Last Updated: May 10, 2026

CLINICAL TRIALS PROFILE FOR ISOCARBOXAZID


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All Clinical Trials for isocarboxazid

Trial ID Title Status Sponsor Phase Start Date Summary
NCT02323217 ↗ I2PETHV - Imidazoline2 Binding Site in Healthy Volunteers Completed GlaxoSmithKline Early Phase 1 2015-01-01 The imdazoline2 binding site (I2BS) is known to reside inside astrocytes. Changes in the numbers of I2BS in post mortem tissue has implicated them in a range of psychiatric conditions such as depression and addiction, along with neurodegenerative disorders such as Alzheimer's disease and Huntington's chorea. Preclinical studies have also demonstrated functional interactions with the opioid system, where I2BS ligands have been shown to affect tolerance to morphine and alleviate some of the morphine withdrawal syndrome in rats. Recently the I2BS and I2BS ligands have been shown to have some interesting analgesic effects in different models of pain and a novel I2BS ligand, CR4056, is currently undergoing Phase II clinical trials as a novel treatment for neuropathic pain and acute non- specific pain states. The location of I2BS on astrocytic glial cells and the possibility that they may in some way regulate glial fibrillary acidic protein have led to increased interest into the role of I2BS and I2BS ligands in conditions characterised by marked gliosis. The number of I2BS has been shown to increase in Alzheimer's disease post mortem, and it has also been suggested that I2BS may be a marker for the severity and malignancy of human glioblastomas. The lack of suitable imaging tools for the I2BS has meant that information regarding the number and distribution of I2BS in the brain has come from preclinical species and in vitro post-mortem studies. The recent development of [11C]BU99008 as a suitable PET ligand to quantify I2BS in vivo, enables the direct quantification of I2BS availability and regional distribution in the living human brain. In this study the investigators plan to utilise [11C]BU99008 to quantify the regional brain availability of I2BS in the human brain in vivo using PET.
NCT02323217 ↗ I2PETHV - Imidazoline2 Binding Site in Healthy Volunteers Completed Imperial College London Early Phase 1 2015-01-01 The imdazoline2 binding site (I2BS) is known to reside inside astrocytes. Changes in the numbers of I2BS in post mortem tissue has implicated them in a range of psychiatric conditions such as depression and addiction, along with neurodegenerative disorders such as Alzheimer's disease and Huntington's chorea. Preclinical studies have also demonstrated functional interactions with the opioid system, where I2BS ligands have been shown to affect tolerance to morphine and alleviate some of the morphine withdrawal syndrome in rats. Recently the I2BS and I2BS ligands have been shown to have some interesting analgesic effects in different models of pain and a novel I2BS ligand, CR4056, is currently undergoing Phase II clinical trials as a novel treatment for neuropathic pain and acute non- specific pain states. The location of I2BS on astrocytic glial cells and the possibility that they may in some way regulate glial fibrillary acidic protein have led to increased interest into the role of I2BS and I2BS ligands in conditions characterised by marked gliosis. The number of I2BS has been shown to increase in Alzheimer's disease post mortem, and it has also been suggested that I2BS may be a marker for the severity and malignancy of human glioblastomas. The lack of suitable imaging tools for the I2BS has meant that information regarding the number and distribution of I2BS in the brain has come from preclinical species and in vitro post-mortem studies. The recent development of [11C]BU99008 as a suitable PET ligand to quantify I2BS in vivo, enables the direct quantification of I2BS availability and regional distribution in the living human brain. In this study the investigators plan to utilise [11C]BU99008 to quantify the regional brain availability of I2BS in the human brain in vivo using PET.
>Trial ID >Title >Status >Phase >Start Date >Summary

Clinical Trial Conditions for isocarboxazid

Condition Name

Condition Name for isocarboxazid
Intervention Trials
Healthy Volunteers 1
Molecular Imaging 1
Alzheimer Disease 1
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Condition MeSH

Condition MeSH for isocarboxazid
Intervention Trials
Alzheimer Disease 1
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Clinical Trial Locations for isocarboxazid

Trials by Country

Trials by Country for isocarboxazid
Location Trials
United Kingdom 1
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Clinical Trial Progress for isocarboxazid

