List of Excipients in Branded Drug DOFETILIDE 0.125MG

Generic Drugs Containing DOFETILIDE 0.125MG

Company	Ingredient	NDC	Excipient
Granules Pharmaceuticals Inc	dofetilide 0.125mg	70010-024	AMMONIA
Granules Pharmaceuticals Inc	dofetilide 0.125mg	70010-024	CELLULOSE, MICROCRYSTALLINE
Granules Pharmaceuticals Inc	dofetilide 0.125mg	70010-024	D&C YELLOW NO. 10
Granules Pharmaceuticals Inc	dofetilide 0.125mg	70010-024	FD&C YELLOW NO. 6
Granules Pharmaceuticals Inc	dofetilide 0.125mg	70010-024	FERROSOFERRIC OXIDE

What are the Most Frequently-Used Excipients in DOFETILIDE 0.125MG?

# Of NDCs	Excipient
1	AMMONIA
1	CELLULOSE, MICROCRYSTALLINE
1	D&C YELLOW NO. 10
1	FD&C YELLOW NO. 6
1	FERROSOFERRIC OXIDE

Dofetilide 0.125 mg Excipient Strategy and Commercial Opportunities

Last updated: August 27, 2026

Dofetilide 0.125 mg is a small-molecule, immediate-release hard capsule used for conversion and maintenance of normal sinus rhythm in patients with atrial fibrillation or atrial flutter. The commercial opportunity is primarily a reliable generic supply platform, not a novel excipient-led product. The strongest opportunities are low-cost capsule manufacturing, hospital and mail-order packaging, supply assurance, and carefully controlled line extensions that preserve exposure, content uniformity, and labeling compliance.

The product has a narrow therapeutic window. Dofetilide initiation and dose adjustment require inpatient electrocardiographic monitoring because excessive exposure can prolong the QT interval and cause torsades de pointes. That clinical risk limits the commercial value of aggressive formulation changes and increases the value of manufacturing consistency, validated content uniformity, and robust quality systems.[1]

What is dofetilide 0.125 mg and who manufactures it?

Dofetilide is a Class III antiarrhythmic that blocks the rapid component of the delayed rectifier potassium current. The 0.125 mg capsule is the lowest marketed strength and is used principally when renal function, QT response, or dose tolerability requires a reduced dose.

Attribute	Dofetilide 0.125 mg
Active ingredient	Dofetilide
Dosage form	Immediate-release hard gelatin capsule
Strength	0.125 mg
Reference product	Tikosyn
Reference applicant	Pfizer
Original U.S. NDA	NDA 20-931
FDA approval	1999
Main indications	Atrial fibrillation and atrial flutter
Dose-selection variables	Creatinine clearance and QT/QTc interval
Initiation requirement	Inpatient monitoring for a minimum of three days or 12 hours after conversion, subject to label requirements
Biosimilar pathway	Not applicable; dofetilide is a small molecule
Primary regulatory pathway for competitors	Abbreviated New Drug Application

FDA-approved generic dofetilide capsules have entered the U.S. market after the reference product’s regulatory and patent barriers ceased to be commercially controlling. Product availability can vary by manufacturer, wholesaler, and strength. The 0.125 mg strength has particular importance because it is used in patients requiring the lowest labeled dose, including some patients with reduced renal clearance.[1,2]

What excipients are used in dofetilide 0.125 mg capsules?

The reference formulation uses conventional immediate-release capsule excipients. The FDA-approved label identifies microcrystalline cellulose, corn starch, sodium starch glycolate, and magnesium stearate as core excipients. The hard gelatin capsule shell contains gelatin and titanium dioxide; capsule-color components can vary by product and manufacturer.[1]

Formulation function	Typical excipient or component	Strategic role
Diluent and compression aid	Microcrystalline cellulose	Supports capsule-fill uniformity and powder handling
Filler and disintegrant contribution	Corn starch	Adds bulk and supports breakup of the fill mass
Superdisintegrant	Sodium starch glycolate	Promotes rapid dispersion after capsule rupture
Lubricant	Magnesium stearate	Controls powder adhesion and manufacturing friction
Capsule shell	Gelatin	Provides the immediate-release dosage form
Opacifier or color component	Titanium dioxide and product-specific colorants	Supports identification and visual differentiation

The label does not establish that each generic manufacturer uses the same qualitative or quantitative excipient composition. Approved generic products may use different inactive ingredients if they meet applicable quality, bioequivalence, labeling, and safety requirements.[1,3]

Are excipient quantities publicly disclosed?

Usually not. FDA labeling identifies inactive ingredients but generally does not disclose the complete quantitative formula, manufacturing process parameters, granulation endpoint, lubricant-mixing time, capsule-fill weight, or critical in-process controls. Those details are held in the chemistry, manufacturing, and controls section of the application.

