List of Excipients in Branded Drug ISOSORBIDE DINITRATE

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Oceanside Pharmaceuticals	ISOSORBIDE DINITRATE	isosorbide dinitrate	68682-193	CELLULOSE, MICROCRYSTALLINE
Oceanside Pharmaceuticals	ISOSORBIDE DINITRATE	isosorbide dinitrate	68682-193	FD&C RED NO. 40
Oceanside Pharmaceuticals	ISOSORBIDE DINITRATE	isosorbide dinitrate	68682-193	LACTOSE MONOHYDRATE
Oceanside Pharmaceuticals	ISOSORBIDE DINITRATE	isosorbide dinitrate	68682-193	MAGNESIUM STEARATE

Generic Drugs Containing ISOSORBIDE DINITRATE

Company	Ingredient	NDC	Excipient
West-ward Pharmaceutical Corp	isosorbide dinitrate	0143-1765	AMMONIUM PHOSPHATE, DIBASIC
West-ward Pharmaceutical Corp	isosorbide dinitrate	0143-1765	ANHYDROUS LACTOSE
West-ward Pharmaceutical Corp	isosorbide dinitrate	0143-1765	CELLULOSE, MICROCRYSTALLINE
West-ward Pharmaceutical Corp	isosorbide dinitrate	0143-1765	D&C YELLOW NO. 10

What are the Most Frequently-Used Excipients in ISOSORBIDE DINITRATE?

# Of NDCs	Excipient
10	AMMONIUM PHOSPHATE, DIBASIC
32	ANHYDROUS LACTOSE
33	CELLULOSE, MICROCRYSTALLINE
1	COLLOIDAL SILICON DIOXIDE

Isosorbide Dinitrate Excipient Strategy and Commercial Opportunities

Last updated: August 28, 2026

Isosorbide dinitrate (ISDN) is an established nitrate vasodilator with generic FDA-approved products in oral sublingual and extended-release dosage forms. Its commercial opportunity is not based on new-molecule exclusivity. It is based on formulation performance, dose convenience, stability, global supply reliability, and differentiated delivery systems. The strongest opportunities are in low-cost generic tablets, orally disintegrating or rapidly dissolving products, modified-release systems, and combination products where excipient selection supports dose uniformity and predictable nitrate release.

What is the FDA regulatory status of isosorbide dinitrate?

Isosorbide dinitrate is an FDA-approved active pharmaceutical ingredient for prevention of angina pectoris due to coronary artery disease. Approved dosage forms include sublingual tablets and oral tablets, including extended-release products. FDA-approved products have been marketed under brands including Isordil and Dilatrate-SR, alongside generic products.[1,2]

Attribute	Isosorbide dinitrate
Active ingredient	Isosorbide dinitrate
Therapeutic class	Organic nitrate; vasodilator
Primary indication	Prevention of angina pectoris
Common dosage forms	Sublingual tablet, immediate-release tablet, extended-release capsule or tablet
Regulatory pathway	Abbreviated New Drug Application for generics; 505(b)(2) possible for differentiated delivery
Patent position	Original compound and conventional products are long off-patent
Current commercial basis	Generic supply, formulation quality, manufacturing efficiency, and niche dosage forms
Biosimilar relevance	None; ISDN is a small molecule

ISDN is also used in combination with hydralazine hydrochloride for heart failure. The commercial product BiDil contains fixed-dose hydralazine hydrochloride and isosorbide dinitrate tablets. The combination has a separate regulatory and patent history from single-agent ISDN products.[3]

When does isosorbide dinitrate lose exclusivity?

Isosorbide dinitrate lost practical compound and conventional formulation exclusivity many years ago. A meaningful current patent barrier for a standard ISDN tablet or sublingual tablet is unlikely.

The relevant exclusivity analysis is product-specific:

Exclusivity category	Current commercial significance
Original compound patent	Expired
Conventional immediate-release formulation patents	Generally expired or commercially irrelevant
Original brand exclusivity	Expired
Orphan-drug exclusivity	Not generally applicable to single-agent ISDN
Pediatric exclusivity	No material current barrier identified
Fixed-dose combination patents	Must be assessed separately for hydralazine/ISDN products
New delivery-system patents	Potentially available for newly developed products
Regulatory exclusivity for a new 505(b)(2) product	Possible if statutory requirements are met

A developer should not assume that the absence of compound patents eliminates all freedom-to-operate risk. A new orally disintegrating tablet, transbuccal system, controlled-release matrix, or combination product may implicate later formulation, manufacturing, or method-of-use rights. Each proposed product requires a current patent search in the United States and target markets.

