When do the PHENERGAN patents expire, and when will generic PHENERGAN be available?

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Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Wyeth Ayerst	PHENERGAN	promethazine hydrochloride	INJECTABLE;INJECTION	008857-002	Approved Prior to Jan 1, 1982		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
Delcor Asset Corp	PHENERGAN	promethazine hydrochloride	TABLET;ORAL	007935-003	Approved Prior to Jan 1, 1982		DISCN	Yes	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
Pharmobedient	PHENERGAN	promethazine hydrochloride	SUPPOSITORY;RECTAL	010926-001	Approved Prior to Jan 1, 1982		DISCN	Yes	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Exclusivity Expiration

Last updated: August 28, 2026

Phenergan is the original brand associated with promethazine, a first-generation antihistamine and phenothiazine used for allergy symptoms, nausea and vomiting, motion sickness, and sedation. Its commercial position is mature and largely genericized. Promethazine remains widely available through tablets, oral solutions, suppositories, and injectable products, but the branded Phenergan franchise does not have the characteristics of a protected growth asset. Revenue is fragmented across generic manufacturers, wholesalers, hospitals, and retail pharmacies, and Pfizer does not separately report Phenergan sales.

What is Phenergan and how is promethazine used?

Phenergan contains promethazine hydrochloride. It is approved in several dosage forms and has historically been marketed for:

Allergic conditions, including allergic rhinitis and conjunctivitis
Nausea and vomiting
Motion sickness
Preoperative and postoperative sedation
Adjunctive use with analgesics

Promethazine is a histamine H1-receptor antagonist with anticholinergic and sedative properties. It is also a phenothiazine, but it is not marketed as an antipsychotic in the manner of chlorpromazine or related products.

The principal commercial forms are:

Dosage form	Typical channel	Commercial status
12.5 mg, 25 mg, and 50 mg tablets	Retail pharmacy	Generic-dominated
Oral solution or syrup	Retail and institutional	Generic-dominated
Rectal suppositories	Retail pharmacy	Limited but established generic segment
Injection	Hospitals and health systems	Generic and institutional market
Branded Phenergan	Historical brand channel	Limited relative to generic supply

The FDA labeling for promethazine products contains a boxed warning against use in children younger than two years because of potentially fatal respiratory depression. Injectable promethazine also carries serious administration risks, including severe tissue injury from extravasation and intra-arterial administration. FDA has required labeling and administration changes for injectable promethazine because of these risks (U.S. Food and Drug Administration, 2009; Pfizer, 2023).

What is the FDA regulatory status of Phenergan?

Phenergan is an FDA-approved legacy product. Promethazine products have been approved for decades, and the active ingredient is available through multiple abbreviated new drug applications, or ANDAs.

The regulatory profile is defined by maturity rather than innovation:

Regulatory factor	Assessment
Active ingredient	Promethazine hydrochloride
FDA pathway	Legacy NDA products and multiple ANDA products
Primary FDA competition	Generic promethazine products
Pediatric restriction	Contraindicated in children younger than two years
Injectable safety	High administration risk; label contains serious tissue-injury warnings
New chemical entity exclusivity	Expired
Orphan-drug exclusivity	Not applicable
Biologic exclusivity	Not applicable

The product is not a biologic, so biosimilar competition is irrelevant. Its competitive threat comes from conventional generic manufacturers, not biosimilar developers.

Phenergan’s risk profile limits some hospital and pediatric use. Clinicians may select alternative antiemetics, including ondansetron, depending on indication, patient age, sedation risk, and route of administration. That substitution pressure is strongest where respiratory depression, delirium, anticholinergic effects, or injection injury are concerns.

What patents protect Phenergan and promethazine products?

The original composition-of-matter and basic-use protections for promethazine are long expired. No commercially meaningful primary patent barrier remains around the active ingredient.

Current protection is better characterized as a combination of:

Expired historical patents covering promethazine and early formulations.
Regulatory exclusivities that have expired.
Limited formulation or manufacturing patents, where applicable.
Trademarks associated with the Phenergan brand.
FDA-approved labeling and manufacturing know-how.

A patent search should distinguish the historical Phenergan brand from current promethazine products. Many older patents and trademark records may reference Phenergan without creating an enforceable barrier to generic entry.

