List of Excipients in Branded Drug DIGITEK

Generic Drugs Containing DIGITEK

Company	Ingredient	NDC	Excipient
Mylan Pharmaceuticals Inc	digoxin	0378-6155	ANHYDROUS LACTOSE
Mylan Pharmaceuticals Inc	digoxin	0378-6155	CROSCARMELLOSE SODIUM
Mylan Pharmaceuticals Inc	digoxin	0378-6155	D&C YELLOW NO. 10
Mylan Pharmaceuticals Inc	digoxin	0378-6155	LACTOSE MONOHYDRATE
Mylan Pharmaceuticals Inc	digoxin	0378-6155	MICROCRYSTALLINE CELLULOSE 101
Mylan Pharmaceuticals Inc	digoxin	0378-6155	SILICON DIOXIDE

What are the Most Frequently-Used Excipients in DIGITEK?

# Of NDCs	Excipient
2	ANHYDROUS LACTOSE
1	CELLULOSE, MICROCRYSTALLINE
2	CROSCARMELLOSE SODIUM
2	D&C YELLOW NO. 10
2	LACTOSE MONOHYDRATE
1	MICROCRYSTALLINE CELLULOSE 101

DIGITEK Excipient Strategy and Commercial Opportunities: Digoxin Formulation, Regulatory and Patent Analysis

Last updated: July 31, 2026

Digitek is a digoxin tablet product whose commercial value is driven by manufacturing reliability, dose uniformity, supply continuity and differentiated delivery formats rather than active-ingredient exclusivity. Digoxin is a long-established generic active pharmaceutical ingredient with no meaningful composition-of-matter patent barrier. The strongest commercial opportunities are lactose-free tablets, pediatric and geriatric dosage forms, dose-flexible oral liquids, improved content-uniformity controls and contract manufacturing for regulated markets.

What is Digitek and which excipients are used?

Digitek is a tablet formulation of digoxin, a cardiac glycoside used primarily in heart failure and ventricular-rate control in selected patients with atrial fibrillation. Digoxin has a narrow therapeutic index, which makes tablet potency, content uniformity and dissolution performance commercially important.

Historical U.S. product labeling identifies Digitek tablets as containing excipients commonly used in immediate-release solid oral dosage forms:

Excipient	Functional role
Lactose monohydrate	Diluent and tablet-mass builder
Microcrystalline cellulose	Diluent, dry binder and compression aid
Pregelatinized starch	Binder and disintegrant
Crospovidone	Superdisintegrant
Colloidal silicon dioxide	Glidant and flow aid
Magnesium stearate	Lubricant
Talc	Processing aid and anti-adherent

The precise inactive-ingredient profile can vary by strength, manufacturing site, market and regulatory filing. Commercial diligence should rely on the current FDA DailyMed label, approved application record and product-specific batch documentation rather than historical label versions [1].

Digitek has been marketed in conventional low-dose tablet strengths, including 0.125 mg and 0.25 mg presentations. At these dose levels, the formulation contains a very small quantity of active ingredient relative to total tablet mass. Excipient selection therefore directly affects dose distribution and tablet-to-tablet consistency.

How does the Digitek excipient system affect product performance?

The primary technical risk is not dissolution speed alone. It is the interaction between low drug loading, powder segregation, blend uniformity, compression behavior and assay variability.

Low-dose content uniformity

Digoxin content is typically a small fraction of the tablet blend. A robust formulation requires:

• Controlled particle-size distribution for digoxin and the principal diluent
• Adequate blending without excessive segregation
• Validated sampling plans
• Tight control of lubricant addition time
• Consistent granule or powder density
• In-process weight and hardness monitoring
• Finished-product assay and uniformity testing

Microcrystalline cellulose and lactose provide bulk, but their density and particle-size differences can create segregation during transfer and tablet compression. Colloidal silicon dioxide can improve flow but may alter blend behavior when used at excessive levels.

Dissolution and disintegration

Crospovidone and pregelatinized starch support rapid tablet breakup. Digoxin absorption is affected by formulation and manufacturing variables, making dissolution control important for both quality and product comparability. Excessive magnesium stearate, prolonged lubrication or hydrophobic excipient surfaces can slow wetting and dissolution.

For a reformulated Digitek product, dissolution should be evaluated across:

• Multiple pH conditions
• Standard and discriminatory media
• Accelerated stability conditions
• Different tablet hardness levels
• Commercial-scale compression speeds

The formulation target should be a narrow dissolution profile that remains stable across manufacturing lots.

Stability and packaging

Digoxin tablets require protection from moisture, heat and manufacturing variability. Packaging opportunities include high-barrier blister systems, desiccant-equipped bottles and unit-dose packaging for institutional use. Packaging is not an excipient strategy in the strict sense, but it can protect a formulation from humidity-driven changes in hardness, disintegration and assay performance.

