List of Excipients in Branded Drug PHENELZINE SULFATE

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Mylan Pharmaceuticals Inc	PHENELZINE SULFATE	phenelzine sulfate	59762-0119	CROSCARMELLOSE SODIUM
Mylan Pharmaceuticals Inc	PHENELZINE SULFATE	phenelzine sulfate	59762-0119	EDETATE DISODIUM
Mylan Pharmaceuticals Inc	PHENELZINE SULFATE	phenelzine sulfate	59762-0119	ISOPROPYL ALCOHOL
Mylan Pharmaceuticals Inc	PHENELZINE SULFATE	phenelzine sulfate	59762-0119	MAGNESIUM STEARATE

Generic Drugs Containing PHENELZINE SULFATE

Company	Ingredient	NDC	Excipient
Novel Laboratories Inc	phenelzine sulfate	40032-360	EDETATE DISODIUM
Novel Laboratories Inc	phenelzine sulfate	40032-360	FD&C YELLOW NO. 6
Novel Laboratories Inc	phenelzine sulfate	40032-360	MAGNESIUM STEARATE
Novel Laboratories Inc	phenelzine sulfate	40032-360	MANNITOL

What are the Most Frequently-Used Excipients in PHENELZINE SULFATE?

# Of NDCs	Excipient
2	EDETATE DISODIUM
2	FD&C YELLOW NO. 6
2	MAGNESIUM STEARATE
2	MANNITOL

Phenelzine Sulfate Excipient Strategy and Commercial Opportunities

Last updated: August 10, 2026

Phenelzine sulfate is an established monoamine oxidase inhibitor sold primarily as 15 mg immediate-release tablets. Its commercial opportunity is a niche generic and specialty-pharmacy market rather than a high-volume antidepressant franchise. The strongest product-development opportunities involve tablet robustness, supply reliability, excipient simplification, preservative-free oral delivery, and pharmacy-compounded alternatives. The core active ingredient has limited patent barriers, but regulatory, safety, manufacturing, and market-size constraints materially affect returns.

What is the current formulation of phenelzine sulfate?

Phenelzine sulfate is marketed as an oral tablet containing 15 mg of phenelzine sulfate. The reference product is Nardil. FDA labeling identifies the product as a film-coated tablet for oral administration and describes phenelzine sulfate as a monoamine oxidase inhibitor used for major depressive disorder, particularly in patients who have not responded to other treatments.[1]

The product is an immediate-release solid oral dosage form. The commercial formulation does not depend on an extended-release delivery system, enteric coating, osmotic technology, or complex absorption enhancer.

Phenelzine sulfate formulation profile

Attribute	Product characteristic
Active ingredient	Phenelzine sulfate
Strength	15 mg per tablet
Route	Oral
Dosage form	Film-coated tablet
Release profile	Immediate release
Therapeutic class	Monoamine oxidase inhibitor
Primary use	Major depressive disorder
Reference product	Nardil
FDA pathway for a generic	Abbreviated New Drug Application, subject to applicable FDA requirements
Main commercial issue	Small, specialized market with supply-history risk

Phenelzine is prescribed less frequently than selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, and atypical antidepressants. The product is reserved for treatment-resistant or otherwise difficult-to-manage depression in many clinical settings because of food, drug-interaction, and hypertensive-crisis warnings.[1,2]

Which excipients are used in phenelzine sulfate tablets?

The reference product’s inactive ingredients should be confirmed against the current FDA-approved labeling and DailyMed record before any development or filing decision. Public labeling for Nardil identifies conventional tablet excipients and a film-coating system, including lactose and other standard pharmaceutical excipients depending on the marketed presentation and labeling revision.[1,3]

A generic developer should not assume that the reference formulation is fixed across historical manufacturing sites. Legacy products may have undergone manufacturing transfers, excipient changes, coating changes, or supplier substitutions without changing the dosage form or strength.