What patents protect isosorbide dinitrate products?

Standard ISDN products are principally exposed to expired composition-of-matter and conventional dosage-form patents. The more relevant patent opportunities now involve delivery technology rather than the active ingredient.

Potentially protectable subject matter includes:

• Sublingual or buccal systems with defined disintegration or dissolution times.
• Controlled-release matrices that reduce peak-to-trough exposure.
• Multiparticulate systems with staged nitrate release.
• Taste-masked orally disintegrating tablets.
• Moisture-resistant packaging and tablet compositions.
• Low-dose formulations with improved content uniformity.
• Fixed-dose combinations with hydralazine.
• Formulations designed to preserve a nitrate-free interval.
• Manufacturing processes that reduce degradation or improve blend uniformity.
• Device-enabled delivery systems.

The patent value of these claims depends on clinical differentiation. A patent covering a minor excipient substitution in a commodity tablet is commercially weak unless it produces a measurable advantage in stability, dissolution, manufacturing yield, or patient adherence.

How strong is the patent estate for isosorbide dinitrate?

The patent estate for conventional ISDN is weak because the molecule and ordinary oral dosage forms are mature. A new product can still create a defensible position if the formulation delivers clinically relevant performance that is difficult to design around.

Patent strategy	Expected strength	Commercial value
Broad ISDN composition claims	Very low	Minimal
Conventional immediate-release tablet	Low	Minimal
Sublingual tablet with standard excipients	Low	Limited
Novel rapid-disintegration platform	Moderate	Depends on clinical and manufacturing data
Controlled-release product with defined PK profile	Moderate to high	Potentially meaningful
ISDN-hydralazine combination	Moderate, product-specific	Established niche
Proprietary packaging and stability system	Low to moderate	Useful as a secondary barrier
Manufacturing process with measurable yield or purity benefit	Moderate	Can support supply advantage
Device or buccal delivery system	Moderate to high	Potentially differentiated

The strongest strategy is usually a layered portfolio: formulation claims, process claims, analytical methods, packaging claims, and use claims where supportable. A single narrow excipient claim is vulnerable to substitution.

What excipients are used in isosorbide dinitrate tablets?

The excipient system depends on the dosage form. Public product labels and inactive-ingredient databases identify common excipient classes used in ISDN products, but the exact composition varies by manufacturer.[1,4]

Immediate-release tablets

Typical excipient functions include:

Function	Candidate excipient classes	Formulation objective
Diluent	Lactose, microcrystalline cellulose, starch, dibasic calcium phosphate	Achieve tablet mass and content uniformity
Binder	Povidone, pregelatinized starch, hydroxypropyl cellulose	Improve granule and tablet strength
Disintegrant	Crospovidone, croscarmellose sodium, sodium starch glycolate	Promote rapid tablet breakup
Lubricant	Magnesium stearate, stearic acid	Prevent sticking and improve ejection
Glidant	Colloidal silicon dioxide, talc	Improve powder flow
Colorant	Approved pigments or lakes	Product identification
Film coating	Hypromellose, polyethylene glycol, titanium dioxide where permitted	Improve handling and appearance

ISDN is a low-dose, potent active ingredient. Content uniformity is therefore a central formulation issue. Direct compression may be attractive for cost and simplicity, but poor segregation control can produce unacceptable dose variability. A pre-blend, ordered mixing process, wet granulation, dry granulation, or engineered carrier may be needed depending on particle size and bulk density.

Sublingual tablets

Sublingual products require rapid wetting, disintegration, and dissolution. Excipients should not produce a hydrophobic barrier or excessive tablet hardness.

Common design priorities include:

• Low compression force consistent with mechanical integrity.
• High-performance disintegrants.
• Water-soluble fillers.
• Low lubricant concentration.
• Controlled particle size of ISDN.
• Limited coating or no coating.
• Low moisture exposure during manufacture and packaging.
• Taste management without slowing dissolution.