What excipient opportunities exist for a new Digitek product?

The most credible opportunities are incremental improvements that reduce patient-handling risk or manufacturing variability.

Lactose-free Digitek tablets

A lactose-free formulation could use anhydrous dibasic calcium phosphate, mannitol, silicified microcrystalline cellulose or selected starch-based diluents. The commercial rationale is strongest for patients with lactose intolerance, excipient sensitivity or complex medication regimens.

Potential benefits include:

• Expanded patient eligibility
• Cleaner institutional formularies
• Differentiation from legacy formulations
• Reduced dependence on lactose supply
• A possible 505(b)(2) or product-line extension strategy, depending on the regulatory pathway

The main technical issue is achieving equivalent dissolution and content uniformity at very low digoxin loading. Calcium phosphate may improve flow and compactability but can produce a harder tablet and slower disintegration. Mannitol can improve mouthfeel but may require a binder or granulation adjustment.

Direct-compression formulation

A direct-compression formulation using co-processed excipients could reduce process steps and improve manufacturing economics. Candidate systems include silicified microcrystalline cellulose, co-processed cellulose and starch, or other low-segregation excipient platforms.

The value proposition is strongest where the product has:

• High batch-to-batch variability
• Granulation capacity constraints
• High labor or energy costs
• A need for multiple low-dose strengths
• Limited manufacturing scale

Direct compression does not automatically create patent protection. Protection would require a defined composition, process parameter or performance limitation that is novel and non-obvious.

Orally disintegrating digoxin tablet

An orally disintegrating tablet could address swallowing difficulty in older patients. Potential excipient systems include mannitol, crospovidone, low-substituted hydroxypropyl cellulose and taste-masking agents.

The product would face material challenges:

• Digoxin has a narrow therapeutic index
• Taste masking may require coating or complexation
• Small dose variation can have clinical relevance
• Mechanical strength must be balanced against rapid disintegration
• Moisture-sensitive packaging may be required

An orally disintegrating product would have more meaningful differentiation than a simple diluent substitution, but it would also create greater development and regulatory risk.

Oral liquid or unit-dose solution

A ready-to-use oral liquid could improve dose flexibility for pediatric, geriatric and enteral-feeding patients. Commercial opportunities include 0.05 mg/mL or other low-concentration presentations, calibrated oral syringes and unit-dose cups.

The formulation must address:

• Chemical stability in solution
• Sorption to container or tubing materials
• Preservative compatibility
• Dose measurement accuracy
• Palatability
• Microbial control
• Excipient safety in children and older adults

A liquid product may qualify for a differentiated regulatory strategy if it introduces a clinically meaningful dosage-form improvement. It would also face competition from existing digoxin oral solutions and generic liquid products.

What formulations are protected by patents?

No broad, commercially significant patent estate is expected around digoxin itself. Digoxin was discovered decades ago, and ordinary immediate-release tablet formulations generally rely on expired or non-patentable technology.

The patentable areas are formulation-specific:

Potential claim area	Commercial value	Patent strength
Lactose-free digoxin tablet	Moderate	Low to moderate
Specific co-processed excipient system	Moderate	Moderate if performance-linked
Orally disintegrating tablet	Moderate to high	Moderate
Taste-masked oral liquid	High if clinically useful	Moderate
Extended-release digoxin dosage form	Potentially high	Difficult to validate clinically
Unit-dose packaging	Low to moderate	Low
Manufacturing process for content uniformity	Moderate	Moderate if narrowly claimed
Combination product with another cardiac drug	Potentially high	Depends on clinical and claim scope

A defensible formulation patent should claim more than a list of familiar excipients. Stronger claims would link the composition to measurable technical results, such as:

• Digoxin assay variability within a defined range
• Dissolution at specified time points
• Segregation resistance
• Tablet tensile strength and disintegration limits
• Stability after defined humidity exposure
• Reduced degradation or improved dose recovery
• Performance across multiple commercial-scale batches

A patent that claims digoxin, lactose, cellulose and magnesium stearate in broad terms would face substantial validity risk from prior art and routine formulation practice.

When does Digitek lose exclusivity?

Digitek does not depend on a current composition-of-matter exclusivity period. Digoxin is an established generic active ingredient, and immediate-release digoxin tablets can generally be challenged through the ANDA pathway if the applicant meets FDA requirements.