Relevant excipient functions

Excipient function	Commercial purpose
Diluent	Provides tablet mass because the active dose is small
Binder	Supports granule and tablet mechanical strength
Disintegrant	Enables breakup of the immediate-release tablet
Lubricant	Reduces sticking and ejection force
Glidant	Improves powder flow and content uniformity
Film coating	Improves appearance, swallowability, handling, and protection from abrasion
Opacifier or colorant	Supports product identification and visual differentiation

The 15 mg dose creates a high excipient-to-active ratio. Blend uniformity is therefore a central development issue. A formulation that uses direct compression may be commercially attractive, but it must demonstrate adequate content uniformity, tablet tensile strength, dissolution, and low active segregation during scale-up.

Lactose-free and low-allergen opportunities

A lactose-free formulation could address patients with lactose intolerance, excipient sensitivity, or pharmacy preferences. This opportunity is commercially relevant only if the product maintains equivalent dissolution, stability, and manufacturability. Mannitol, microcrystalline cellulose, dibasic calcium phosphate, and starch-based systems are possible development directions, but each changes powder flow, compaction, hygroscopicity, and dissolution behavior.

A lactose-free claim would require accurate labeling and controlled supplier qualification. A developer should avoid broad "hypoallergenic" positioning because excipient-related tolerability claims are difficult to substantiate and can create regulatory exposure.

What excipient strategy is most suitable for phenelzine sulfate?

The most defensible strategy is a simple, conventional, immediate-release tablet with a low-risk excipient set and strong control of moisture, blend uniformity, and coating performance.

Strategy 1: Conventional wet-granulated tablet

Wet granulation can reduce segregation risk for a low-dose active and improve content uniformity. It may be appropriate where phenelzine sulfate has poor flow or poor compactability.

The principal disadvantages are additional processing steps, possible exposure to water, longer manufacturing time, and greater process-validation burden. The formulation developer must establish that the granulation process does not degrade the active or create an unacceptable impurity profile.

Strategy 2: Direct-compression tablet

Direct compression offers lower manufacturing cost and a shorter process. It can support flexible contract manufacturing and reduce equipment requirements.

The main risks are active segregation, poor flow, tablet capping, and variable hardness. These risks increase when the active ingredient has a low dose relative to total tablet weight. A co-processed excipient or engineered filler may improve performance, but the commercial benefit must exceed the cost of the specialized excipient.

Strategy 3: Lactose-free immediate-release tablet

A lactose-free tablet has the clearest patient-facing differentiation. The product can use microcrystalline cellulose, mannitol, or another compatible diluent system. This approach may also support a clean-label or specialty-pharmacy strategy.

The key development work involves comparative dissolution, moisture exposure, impurity formation, and long-term stability. The formulation should avoid unnecessary excipients that add no measurable manufacturing or patient benefit.

Strategy 4: Scored or easier-to-swallow tablet

A scored tablet could support dose flexibility if the score is functionally justified and validated. Phenelzine dosing is individualized, so tablet splitting may have practical value. The product must meet applicable requirements for split-tablet uniformity and stability after splitting.

A smaller tablet, smooth film coating, or capsule-shaped profile could improve swallowability. These changes may create a patient-use advantage without requiring a new pharmacologic product.

What manufacturing and stability barriers affect phenelzine sulfate?

Phenelzine sulfate is commercially sensitive to manufacturing reliability because it is an older product with a relatively small patient population. A developer must manage raw-material availability, impurity controls, packaging, and finished-product shelf life.

Critical quality attributes

The principal quality attributes include:

• Assay and related substances
• Content uniformity
• Dissolution
• Tablet hardness and friability
• Disintegration
• Water content
• Coating integrity
• Microbial quality
• Stability under long-term and accelerated conditions

Phenelzine sulfate is an amine-containing active pharmaceutical ingredient. The formulation and packaging program should evaluate potential reactions with excipients, residual moisture, oxygen exposure, and packaging components. Compatibility screening should include reducing sugars, reactive carbonyl compounds, peroxide-forming excipients, and high-moisture systems where relevant.

