037	CELLULOSE, MICROCRYSTALLINE
Greenstone LLC	DOFETILIDE	dofetilide	59762-0037	MAGNESIUM STEARATE
Greenstone LLC	DOFETILIDE	dofetilide	59762-0037	SILICON DIOXIDE
Greenstone LLC	DOFETILIDE	dofetilide	59762-0037	STARCH, CORN

Generic Drugs Containing DOFETILIDE

Company	Ingredient	NDC	Excipient
Major Pharmaceuticals	dofetilide	0904-6681	ALCOHOL
Major Pharmaceuticals	dofetilide	0904-6681	AMMONIA
Major Pharmaceuticals	dofetilide	0904-6681	BUTYL ALCOHOL
Major Pharmaceuticals	dofetilide	0904-6681	CELLULOSE, MICROCRYSTALLINE
Major Pharmaceuticals	dofetilide	0904-6681	FERRIC OXIDE RED
Major Pharmaceuticals	dofetilide	0904-6681	FERRIC OXIDE YELLOW
Major Pharmaceuticals	dofetilide	0904-6681	FERROSOFERRIC OXIDE

What are the Most Frequently-Used Excipients in DOFETILIDE?

# Of NDCs	Excipient
12	ALCOHOL
15	AMMONIA
2	ANHYDROUS CITRIC ACID
12	BUTYL ALCOHOL
21	CELLULOSE, MICROCRYSTALLINE
2	COPOVIDONE
2	D&C RED NO. 28

Dofetilide Excipient Strategy and Commercial Opportunities

Last updated: September 25, 2026

Dofetilide is a narrow-therapeutic-index Class III antiarrhythmic sold in oral capsules under the Tikosyn brand and through generic versions. The commercial opportunity is not a new active-ingredient market. It is a controlled reformulation and supply-chain market built around dose accuracy, impurity control, capsule performance, renal-dose flexibility, and reduced manufacturing cost.

The most attractive strategies are:

1. A robust, low-variability generic capsule platform.
2. An excipient-optimized capsule for patients with lactose, gelatin, colorant, or other formulation restrictions.
3. A lower-cost manufacturing process using direct compression or simplified granulation.
4. A differentiated oral dosage form, such as a sprinkle capsule or liquid preparation, if supported by bioequivalence and FDA requirements.
5. A commercial supply position based on reliable availability, since dofetilide initiation requires inpatient monitoring and treatment interruptions can create operational problems.

Dofetilide has no biosimilar pathway because it is a synthetic small molecule. Generic competition, not biologic substitution, is the primary market risk.

What is dofetilide and why does excipient selection matter?

Dofetilide blocks the rapid component of the delayed rectifier potassium current and prolongs cardiac repolarization. The drug is indicated for maintenance of normal sinus rhythm in patients with atrial fibrillation or atrial flutter and for conversion in selected patients under monitored conditions.[1]

Its formulation risk is higher than that of many routine oral solid drugs because excessive exposure can prolong the QT interval and increase the risk of torsades de pointes. Dofetilide dosing is determined in part by renal function, and the FDA label requires dose adjustment according to calculated creatinine clearance.[1]

The product therefore requires:

• Accurate delivery of 125 micrograms, 250 micrograms, and 500 micrograms.
• Low unit-to-unit weight and assay variability.
• Consistent dissolution across manufacturing lots.
• Stable potency through the labeled shelf life.
• Limited risk of dose dumping or delayed release.
• Tight control over formulation changes that could alter exposure.

The commercial formulation is a hard gelatin capsule. FDA labeling identifies inactive ingredients used in the branded product, including common excipients such as lactose, microcrystalline cellulose, starch-based materials, crospovidone, silicon dioxide, magnesium stearate, and capsule-shell components.[1][2] Exact excipient composition varies by manufacturer and strength.

What excipients are used in dofetilide capsules?

