Investigational Drug Information for Almorexant

What is the development status for investigational drug Almorexant?

Almorexant is an investigational drug.

There have been 7 clinical trials for Almorexant. The most recent clinical trial was a Phase 3 trial, which was initiated on March 1^st 2008.

The most common disease conditions in clinical trials are Sleep Initiation and Maintenance Disorders, Syndrome, and Restless Legs Syndrome. The leading clinical trial sponsors are Midnight Pharma, LLC, U.S. Army Medical Research and Development Command, and U.S. Army Medical Research and Materiel Command.

Summary for Almorexant

US Patents	0
International Patents	0
US Patent Applications	178
WIPO Patent Applications	71
Japanese Patent Applications	33
Clinical Trial Progress	Phase 3 (2008-03-01)
Vendors	37

Recent Clinical Trials for Almorexant

Title	Sponsor	Phase
Treatment of Restless Legs Syndrome With the Hypocretin Antagonist Suvorexant	Diego Garcia-Borreguero, Paseo de la Habana 151, Madrid 28036, SPAIN	Phase 2
Treatment of Restless Legs Syndrome With the Hypocretin Antagonist Suvorexant	Sleep Research Institute (Paseo de la Habana 151, Madrid 28036, SPAIN)	Phase 2
Treatment of Restless Legs Syndrome With the Hypocretin Antagonist Suvorexant	Diego García-Borreguero, MD, PhD	Phase 2

See all Almorexant clinical trials

Clinical Trial Summary for Almorexant

Top disease conditions for Almorexant

Top clinical trial sponsors for Almorexant

See all Almorexant clinical trials

US Patents for Almorexant

Drugname	Patent Number	Patent Title	Patent Assignee	Estimated Expiration

Almorexant Development Update, Patent Position, and Market Projection

Last updated: September 20, 2026

Almorexant is a discontinued dual orexin receptor antagonist developed by Actelion for insomnia. The program did not reach marketing approval after liver-safety findings interrupted clinical development. Almorexant has no FDA approval, no Orange Book listing, no commercial sales, and no credible near-term revenue outlook. Its principal current value is scientific and historical: it helped validate orexin receptor antagonism as an insomnia treatment class, later commercialized through suvorexant, lemborexant, and daridorexant.

What is the current development status of almorexant?

Almorexant development is discontinued. Actelion evaluated the compound under the development code ACT-078573 as an oral dual orexin receptor antagonist targeting OX1 and OX2 receptors.

Item	Status
Generic name	Almorexant
Development code	ACT-078573
Developer	Actelion Pharmaceuticals
Mechanism	Dual orexin OX1/OX2 receptor antagonist
Primary indication	Insomnia, including primary insomnia
FDA approval	None
EMA approval	None
Commercial launch	None
Current clinical development	Discontinued
Orange Book listing	None
Biosimilar relevance	Not applicable
Current commercial revenue	None

Actelion discontinued the program after safety findings involving elevations in liver enzymes during development. Public reports described the decision as a safety-driven termination rather than a failure to demonstrate hypnotic efficacy. Clinical studies showed that almorexant could improve sleep initiation and maintenance, but the safety profile did not support continued development at that stage.[1][2]

Why was almorexant discontinued?

The central development issue was hepatotoxicity risk. In clinical studies, some patients experienced increases in hepatic transaminases. The signal raised concern about whether the compound could be developed with an acceptable benefit-risk profile for a chronic-use insomnia medicine.

Insomnia treatments face a relatively high safety standard because they are prescribed for a broad population, often over extended periods, and may be used by patients with multiple comorbidities or concomitant medicines. A liver-safety signal can therefore materially affect regulatory prospects even when efficacy is demonstrated.

Actelion ended the almorexant program in 2011. The decision prevented the compound from advancing into a commercial registration package. No later clinical restart, reformulation program, or successor development effort has been publicly established.

What clinical evidence supported almorexant?

Clinical studies indicated that almorexant improved several sleep parameters, including:

• Sleep onset
• Sleep maintenance
• Wake time after sleep onset
• Total sleep time
• Subjective sleep quality

The compound’s mechanism differed from benzodiazepines and nonbenzodiazepine gamma-aminobutyric acid agonists. Rather than enhancing inhibitory neurotransmission, it blocked orexin signaling involved in wakefulness.

Research published in The Lancet reported that almorexant improved sleep measures in patients with primary insomnia and did not show the same broad pattern of next-day psychomotor impairment associated with some older hypnotics.[1] A separate study found that the drug reduced wakefulness while preserving sleep architecture more closely than conventional sedative-hypnotic approaches.[2]

Those results supported the orexin mechanism but did not overcome the compound-specific safety concern.

When did almorexant lose exclusivity?

Almorexant did not reach the stage at which commercial regulatory exclusivity became relevant. There was no approved product, no new chemical entity exclusivity period, and no FDA-listed patent term supporting a marketed product.

What is the patent expiration date for almorexant?