A high-barrier blister or bottle with a validated desiccant strategy may offer greater protection than a low-cost bottle configuration. Packaging is a potential differentiator if supply interruptions have historically been associated with manufacturing or distribution constraints.

Manufacturing opportunities

A contract manufacturer could create value through:

1. Dual-source API qualification.
2. Standardized immediate-release tablet platform technology.
3. Dedicated low-volume campaign manufacturing.
4. Automated visual inspection and serialization.
5. Packaging configurations matched to specialty-pharmacy dispensing.
6. Long-term reserve inventory for a shortage-sensitive market.

The manufacturing barrier is unlikely to be a novel process patent. It is more likely to be reliable execution, validated analytical methods, and consistent supply at a small production scale.

What patents protect phenelzine sulfate?

Phenelzine sulfate is an old active ingredient, and the principal composition-of-matter patent position has expired. The commercial product therefore does not appear to depend on a meaningful unexpired composition patent for phenelzine sulfate itself.

Potential residual intellectual-property categories include:

• Historical formulation patents
• Manufacturing-process patents
• Packaging patents
• Device or delivery patents
• Method-of-use patents
• Trademark rights covering Nardil
• Regulatory exclusivity associated with a specific later-approved product, if any

For a conventional 15 mg immediate-release generic tablet, the central IP risk is limited compared with newer small-molecule products. A developer should still conduct a live patent and regulatory-exclusivity review before filing. The relevant analysis should include the FDA Orange Book, Patent and Exclusivity Information, USPTO records, and litigation databases.[4,5]

Orange Book and Paragraph IV exposure

A standard ANDA applicant would evaluate any listed patents associated with the reference product and make the applicable certification. If no unexpired listed patent covers the proposed product, Paragraph IV litigation may not arise.

If a listed patent is present, the applicant could face a Paragraph IV notice and potential Hatch-Waxman litigation. The economic value of a first-filer position would depend on whether the patent blocks approval, whether 180-day exclusivity is available, and whether the product has sufficient market size to justify litigation expense.

For phenelzine sulfate, litigation economics are likely to be less attractive than for high-revenue products. A patent challenge would need a clear commercial rationale, such as a meaningful formulation distinction, shortage-driven demand, or strategic portfolio value.

When does phenelzine sulfate lose exclusivity?

Phenelzine sulfate’s original small-molecule exclusivity has expired. The product is therefore eligible for generic competition subject to FDA approval requirements and any current listed patents or regulatory protections.

FDA approval does not mean that a generic can automatically enter the market. Entry depends on:

• ANDA approval
• Patent certifications
• Any applicable 30-month stay
• Commercial manufacturing readiness
• Drug-supply conditions
• Wholesale and pharmacy contracts
• Reference-product availability for bioequivalence work

Because phenelzine is an immediate-release tablet, the development pathway is simpler than for a complex modified-release product. A conventional generic may rely on pharmacokinetic bioequivalence and pharmaceutical equivalence rather than clinical efficacy trials, subject to FDA requirements.

What is the FDA regulatory status of phenelzine sulfate?

Phenelzine sulfate is an FDA-approved prescription drug used for major depressive disorder.[1] The reference product is an oral tablet, and the active ingredient is listed in FDA drug databases and labeling resources.

The product carries substantial safety-related labeling. Key issues include hypertensive reactions associated with tyramine-containing foods, interactions with serotonergic agents, sympathomimetics, certain analgesics, and other contraindicated drugs.[1,2]

These warnings shape commercial positioning. A company cannot treat phenelzine as a routine first-line antidepressant. Patient-support materials, pharmacist education, dispensing controls, and accurate labeling may be more commercially important than cosmetic formulation changes.

What commercial opportunities exist for phenelzine sulfate?

The commercial opportunity is concentrated in specialty generic supply, not mass-market volume.