Mannitol, lactose, microcrystalline cellulose, crospovidone, croscarmellose sodium, and low concentrations of magnesium stearate are potential starting points. The correct system must be confirmed through dissolution, disintegration, friability, assay, and content-uniformity testing.

Extended-release formulations

Extended-release ISDN products require a release-controlling mechanism. Potential platforms include:

• Hydrophilic polymer matrices using hydroxypropyl methylcellulose.
• Hydrophobic matrices using waxes or insoluble polymers.
• Coated multiparticulates.
• Osmotic or diffusion-controlled systems.
• Ion-exchange or reservoir systems, where technically justified.

The primary challenge is balancing prolonged exposure with the nitrate-free interval required to reduce tolerance. A formulation that maintains continuous nitrate exposure may undermine the pharmacological rationale of intermittent dosing. The product label and clinical pharmacology program must support the proposed release profile.[2,5]

What excipient strategy is best for a generic ISDN product?

For a conventional generic, the optimal strategy is a low-cost, compendial excipient system with a robust manufacturing process and a conservative stability profile.

A practical development sequence is:

1. Select a narrow particle-size distribution for ISDN.
2. Establish blend uniformity using a validated sampling plan.
3. Compare direct compression with dry or wet granulation.
4. Screen disintegrants for rapid dissolution without capping or friability.
5. Minimize lubricant exposure to avoid dissolution retardation.
6. Evaluate lactose-containing and lactose-free alternatives.
7. Perform forced-degradation and photostability studies.
8. Select unit-dose or high-barrier packaging based on moisture and light sensitivity.
9. Match dissolution across relevant pH conditions.
10. Confirm bioequivalence against the applicable reference product.

Excipient selection should be linked to a measurable product attribute. For example, crospovidone is commercially useful when it improves rapid disintegration without compromising tablet strength. A premium excipient is not justified if it does not improve dissolution, stability, yield, or patient use.

What formulations are protected by potential new ISDN patents?

New patentable formulations are most likely to arise from differentiated dosage forms.

Orally disintegrating tablets

An ISDN orally disintegrating tablet could target patients who have difficulty swallowing or need rapid administration. Commercial differentiation would require more than fast disintegration. The product should demonstrate:

• Short disintegration time.
• Acceptable taste.
• Low friability.
• Stable potency under humidity stress.
• Reliable dose delivery in unit-dose packaging.
• Dissolution performance appropriate for the intended use.

Taste-masking systems must be evaluated carefully because polymer coatings, ion-complexing agents, or lipid barriers can delay ISDN release.

Buccal films and mucoadhesive systems

A buccal film could provide rapid absorption and reduce dependence on tablet disintegration. Potential patent claims could cover polymer composition, drug loading, film thickness, mucoadhesion, drying conditions, and release kinetics.

The commercial risks are substantial. ISDN loading may be limited, nitrate stability must be maintained, and packaging must protect the film from humidity. A film product would likely require a more extensive clinical and regulatory package than a standard generic tablet.

Controlled-release products

A controlled-release product could address dosing frequency and peak-related adverse effects. The formulation must preserve an appropriate nitrate-free interval or use an intermittent dosing regimen. Patent claims could cover polymer ratios, coating thickness, release windows, and pharmacokinetic parameters.

Combination products

Hydralazine/ISDN products offer the clearest established differentiation. BiDil is approved for use in certain patients with heart failure, including self-identified Black patients receiving combination therapy under the approved indication.[3] A competitor could pursue an authorized generic, a generic equivalent where permitted, or a separate 505(b)(2) product with a different strength, ratio, or delivery format.

What generic entry risks exist for isosorbide dinitrate?

Generic entry risk is high for standard ISDN tablets and sublingual products because:

• The active ingredient is old and widely available.
• Conventional excipients are inexpensive.
• Manufacturing technology is mature.
• Clinical differentiation is limited.
• Substitution by pharmacies is likely where state and payer rules permit.
• Multiple suppliers can reduce dependence on a single manufacturer.

