List of Excipients in Branded Drug NEFAZODONE HYDROCHLORIDE

Generic Drugs Containing NEFAZODONE HYDROCHLORIDE

Company	Ingredient	NDC	Excipient
Teva Pharmaceuticals USA Inc	nefazodone hydrochloride	0093-7178	CELLULOSE, MICROCRYSTALLINE
Teva Pharmaceuticals USA Inc	nefazodone hydrochloride	0093-7178	FERRIC OXIDE RED
Teva Pharmaceuticals USA Inc	nefazodone hydrochloride	0093-7178	MAGNESIUM STEARATE
Teva Pharmaceuticals USA Inc	nefazodone hydrochloride	0093-7178	POVIDONE K30
Teva Pharmaceuticals USA Inc	nefazodone hydrochloride	0093-7178	SILICON DIOXIDE

What are the Most Frequently-Used Excipients in NEFAZODONE HYDROCHLORIDE?

# Of NDCs	Excipient
7	CELLULOSE, MICROCRYSTALLINE
1	COLLOIDAL SILICON DIOXIDE
3	FERRIC OXIDE RED
4	FERRIC OXIDE YELLOW
7	MAGNESIUM STEARATE

Nefazodone Hydrochloride Excipient Strategy and Commercial Opportunities

Last updated: September 8, 2026

Nefazodone hydrochloride has limited commercial attractiveness as a conventional generic because the active ingredient is old, widely substitutable, and associated with serious hepatotoxicity concerns. The strongest opportunities are formulation-led: improved dose uniformity, lower pill burden, modified release, improved swallowability, and tightly controlled excipient systems that support a 505(b)(2) or specialty-generic strategy.

The main development constraint is safety. Excipients can improve manufacturability and pharmacokinetics, but they cannot remove nefazodone’s intrinsic hepatic risk or its interaction potential through CYP3A4 inhibition. Any reformulation would require a robust clinical and regulatory rationale, not simply a new excipient composition.

What is nefazodone hydrochloride and how is it supplied?

Nefazodone hydrochloride is the hydrochloride salt of nefazodone, an antidepressant classified pharmacologically as a serotonin modulator. The historical U.S. product, Serzone, was supplied as immediate-release tablets in 50 mg, 100 mg, 150 mg, 200 mg, and 250 mg strengths. Generic nefazodone hydrochloride tablets have used the same basic oral tablet platform.

Nefazodone is metabolized extensively in the liver. Its major metabolites include hydroxynefazodone and triazoledione, with CYP3A4 contributing materially to its metabolism. The product label identifies clinically important drug interactions and serious liver injury risk, including rare cases requiring transplantation or resulting in death (FDA, 2003; DailyMed, n.d.).

Attribute	Nefazodone hydrochloride
Dosage form	Immediate-release oral tablet
Historical strengths	50, 100, 150, 200 and 250 mg
Therapeutic category	Antidepressant; serotonin modulator
Key metabolic pathway	Hepatic metabolism, including CYP3A4
Primary formulation concern	Oral dose delivery with hepatic safety constraints
Primary commercial concern	Small market, generic competition and safety-related prescribing limitations
Main formulation opportunity	Differentiated oral delivery rather than routine tablet replication

What excipients are used in nefazodone hydrochloride tablets?

Historical nefazodone tablet formulations use standard solid-dose excipients. Depending on the manufacturer and jurisdiction, the excipient system may include microcrystalline cellulose, lactose or another diluent, povidone, a disintegrant such as croscarmellose sodium or sodium starch glycolate, colloidal silicon dioxide, magnesium stearate, and film-coating materials.

The exact excipient profile is manufacturer-specific. A generic developer must distinguish between:

1. Excipients listed in the reference product.
2. Excipients used in a current generic product.
3. Excipients acceptable under FDA inactive-ingredient precedent.
4. Excipients that may alter dissolution, absorption or tolerability.

A practical reference formulation would normally contain:

Formulation function	Candidate excipients	Commercial rationale
Diluent	Microcrystalline cellulose, lactose monohydrate, mannitol, dibasic calcium phosphate	Controls tablet weight, compression and cost
Binder	Povidone, copovidone, hydroxypropyl cellulose	Improves granule strength and content uniformity
Disintegrant	Croscarmellose sodium, crospovidone, sodium starch glycolate	Supports immediate release
Glidant	Colloidal silicon dioxide	Improves powder flow
Lubricant	Magnesium stearate, sodium stearyl fumarate	Supports tableting and ejection
Wetting aid	Polysorbate 80, sodium lauryl sulfate, poloxamer	May improve wetting of a lipophilic active
Film coating	Hypromellose, polyvinyl alcohol, polyethylene glycol, titanium dioxide	Improves appearance, handling and swallowability

Excipient selection should preserve the dissolution profile of the reference product. Excessive hydrophobic lubrication, high polymer loading or overly dense compaction could delay release and create bioequivalence risk.