The branded capsule uses a conventional immediate-release excipient system. The formulation architecture generally includes:

Functional role	Typical excipient category	Relevance to dofetilide
Diluent	Lactose, microcrystalline cellulose	Controls fill weight and content uniformity
Disintegrant	Crospovidone, sodium starch glycolate or similar material	Supports rapid capsule rupture and drug release
Glidant	Colloidal silicon dioxide	Improves powder flow at low drug load
Lubricant	Magnesium stearate	Reduces manufacturing friction
Granulation or filler aid	Corn starch or related starch	Supports blend uniformity and processing
Capsule shell	Gelatin or alternative polymer shell	Determines shell compatibility and patient acceptability
Colorant or opacifier	Titanium dioxide or approved colorants	Supports product identification and strength differentiation

The active ingredient represents a small fraction of total capsule fill weight. That makes powder segregation, electrostatic charging, and blend uniformity more important than the nominal drug concentration suggests.

A generic manufacturer should evaluate each excipient for:

• Particle-size distribution.
• Bulk and tapped density.
• Moisture content.
• Electrostatic behavior.
• Compatibility with dofetilide.
• Effect on blend segregation.
• Effect on dissolution and disintegration.
• Regulatory status in the FDA Inactive Ingredient Database.
• Availability from at least two qualified suppliers.

How should a dofetilide excipient strategy be designed?

Use a low-variability blend system

The primary formulation objective should be content uniformity. A low-dose, high-potency active ingredient requires a process that minimizes segregation between dofetilide particles and larger excipient particles.

A practical development sequence is:

1. Characterize active-ingredient particle size, morphology, density, moisture, and surface charge.
2. Match the active ingredient with a diluent system that has compatible flow and density.
3. Compare direct blending with dry granulation or wet granulation.
4. Measure blend uniformity at multiple locations and time points.
5. Confirm capsule-fill weight, assay, and content uniformity after scale-up.
6. Conduct dissolution testing under discriminatory conditions rather than relying only on compendial release conditions.

Microcrystalline cellulose can provide structural bulk and acceptable compaction. Lactose can reduce cost and support capsule fill, but it creates a product-positioning issue for patients who avoid lactose or for markets with stricter excipient labeling preferences. A lactose-free formulation may create commercial differentiation even if it does not create strong intellectual-property protection.

Control lubricant exposure

Magnesium stearate is widely used but can slow wetting or dissolution when overmixed or used at excessive concentration. This issue is relevant to dofetilide because small dissolution changes can affect the exposure profile of a narrow-therapeutic-index drug.

The process should control:

• Lubricant concentration.
• Lubrication time.
• Blend shear.
• Order of ingredient addition.
• Hold time before encapsulation.
• Environmental humidity.

A low-shear, short-lubrication process may provide a more consistent dissolution profile than an extended blending cycle.

Optimize disintegration without creating dose dumping

Crospovidone and related superdisintegrants can support rapid capsule-content dispersion. The formulation should avoid excessive reliance on a single disintegrant grade because raw-material variability can change water uptake and dissolution.

Development should compare:

• Crospovidone versus sodium starch glycolate.
• Intragr anular versus extragranular disintegrant placement.
• Different particle-size grades.
• Capsule-shell moisture levels.
• Dissolution in media representing gastric pH conditions.

The target is rapid and reproducible release, not the fastest possible release. For dofetilide, an unnecessarily aggressive release profile could complicate bioequivalence or safety evaluation.

What formulation patents protect dofetilide products?

The original commercial opportunity was centered on the active ingredient and branded product, not on a durable excipient platform. Dofetilide is now a mature generic small-molecule product. The core patent and regulatory exclusivity periods associated with the original product have expired, and generic dofetilide products have been approved through the ANDA pathway.[3][4]

Potential formulation protection remains possible but is commercially narrower. Patentable subject matter could include:

• A specific excipient ratio that improves content uniformity.
• A defined particle-size distribution for dofetilide.
• A low-moisture capsule formulation.
• A lactose-free or gelatin-free capsule.
• A modified-release formulation.
• A stability-enhancing packaging configuration.
• A sprinkle formulation with demonstrated bioequivalence.
• A liquid preparation with a defined concentration and preservative system.
• A manufacturing process that reduces impurity formation or assay variability.