For a competitor, the practical target is not to copy the reference formula exactly. The target is to develop a formulation with:

• Equivalent immediate-release performance.
• Reliable 0.125 mg content uniformity.
• Acceptable dissolution across relevant pH conditions.
• Low segregation risk during blending and encapsulation.
• Stable assay and impurity profile through shelf life.
• Capsule appearance that avoids medication-error risk.
• A manufacturing process compatible with low-dose potency.

How should an excipient strategy address the 0.125 mg dose?

The key formulation problem is low drug loading. A 0.125 mg capsule contains a small quantity of active pharmaceutical ingredient relative to the excipient mass. Blend uniformity and segregation control are therefore more important than simply selecting a rapid-disintegrating excipient.

Low-dose content uniformity

A direct-blend process may be commercially attractive, but it requires tight control of particle-size distribution, density, electrostatic behavior, and order of addition. A preblend or geometric dilution process can improve distribution of dofetilide through the excipient matrix. Granulation may reduce segregation but can introduce additional process variables, including solvent exposure, drying conditions, and changes in dissolution.

The highest-value controls are likely to include:

1. API particle-size and morphology specifications.
2. Validated blend uniformity sampling.
3. Defined lubricant addition and mixing limits.
4. Capsule-fill weight control.
5. Individual-capsule assay or a statistically justified sampling plan.
6. Stability monitoring for assay, degradation products, and dissolution.

A 0.125 mg product can be commercially differentiated through superior lot-release reliability and fewer supply interruptions, even when its excipient list is conventional.

Disintegration and dissolution

Sodium starch glycolate and corn starch support immediate release, while microcrystalline cellulose contributes bulk and mechanical behavior. Excessive lubricant concentration or overmixing can slow wetting and dissolution. A formulation developer should evaluate the interaction between magnesium stearate, capsule-fill density, disintegrant level, and API particle size.

The commercial objective is a reproducible dissolution profile rather than the fastest possible release. Dofetilide exposure is dose-sensitive, and an altered release profile could create regulatory and clinical risk even if total assay remains within specification.

Capsule identification

Dofetilide strengths are clinically important because dosing is selected from renal function and QT response. The 0.125 mg capsule should have clear strength differentiation from 0.25 mg and 0.5 mg products. Color, imprint, packaging, and barcode controls can reduce dispensing errors.

A manufacturer should avoid unnecessary visual similarity between strengths. The value of colorants is operational rather than therapeutic, but the selection must account for gelatin compatibility, light stability, regional regulatory status, and documented absence of unacceptable impurities.

What patents protect dofetilide 0.125 mg?

The core U.S. composition-of-matter and product exclusivity barriers for dofetilide are historical rather than current commercial barriers. Tikosyn was approved in 1999, and the principal opportunity today is generic or contract supply rather than a new patented composition.

Protection category	Commercial relevance
Dofetilide compound patents	Historical protection; generally expired before current generic commercialization
Reference-product regulatory exclusivity	Expired
Product-specific formulation patents	Must be checked in the current FDA Orange Book and patent databases; conventional excipient changes are unlikely to create broad blocking rights
Method-of-use patents	Potentially relevant only if listed, unexpired, and tied to an approved use
Manufacturing patents	Could affect a specific process but generally do not block all capsule manufacture
Trade secrets	More likely to protect process settings, supplier controls, and scale-up know-how than the basic excipient concept

A current diligence review should use the FDA Orange Book, Drugs@FDA, and relevant U.S. patent records to confirm the live status of any listed patent or pediatric exclusivity. Patent expiration for the original dofetilide estate should not be confused with the continuing regulatory requirement for a generic applicant to demonstrate pharmaceutical equivalence and bioequivalence.[2,4]

When did dofetilide lose exclusivity, and what is the generic entry risk?

The core exclusivity period ended years ago. The remaining commercial risk is not usually a new composition patent. It is the possibility of manufacturing disruption, limited supplier participation, or a competitor obtaining reliable access to hospitals, specialty pharmacies, and wholesalers.

Paragraph IV challenges

Paragraph IV certification was the principal mechanism for challenging any unexpired Orange Book-listed patent during generic entry. Because dofetilide’s original market exclusivity is historical, Paragraph IV litigation is less likely to define current commercial strategy than it would for a recently approved branded medicine.

For a new entrant, the key legal questions are:

• Whether any unexpired patent remains listed against the reference product.
• Whether a proposed formulation or process implicates a listed claim.
• Whether the applicant can use a Paragraph III certification or a section viii carve-out.
• Whether the product label can omit a patented method of use without creating substitution or prescribing barriers.
• Whether any settlement agreement restricts launch timing or supply relationships.

A generic applicant should not assume that an old product has no remaining patent exposure. The relevant analysis is claim-specific and must be conducted against the current Orange Book record and the proposed product process.[4,5]

What is the Orange Book status of dofetilide 0.125 mg?