Which excipient strategy is best for a conventional generic?

The lowest-risk approach is a conventional immediate-release, film-coated tablet using a direct-compression or dry-granulation platform. This strategy minimizes manufacturing complexity and limits the need for clinical differentiation.

A practical development sequence is:

Direct-compression platform

Direct compression is attractive when the active pharmaceutical ingredient has adequate flow, compressibility and content uniformity. It reduces solvent exposure and processing steps. Microcrystalline cellulose, mannitol or lactose can provide the principal diluent system, with crospovidone or croscarmellose sodium as the disintegrant.

The risk is segregation, especially in low-strength tablets where the active represents a small fraction of total tablet weight. Blend uniformity must be demonstrated across the full strength range.

Dry granulation

Roller compaction can improve flow and reduce segregation without introducing water or heat. It may be preferable if the active or salt form has poor flow or if wet granulation changes solid-state properties.

The principal risks are over-compaction and slower tablet disintegration. These can be managed through granule porosity, lubricant concentration and disintegrant placement.

Wet granulation

Wet granulation can improve content uniformity and tablet robustness, but it creates additional process variables. The developer must evaluate hydrate formation, salt stability, residual moisture and possible changes in dissolution.

For a mature generic product, wet granulation is usually justified only if direct compression and dry granulation fail to provide acceptable manufacturing performance.

What excipients could improve nefazodone dissolution and absorption?

Nefazodone hydrochloride is a salt, but salt formation does not guarantee rapid or complete dissolution across gastrointestinal pH conditions. The molecule is lipophilic, and its absorption can be affected by formulation wetting, particle size, gastric conditions and food intake.

Potential enabling excipient systems include:

Surfactant-assisted immediate release

Low concentrations of sodium lauryl sulfate, polysorbate 80 or poloxamer may improve wetting and reduce dissolution variability. These excipients are commercially available and familiar to regulators, but they can affect gastrointestinal tolerability and may produce an overly rapid release profile.

The formulation target should be reproducible dissolution, not the highest possible dissolution rate.

Amorphous solid dispersion

A polymeric dispersion using copovidone, hydroxypropyl methylcellulose acetate succinate or a related carrier could increase apparent solubility. This approach is technically more complex and may be unnecessary for a conventional tablet.

The main risks are recrystallization, humidity sensitivity, scale-up complexity and the need for solid-state controls. An amorphous system becomes more commercially defensible if it produces a clinically meaningful reduction in food effect, dose variability or tablet burden.

Lipid-based delivery

Self-emulsifying or lipid-based systems could improve dissolution of a lipophilic active. These systems are less natural fits for a standard tablet and may require softgel, capsule or multiparticulate delivery.

They also introduce questions about food effects, excipient tolerability, capsule compatibility and long-term stability. A lipid formulation would need a strong pharmacokinetic rationale.

Particle-size engineering

Micronization or controlled particle-size distribution can improve dissolution without introducing a new excipient system. It is comparatively simple, but it may create electrostatic handling issues and does not necessarily solve pH-dependent solubility.

What formulation patents could protect a nefazodone product?

The original composition-of-matter protection for nefazodone is long expired. A new commercial opportunity would therefore depend on formulation, process, delivery or method-of-use claims rather than basic molecule protection.

Potential claim categories include:

Patent category	Possible protected subject matter	Relative commercial value
Composition	Specific excipient ratios, solid dispersions or granules	Moderate if linked to measurable performance
Dissolution	Release profile across specified pH conditions	Moderate, but difficult to enforce alone
Modified release	Matrix, coated multiparticulates or osmotic delivery	High if clinically differentiated
Manufacturing	Granulation, drying, milling or coating process	Moderate; depends on detectability
Stability	Moisture-control system or stabilized solid form	Moderate
Combination product	Nefazodone with a tolerability or adherence component	Limited unless medically meaningful
Method of use	Reduced dosing frequency, specific patient population or titration regimen	Potentially valuable but vulnerable to invalidity and label restrictions

A patent on a simple mixture of conventional excipients is unlikely to create durable commercial protection unless it produces an unexpected technical effect. Stronger claims would connect the formulation to a defined dissolution profile, pharmacokinetic result, stability improvement or clinical advantage.

When does nefazodone lose exclusivity?

Nefazodone’s original small-molecule exclusivity and primary patent protection have expired. The relevant commercial issue is not loss of basic exclusivity but the absence of a large, protected market.