Exclusivity analysis should separate four concepts:

Exclusivity category	Digitek relevance
Active-ingredient patent	No meaningful remaining barrier expected
Formulation patent	Possible only for a specific reformulated product
Method-of-use patent	Potentially relevant but limited by approved labeling and claim scope
FDA regulatory exclusivity	Depends on any new application or qualified product

A newly developed dosage form could obtain regulatory protection only if it satisfies the applicable statutory requirements. A conventional generic tablet would not receive market exclusivity merely because it uses a different excipient supplier or manufacturing process.

What is the Orange Book status of Digitek?

The Orange Book analysis should focus on the currently listed reference product, approved application number, therapeutic equivalence codes and any patents or exclusivity entries associated with the product. Historical Digitek labeling and product availability do not establish a current Orange Book listing.

For a new commercial program, the key questions are:

1. Is Digitek the listed reference drug or only a historical brand?
2. Is a current reference-listed drug available for the intended dosage form?
3. Are any patents or exclusivity periods listed for the reference product?
4. Can the proposed product be filed as an ANDA?
5. Would a 505(b)(2) application be needed because of dosage form, concentration, route or clinical reliance?

The FDA Orange Book and Drugs@FDA databases are the controlling sources for current listing and regulatory status [2,3].

Which companies are challenging Digitek or competing with it?

Competition is primarily from generic digoxin manufacturers rather than branded companies pursuing a direct patent challenge. The market includes manufacturers of:

• Digoxin tablets
• Digoxin oral solutions
• Hospital and institutional unit-dose presentations
• Imported or region-specific digoxin products
• Contract-manufactured low-dose cardiac tablets

The competitive set can change because digoxin is a mature product with intermittent supply, manufacturing discontinuations and limited commercial promotion. The relevant competitive advantage is often product availability rather than brand recognition.

A company entering the market would compete on:

• Consistent supply
• Reliable low-dose content uniformity
• Competitive acquisition cost
• Tablet scoring and dose flexibility
• Packaging for institutional dispensing
• Absence of selected excipients
• Oral-liquid availability
• Regulatory and quality-system performance

What patent litigation affects Digitek?

No major active litigation position can be inferred solely from the Digitek brand name. The historical commercial risk associated with Digitek was primarily product quality and recall-related, not a blocking patent dispute.

In 2008, Actavis recalled certain digoxin tablets marketed under the Digitek name after reports that some tablets contained more or less than the labeled amount of digoxin. The FDA described the issue as a potential dosage-content problem involving tablets that could be oversized or undersized [4]. That history remains commercially relevant because it raises the importance of validated blend uniformity, tablet-weight controls, visual inspection and market surveillance.

For a new entrant, litigation exposure is more likely to arise from:

• Product liability claims
• Manufacturing-defect allegations
• Trade-secret disputes involving formulation or process parameters
• Supplier-related quality claims
• Patent claims directed to a novel delivery system
• Regulatory disputes over substitutability or reference-product status

What generic launch risks exist for Digitek?

A generic launch would face low patent risk but meaningful technical and commercial risk.

Regulatory risks

FDA review would focus on pharmaceutical equivalence, bioequivalence where applicable, manufacturing controls, stability, dissolution and labeling. Digoxin has a narrow therapeutic index, so the applicant should expect close scrutiny of analytical methods and product comparability.

Manufacturing risks

The central manufacturing risks are:

• Blend segregation
• Assay variability
• Tablet-weight drift
• Inadequate process capability
• Lubrication-related dissolution changes
• Supplier variation in lactose or cellulose
• Compression defects at low tablet weights

Commercial risks

The U.S. digoxin market is mature and price-sensitive. A new conventional tablet may face limited pricing power unless it solves a recognized problem. The strongest opportunities are likely to involve:

• Supply-constrained strengths
• Pediatric or geriatric dosing
• Lactose-free products
• Oral liquids
• Unit-dose institutional packaging
• Dual-source or backup manufacturing
• Markets with limited local production

How does Digitek compare with other digoxin dosage forms?

Product concept	Patient value	Development complexity	Differentiation	Commercial outlook
Conventional tablet	Low to moderate	Low	Low	Price-driven
Lactose-free tablet	Moderate	Low to moderate	Moderate	Niche expansion
Scored tablet	Moderate	Low	Low to moderate	Useful for dose flexibility
Orally disintegrating tablet	Moderate to high	Moderate to high	High	Targeted opportunity
Oral liquid	High for selected patients	Moderate	High	Attractive specialty niche
Unit-dose tablet	Moderate for institutions	Low to moderate	Moderate	Procurement-driven
Extended-release product	Uncertain	High	High	Clinical validation required

The conventional tablet remains the lowest-risk development option. The oral liquid and orally disintegrating tablet offer greater differentiation, but they require more extensive stability, palatability, dose-delivery and clinical-performance work.

What is the revenue exposure and commercial opportunity?