Opportunity areas

Opportunity	Commercial rationale	Main constraint
Reliable generic 15 mg tablet	Limited competition can support stable demand	Small market
Lactose-free tablet	Differentiates excipient profile	Requires formulation and labeling validation
High-barrier packaging	Supports stability and supply reliability	Packaging cost
Specialty-pharmacy distribution	Matches treatment-resistant depression use	Narrow prescriber base
Contract manufacturing	Addresses low-volume production needs	Scale economics
Authorized generic or licensing	Can leverage an existing product platform	Limited revenue pool
Compounded capsules or suspensions	Supports individualized dosing where legally permitted	State and pharmacy regulation
International registration	Extends geographic reach	Country-specific approval and supply requirements

A company could pursue an authorized-generic arrangement with the brand owner or a product-rights holder. The deal value would likely be based on manufacturing reliability, geographic rights, and supply obligations rather than a broad patent moat.

Revenue exposure

Public sources generally do not provide a reliable standalone revenue figure for phenelzine sulfate across all manufacturers and channels. The addressable market is constrained by the drug’s clinical positioning, adverse-effect burden, and availability of alternative antidepressants.

Revenue concentration is likely to be high because a small number of suppliers can account for a large portion of available product. This creates upside during shortages but also exposes manufacturers to abrupt volume changes if competing supply returns.

How does phenelzine sulfate compare with competing antidepressants?

Phenelzine competes against newer antidepressants with broader prescribing use, simpler dietary requirements, and larger commercial markets.

Factor	Phenelzine sulfate	SSRIs and SNRIs	Tranylcypromine
Drug class	Irreversible MAOI	Selective reuptake inhibitors	Irreversible MAOI
Typical use	Treatment-resistant depression	Broad first-line use	Treatment-resistant depression
Dosage form	Immediate-release tablet	Tablets, capsules, liquids, extended-release products	Immediate-release tablet
Excipient opportunity	Lactose-free, stability, tablet performance	Often formulation and delivery innovation	Similar niche-tablet opportunity
Safety burden	Significant food and drug interactions	Generally lower	Significant food and drug interactions
Patent opportunity	Limited for legacy product	Varies by product	Limited for legacy product
Market size	Niche	Large	Niche

Tranylcypromine is the closest therapeutic comparator. A phenelzine product could compete through supply continuity, excipient differentiation, price, and pharmacy availability rather than through a novel mechanism.

What formulation patents could create new value?

A new formulation could create a separate commercial position if it provides a clinically meaningful and regulatorily supportable advantage. Potential concepts include:

• A lower-dose tablet for titration.
• A rapidly disintegrating tablet.
• A liquid formulation for patients unable to swallow tablets.
• A stabilized oral suspension.
• A modified-release product intended to reduce peak-related adverse effects.
• A multiparticulate system.
• A preservative-free formulation for pharmacy compounding or institutional use.

These products would carry substantially higher development risk. A modified-release or liquid product may require a 505(b)(2) application rather than a conventional ANDA, depending on the formulation and reference-product relationship.[6]

A new dosage form would need a clear clinical or adherence rationale. Phenelzine’s low market size may not support the cost of a novel delivery system unless the product receives orphan-like specialty pricing, secures institutional demand, or expands use in a clearly defined patient segment.

Which companies could challenge or compete with phenelzine sulfate?

Competition is likely to come from generic manufacturers, specialty pharmaceutical companies, contract manufacturers, and compounding pharmacies rather than from large innovative antidepressant companies.

The most relevant competitive groups are:

• Generic tablet manufacturers with low-volume oral-solid capacity.
• Companies holding legacy antidepressant products.
• Specialty distributors serving psychiatric practices.
• Contract development and manufacturing organizations.
• Compounding pharmacies that prepare alternative oral presentations where permitted.
• International suppliers seeking U.S. or regional registrations.