Clinical Trial Phase

Clinical Trial Phase for isocarboxazid
Clinical Trial Phase Trials
Early Phase 1 1
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Clinical Trial Status

Clinical Trial Status for isocarboxazid
Clinical Trial Phase Trials
Completed 1
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Clinical Trial Sponsors for isocarboxazid

Sponsor Name

Sponsor Name for isocarboxazid
Sponsor Trials
GlaxoSmithKline 1
Imperial College London 1
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Sponsor Type

Sponsor Type for isocarboxazid
Sponsor Trials
Industry 1
Other 1
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Isocarboxazid (Marplan): Clinical Trials Update and Market Outlook

Last updated: May 4, 2026

What is isocarboxazid and who manufactures it?

Isocarboxazid is an oral monoamine oxidase inhibitor (MAOI) used for major depressive disorder. The drug is marketed in the U.S. as Marplan by Bausch Health (historically also branded by other legacy holders in different markets).

What do current clinical-trial signals show?

No reliable, current, end-to-end clinical development pipeline can be stated from the available information in this prompt. A complete and accurate “clinical trials update” for isocarboxazid requires direct trial-level facts (trial IDs, phases, status dates, endpoints) and sponsor documentation, which are not provided here.

What is the addressable market today?

A market sizing and projection requires current supply, prescribing, payer coverage, and competitor (other MAOIs) and substitute (SSRIs/SNRIs/atypicals) utilization data. Those market inputs are not provided in the prompt, so a complete and accurate market analysis and projection cannot be produced to professional standard.

How does the drug compete (positioning) in depression treatment?

Isocarboxazid competes primarily within the broader depression therapeutics landscape where MAOIs are niche due to dietary restrictions, monitoring needs, and safety management relative to first-line antidepressants. In practice, MAOIs are typically reserved for treatment-resistant cases or when other classes have failed, which compresses peak volume and keeps demand smaller than modern, high-utilization classes.

What would a credible projection require (and why it is not deliverable here)?

A defensible forecast for isocarboxazid would need at minimum:

  • Prescription trend baseline (U.S. and major ex-U.S. markets)
  • Formulary status and access (commercial and Medicare Part D coverage)
  • Utilization drivers (dose, treatment duration, patient mix)
  • Supply and discontinuation risk (manufacturing continuity)
  • Competitive pricing and equivalency (brand vs authorized generics, if applicable)

None of these inputs are in the prompt; therefore a complete and accurate projection is not possible.

Is there an IP or lifecycle issue affecting commercial outlook?

A complete lifecycle analysis requires patent status, exclusivity expirations, and any litigation or authorized generic arrangements by geography. These data are not provided here.

Can an actionable investment or R&D view be issued?

Not without trial identifiers and market inputs. High-stakes decisions require evidenced pipeline status and evidenced demand dynamics; the prompt contains neither.


Key Takeaways

  • Isocarboxazid is a legacy oral MAOI marketed in the U.S. as Marplan (Bausch Health).
  • A complete and accurate clinical trials update cannot be produced from the provided inputs because trial-level facts are not present.
  • A complete and accurate market analysis and projection cannot be produced because prescribing, payer, supply, and competitive utilization data are not present.

FAQs

1) Is isocarboxazid still prescribed for major depressive disorder?

Yes. Isocarboxazid remains indicated for major depressive disorder, but real-world use is typically niche versus first-line antidepressant classes due to safety and dietary constraints.

2) Are there new phase 3 or registration trials ongoing for isocarboxazid?

The prompt does not provide trial identifiers, phases, or status dates; an evidence-based answer cannot be produced here.

3) Who holds the U.S. brand for isocarboxazid?

Marplan is associated with Bausch Health in the U.S. market.

4) What are the main commercial headwinds for MAOIs like isocarboxazid?

Treatment access constraints driven by diet interactions, monitoring requirements, and prescriber preference relative to newer antidepressant classes.

5) What metrics determine a market forecast for a legacy antidepressant?

Prescription volume trends, payer formulary positioning, treatment duration patterns, supply stability, and competitive substitution effects.


References (APA)

[1] Bausch Health. Marplan (isocarboxazid) prescribing information.

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