Is Phenergan listed in the Orange Book?

The FDA Orange Book historically included approved Phenergan products and related NDA records. The commercial significance of any current listing depends on whether an unexpired patent or regulatory exclusivity is listed against a specific NDA.

For a mature promethazine product, the operative conclusion is that generic competition is established and the principal active-ingredient patents have expired. Any remaining Orange Book patent listing would need to be evaluated at the product and dosage-form level rather than assumed from the Phenergan brand name alone (U.S. Food and Drug Administration, 2024a).

When did Phenergan lose exclusivity?

Phenergan lost meaningful market exclusivity decades ago. The drug was introduced in the mid-20th century, well before the modern Hatch-Waxman framework. Its core patent and regulatory protections therefore expired long before the current generic market developed.

A simplified exclusivity timeline is:

Period	Event	Commercial effect
Mid-20th century	Promethazine introduced and marketed as Phenergan	Brand-led market
1980s and 1990s	Generic promethazine products enter and expand	Price competition begins
2000s	Broad generic availability across oral dosage forms	Brand share declines
2010s	Institutional scrutiny of injectable administration risks	Route-specific demand pressure
2020s	Mature, multi-source generic market	Low brand pricing power

The precise patent expiration dates for the original historical rights are less relevant to current competition than the fact that no active core patent estate protects promethazine as a molecule.

Which companies compete with Phenergan?

Competition is divided between generic promethazine suppliers and substitute antiemetic or antihistamine products.

Generic promethazine manufacturers

The U.S. market has included products from manufacturers such as:

Teva Pharmaceuticals
Hikma Pharmaceuticals
Sandoz
Rising Pharmaceuticals
Major Pharmaceuticals
Perrigo and other private-label suppliers
Hospital-focused injectable manufacturers

Supplier participation changes by dosage form, shortage conditions, manufacturing capacity, and wholesaler contracting. Injectable promethazine has a different competitive structure from tablets and oral solutions because hospital purchasing, supply reliability, and injectable safety controls carry greater weight than retail brand recognition.

Therapeutic substitutes

Product or class	Competitive overlap with promethazine
Ondansetron	Strong substitute for nausea and vomiting; less sedating
Diphenhydramine	Overlap in allergy and sedating antihistamine use
Meclizine	Motion sickness and vestibular indications
Metoclopramide	Nausea and gastrointestinal indications
Prochlorperazine	Nausea and phenothiazine-related use
Cetirizine and loratadine	Lower-sedation allergy alternatives

Ondansetron has been especially important in reducing promethazine’s role in acute nausea treatment. Its generic availability has lowered the cost of switching, while its lower sedation burden supports use in emergency, outpatient, and pediatric settings.

What is the financial trajectory for Phenergan?

Phenergan does not have a separately disclosed public revenue stream in Pfizer’s reported financial statements. Pfizer reports at a portfolio and therapeutic-area level and does not identify Phenergan as a material standalone product in its current annual-report revenue tables (Pfizer Inc., 2024).

The financial trajectory is therefore best assessed through market structure rather than a reported brand-sales series.

Historical trajectory

Phenergan’s historical economics followed the standard pattern for a mature small-molecule medicine:

Brand adoption during the protected or brand-dominant period.
Generic entry after loss of exclusivity.
Rapid price erosion across common oral dosage forms.
Declining brand relevance.
Continued unit demand sustained by low cost and broad clinical familiarity.

The product can remain clinically visible after branded revenue becomes economically modest. Promethazine is inexpensive, stocked in many pharmacies, and used in several indications. That produces durable volume without restoring historical brand margins.

Current financial profile

Financial variable	Current assessment
Brand pricing power	Low
Generic price competition	High
Volume stability	Moderate, with variation by dosage form
Retail brand growth	Limited
Hospital injectable value	Concentrated and supply-sensitive
Standalone manufacturer disclosure	Not available from Pfizer reporting
Innovation premium	Minimal
Licensing value	Low for the legacy product alone

The oral tablet market is likely the most commoditized segment. Oral solutions can retain some value because of pediatric and swallowing-related use, although pediatric safety restrictions narrow the eligible population. Suppositories occupy a smaller niche and can experience supply sensitivity because fewer manufacturers may participate.

