SILENOR Drug Patent Profile

When do Silenor patents expire, and what generic alternatives are available?

Silenor is a drug marketed by Currax and is included in one NDA. There are sixteen patents protecting this drug and one Paragraph IV challenge.

This drug has sixteen patent family members in four countries.

The generic ingredient in SILENOR is doxepin hydrochloride. There are seven drug master file entries for this compound. Forty-nine suppliers are listed for this compound. Additional details are available on the doxepin hydrochloride profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Silenor

A generic version of SILENOR was approved as doxepin hydrochloride by MYLAN PHARMS INC on May 13^th, 1986.

Summary for SILENOR

International Patents:	16
US Patents:	16
Applicants:	1
NDAs:	1
Finished Product Suppliers / Packagers:	2
Raw Ingredient (Bulk) Api Vendors:	96
Clinical Trials:	2
Patent Applications:	1,453
Drug Prices:	Drug price information for SILENOR
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for SILENOR
What excipients (inactive ingredients) are in SILENOR?	SILENOR excipients list
DailyMed Link:	SILENOR at DailyMed

See drug prices for SILENOR

See drug sales revenues for SILENOR

Recent Clinical Trials for SILENOR

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

Sponsor	Phase
University of Balamand	Phase 4
Henry Ford Hospital	Phase 4
Pernix Theraputics LLC	Phase 4

See all SILENOR clinical trials

Pharmacology for SILENOR

Drug Class

Tricyclic Antidepressant

Paragraph IV (Patent) Challenges for SILENOR

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 SILENOR

SILENOR is protected by sixteen US patents.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-002	Mar 17, 2010	AB	RX	Yes	Yes	9,532,971		Y
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-002	Mar 17, 2010	AB	RX	Yes	Yes	11,110,074
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-002	Mar 17, 2010	AB	RX	Yes	Yes	11,096,920

Expired US Patents for SILENOR

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-002	Mar 17, 2010	5,866,166
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-002	Mar 17, 2010	5,502,047
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-001	Mar 17, 2010	5,948,438

International Patents for SILENOR

See the table below for patents covering SILENOR around the world.

Country	Patent Number	Title	Estimated Expiration
World Intellectual Property Organization (WIPO)	2008128115
Japan	3728321
Norway	321771

Market Dynamics and Financial Trajectory for Silenor (Doxepin) in the Pharmaceutical Landscape

Last updated: July 27, 2025

Introduction

Silenor (doxepin) is a tricyclic antidepressant traditionally utilized for depression and anxiety, which gained approval in 2010 from the U.S. Food and Drug Administration (FDA) as a treatment for insomnia characterized by difficulty staying asleep. Its repositioning as a sleep aid marked a strategic move to capture a segment of the sleep disorder market, estimated to be worth over $80 billion globally[1]. This article analyzes the evolving market dynamics and financial trajectory of Silenor, emphasizing key factors influencing its commercial outlook within the competitive sleep aid landscape.

Market Overview and Positioning

Therapeutic Niches and Regulatory Status

Initially approved as an antidepressant, doxepin's sedative properties led to the formulation of Silenor, a low-dose version targeted explicitly at sleep maintenance issues. Unlike newer sleep agents such as zolpidem or suvorexant, Silenor’s unique mechanism—antagonism at H1 histamine receptors—caters to patients with persistent insomnia, particularly those sensitive to side effects associated with benzodiazepines. The drug's positioning appeals to an aging population with comorbidities needing safer sleep solutions.

Market Penetration and Commercial Strategy

Despite its unique profile, Silenor's market penetration has been modest. Sales faced hurdles such as limited clinician awareness, competition from over-the-counter (OTC) supplements, and the dominance of established drugs like Ambien (zolpidem) and Lunesta (eszopiclone). The drug’s prescribing rates have remained stable but have not expanded aggressively, attributable partly to cautious prescription behaviors amid evolving regulatory scrutiny of sleep medications[2].

Market Dynamics

Competitive Landscape

The sleep aid market is intensely competitive, with a mix of prescription drugs and OTC products. While Silenor differentiates through its non-habit-forming profile and tolerability, its competitors often boast broader marketing campaigns and strong brand recognition. Notably, newer orexin receptor antagonists like suvorexant and lemborexant, approved in recent years, have gained traction due to their novel mechanisms of action and marketing efforts.

Regulatory and Safety Considerations

Safety concerns surrounding traditional sleep aids—particularly parasomnia, dependency potential, and cognitive impairment—have compelled prescribers and regulators to favor drugs with favorable safety profiles. Silenor benefits from a track record of low dependency risk but faces ongoing scrutiny over off-label use and dosing practices, which can influence market acceptance.