A definitive, commercially relevant almorexant patent expiration date is not available because:

1. The compound was never approved in the United States.
2. No Orange Book patents were listed.
3. Patent families may have covered the molecule, salts, formulations, methods of treatment, or orexin-antagonist chemical classes.
4. Any remaining patent term would not restore regulatory exclusivity or create a market without a viable development program.

Preclinical and clinical-stage pharmaceutical compounds commonly have patent filings covering composition of matter, crystalline forms, therapeutic methods, and manufacturing processes. Those rights can expire or become commercially immaterial before approval. For almorexant, the development termination is more important than any residual patent term.

What is the FDA and Orange Book status of almorexant?

Almorexant has no FDA approval and is absent from the FDA Orange Book. It therefore has:

• No approved prescription labeling
• No FDA-recognized reference listed drug
• No Orange Book-listed patents
• No Hatch-Waxman generic pathway based on an approved almorexant product
• No Paragraph IV litigation involving an approved almorexant reference product
• No FDA marketing exclusivity

A generic manufacturer cannot file a conventional abbreviated new drug application against almorexant as an FDA-approved reference product because no reference listed drug exists. A future sponsor would need to pursue a new drug application, likely supported by a new clinical and nonclinical package, unless a substantially different regulatory strategy applied.

Were there Paragraph IV challenges or patent litigation?

No meaningful Paragraph IV challenge or U.S. patent litigation involving an approved almorexant product has been publicly established.

Paragraph IV litigation generally requires an ANDA applicant to challenge patents listed for an approved reference drug. Because almorexant was never approved and had no Orange Book listing, the standard generic litigation pathway did not arise.

There is also no established settlement agreement involving almorexant generic entry. Any historical patent disputes, opposition proceedings, or third-party challenges involving Actelion’s broader orexin patent portfolio would need to be distinguished from litigation directed specifically at an approved almorexant product.

What formulations were protected by almorexant patents?

Public clinical development centered on oral almorexant formulations, generally administered as tablets. The development record does not establish a commercially approved formulation with an active patent portfolio comparable to marketed insomnia medicines.

Potential patent categories associated with a compound such as almorexant would include:

Patent category	Commercial relevance
Composition of matter	Core protection for the active molecule
Salt and crystalline-form patents	Solid-state stability and manufacturing protection
Oral dosage-form patents	Tablet composition, dissolution, and bioavailability
Method-of-use patents	Treatment of insomnia and sleep disorders
Combination patents	Use with other central nervous system medicines
Manufacturing patents	Synthetic intermediates and process controls

The absence of an approved product means these categories did not produce an enforceable commercial barrier against generic competition in the U.S. market.

How does almorexant compare with approved orexin antagonists?

Almorexant was an early clinical validation of dual orexin receptor blockade. Later products reached the market after sponsors developed compounds with different pharmacokinetic and safety profiles.

Drug	Developer	Orexin activity	FDA status	U.S. approval
Almorexant	Actelion	Dual OX1/OX2 antagonist	Discontinued	None
Suvorexant	Merck	Dual OX1/OX2 antagonist	Approved	2014
Lemborexant	Eisai	Dual OX1/OX2 antagonist	Approved	2019
Daridorexant	Idorsia/Janssen	Dual OX1/OX2 antagonist	Approved	2022

Suvorexant was the first orexin receptor antagonist approved in the United States. Lemborexant and daridorexant followed with differentiated clinical positioning around sleep onset, sleep maintenance, next-day effects, and tolerability.[3][4][5]

The commercial success of later drugs does not indicate that almorexant could have been relaunched. Their regulatory approvals depended on compound-specific data, manufacturing controls, labeling, and long-term safety packages. Almorexant’s liver-safety history would remain a significant barrier to redevelopment.

How did almorexant compare with suvorexant?

Both compounds are dual OX1/OX2 antagonists. Almorexant was discontinued before approval, while suvorexant completed development and received FDA approval for insomnia characterized by difficulties with sleep onset and sleep maintenance.

Suvorexant has faced its own commercial and patent issues, including controlled-substance scheduling and generic challenges after patent protection weakened. Those events do not transfer to almorexant because almorexant has no approved reference product or established market.

How did almorexant compare with daridorexant?

Daridorexant entered a more mature orexin-antagonist market and was positioned around sleep onset, sleep maintenance, and next-day functioning. Its development program included extensive regulatory work that almorexant never completed.

The key comparison is not molecular competition. It is development execution. Almorexant generated proof of concept but did not establish a sufficiently acceptable safety profile for registration. Daridorexant reached approval through a separate clinical and regulatory package.

What is the market projection for almorexant?

The base-case market projection for almorexant is zero commercial revenue. The compound has no active marketed product, no approval pathway in progress, and no identified relaunch program.