The Orange Book identifies approved reference and generic products and records patent and exclusivity information associated with approved applications. The reference product is Tikosyn, with dofetilide as the active ingredient. The current commercial relevance of any listed patent must be assessed by expiration date, pediatric extension, patent-term adjustment, and the scope of the approved use.

A product-specific review should capture:

Orange Book field	Why it matters
NDA and ANDA numbers	Establishes the approved product family
Dosage form and strength	Confirms whether the patent entry applies to 0.125 mg capsules
Patent number	Identifies the asserted legal right
Patent expiration	Determines potential blocking period
Pediatric exclusivity	Can extend enforceability of listed patents
Therapeutic-equivalence code	Indicates substitutability status
Marketing status	Distinguishes active, discontinued, and withdrawn products

Generic substitution depends on the individual product’s therapeutic-equivalence designation and state pharmacy law. A manufacturer can have an approved product but still experience limited commercial uptake if wholesaler inventory, reimbursement, or supply reliability is weak.[4]

What formulation patents could protect a new dofetilide product?

A conventional capsule using microcrystalline cellulose, starch, sodium starch glycolate, and magnesium stearate is unlikely to create a strong patent position by itself. Patent value would require a defensible technical difference, such as:

• A demonstrated low-dose uniformity process.
• A novel particle-engineering approach.
• A controlled-release system with a clinically justified profile.
• A stability-enhancing formulation that solves a documented degradation problem.
• A capsule or packaging system that materially improves dose identification or storage.
• A method that reduces manufacturing failures while preserving bioequivalence.

Controlled release is a weak opportunity unless supported by a clear clinical rationale. Dofetilide dosing is tightly linked to exposure and QT effects. A modified-release product could require a new clinical and regulatory strategy rather than a straightforward generic filing.

Manufacturing patents may be more practical than formulation patents. A process that produces consistently uniform 0.125 mg capsules at commercial scale could support licensing or trade-secret value, even if it does not prevent all competing products.

What FDA regulatory requirements affect commercial launch?

A generic dofetilide capsule must meet the requirements for an ANDA, including pharmaceutical equivalence, bioequivalence, chemistry and manufacturing controls, labeling, and facility compliance.[3]

The most important regulatory constraints are:

• Immediate-release capsule equivalence.
• Dose-specific strength and labeling compliance.
• Stability through the proposed shelf life.
• Control of nitrosamines and other relevant impurities where applicable.
• Demonstration of consistent assay at the low 0.125 mg strength.
• Adequate dissolution testing.
• Compliance with current good manufacturing practice.
• Risk controls associated with a drug known to cause QT prolongation.

The three-day inpatient initiation requirement applies to starting or restarting dofetilide therapy under the FDA label. It does not automatically apply to every refill, but it affects prescribing, hospital protocols, and demand forecasting.[1]

What commercial opportunities exist for dofetilide 0.125 mg?

Generic capsule supply

The most direct opportunity is a dependable multisource generic product. Market access depends on obtaining ANDA approval, therapeutic-equivalence status, commercial-scale capacity, and wholesaler placement.

Hospital and institutional supply

Hospitals and cardiology systems value continuity because interruptions can complicate rhythm-management protocols. Unit-dose packaging, clear strength differentiation, and electronic product data can improve institutional adoption.

Contract manufacturing

A manufacturer with low-dose encapsulation capability can offer dofetilide production to smaller generic companies. The competitive advantage would be validated process control, not a novel excipient claim.

Private-label and regional distribution

Regional generic distributors may seek a stable source for 0.125 mg capsules where the lowest strength is intermittently unavailable. This opportunity is strongest in markets with limited approved suppliers.

Packaging and medication-error reduction

Commercial differentiation can include:

• Blister packaging for adherence and strength identification.
• Tall-man or prominent strength labeling where permitted.
• Unit-dose hospital cartons.
• Barcode-ready packaging.
• Separate packaging for 0.125 mg, 0.25 mg, and 0.5 mg strengths.
• Tamper-evident packaging with improved moisture protection.

These features may support customer preference but generally do not justify a major price premium without documented supply or safety benefits.

How does dofetilide compare with competing antiarrhythmics?

Dofetilide occupies a specific position among rhythm-control drugs because it can be used in patients with structural heart disease, but it requires inpatient initiation and renal-function-based dosing. Amiodarone has broader use but carries substantial long-term organ toxicity concerns. Sotalol also has QT and renal considerations. Dronedarone has different efficacy and contraindication limitations.