Historical regulatory protection for an older antidepressant does not create a current barrier to ordinary generic competition. Any new exclusivity would need to arise from a newly approved formulation, method of use, orphan indication or other qualifying regulatory pathway.

The likely regulatory routes are:

• Abbreviated New Drug Application for a therapeutically equivalent immediate-release product.
• 505(b)(2) application for a materially different formulation, delivery system, dosage form or dosing regimen.
• Full NDA if the product cannot rely adequately on prior findings of safety and efficacy.

A conventional generic has limited ability to use formulation innovation to command premium pricing. A 505(b)(2) product could obtain stronger differentiation, but it would require comparative pharmacokinetic or clinical evidence and could face patent litigation if the sponsor lists relevant patents.

What is the Orange Book status of nefazodone hydrochloride?

The Orange Book remains the relevant source for listed U.S. reference products, therapeutic-equivalence codes and patent or exclusivity information. Nefazodone’s commercial history includes the Serzone reference product and generic tablet approvals. Current listing status should be assessed by product number and sponsor because discontinued products and withdrawn marketing status can change the practical reference-product strategy.

For development purposes, the key questions are:

1. Which nefazodone reference product is currently designated for the proposed strength and dosage form?
2. Is the proposed product eligible for a standard ANDA pathway?
3. Are any unexpired patents or regulatory exclusivities listed for the target product?
4. Does the formulation differ enough to require a 505(b)(2) application?
5. Is the reference product commercially available for bioequivalence testing?

A Paragraph IV challenge would have little strategic relevance against expired original patents. It could become relevant only if a new sponsor obtains listed patents covering an improved formulation or method of use.

What is the Paragraph IV and litigation risk?

For a conventional nefazodone hydrochloride tablet, Paragraph IV risk is likely to be low because the principal molecule patents are historical. The greater risks are regulatory and commercial:

• Failure to establish bioequivalence across multiple strengths.
• Dissolution differences caused by excipient changes.
• Inability to obtain a commercially meaningful reference product.
• Labeling and safety restrictions related to hepatotoxicity.
• Limited prescriber demand.
• Product discontinuation or supply-chain interruptions.

A differentiated 505(b)(2) product would create a new patent landscape. Its risks would include obviousness challenges against formulation claims, written-description issues, lack of unexpected results and attempts to design around narrow release-profile limitations.

No active litigation or settlement should be assumed without a current review of PACER, FDA Orange Book listings, ANDA litigation records and sponsor disclosures.

How does nefazodone compare with competing antidepressants?

Nefazodone competes against selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, atypical antidepressants and generic trazodone. Its commercial position is weakened by safety monitoring and familiarity advantages held by competing products.

Product category	Generic competition	Safety or tolerability positioning	Formulation opportunity
Nefazodone	High	Hepatic risk and CYP3A4 interaction concerns	Modified release, adherence and specialty use
Trazodone	High	Sedation and orthostatic effects	Extended release and abuse-resistant delivery
SSRIs	Very high	Broad prescribing familiarity	Low-cost standard tablets and liquids
SNRIs	High	Blood-pressure and withdrawal considerations	Extended release
Bupropion	High	Different mechanism; seizure-related restrictions	Modified release and dose simplification

A nefazodone product would need a clear advantage over generic alternatives. A lower-cost tablet alone is unlikely to justify investment in a new excipient platform.

What commercial opportunities exist for nefazodone excipients?

The most credible opportunities are narrow and product-specific.

Modified-release tablets

A once-daily formulation could reduce dosing frequency and improve adherence. Hydrophilic matrix polymers such as hypromellose or polyethylene oxide could provide release control. The formulation would need to address dose dumping, food effects and the pharmacokinetics of nefazodone metabolites.

This is the strongest potential product-differentiation route, but also the most expensive because it may require a 505(b)(2) program.

Orally disintegrating tablets

An orally disintegrating tablet could address swallowing difficulty and reduce administration barriers. Mannitol, crospovidone, low-substituted hydroxypropyl cellulose and taste-masking agents are plausible excipient choices.

Taste masking may be difficult because the active drug and its salt can have a strong taste. The dosage form also must preserve dose uniformity across strengths.

Lower-pill-burden dosage forms

Higher-strength tablets or multiparticulates could simplify titration. This opportunity is limited by the need to replicate the established dose range and avoid accidental overexposure during dose escalation.

Stability and supply-chain optimization

A robust low-cost tablet platform using commonly available excipients may have value in contract manufacturing, institutional supply and geographically fragmented markets. Moisture-barrier film coatings, high-density packaging and controlled lubricant levels could improve product stability without creating a new clinical claim.

