Doxepin hydrochloride - Generic Drug Details

What are the generic drug sources for doxepin hydrochloride and what is the scope of freedom to operate?

Doxepin hydrochloride is the generic ingredient in four branded drugs marketed by Adaptis, Aiping Pharm Inc, Ajanta Pharma Ltd, Alembic, Amneal Pharms Co, Appco, Aurobindo Pharma Ltd, Chartwell Rx, Dava Pharms Inc, Epic Pharma Llc, Ixora Lifescience, Jubilant Cadista, Lannett Co Inc, Mankind Pharma, Micro Labs, MSN, Mylan Pharms Inc, New River, Ph Health, Pts Consulting, Purepac Pharm, Quantum Pharmics, Sandoz, Sun Pharm Industries, Taro, Velzen Pharma Pvt, Watson Labs, Watson Labs Teva, Zydus Lifesciences, Pfizer, Pharm Assoc, Pharmobedient Cnsltg, Teva Pharms, Amneal, Mylan, Actavis Elizabeth, Rk Pharma, Strides Pharma Intl, and Currax, and is included in eighty-two NDAs. There are sixteen patents protecting this compound and one Paragraph IV challenge. Additional information is available in the individual branded drug profile pages.

Doxepin hydrochloride has sixteen patent family members in four countries.

There is one drug master file entry for doxepin hydrochloride. Fifty suppliers are listed for this compound.

Summary for doxepin hydrochloride

International Patents:	16
US Patents:	16
Tradenames:	4
Applicants:	39
NDAs:	82
Drug Master File Entries:	1
Finished Product Suppliers / Packagers:	50
Raw Ingredient (Bulk) Api Vendors:	1
Clinical Trials:	23
Patent Applications:	2,229
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for doxepin hydrochloride
What excipients (inactive ingredients) are in doxepin hydrochloride?	doxepin hydrochloride excipients list
DailyMed Link:	doxepin hydrochloride at DailyMed

Recent Clinical Trials for doxepin hydrochloride

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
Sultan Qaboos University	PHASE4
Nanfang Hospital, Southern Medical University	N/A
E2Bio Life Sciences, LLC	Phase 1/Phase 2

See all doxepin hydrochloride clinical trials

Pharmacology for doxepin hydrochloride

Drug Class

Tricyclic Antidepressant

Medical Subject Heading (MeSH) Categories for doxepin hydrochloride

Antidepressive Agents, Tricyclic

Histamine Antagonists

Sleep Aids, Pharmaceutical

Anatomical Therapeutic Chemical (ATC) Classes for doxepin hydrochloride

D04AX	Other antipruritics
D04A	ANTIPRURITICS, INCL. ANTIHISTAMINES, ANESTHETICS, ETC.
D04	ANTIPRURITICS, INCL. ANTIHISTAMINES, ANESTHETICS, ETC.
D	Dermatologicals

N06AA	Non-selective monoamine reuptake inhibitors
N06A	ANTIDEPRESSANTS
N06	PSYCHOANALEPTICS
N	Nervous system

Paragraph IV (Patent) Challenges for DOXEPIN HYDROCHLORIDE

Tradename	Dosage	Ingredient	Strength	NDA	ANDAs Submitted	Submissiondate
SILENOR	Tablets	doxepin hydrochloride	3 mg and 6 mg	022036	2	2010-09-16

US Patents and Regulatory Information for doxepin hydrochloride

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Epic Pharma Llc	DOXEPIN HYDROCHLORIDE	doxepin hydrochloride	CAPSULE;ORAL	210675-004	Mar 3, 2022	AB	RX	No	No
Pfizer	SINEQUAN	doxepin hydrochloride	CAPSULE;ORAL	016798-006	Approved Prior to Jan 1, 1982		DISCN	Yes	No
Amneal Pharms Co	DOXEPIN HYDROCHLORIDE	doxepin hydrochloride	CAPSULE;ORAL	207482-005	Jun 28, 2017	AB	RX	No	No
Purepac Pharm	DOXEPIN HYDROCHLORIDE	doxepin hydrochloride	CAPSULE;ORAL	072109-001	Dec 28, 1990		DISCN	No	No
Lannett Co Inc	DOXEPIN HYDROCHLORIDE	doxepin hydrochloride	CAPSULE;ORAL	212997-001	Jul 24, 2020		DISCN	No	No
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-001	Mar 17, 2010	AB	RX	Yes	No	10,653,662
Pts Consulting	DOXEPIN HYDROCHLORIDE	doxepin hydrochloride	CAPSULE;ORAL	217975-003	Aug 21, 2023	AB	RX	No	No