Injectable promethazine can generate greater value per contract than tablets, but it carries higher liability, administration, and compliance risks. Hospitals may prefer alternatives or impose administration protocols, including dilution and controlled delivery, to reduce tissue-injury risk.

What commercial factors drive promethazine demand?

Persistent demand drivers

Promethazine retains demand because it is:

Inexpensive
Available in several dosage forms
Familiar to prescribers
Useful for nausea, motion sickness, allergy symptoms, and sedation
Distributed through retail and institutional channels
Supported by long-standing clinical experience

The product’s broad label creates a wider demand base than a single-indication generic. Demand is also supported by continued use in settings where sedation is acceptable or where a low-cost multi-purpose product is preferred.

Demand constraints

The principal constraints are:

Sedation and impaired alertness
Anticholinergic adverse effects
Respiratory-depression risk in young children
Injection-related tissue injury
Substitution by ondansetron and newer antihistamines
Reduced use in older adults at risk of confusion or falls
Generic price compression

Guideline preferences and institutional protocols can shift demand rapidly between promethazine and ondansetron. The impact is greater in emergency departments, pediatric care, ambulatory surgery, and hospital formularies.

What generic entry risks exist for Phenergan?

Generic entry is already established, so the relevant risk is not a future first generic launch. It is ongoing erosion of supplier economics and market share.

Generic launch scenarios

Scenario	Likely market effect
Additional tablet suppliers enter	Further price compression and lower supplier utilization
One or more suppliers exit	Short-term shortage risk and improved pricing for remaining manufacturers
Injectable supply disruption	Hospital substitution and temporary price increases
Brand relaunch or authorized generic	Limited effect unless supported by reliable supply or contracting
New formulation approval	Possible niche pricing, but weak protection without patent support

A shortage can temporarily improve pricing for manufacturers with available inventory, but it does not create durable exclusivity. The market remains exposed to purchasing-consolidation pressure and substitution by other antiemetics.

What patent litigation and Paragraph IV challenges affect Phenergan?

No major current Paragraph IV litigation is central to the commercial outlook for legacy Phenergan. Paragraph IV disputes are most relevant when a generic applicant challenges an unexpired patent listed for a branded NDA. Promethazine’s core patents expired long ago, and generic products have been marketed for many years.

Potential disputes could still arise around:

A new dosage form
A controlled-release formulation
A combination product
A manufacturing process
A device or delivery system
A later-added method-of-use patent

Such rights would protect only the specific claimed formulation, method, or process. They would not restore broad exclusivity to promethazine hydrochloride.

What formulations are protected by Phenergan-related intellectual property?

The commercially important historical formulations include tablets, oral solutions, suppositories, and injections. These dosage forms are generally exposed to generic competition.

A later formulation patent could have value only if it delivers a clinically meaningful advantage, such as:

Lower injection injury risk
Reduced sedation
Improved stability
Easier pediatric dosing
Better taste or adherence
Modified release
A safer delivery device

The patent position would depend on claim scope, validity, regulatory substitutability, and whether FDA-approved generic products could design around the claims. A formulation patent with narrow claims would not block ordinary immediate-release promethazine tablets or solutions.

How strong is the Phenergan patent estate?

The legacy patent estate is weak as a barrier to generic competition.

Patent-estate factor	Assessment
Core molecule patents	Expired
Core indication patents	Expired or commercially ineffective
Broad formulation protection	Not a material current barrier
Orange Book leverage	Limited
Paragraph IV exposure	Low relevance to established products
Trademark value	Recognizable but insufficient to prevent substitution
Manufacturing know-how	Potentially useful, but not exclusivity-creating
Litigation leverage	Low

The strongest remaining commercial assets are brand recognition, channel relationships, manufacturing reliability, and access to hospital contracts. Those are business advantages rather than patent exclusivity.

What is the geographic coverage of Phenergan?

Promethazine is marketed internationally under the Phenergan name and under local generic names, but regulatory status varies by jurisdiction. The United States is a mature generic market. In other countries, the brand may retain greater recognition, while generic penetration, reimbursement, and restrictions differ.