An excipient patent is more valuable if it produces a measurable technical effect, such as improved stability, reduced segregation, or a clinically relevant release profile. A simple substitution of one conventional filler for another is less likely to support a strong commercial position.

Because dofetilide is an old molecule with generic competition, a new formulation would need a credible 505(b)(2) or other regulatory strategy, a clinically meaningful use case, or a defensible manufacturing advantage. A reformulation that only changes capsule color or filler composition would face limited pricing power.

When does dofetilide lose exclusivity, and what is the current Orange Book status?

Dofetilide lost branded exclusivity years ago. Tikosyn was approved by the FDA on October 1, 1999.[1] The product is now marketed through generic versions approved under ANDAs, which rely on the reference listed drug for safety and efficacy rather than requiring a full new clinical-development program.[3]

Milestone	Date or status
Tikosyn NDA approval	October 1, 1999
Active ingredient	Dofetilide
Dosage form	Immediate-release oral capsule
Common strengths	125 mcg, 250 mcg, 500 mcg
Regulatory pathway for generics	ANDA
Current competitive model	Generic small-molecule competition
Biosimilar applicability	None
Core market barrier	Bioequivalence, process control, supply reliability, and inpatient initiation requirements

The FDA Orange Book remains the controlling source for reference-listed-drug status, patent listings, exclusivity codes, and approved generic applicants.[3] A commercial diligence review should distinguish expired historical patents from any currently listed patent directed to a later-approved formulation or method of use.

What generic entry risks exist for dofetilide?

The principal generic risk is price competition. Dofetilide does not require a complex delivery device, injectable presentation, or biologic manufacturing process. Once an ANDA is approved, a manufacturer can compete through:

• Lower acquisition cost.
• Contract-pharmacy supply.
• Hospital formulary access.
• Wholesaler availability.
• Reliable supply during drug shortages.
• Multiple capsule strengths.
• Simplified packaging.

The product still has meaningful operational barriers. Dofetilide initiation or re-initiation requires hospitalization for continuous ECG monitoring, renal-function assessment, and dose selection under the FDA labeling requirements.[1] This restricts casual prescribing and gives hospitals, cardiology groups, and specialty pharmacies influence over product selection.

A generic manufacturer must also support all three standard strengths. A portfolio limited to one strength may be commercially incomplete because dose selection depends on renal function and QT response.

How can excipients create commercial differentiation?

Lactose-free capsules

A lactose-free formulation could address patients with lactose intolerance or institutional procurement policies that prefer simplified excipient profiles. This is a positioning opportunity rather than a broad clinical advantage. The commercial value would depend on clear labeling, reliable availability, and formulary adoption.

Gelatin-free capsules

Vegetarian or religious dietary requirements may support demand for hypromellose or other non-gelatin capsule shells. The shell change would require evaluation of moisture transmission, mechanical strength, dissolution, stability, and manufacturing performance.

Colorant-reduced products

A colorant-free or low-colorant capsule could appeal to patients with excipient sensitivities and reduce dependence on selected pigment suppliers. The tradeoff is weaker visual differentiation between strengths, which may increase medication-error risk unless imprinting and packaging are improved.

Sprinkle or opening-compatible capsules

A capsule designed for administration by sprinkling onto soft food could address swallowing difficulty. This strategy presents a higher regulatory burden because opening the capsule could alter dose recovery, blend uniformity, and administration behavior. The product would require explicit instructions and supporting performance data.

Stability-oriented formulations

A formulation with lower moisture uptake or improved protection against oxidation could support longer shelf life and lower wastage. This is especially relevant if dofetilide or its impurities show sensitivity to humidity, light, or elevated temperature. Alu-Alu blister packaging, high-barrier bottles, desiccants, or unit-dose hospital packaging can complement the excipient strategy.

What manufacturing and intellectual-property barriers remain?

The strongest practical barriers are process-based.