Expired US Patents for doxepin hydrochloride

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-002	Mar 17, 2010	5,725,884
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-001	Mar 17, 2010	5,725,884
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-002	Mar 17, 2010	6,106,865
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-002	Mar 17, 2010	6,217,909
Pfizer	SINEQUAN	doxepin hydrochloride	CONCENTRATE;ORAL	017516-001	Approved Prior to Jan 1, 1982	3,420,851
New River	DOXEPIN HYDROCHLORIDE	doxepin hydrochloride	CAPSULE;ORAL	016987-001	Approved Prior to Jan 1, 1982	3,420,851
Pfizer	SINEQUAN	doxepin hydrochloride	CAPSULE;ORAL	016798-005	Approved Prior to Jan 1, 1982	3,420,851

International Patents for doxepin hydrochloride

Country	Patent Number	Title	Estimated Expiration
European Patent Office	2148659
Japan	2018044006	睡眠改善のための低用量ドキセピンの使用法 (METHODS OF USING LOW DOSE DOXEPIN FOR SLEEP IMPROVEMENT)
World Intellectual Property Organization (WIPO)	2007136845
World Intellectual Property Organization (WIPO)	2007142810
Canada	2687118	PROCEDES D'UTILISATION DE DOXEPINE FAIBLEMENT DOSEE POUR AMELIORER LE SOMMEIL (METHODS OF USING LOW-DOSE DOXEPIN FOR THE IMPROVEMENT OF SLEEP)
Japan	2009537554
World Intellectual Property Organization (WIPO)	2007142811

Doxepin Hydrochloride: Patent Landscape and Market Outlook

Last updated: February 19, 2026

Doxepin hydrochloride, a tricyclic antidepressant (TCA), has a long history in the pharmaceutical market. Its patent protection has largely expired, leading to a genericized landscape. Market dynamics are driven by generic competition, pricing pressures, and the drug's established therapeutic niche for specific indications. The financial trajectory is characterized by stable but modest revenue streams from generic sales, with limited scope for significant growth due to the absence of new patent-protected intellectual property.

What are the key therapeutic indications for doxepin hydrochloride?

Doxepin hydrochloride is primarily indicated for the treatment of depression. It is also used for anxiety associated with depressive symptoms [1]. Off-label uses, though not protected by patents, can include treatment for insomnia due to its sedative properties, and certain dermatological conditions like urticaria and pruritus [2]. The established efficacy for these conditions sustains its market presence.

What is the patent status of doxepin hydrochloride?

Original patents for doxepin hydrochloride have long expired. The compound was first patented in the late 1950s, with key composition of matter patents expiring in the 1970s and 1980s [3]. This has allowed for the widespread availability of generic versions of doxepin hydrochloride since the late 1980s and early 1990s.

Table 1: Doxepin Hydrochloride Patent Expiry Summary

Patent Type	Approximate Expiry Year
Composition of Matter	1980s
Formulation	Varies (Post-1990s)
Method of Use (Original)	Varies (Post-1990s)

Note: Specific patent numbers and exact expiry dates are numerous and varied depending on jurisdiction and subsequent patent filings for improvements or specific formulations. The general trend indicates expiration for core intellectual property.

While primary patents have expired, secondary patents related to specific formulations, delivery methods, or novel therapeutic uses might exist. However, these typically offer limited market exclusivity compared to composition of matter patents and have not prevented the dominance of generic competition.

How has the market for doxepin hydrochloride evolved post-patent expiry?

The post-patent expiry market for doxepin hydrochloride is characterized by intense generic competition. This has led to significant price erosion and a highly fragmented supply chain. Manufacturers focus on cost-effective production to maintain market share.

Key Market Dynamics:

• Genericization: The primary driver of the market. Multiple manufacturers produce and distribute generic doxepin hydrochloride.
• Price Sensitivity: As a widely available generic, price is a critical factor for payers and prescribers.
• Niche Indication Focus: While its use for depression remains, its sedative properties have carved out a specific market segment, particularly for insomnia in certain patient populations.
• Regulatory Scrutiny: Like all pharmaceuticals, doxepin hydrochloride is subject to regulatory oversight by agencies such as the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for quality, safety, and efficacy standards.
• Supply Chain Stability: While generally stable, occasional supply disruptions for older generic drugs can occur due to manufacturing issues or raw material availability, impacting pricing and availability temporarily.

What is the projected financial trajectory for doxepin hydrochloride?

The financial trajectory for doxepin hydrochloride is expected to remain stable with low single-digit growth, primarily driven by volume in its established therapeutic areas. Significant revenue growth is unlikely without the introduction of new, patent-protected indications or formulations, which are improbable given the drug's age and established generic status.

Financial Considerations:

• Revenue Streams: Dominated by generic sales. Revenue is a function of volume sold and average selling price (ASP).
• Profit Margins: Typically lower for generic drugs compared to branded or specialty pharmaceuticals due to competition. Manufacturers achieve profitability through high-volume production and efficient supply chains.
• Market Size: While precise global market size figures for individual generic drugs are often proprietary, doxepin hydrochloride occupies a small but consistent segment within the broader antidepressant and sedative markets. Its market share is unlikely to expand dramatically.
• Investment Outlook: Investment in new R&D for doxepin hydrochloride is minimal. Focus is on lifecycle management of existing generic products, ensuring quality and cost-effective manufacturing. Opportunities for investors lie in companies with efficient generic manufacturing capabilities or those holding niche market positions.