Digitek-specific revenue exposure should not be estimated from historical brand sales without current prescription, payer, channel and supply data. The relevant market is the broader digoxin market, which is mature, genericized and relatively small compared with newer cardiovascular therapies.

A commercial model should separate:

• Tablet volume by strength
• Oral-liquid volume
• Retail versus institutional sales
• Average selling price
• Gross-to-net deductions
• Manufacturing cost per tablet
• Packaging and serialization costs
• Recall and remediation reserves
• Probability of supply interruption
• Regulatory filing and post-approval costs

The highest-margin opportunity is unlikely to be another undifferentiated 0.125 mg or 0.25 mg tablet. A differentiated dosage form can support better economics if it has a clear patient or procurement advantage and avoids a complex clinical-development burden.

How strong is the patent estate for a new Digitek formulation?

A new Digitek patent estate would be weak if it relies only on conventional excipients. It could be moderate if it combines:

• A defined low-dose formulation
• A measurable content-uniformity advantage
• A reproducible manufacturing process
• Improved dissolution or stability
• A clinically relevant dosage-form benefit

The recommended intellectual-property structure would include separate filings for:

1. Composition of matter for the excipient system
2. Manufacturing process and blending sequence
3. Tablet architecture or dosage-form design
4. Packaging and moisture-control system
5. Oral-liquid stability or container-closure combination
6. Use claims tied to a specific patient population, where legally supportable

Freedom-to-operate work should cover U.S., European, Canadian, Japanese and other target-market patent databases. Geographic protection is more likely to matter for a novel liquid, orally disintegrating system or combination product than for a standard digoxin tablet.

What regulatory pathway is most practical?

An ANDA is generally the most efficient route for a conventional digoxin tablet that is pharmaceutically equivalent and bioequivalent to the relevant reference product.

A 505(b)(2) strategy may be more appropriate for:

• A novel oral liquid concentration
• An orally disintegrating product
• A substantially different excipient system
• A new dosage form
• A product requiring reliance on published literature or existing FDA findings without being a direct generic equivalent

The regulatory pathway should be selected before excipient development because it determines the required comparability package, clinical evidence, labeling strategy and potential exclusivity.

Key Takeaways

• Digitek is a mature digoxin tablet product with limited active-ingredient patent value.
• The commercial opportunity lies in formulation performance, supply reliability and differentiated dosage forms.
• Lactose-free tablets, oral liquids, orally disintegrating tablets and institutional unit-dose formats offer the clearest opportunities.
• Low-dose content uniformity is the central technical challenge.
• Conventional excipient combinations provide weak patent protection unless tied to measurable performance benefits.
• The FDA Orange Book, Drugs@FDA and current DailyMed labeling control the regulatory and listing analysis.
• A conventional tablet is most suitable for an ANDA strategy; differentiated dosage forms may support a 505(b)(2) pathway.
• The 2008 Digitek recall makes manufacturing controls and dose uniformity central to product positioning.
• A new entrant should compete on quality, availability and patient-use advantages rather than brand promotion alone.

FAQs

Is Digitek still a protected brand-name drug?

Digoxin is a long-established active ingredient, and ordinary immediate-release digoxin tablets do not have meaningful remaining composition-of-matter protection. Current product-specific exclusivity must be checked against FDA databases.

Can a lactose-free digoxin tablet obtain patent protection?

Yes, but a broad lactose-free claim would likely be vulnerable if it merely substitutes a known diluent. Stronger protection would require a defined excipient system with demonstrated stability, dissolution or content-uniformity advantages.

Is digoxin considered a narrow therapeutic index drug?

Digoxin has a narrow therapeutic range, and small changes in exposure or dose can have clinical consequences. Formulation development should prioritize assay accuracy, content uniformity, dissolution and dosing controls.

Would a digoxin oral liquid have commercial value?

Yes. An oral liquid can address dose flexibility and swallowing limitations in pediatric, geriatric and enteral-feeding populations. Its value depends on stability, dosing accuracy, palatability and reliable reimbursement or institutional demand.

What caused the historical Digitek recall?

The 2008 recall involved reports that some Digitek tablets contained more or less than the labeled amount of digoxin, with tablet-size variation identified as part of the product-quality issue [4].

References

1. U.S. National Library of Medicine. (n.d.). DailyMed: Digoxin tablet labeling. https://dailymed.nlm.nih.gov/
2. U.S. Food and Drug Administration. (n.d.). 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
3. U.S. Food and Drug Administration. (n.d.). Drugs@FDA. https://www.accessdata.fda.gov/scripts/cder/daf/
4. U.S. Food and Drug Administration. (2008). Actavis announces nationwide recall of Digitek digoxin tablets. FDA Drug Safety Communications and recall materials. https://www.fda.gov/ ---