Content uniformity

Low-dose capsule filling creates a risk that active ingredient will segregate from larger filler particles. A manufacturer with a robust blending and sampling design may have a practical advantage even when the composition is not patent-protected.

Scale-up reproducibility

A formulation that performs in laboratory equipment may fail during commercial scale-up because of changes in shear, residence time, hopper behavior, and capsule-filling speed.

Impurity control

The manufacturer must establish a qualified impurity profile and control degradation products through raw-material specifications, validated analytical methods, and stability studies.

Capsule-shell performance

Gelatin and hypromellose shells differ in moisture behavior and mechanical properties. Switching shell materials without a complete evaluation can change dissolution, brittleness, storage stability, and machine performance.

Packaging

Unit-dose blister packaging can improve medication control in hospitals and support strength differentiation. Bottles may reduce cost but create more exposure to humidity and dispensing errors.

Process patents

A company may pursue process claims covering active-particle treatment, ordered mixing, granulation conditions, capsule filling, or packaging. Such claims are most useful when they reduce variability or solve a documented scale-up problem.

Which companies are challenging or competing with dofetilide?

The market is primarily composed of the branded reference product and multiple generic manufacturers. The generic competitive field can change as ANDAs are approved, withdrawn, transferred, or placed on shortage status. FDA Drugs@FDA, the Orange Book, and DailyMed provide the relevant product and labeling records.[2][3][4]

The competitive landscape should be evaluated on four dimensions:

Dimension	Commercial question
Regulatory	Does the supplier have approved 125 mcg, 250 mcg, and 500 mcg products?
Supply	Can the supplier maintain uninterrupted hospital and wholesaler availability?
Formulation	Does the product use lactose, gelatin, colorants, or other restricted excipients?
Economics	Can the supplier compete after API, testing, packaging, and distribution costs?

Because this is a small, mature market, supply reliability may matter more than formulation novelty. A manufacturer with a complete strength portfolio and dependable distribution can capture business without owning a major formulation patent.

What is the Paragraph IV and litigation risk for dofetilide?

Paragraph IV litigation is most important during the period when an ANDA applicant challenges an unexpired Orange Book patent. Dofetilide is a mature generic product, so the principal historical Paragraph IV risk related to the original product has largely passed.

Current legal diligence should focus on:

• Any later-listed formulation patents.
• Patents covering a new dosage form.
• Method-of-use claims involving atrial fibrillation or dose initiation.
• ANDA certification status.
• Product-specific settlement agreements.
• Active district-court or Federal Circuit proceedings.

A new entrant developing a conventional immediate-release capsule is more likely to face regulatory and commercial competition than a meaningful core-patent barrier. A reformulated product could create new patent exposure if it relies on a third party’s protected capsule technology, excipient system, or manufacturing process.

What licensing opportunities exist for dofetilide excipients and formulations?

Licensing opportunities are more credible in enabling technology than in the dofetilide molecule itself. Potential targets include:

• Low-dose blend-uniformity platforms.
• Non-gelatin capsule technologies.
• Moisture-barrier packaging.
• Unit-dose hospital packaging.
• Sprinkle-capable capsule systems.
• Oral-liquid vehicles.
• Continuous manufacturing platforms.
• Analytical methods for trace-level impurities.

A license should be evaluated against the small size of the dofetilide market. A technology that requires a high royalty rate, specialized equipment, or a separate clinical study may not support acceptable economics unless it also applies to other narrow-therapeutic-index drugs.

How does dofetilide compare with competing antiarrhythmics?

Attribute	Dofetilide	Amiodarone	Sotalol
Drug class	Class III potassium-channel blocker	Multichannel antiarrhythmic	Class III and beta-blocking activity
Dosage form opportunity	Immediate-release capsule, potential reformulations	Tablets and other presentations	Tablets, with broader generic competition
Key safety issue	QT prolongation and torsades risk	Organ toxicity and drug interactions	QT prolongation, renal dosing, bradycardia
Initiation burden	Inpatient monitoring required	Often less formalized than dofetilide	Monitoring requirements vary
Excipient opportunity	High value from dose uniformity and renal-dose strengths	More conventional solid-dose competition	Similar dose-control and renal considerations
Biosimilar risk	None	None	None

Dofetilide’s inpatient initiation requirement narrows the prescriber base but also makes institutional supply and packaging important. Its excipient opportunity is strongest where formulation quality reduces dispensing, administration, or supply risks.

