DOXEPIN HYDROCHLORIDE - Generic Drug Details

What are the generic sources for doxepin hydrochloride and what is the scope of patent protection?

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. Forty-nine 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:	49
Raw Ingredient (Bulk) Api Vendors:	1
Clinical Trials:	23
Patent Applications:	2,212
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
Hematology Center after Prof. R. Yeolyan	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
Watson Labs	DOXEPIN HYDROCHLORIDE	doxepin hydrochloride	CAPSULE;ORAL	071239-001	Apr 30, 1987		DISCN	No	No
Ixora Lifescience	DOXEPIN HYDROCHLORIDE	doxepin hydrochloride	CAPSULE;ORAL	211619-004	Mar 9, 2021	AB	RX	No	No
Pts Consulting	DOXEPIN HYDROCHLORIDE	doxepin hydrochloride	CAPSULE;ORAL	217975-002	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	022036-001	Mar 17, 2010	6,103,219
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-001	Mar 17, 2010	5,866,166
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-002	Mar 17, 2010	6,106,865

International Patents for DOXEPIN HYDROCHLORIDE

Country	Patent Number	Title	Estimated Expiration
World Intellectual Property Organization (WIPO)	2007142810
Japan	2013237694	METHOD OF USING LOW-DOSE DOXEPIN FOR IMPROVEMENT OF SLEEP
Canada	2687124	FORMULATIONS DE DOXEPINE A FAIBLE DOSE, INCLUANT DES FORMULATIONS BUCCALES, SUBLINGUALES ET A DISSOLUTION RAPIDE, ET LEURS UTILISATIONS POUR TRAITER L'INSOMNIE (LOW DOSE DOXEPIN FORMULATIONS, INCLUDING BUCCAL, SUBLINGUAL AND FASTMELT FORMULATIONS, AND USES OF THE SAME TO TREAT INSOMNIA)

Market Dynamics and Financial Trajectory for Doxepin Hydrochloride

Last updated: July 27, 2025

Introduction

Doxepin hydrochloride, a tricyclic antidepressant (TCA), has been utilized primarily for depression, anxiety disorders, and sleep disturbances. Since its approval in the mid-20th century, its market presence has undergone significant shifts driven by evolving pharmaceutical landscapes, patent expirations, and the emergence of newer therapies. This analysis explores the intricate market dynamics, patent status, competitive landscape, and forecasted financial trajectory of doxepin hydrochloride, emphasizing factors influencing its commercial viability.

Pharmacological Profile and Clinical Indications

Originally marketed under brand names such as Silenor and Silenor, doxepin hydrochloride exerts its anxiolytic and sedative effects through serotonergic and noradrenergic mechanisms. Its indications encompass major depressive disorder, generalized anxiety disorder, and topical applications for pruritus. Notably, its sleep aid formulations differentiate from traditional antidepressant uses, offering a niche market segment focused on sleep disorders [1].

Market Dynamics

1. Patent Status and Regulatory Landscape

Doxepin hydrochloride's patent protection, introduced in the 1950s, expired globally by the early 2000s, leading to the proliferation of generic formulations. The expiration significantly increased market penetration due to lower priced generics, constraining branded drug revenues and intensifying price competition. The absence of active patent protection now positions doxepin as a generic commodity, subject to pricing erosion and low-margin dynamics.

2. Competitive Environment

The antidepressant market has become saturated with second-generation agents such as SSRIs (selective serotonin reuptake inhibitors) and SNRIs (serotonin-norepinephrine reuptake inhibitors), which boast improved safety profiles and tolerability over TCAs. Consequently, doxepin's market share for depression and anxiety management has declined.

However, it maintains a unique foothold in sleep management. The FDA-approved low-dose formulation for sleep disturbance, marketed as Silenor, faced less direct competition initially but now contends with non-prescription sleep aids and newer pharmacotherapies. The generic availability of doxepin sleep formulations has further compressed margins, impacting revenue streams [2].

3. Manufacturing and Supply Chain Factors

Manufacturers have streamlined production processes given the expirations of patents, leading to lower manufacturing costs but also increased price competition. Supply chain disruptions, especially amid global health crises, can impact availability and sales, although established manufacturing bases for generic doxepin mitigate such risks.

4. Regulatory and Off-Patent Market Trends

Enhanced global regulatory standards and off-label use in niche conditions sustain some demand. Additionally, off-label applications for pruritus and dermatological conditions in topical form present potential growth avenues, though regulatory hurdles and clinical efficacy evidence influence market acceptance.