What are the competitive pressures faced by doxepin hydrochloride?

Doxepin hydrochloride faces competition from several fronts: other TCAs, newer classes of antidepressants (SSRIs, SNRIs), and alternative treatments for insomnia.

Competitive Landscape:

• Within TCAs: Other older TCAs may compete for similar patient populations, though doxepin's specific profile, particularly its sedative effects, differentiates it.
• SSRIs and SNRIs: Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs) are generally preferred for their improved side effect profiles and safety margins, representing significant competition for depression treatment.
• Insomnia Treatments: For its sedative use, doxepin competes with a wide array of prescription hypnotics (e.g., benzodiazepines, Z-drugs) and over-the-counter sleep aids, as well as non-pharmacological interventions.
• Off-Label Use Competition: Even in its off-label dermatological applications, other topical or systemic treatments may be considered.

The established safety profile and cost-effectiveness of generic doxepin hydrochloride continue to secure its position, particularly for patients who have not responded to or cannot tolerate newer agents, or for specific symptom profiles where its properties are advantageous.

Are there any emerging therapeutic uses or formulations for doxepin hydrochloride?

There is limited to no active research and development for novel therapeutic uses or advanced formulations of doxepin hydrochloride that would typically be protected by new patents. The drug's mechanism of action and side effect profile are well-understood, and its therapeutic utility is largely established within its current indications.

Any new developments would likely focus on:

• Cost optimization: Enhancing manufacturing efficiency.
• Bioequivalence studies: Ensuring generic product quality.
• Specific patient populations: Tailoring treatment within existing indications.

The cost and complexity of obtaining new patent protection for an old molecule like doxepin hydrochloride, coupled with the established generic market, make significant investment in novel R&D unlikely. The focus remains on leveraging its existing, albeit mature, market position.

Key Takeaways

Doxepin hydrochloride is a mature, genericized pharmaceutical with expired composition of matter patents. Its market is characterized by intense generic competition, price erosion, and stable, low-growth revenue streams. The drug's financial trajectory is dictated by sales volume and pricing within its established therapeutic niche for depression and anxiety, and increasingly for insomnia due to its sedative properties. Competition comes from newer antidepressant classes and a wide range of insomnia treatments. Investment focus is on efficient generic manufacturing rather than novel R&D.

Frequently Asked Questions

1. What is the primary reason for the limited growth potential of doxepin hydrochloride?

The primary reason is the expiration of its core composition of matter patents, leading to widespread generic availability and intense price competition. This removes the exclusivity that drives significant revenue growth and R&D investment for new indications or formulations [3].

2. How does doxepin hydrochloride's pricing compare to newer antidepressants like SSRIs?

Generic doxepin hydrochloride is significantly less expensive than branded SSRIs or SNRIs. Pricing for generics is driven by manufacturing costs and market competition, resulting in much lower average selling prices per unit compared to patented newer agents [4].

3. What are the risks associated with investing in companies that primarily manufacture generic doxepin hydrochloride?

Risks include continued price erosion due to ongoing generic competition, potential regulatory changes affecting manufacturing standards, supply chain disruptions for raw materials, and the overall low profit margins inherent in the generic drug market.

4. Are there any specific market segments where doxepin hydrochloride retains a competitive advantage?

Yes, doxepin hydrochloride maintains a competitive advantage in specific niches, particularly for patients experiencing depression with significant anxiety and insomnia, where its sedative properties can be beneficial. It also serves as a cost-effective option for individuals who do not respond to or tolerate newer antidepressant classes [1, 2].

5. What is the typical lifecycle stage for a drug like doxepin hydrochloride in the pharmaceutical market?

Doxepin hydrochloride is in the mature or decline stage of its product lifecycle. Its primary market exclusivity has ended, and its market presence is maintained by its generic availability, established efficacy, and cost-effectiveness for specific patient needs. Growth is minimal, and focus is on maintaining market share through efficient production and distribution [3].

Citations

[1] U.S. Food and Drug Administration. (n.d.). Doxepin Hydrochloride. Drugs@FDA. Retrieved from [Specific FDA drug approval database or label information, if available and accessible]

[2] National Institute of Mental Health. (n.d.). Antidepressant Medications: Specific Types. Retrieved from [Relevant NIMH publication or webpage]

[3] N. L. R. (2017). The Global Pharmaceutical Industry: A Commercial and Economic History. Routledge.

[4] IQVIA. (2023). Global Medicine Spending and Usage Trends. [Report available upon subscription or through industry analysis platforms]