International commercial performance is affected by:

Local approval of dosage forms
Prescription and scheduling rules
Pediatric labeling
Hospital procurement systems
National reimbursement pricing
Local generic-manufacturer participation
Supply-chain and pharmacovigilance requirements

A U.S. patent conclusion cannot be applied directly to Europe, Canada, Asia-Pacific, or emerging markets. Patent, trademark, regulatory, and market authorization records must be reviewed jurisdiction by jurisdiction.

What licensing deals affect Phenergan?

No major current licensing transaction appears to define the commercial outlook for Phenergan. Historical brand rights, manufacturing arrangements, and distribution agreements may have changed over time, particularly following pharmaceutical portfolio transactions, but Phenergan is not a major disclosed licensing-growth asset in Pfizer’s current reporting.

The product’s low unit economics reduce the rationale for large upfront licensing payments. Commercial arrangements are more likely to involve supply, private-label distribution, hospital contracting, or regional marketing rights.

What is the outlook for Phenergan revenue and investment value?

Phenergan has a stable but low-growth profile. Its value is tied to continued generic demand rather than brand expansion.

Base case

The most likely base case is:

Stable clinical use in selected indications
Continued generic price pressure
Low or immaterial standalone branded revenue
Periodic supply volatility, especially for injectables
Gradual substitution in nausea and pediatric settings
No meaningful patent-driven revenue reset

Upside case

An upside case would require one of the following:

A safer injectable formulation
A differentiated delivery system
A new combination product
A supply shortage that materially improves contract pricing
Expansion in a market where generic competition is less developed

Downside case

The principal downside risks are:

Further substitution by ondansetron and lower-sedation antihistamines
Product liability exposure linked to injectable administration
Pediatric safety concerns
Manufacturer exits and subsequent channel disruption
Loss of hospital formulary access
Intensified retail generic price competition

The asset is more relevant as a dependable mature-product supply opportunity than as a conventional branded pharmaceutical growth investment.

Key Takeaways

Phenergan is the legacy brand for promethazine hydrochloride.
Core patent and exclusivity protections expired decades ago.
Generic promethazine dominates the U.S. market.
Biosimilar risk does not apply because promethazine is a small-molecule drug.
No current Paragraph IV challenge is central to the commercial outlook.
Tablets, oral solutions, suppositories, and injections have different supply and pricing dynamics.
Injectable promethazine carries significant administration and tissue-injury risks.
Ondansetron and lower-sedation antihistamines are important substitutes.
Pfizer does not separately disclose Phenergan revenue.
The product has durable demand but limited pricing power, weak patent leverage, and low standalone growth potential.

FAQs About Phenergan Market Exclusivity and Competition

Is Phenergan still a branded drug?

Phenergan remains a recognized brand name, but most promethazine volume in the United States is supplied by generic manufacturers.

Can a generic manufacturer launch promethazine without a Paragraph IV lawsuit?

Yes. Core promethazine exclusivity has expired, and generic products have been marketed for many years. A Paragraph IV certification would matter only if a relevant unexpired patent were listed for a particular NDA product.

Does Phenergan have a biosimilar threat?

No. Promethazine is a conventional small-molecule drug. Its competitive threat comes from generic manufacturers and therapeutic substitutes.

Why might hospitals restrict injectable promethazine?

Hospitals may restrict it because of severe tissue-injury risks associated with improper injection, including extravasation and intra-arterial administration. The FDA labeling contains prominent warnings on administration and patient safety.

Could a new promethazine formulation command premium pricing?

Potentially, but only if it provides a clinically meaningful advantage and obtains regulatory approval. A new formulation would also need defensible patent claims and protection from automatic substitution or rapid generic design-around.

References

Pfizer Inc. (2023). Phenergan (promethazine hydrochloride) injection prescribing information. Pfizer Labeling.
Pfizer Inc. (2024). 2023 annual report. Pfizer Investor Relations.
U.S. Food and Drug Administration. (2009). FDA requires boxed warning for promethazine hydrochloride injection. FDA Drug Safety Communication.
U.S. Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services.
U.S. Food and Drug Administration. (2024b). DailyMed: Promethazine hydrochloride drug labels. National Library of Medicine.

US Patents:	0
Applicants:	4
NDAs:	6
Raw Ingredient (Bulk) Api Vendors:	110
Clinical Trials:	17
Patent Applications:	2,749
Drug Prices:	Drug price information for PHENERGAN
DailyMed Link:	PHENERGAN at DailyMed

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