What revenue exposure and launch scenarios exist?

The revenue opportunity is generally modest compared with high-volume cardiovascular products. A manufacturer should model the market as a specialty generic with limited unit volume but potentially stable demand.

Base-case generic capsule launch

The company launches all three strengths with a conventional formulation and competes on price and availability. This has the lowest development risk and the fastest route to market.

Premium excipient-profile launch

The company launches a lactose-free, gelatin-free, or reduced-colorant version. The price premium depends on hospital and pharmacy acceptance. The formulation must offer clear labeling value because clinical efficacy is not expected to differ.

Hospital-focused packaging launch

The company supplies unit-dose blisters, barcoded packaging, and clear strength differentiation. This may improve institutional adoption without requiring a novel dosage form.

505(b)(2) formulation launch

The company develops a liquid, sprinkle, or alternative capsule presentation. This creates more differentiation but requires stronger clinical, bioequivalence, stability, and commercialization evidence.

The most defensible commercial sequence is to begin with a standard ANDA product, establish supply, then evaluate a differentiated formulation using the same API and quality infrastructure.

Key Takeaways

• Dofetilide is a mature generic small-molecule market with no biosimilar pathway.
• The principal formulation challenge is accurate delivery of a low-dose, narrow-therapeutic-index drug.
• Lactose, gelatin, colorant, and moisture-control strategies can create commercial differentiation, but they do not automatically create strong patent protection.
• The highest-value technical work is likely to involve content uniformity, dissolution control, impurity management, capsule-shell performance, and packaging.
• A complete three-strength product portfolio is important because dosing depends on renal function and clinical response.
• A conventional ANDA capsule is the lowest-risk entry strategy.
• A 505(b)(2) liquid, sprinkle, or alternative capsule could create differentiation but would require materially greater regulatory investment.
• Generic supply reliability may be more valuable than a narrow excipient patent in this mature market.
• Current Orange Book, Drugs@FDA, DailyMed, and litigation records should control any final assessment of listed patents, active ANDA challenges, settlements, and supplier status.

FAQs

Can dofetilide capsules be made without lactose?

Yes. A lactose-free formulation can use microcrystalline cellulose, starches, or other qualified diluents. The manufacturer must demonstrate acceptable content uniformity, dissolution, stability, and bioequivalence.

Is a liquid dofetilide formulation commercially attractive?

It could address swallowing difficulties and dose-measurement needs, but the narrow therapeutic index creates a substantial dose-accuracy burden. A liquid product would require strong safeguards against measuring errors and would likely need a separate regulatory strategy.

Does dofetilide require a biosimilar application?

No. Dofetilide is a synthetic small molecule. Generic versions are submitted through the ANDA pathway, while a materially different formulation may require a 505(b)(2) application.

Can an excipient change create a new dofetilide patent?

Potentially. Patentability would depend on a novel formulation or process and a defensible technical effect, such as improved stability, reduced segregation, or a distinct release profile. Routine substitution of standard excipients is less likely to support strong exclusivity.

What is the most valuable formulation improvement for dofetilide?

For a conventional generic capsule, the most valuable improvement is usually reproducible low-dose content uniformity combined with stable dissolution and reliable commercial supply. For product differentiation, lactose-free or gelatin-free capsules and hospital-oriented packaging are more practical than complex modified-release designs.

References

1. U.S. Food and Drug Administration. (1999). Tikosyn (dofetilide) prescribing information. FDA.

2. National Library of Medicine. (n.d.). DailyMed: Dofetilide capsule labeling. DailyMed.

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

4. U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs database. FDA.

5. U.S. Food and Drug Administration. (n.d.). Inactive Ingredient Database. FDA.