Risk is lower for products requiring specialized manufacturing or clinical bridging:

Product type	Generic entry risk	Main barrier
Standard immediate-release tablet	High	Price competition only
Standard sublingual tablet	High	Dissolution and content uniformity
Extended-release product	Moderate	Release profile and bioequivalence
Orally disintegrating tablet	Moderate	Taste, stability, and performance
Buccal film	Moderate to low	Manufacturing and clinical evidence
Fixed-dose hydralazine/ISDN product	Moderate	Combination bioequivalence and market size

A first generic may obtain temporary commercial advantage through limited competition, but long-term pricing power is likely to be weak unless the product has a supply, packaging, or dosage-form distinction.

What is the Orange Book status of isosorbide dinitrate?

The Orange Book should be reviewed by product and dosage form because listing status can change as products are discontinued, withdrawn, or replaced.[1] Older reference products may appear with discontinued marketing status, while generic approvals can remain listed depending on the regulatory record.

For diligence, the relevant checks are:

• Active reference-listed drug status.
• Therapeutic-equivalence codes.
• Strength and dosage-form matching.
• Listed patents and exclusivity.
• Withdrawal status.
• ANDA approval history.
• Whether a product is eligible for substitution.
• Whether a fixed-dose combination is treated separately from single-agent ISDN.

A generic applicant should not rely on the presence or absence of a single Orange Book entry without reviewing FDA approval records and current product labeling.

Which companies are challenging isosorbide dinitrate exclusivity?

The market is primarily a multi-source generic market rather than a branded patent contest. Publicly visible competition has historically included manufacturers of generic ISDN tablets, sublingual tablets, extended-release products, and hydralazine/ISDN combinations. Exact active supplier rankings require current FDA, IQVIA, or wholesaler data.

The competitive landscape is divided into four groups:

1. Large generic manufacturers competing on cost and supply scale.
2. Contract manufacturers supplying private-label products.
3. Specialty companies offering niche dosage forms.
4. Branded or authorized-generic suppliers focused on combination products.

Paragraph IV litigation is less likely to be commercially central for old, standard ISDN products than for newly launched formulation variants. A Paragraph IV filing could still arise if a new extended-release, buccal, or combination product has listed patents. For legacy immediate-release ISDN, patent litigation risk is generally lower than price and supply risk.

What manufacturing and intellectual-property barriers affect ISDN?

ISDN manufacturing is not technically comparable to a complex biologic, but nitrate chemistry creates quality and safety requirements. Key barriers include:

• Control of raw-material purity.
• Prevention of cross-contamination with potent nitrate materials.
• Moisture and temperature control.
• Safe handling of nitrate-containing intermediates.
• Control of degradation products.
• Blend uniformity at low drug loading.
• Validated cleaning procedures.
• Packaging that limits light and humidity exposure.
• Reliable supply of qualified API.

Process patents for the original synthesis are unlikely to provide a meaningful current barrier. Manufacturing know-how, validated process parameters, supplier qualification, and regulatory history are more important than legacy synthesis patents.

How does isosorbide dinitrate compare with isosorbide mononitrate?

Isosorbide mononitrate has a different commercial and pharmacokinetic profile. It is commonly used in extended-release products and has more extensive positioning around once-daily or sustained dosing. ISDN is more associated with immediate-release and sublingual administration, as well as combination therapy with hydralazine.

Factor	Isosorbide dinitrate	Isosorbide mononitrate
Nitrate groups	Two	One
Common rapid-use format	Sublingual tablet	Less prominent
Extended-release opportunity	Present	Stronger established market
Combination with hydralazine	Established	Not the principal branded combination
Generic competition	High	High
Formulation challenge	Rapid release and low-dose uniformity	Sustained release and dose scheduling
Patent opportunity	Delivery and combination products	Extended-release and delivery systems

A company selecting between the two molecules should evaluate clinical positioning, reference-product availability, bioequivalence requirements, and expected market size rather than excipient cost alone.

What commercial opportunities exist for ISDN excipient innovation?

The most credible opportunities are:

Low-cost, robust generic tablets

This is the largest-volume opportunity but also the least defensible. Value comes from reliable supply, low manufacturing cost, strong dissolution performance, and minimal product complaints.

Premium sublingual dosage forms

Rapid-dissolving tablets or films may support higher pricing if they improve administration, reduce handling, or provide consistent absorption. The product must demonstrate a clear advantage over existing sublingual tablets.