Patient Demographics and Usage Trends

The aging demographic, with increased incidence of insomnia among older adults, presents a growth avenue. However, heightened awareness of polypharmacy risks and sedative-related falls has prompted conservative prescribing patterns. The rise of non-pharmacological interventions, such as cognitive-behavioral therapy for insomnia (CBT-I), also constrains drug market expansion[3].

Pricing and Reimbursement Environment

Silenor’s price point remains competitive relative to branded sedatives, yet reimbursement policies and formulary placements significantly influence prescribing. Insurers’ preference for drugs with broader coverage and proven safety profiles affects market share, especially as generics for competing drugs become available.

Financial Trajectory

Revenue Trends and Forecasts

Data from IQVIA indicates that Silenor’s U.S. sales have plateaued, with annual revenues hovering around $50-70 million since 2015. The stagnation stems from limited growth drivers and increasing competition, with market share confined primarily to niche segments. Forecasts suggest a marginal decline in mid-term outlook unless new indications or formulations emerge[4].

Impact of Patent Status and Generic Competition

Doxepin, the generic form of Silenor, has been available for several years. The loss of exclusivity diminishes profitability for the branded version, pushing the manufacturer toward lifecycle management strategies like seeking new indications or developing extended-release formulations to sustain revenue streams.

Potential Revenue Expansion Strategies

To enhance financial trajectory, strategies include:

• Expanding market access through clinician education emphasizing Silenor’s safety profile.
• Developing new formulations, such as once-nightly delivery, to improve adherence.
• Securing additional indications, for example, secondary sleep maintenance or anxiety-related disorders.
• Leverage digital health tools to monitor and promote adherence.

Market Opportunities and Challenges

Opportunities

• Growing insomnia prevalence: An aging population with higher insomnia rates presents sustained demand.
• Shift toward non-scheduled medications: Increasing preference for treatments with low dependency potential.
• Integration with digital health: Opportunities exist to combine Silenor with sleep-tracking devices, enhancing personalized medicine.

Challenges

• Emergence of new competitors: Particularly orexin receptor antagonists gaining market share.
• Regulatory hurdles: Heightened scrutiny of sleep medicine safety profiles.
• Changing prescribing behaviors: Rising emphasis on non-pharmacological interventions like CBT-I.

Conclusion

While Silenor faces stiff competition within the sleep aid market, its unique safety profile provides niche opportunities in the management of insomnia, especially among older adults. The financial trajectory remains stable but limited without strategic innovation or market expansion. The evolution of the sleep medicine landscape, driven by technological advances, regulatory changes, and demographic shifts, will significantly influence Silenor’s future positioning.

Key Takeaways

• Silenor’s market is constrained by competition and modest prescribing rates, with revenues plateauing.
• The drug’s safety profile offers competitive differentiation but requires strategic positioning to expand market share.
• Expanding indications, developing new formulations, and leveraging digital health can bolster financial performance.
• Market entry barriers include regulatory scrutiny, patent expiration, and the rise of newer, more targeted therapies.
• Growth prospects hinge on the ability to adapt to evolving regulatory, clinical, and consumer preferences within the sleep aid sector.

FAQs

Q1: What differentiates Silenor from other sleep aids?
A: Silenor (doxepin) offers a non-habit-forming profile and fewer cognitive side effects, making it attractive for older adults with comorbidities, unlike some traditional sedatives.

Q2: How does patent expiration impact Silenor's profitability?
A: Loss of patent exclusivity leads to increased generic competition, reducing sales and margins unless supplemented by new formulations or indications.

Q3: Are there ongoing efforts to expand Silenor’s indications?
A: Currently, no significant FDA-approved additional indications exist; however, clinical studies may explore broader applications, potentially enhancing its market.

Q4: What role does digital health integration play in Silenor’s future?
A: Digital sleep monitoring and adherence tools could help optimize therapy outcomes, foster patient engagement, and provide competitive advantages.

Q5: What are the primary challenges facing Silenor in the current market?
A: Competition from newer drugs, regulatory scrutiny, and the shift toward non-pharmacological treatments challenge Silenor’s growth prospects.

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References

[1] IQVIA. "Global Sleep Aid Market Report." 2022.
[2] FDA. "Doxepin Approval for Insomnia." 2010.
[3] National Sleep Foundation. "Sleep Disorders and Pharmacologic Treatments." 2021.
[4] Evaluate Pharma. "Pharmaceutical Market Forecasts." 2022.