Drug	Main commercial distinction	Key operational burden
Dofetilide	Rhythm control with strict renal and QT dosing	Inpatient initiation and monitoring
Amiodarone	Broad rhythm-control use	Long-term systemic toxicity monitoring
Sotalol	Antiarrhythmic and beta-blocking activity	QT, renal, and bradycardia management
Dronedarone	Oral rhythm-control alternative	Contraindications and efficacy limitations

Dofetilide’s low-dose capsule opportunity depends on patients who remain appropriate for the therapy after initiation. The market is therefore clinically constrained but relatively specialized. Commercial volume should be modeled from treated patients and strength mix, not from the broader atrial-fibrillation population.

What litigation and settlement issues affect dofetilide?

The main historical litigation risk would have involved Hatch-Waxman challenges to listed patents for Tikosyn. Current diligence should examine FDA Orange Book records, federal court filings, and any public settlement terms for restrictions on launch timing, authorized-generic supply, or patent-related licensing.

For a new entrant, the more immediate legal risks are:

• Patent infringement based on a surviving formulation or method claim.
• Trade-secret disputes involving a contract manufacturer.
• Product-liability exposure arising from content-uniformity failures.
• Labeling or packaging claims that create strength-selection errors.
• Distribution agreements that limit access to wholesalers or hospital systems.

No biosimilar litigation pathway applies because dofetilide is a chemically synthesized small molecule.

How strong is the patent estate for dofetilide 0.125 mg?

The core patent estate is weak as a current barrier to ordinary generic capsule entry because the product has been marketed for decades and generic competition exists. A new formulation or manufacturing patent could have value, but its strength would depend on measurable technical performance and claim breadth.

Patent strategy	Likely strength
Claim to dofetilide itself	Low current blocking value because historical protection has expired
Conventional excipient combination	Low
Capsule-color or packaging claim	Low to moderate, usually narrow
Low-dose uniformity manufacturing process	Moderate if technically specific and difficult to design around
Modified-release formulation	Uncertain and clinically burdensome
Stability-enhancing formulation	Moderate if supported by comparative data
Device or adherence system	Moderate but commercially separate from the core drug

Key Takeaways

• Dofetilide 0.125 mg is an immediate-release hard capsule with a conventional excipient platform.
• The principal formulation challenge is uniform distribution of a very low API quantity.
• Microcrystalline cellulose, corn starch, sodium starch glycolate, magnesium stearate, gelatin, and titanium dioxide are the principal label-identified components of the reference product.
• The strongest commercial opportunity is reliable generic supply with excellent content uniformity and differentiated packaging.
• The original composition and regulatory exclusivity barriers are historical; current diligence must verify any live Orange Book patents.
• Paragraph IV risk is likely less important than manufacturing, supply, therapeutic-equivalence, and distribution execution.
• Biosimilar competition is not relevant because dofetilide is a small molecule.
• A conventional excipient combination is unlikely to create a strong patent estate. A validated low-dose manufacturing process or stability-enhancing formulation offers a stronger IP pathway.
• The 0.125 mg strength has specialized demand because dosing depends on renal function and QT response.
• Hospital supply, contract manufacturing, regional distribution, and medication-error-reduction packaging are the clearest commercial opportunities.

FAQs about dofetilide 0.125 mg excipients and market entry

Can dofetilide 0.125 mg be manufactured as a tablet instead of a capsule?

Yes, a tablet could be developed, but it would not be a routine capsule-equivalent change. The applicant would need to establish pharmaceutical equivalence, bioequivalence, dissolution performance, stability, and acceptable low-dose content uniformity. Tablet development could also require different labeling and product-identification controls.

Is lactose a necessary excipient in dofetilide capsules?

No. The reference formulation identified by FDA uses microcrystalline cellulose, corn starch, sodium starch glycolate, and magnesium stearate in the capsule fill. A generic product may use a different excipient system if it meets regulatory requirements.

Can a generic manufacturer launch only the 0.125 mg strength?

A single-strength launch may be possible if the application and commercial strategy support it. The manufacturer must account for dose titration and clinical use across the full product line. Offering only the lowest strength can reduce manufacturing complexity but may limit hospital and pharmacy adoption.

Does a new capsule color create patent protection for dofetilide?

Usually not meaningful patent protection. Capsule color can support product identification and medication-error reduction, but a color claim is generally narrow and may be vulnerable to design-around strategies. Regulatory acceptability and trade-dress considerations also apply.

Is dofetilide suitable for an authorized-generic strategy?

Yes. An authorized-generic model could use the reference sponsor’s or a licensed manufacturer’s product and distribution infrastructure. The commercial value depends on supply agreements, channel access, pricing strategy, and any remaining contractual or patent restrictions.

References

1. U.S. Food and Drug Administration. (2023). Tikosyn (dofetilide) capsules prescribing information. Pfizer Laboratories.
2. U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs, Tikosyn application information.
3. U.S. Food and Drug Administration. (2024). Abbreviated new drug application (ANDA) process and requirements.
4. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book.
5. U.S. Food and Drug Administration. (2024). Paragraph IV certifications and patent information for approved drug products.