Fixed-dose hydralazine/ISDN products

Combination products may offer better commercial protection than single-agent ISDN because they address a specific treatment regimen. The market is smaller but more differentiated.

Specialty packaging

Unit-dose blister packaging, humidity-resistant systems, and patient-friendly packaging can reduce stability failures and improve adherence. Packaging patents alone are unlikely to support a large premium, but they can strengthen a broader product strategy.

Emerging-market supply

ISDN is relevant in markets where low-cost cardiovascular medicines remain important and access to newer therapies is limited. Regulatory registration, local manufacturing, and supply continuity may create more value than U.S. patent protection.

What revenue exposure does ISDN create for manufacturers?

Single-agent ISDN revenue is generally not separately disclosed by diversified pharmaceutical companies. Its commercial value is typically embedded in generic portfolios or contract-manufacturing revenue. The largest financial exposure is therefore operational:

• Loss of a low-margin contract due to price erosion.
• Product shortage caused by API or packaging disruption.
• Manufacturing failure from low-dose blend nonuniformity.
• Recall risk from dissolution or potency issues.
• Reduced portfolio value if a combination product loses differentiation.

A differentiated ISDN product can generate higher gross margin, but the addressable market is likely smaller than that for high-volume cardiovascular generics. Investment should be based on forecasted units, price per prescription, manufacturing cost, regulatory cost, and expected competition rather than the historical branded value of Isordil or BiDil.

Key Takeaways

• ISDN is a mature, off-patent small molecule with high generic competition.
• The commercial opportunity is formulation-led, not compound-patent-led.
• Immediate-release tablets offer volume but limited pricing power.
• Sublingual, orally disintegrating, buccal, and controlled-release systems provide the strongest formulation opportunities.
• Excipients should be selected against measurable targets: content uniformity, disintegration, dissolution, stability, taste, and manufacturing yield.
• Hydralazine/ISDN combination products have more regulatory and commercial differentiation than single-agent ISDN.
• Biosimilar risk is irrelevant because ISDN is a small molecule.
• Current Orange Book, FDA labeling, ANDA, and patent records must be reviewed at the product level.
• Manufacturing know-how, packaging, supply reliability, and regulatory execution are more important than legacy compound patents.
• A defensible portfolio should combine formulation, process, packaging, and potentially method-of-use claims.

FAQs

Can a new ISDN excipient combination receive patent protection?

Yes, but only if the formulation provides a novel and non-obvious composition or performance advantage. Routine substitution of lactose, starch, povidone, or magnesium stearate is unlikely to support strong claims without unexpected results.

Is isosorbide dinitrate suitable for a 505(b)(2) application?

Potentially. A 505(b)(2) strategy may be relevant to a new buccal film, orally disintegrating product, controlled-release dosage form, or other delivery system that relies partly on an existing ISDN product while requiring new clinical or pharmacokinetic support.[5]

Does ISDN have biosimilar competition?

No. ISDN is a chemically synthesized small molecule. Competition occurs through generic drug applications, not biosimilar applications.

Can an ISDN sublingual product command a premium price?

Only if it demonstrates a meaningful advantage in speed, dose consistency, patient usability, storage stability, or adherence. A conventional sublingual tablet is likely to face generic price competition.

What is the main freedom-to-operate risk for a new ISDN product?

The principal risk is later patent coverage on a delivery platform, combination product, manufacturing process, or formulation performance parameter. Legacy composition-of-matter patents are unlikely to be the main constraint.

References

1. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: The Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book-data-files
2. DailyMed. (2024). Isosorbide dinitrate product labeling. National Library of Medicine. https://dailymed.nlm.nih.gov/
3. U.S. Food and Drug Administration. (2024). BiDil prescribing information. https://www.accessdata.fda.gov/
4. U.S. Food and Drug Administration. (2024). Inactive Ingredient Database. https://www.accessdata.fda.gov/scripts/cder/iig/index.cfm
5. U.S. Food and Drug Administration. (2019). Applications covered by section 505(b)(2). https://www.fda.gov/drugs/development-resources/applications-covered-section-505b2- fdli/fda-guidance-documents