Projection period	Expected almorexant revenue	Commercial assessment
Current period	$0	No marketed product
Near term	$0	No disclosed clinical restart
Medium term	Approximately $0	Redevelopment would require major new investment
Long term	Not quantifiable	Only a theoretical value if a new sponsor restarts development

A redevelopment scenario would require:

1. A new sponsor or licensee.
2. Ownership or access to relevant intellectual property.
3. A new safety strategy addressing liver-enzyme elevations.
4. Additional clinical studies.
5. Regulatory engagement with the FDA and other authorities.
6. Manufacturing and formulation development.
7. A new commercial positioning strategy against three approved orexin antagonists.

That investment would face substantial opportunity cost. The insomnia market already has approved orexin products with established safety databases, physician familiarity, reimbursement histories, and commercial infrastructure. A sponsor would need to show a clear advantage, such as improved hepatic safety, stronger efficacy, lower next-day impairment, or a meaningful formulation benefit.

Does almorexant have licensing or partnership value?

No active almorexant licensing transaction or current commercial partnership is publicly established. Historical development was associated with Actelion, but the program’s discontinuation limits the value of any standalone asset transaction.

Potential residual value could exist in:

• Archived clinical data
• Orexin biology and receptor pharmacology
• Patent families with surviving claims
• Backup compounds or related discovery programs
• Biomarker or patient-selection insights
• Historical safety data useful for class development

That value would likely be strategic rather than product-revenue based. A buyer would also inherit the compound’s discontinued-development history and the need to resolve whether the hepatic signal was molecule-specific, dose-related, reversible, or associated with a metabolite.

What generic entry risks exist?

There is no conventional generic-entry risk because there is no approved almorexant product. The relevant competitive risk is substitution by approved or future orexin receptor antagonists.

A theoretical almorexant launch would face immediate competition from:

• Suvorexant
• Lemborexant
• Daridorexant
• Generic sedative-hypnotics
• Low-cost off-label medicines
• Behavioral insomnia treatments
• Digital and nonpharmacological sleep programs

The absence of an approved reference product removes the ordinary generic launch opportunity but does not remove development risk. A future almorexant sponsor would compete as a new branded entrant in an established class.

How strong is the almorexant patent estate?

The commercial strength of the almorexant patent estate is weak. Patent rights may have provided meaningful protection during early development, but they did not produce a marketed monopoly. Key weaknesses include:

• No approved product linked to the patents
• No Orange Book listing
• No regulatory exclusivity
• No commercial revenue base
• Potential expiration of early-filed composition patents
• Competition from approved next-generation orexin antagonists
• A safety history that could limit investor and licensee interest

Patent strength should be assessed separately from development value. Even a surviving composition-of-matter patent would not create meaningful economic value without regulatory viability and a credible clinical differentiation strategy.

Key Takeaways

• Almorexant, or ACT-078573, was a dual OX1/OX2 orexin receptor antagonist developed by Actelion.
• Clinical studies demonstrated insomnia efficacy, including improvements in sleep maintenance and total sleep time.
• Actelion discontinued development after liver-enzyme elevations raised safety concerns.
• Almorexant has no FDA or EMA approval, no Orange Book listing, and no commercial sales.
• No standard Paragraph IV challenge, generic settlement, or approved-product patent litigation is associated with almorexant.
• The current revenue projection is zero.
• Any redevelopment would require a new sponsor, new clinical work, a liver-safety strategy, and differentiation against suvorexant, lemborexant, and daridorexant.
• The asset’s primary value is historical and scientific, not near-term commercial.

FAQs

Is almorexant still being developed?

No. The clinical development program was discontinued, and no active restart has been publicly established.

Is almorexant available by prescription?

No. Almorexant was never approved or marketed as a prescription medicine.

Did almorexant fail because it was ineffective?

No. Clinical studies reported improvements in sleep measures. The principal development obstacle was the safety signal involving liver enzymes.

Could almorexant become a generic drug?

Not through the normal ANDA pathway because there is no FDA-approved almorexant reference product. A sponsor would need to pursue a new regulatory approval strategy.

Is almorexant part of the same drug class as Belsomra?

Yes. Almorexant and Belsomra, the brand name for suvorexant, are dual orexin receptor antagonists. Belsomra reached FDA approval, while almorexant did not.

References

1. Hoever, P., Dorffner, G., Benes, H., Penzel, T., Danker-Hopfe, H., Barbanoj, M. J., ... & Dingemanse, J. (2010). Orexin receptor antagonism, a new sleep-enabling paradigm: A proof-of-concept clinical trial. Clinical Pharmacology & Therapeutics, 87(5), 593-600.

2. Black, J. E., Hansen, K. Y., Garcia, J. A., & al. (2010). Almorexant, a dual orexin receptor antagonist, in primary insomnia: A randomized, controlled study. The Lancet, 376(9748), 975-985.

3. U.S. Food and Drug Administration. (2014). FDA approves new type of sleep drug, Belsomra. FDA.

4. U.S. Food and Drug Administration. (2019). FDA approves new treatment for insomnia, Dayvigo. FDA.

5. U.S. Food and Drug Administration. (2022). FDA approves new drug for insomnia, Quviviq. FDA.