5. Emerging Competitors and Therapies

While traditional TCAs like doxepin have declined in depression markets, emerging drugs with novel mechanisms—such as ketamine and its derivatives—reshape treatment paradigms. These newer agents offer rapid benefits but come with regulatory, safety, and cost considerations that influence their competitive standing relative to doxepin.

Financial Trajectory

1. Revenue Trends

Post-patent expiry, the global revenues for doxepin manufacturers have plateaued or declined, with global sales estimated to be under $100 million annually, predominantly driven by the sleep aid segment in North America [3]. The US market, as the largest contributor, accounts for the majority of revenues, owing to high prescribing rates and the approval of low-dose sleep formulations.

2. Pricing and Market Penetration

Generic manufacturing led to substantial price reductions, with retail prices falling by over 50% in many markets in the past decade. Despite volume sales remaining relatively stable in niche segments, declining margins challenge profitability for drugmakers.

3. R&D Investments and Pipeline Prospects

Limited R&D activity targets doxepin itself, as pharmacological de-risking favors pipeline drugs with novel mechanisms. Strategic investments focus on formulation innovations—such as extended-release versions—and off-label vitality through topical formulations, aimed at niche segments like pruritus.

4. Market Growth Projections

Given the current landscape, the overall market for doxepin hydrochloride is projected to decline marginally over the next five years, barring significant innovation or regulatory approvals. However, the sleep disorder segment is anticipated to be the primary growth driver, with CAGR estimates approaching 2-3% contingent on the success of new formulations and expanded indications [4].

5. Regional Market Dynamics

North America dominates the doxepin market, influenced by high awareness, established healthcare infrastructure, and favorable regulatory pathways for sleep-related formulations. Europe exhibits moderate growth, with regulatory challenges and conservative prescribing impacting uptake. In emerging markets, price sensitivity and local manufacturing influence market penetration.

Strategic Opportunities and Challenges

• Opportunities: Reformulation efforts, such as extended-release dosage forms, topical applications for dermatological conditions, and combination therapies, could rejuvenate market interest. Expanding approvals for sleep-related indications beyond the US may unlock new revenue streams.

• Challenges: Market erosion from generics, competition from novel agents (e.g., melatonin receptor agonists), safety concerns associated with TCAs, and declining prescribing frequencies hinder growth. Additionally, clinical preference for agents with superior safety profiles constrains doxepin's applicability.

Conclusion

Doxepin hydrochloride's market is emblematic of the lifecycle progression of off-patent pharmaceuticals. The drug’s financial trajectory is characterized by stagnation and decline in traditional indications, offset by niche applications like sleep aids. Future growth hinges on formulation innovation, expanded indications, and strategic positioning within competitive therapeutic landscapes.

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Key Takeaways

• Market saturation and patent expirations have led to commoditization, diminishing revenues for doxepin hydrochloride.
• While original indications experience declining demand, niche segments like sleep disorders offer growth opportunities.
• Pricing pressures intensify due to widespread generic availability, impacting profit margins.
• Innovation in formulation and new indications are vital to sustain or expand revenue streams.
• The competitive landscape demands strategic differentiation amid emerging therapies and changing prescribing patterns.

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FAQs

1. What are the primary clinical applications of doxepin hydrochloride today?
Doxepin is mainly used for sleep disturbances at low doses and as an antidepressant or anxiolytic in clinical settings, though its use in depression has declined due to safety concerns and competition from newer agents.

2. How does patent expiration affect the market presence of doxepin?
Patent expiration allows multiple generic manufacturers to produce and sell doxepin, leading to price competition, reduced revenues for brand-name producers, and broader accessibility for patients.

3. Are there any upcoming formulations or indications for doxepin?
Research focuses on extended-release formulations and topical applications for dermatological conditions; however, large-scale commercial strategies remain limited.

4. What competitive challenges does doxepin face in the current pharmaceutical landscape?
It faces competition from newer, safer therapies for depression and sleep disorders, as well as non-prescription sleep aids and alternative therapies, limiting its market share.

5. What is the long-term forecast for doxepin’s market viability?
While traditional markets are declining, niche applications may sustain some revenue. Growth prospects depend on innovation, regulatory approvals, and evolving clinical preferences favoring newer agents.

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References

[1] Goodman & Gilman's The Pharmacological Basis of Therapeutics, 13th Edition, 2017.
[2] IMS Health Data, 2022.
[3] EvaluatePharma, 2022.
[4] MarketWatch, "Sleep Aids Market Outlook," 2022.