What manufacturing and intellectual-property barriers exist?

Manufacturing barriers are manageable for an immediate-release tablet but increase sharply for advanced delivery systems.

Key technical controls include:

• Salt identity and purity.
• Particle-size distribution.
• Blend uniformity across strengths.
• Tablet tensile strength and friability.
• Disintegration and dissolution at multiple pH values.
• Stability under accelerated and long-term conditions.
• Control of degradation products.
• Compatibility between the active and lubricants, surfactants and polymers.
• Packaging protection from moisture and light.

The most defensible intellectual property would cover a reproducible formulation-performance relationship. Examples include a defined release profile, a stable amorphous system, a specific multiparticulate architecture or a pharmacokinetic improvement demonstrated against the immediate-release reference product.

What FDA regulatory issues affect a new nefazodone product?

The FDA’s principal concern is the established risk-benefit profile of nefazodone. Product labeling historically includes warnings about potentially fatal hepatic failure and recommends attention to liver-related symptoms and clinical management (FDA, 2003).

A new product would need to preserve or appropriately update safety labeling. A modified-release formulation could not claim reduced liver risk without substantial evidence. Lower peak concentrations might support tolerability, but they would not eliminate hepatic metabolism or idiosyncratic liver injury.

The sponsor would also need to consider:

• Bioequivalence methodology for each strength.
• Food-effect testing.
• Multiple-dose pharmacokinetics.
• Metabolite exposure.
• Drug-drug interaction potential.
• Dose proportionality.
• Pediatric and geriatric administration.
• Postmarketing safety obligations.
• Current FDA inactive-ingredient precedent.

Key Takeaways

• Nefazodone hydrochloride is an old generic antidepressant with expired primary exclusivity and limited current market depth.
• Conventional excipient replication offers the lowest regulatory risk but limited commercial upside.
• Microcrystalline cellulose, lactose or mannitol, povidone, croscarmellose sodium or crospovidone, colloidal silicon dioxide and magnesium stearate are practical starting points for an immediate-release tablet.
• Surfactants and polymeric systems may improve dissolution but create additional safety, stability and bioequivalence risks.
• Modified release is the most credible differentiation strategy, but it would likely require a 505(b)(2) pathway and new clinical or pharmacokinetic evidence.
• Excipients cannot remove nefazodone’s intrinsic hepatotoxicity or CYP3A4 interaction risk.
• Paragraph IV risk is likely limited for historical molecule patents; new formulation patents would create the principal litigation exposure.
• Commercial viability depends more on a defensible clinical or adherence benefit than on ordinary tablet-cost reduction.

FAQs

Can nefazodone hydrochloride be developed as an orally disintegrating tablet?

Yes. Mannitol, crospovidone and low-substituted hydroxypropyl cellulose are plausible platform excipients. Taste masking, dose uniformity and rapid disintegration would be the central development issues.

Would a lipid formulation eliminate nefazodone food effects?

No. A lipid formulation could alter dissolution and absorption, but it could also introduce a new food effect. Comparative pharmacokinetic studies would be required.

Is a nefazodone extended-release product commercially attractive?

Only if it produces a meaningful dosing, adherence or pharmacokinetic advantage. The safety history and competition from established generic antidepressants make an incremental extended-release product difficult to commercialize without strong differentiation.

Can a new excipient combination obtain patent protection?

Yes, but broad protection for routine excipient combinations would be vulnerable. Stronger patent claims would require unexpected performance, a defined release profile, improved stability or a demonstrated pharmacokinetic benefit.

Are biosimilars relevant to nefazodone hydrochloride?

No. Nefazodone is a chemically synthesized small molecule, not a biologic. The relevant competitive products are generic drugs and reformulated small-molecule products, not biosimilars.

References

1. DailyMed. (n.d.). Nefazodone hydrochloride tablet prescribing information. National Library of Medicine. https://dailymed.nlm.nih.gov/

2. U.S. Food and Drug Administration. (2003). Nefazodone hydrochloride product labeling. FDA. https://www.accessdata.fda.gov/

3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA. https://www.accessdata.fda.gov/scripts/cder/ob/

4. U.S. Food and Drug Administration. (2017). Waiver of in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms based on a biopharmaceutics classification system. FDA Guidance for Industry. https://www.fda.gov/

5. U.S. Food and Drug Administration. (2019). Applications covered by Section 505(b)(2). FDA Guidance for Industry. https://www.fda.gov/

6. National Center for Biotechnology Information. (n.d.). PubChem compound summary: Nefazodone. PubChem. https://pubchem.ncbi.nlm.nih.gov/