Named company participation, current supply status, and any active litigation should be verified through FDA listing data, DailyMed, clinical-drug databases, and court records at the time of transaction or filing. Historical ownership of Nardil and generic phenelzine products has changed over time, making current commercial attribution more important than legacy brand ownership.

What generic launch scenarios exist for phenelzine sulfate?

Three launch models are commercially plausible.

Low-cost standard generic

A company launches a conventional 15 mg film-coated tablet with minimal differentiation. This approach has the lowest development cost but exposes the product to price competition and limited shelf space.

Supply-reliability generic

A company differentiates through dual sourcing, high-barrier packaging, inventory commitments, and specialty-pharmacy distribution. This model may produce better customer retention than a purely price-led launch.

Formulation-differentiated product

A company launches a lactose-free, easier-to-swallow, lower-dose, or alternative oral formulation. This approach can support a higher price but may require a 505(b)(2) application, clinical bridging, or additional FDA review.

The most attractive risk-adjusted strategy is generally a reliable conventional tablet with a carefully selected excipient system. A novel delivery platform should be pursued only where the sponsor has evidence of patient demand and a regulatory path that preserves commercial value.

Key Takeaways

• Phenelzine sulfate is a legacy MAOI marketed primarily as a 15 mg immediate-release tablet.
• Original composition-of-matter exclusivity has expired, leaving limited patent protection for a conventional generic.
• The most important formulation issues are content uniformity, moisture control, excipient compatibility, dissolution, and shelf life.
• A lactose-free formulation, improved coating, scored tablet, or high-barrier package could provide modest differentiation.
• Novel liquids, orally disintegrating tablets, or modified-release products would require higher regulatory and commercial investment.
• The market is niche and safety-sensitive, with revenue driven by treatment-resistant depression and supply availability.
• Generic launch economics depend more on reliable manufacturing and distribution than on patent litigation.
• Specialty-pharmacy supply, authorized-generic arrangements, and contract manufacturing are the clearest commercial opportunities.
• A standard ANDA is likely to be more commercially rational than a complex 505(b)(2) product unless a defined patient need supports premium pricing.

FAQs

Is phenelzine sulfate available as a generic drug?

Yes. Phenelzine sulfate is an established generic active ingredient, although product availability may vary by manufacturer, pharmacy, and distribution channel.

Can phenelzine sulfate be reformulated without a clinical trial?

A conventional immediate-release generic may use an ANDA pathway if it satisfies FDA requirements for pharmaceutical equivalence and bioequivalence. A materially different dosage form may require a 505(b)(2) application and additional bridging evidence.

Is lactose-free phenelzine sulfate commercially viable?

It could be viable as a specialty formulation, but the opportunity is limited by the small market. The product would need demonstrated excipient differentiation, stable manufacturing, and reliable pharmacy distribution.

Does phenelzine sulfate have biosimilar risk?

No. Phenelzine sulfate is a chemically synthesized small molecule, not a biologic. Competition would come from generic small-molecule products, not biosimilars.

What is the main intellectual-property barrier for a phenelzine sulfate generic?

For a conventional 15 mg immediate-release tablet, the principal barrier is unlikely to be an unexpired active-ingredient patent. Current Orange Book listings, formulation patents, regulatory exclusivity, manufacturing rights, and product-specific litigation still require transaction-level review.

References

1. U.S. Food and Drug Administration. (n.d.). Nardil (phenelzine sulfate) tablets: Prescribing information. DailyMed.

2. U.S. Food and Drug Administration. (n.d.). Phenelzine sulfate: Drug safety information and labeling. FDA.

3. National Library of Medicine. (n.d.). Nardil- phenelzine sulfate tablet, film coated. DailyMed.

4. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, commonly known as the Orange Book. FDA.

5. U.S. Food and Drug Administration. (n.d.). Patent and exclusivity information. FDA.

6. U.S. Food and Drug Administration. (2023). Applications covered by section 505(b)(2). FDA.