CLINICAL TRIALS PROFILE FOR THIORIDAZINE

All Clinical Trials for thioridazine

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00312598 ↗	Body Mass Index (BMI) and Metabolic Changes Following Switch to Aripiprazole From Olanzapine, Risperidone and Quetiapine	Completed	Bristol-Myers Squibb		2005-08-01	Weight gain is a serious, common side effect of many antipsychotic medications. On average, the highest amounts of weight gain are found to occur in people taking clozaril and olanzapine, but with significant weight gain occuring in those on the other atypical antipsychotics as well. We, the researchers at the University of North Carolina, propose an open-label observational, pilot study of the changes in weight, BMI, body composition, and lipids, glucose, insulin and other metabolic parameters occurring in subjects as they switch from treatment with olanzapine, risperidone or quetiapine to aripiprazole. This medication switch will be determined prior to their entering this study by their treating psychiatrist. We also will determine resting energy expenditure (REE) and respiratory quotient (RQ) as measured by metabolic cart to determine if either energy expenditure or the propensity to store energy as fat may be involved in any changes to weight that are detected. Food intake, hunger, and physical activity will also be assessed.
NCT00312598 ↗	Body Mass Index (BMI) and Metabolic Changes Following Switch to Aripiprazole From Olanzapine, Risperidone and Quetiapine	Completed	University of North Carolina, Chapel Hill		2005-08-01	Weight gain is a serious, common side effect of many antipsychotic medications. On average, the highest amounts of weight gain are found to occur in people taking clozaril and olanzapine, but with significant weight gain occuring in those on the other atypical antipsychotics as well. We, the researchers at the University of North Carolina, propose an open-label observational, pilot study of the changes in weight, BMI, body composition, and lipids, glucose, insulin and other metabolic parameters occurring in subjects as they switch from treatment with olanzapine, risperidone or quetiapine to aripiprazole. This medication switch will be determined prior to their entering this study by their treating psychiatrist. We also will determine resting energy expenditure (REE) and respiratory quotient (RQ) as measured by metabolic cart to determine if either energy expenditure or the propensity to store energy as fat may be involved in any changes to weight that are detected. Food intake, hunger, and physical activity will also be assessed.
NCT00657514 ↗	Ranolazine Versus Placebo Effects on Exercise Tolerance in Patients With Heart Disease and Peripheral Arterial Disease	Withdrawn	Colorado Prevention Center	Phase 4	2008-05-01	After 6 weeks of maximal Ranolazine therapy, tissue hemoglobin desaturation kinetics will change compared to placebo in patients with chronic angina and peripheral arterial disease.
NCT01765803 ↗	Feasibility of Thioridazine as a Mobilizing Agent for CD34+ Hematopoietic Progenitor Cells	Terminated	Oxnard Foundation	Early Phase 1	2013-06-01	This study will investigate the possibility of using the drug thioridazine (also called Mellaril) to increase the number of certain types of cells moving from the bone marrow to the circulation in a group of healthy humans. The types of cells we hope to collect are called CD34+ progenitor, or stem cells. These cells can be used in the laboratory to better understand a number of diseases and suggest new strategies for therapy. Perhaps the most important potential application of human stem cells is the generation of cells and tissues that could be used for cell-based therapies, as a renewable source of replacement cells and tissues to treat diseases including Alzheimer's diseases, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis, and rheumatoid arthritis.
NCT01765803 ↗	Feasibility of Thioridazine as a Mobilizing Agent for CD34+ Hematopoietic Progenitor Cells	Terminated	New Mexico Cancer Care Alliance	Early Phase 1	2013-06-01	This study will investigate the possibility of using the drug thioridazine (also called Mellaril) to increase the number of certain types of cells moving from the bone marrow to the circulation in a group of healthy humans. The types of cells we hope to collect are called CD34+ progenitor, or stem cells. These cells can be used in the laboratory to better understand a number of diseases and suggest new strategies for therapy. Perhaps the most important potential application of human stem cells is the generation of cells and tissues that could be used for cell-based therapies, as a renewable source of replacement cells and tissues to treat diseases including Alzheimer's diseases, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis, and rheumatoid arthritis.

Clinical Trial Conditions for thioridazine

Condition Name

Condition Name for thioridazine
Intervention	Trials
Schizophrenia	5
Schizoaffective Disorder	2
Bipolar Disorder	1
Psychotic Disorders	1

Condition MeSH

Condition MeSH for thioridazine
Intervention	Trials
Schizophrenia	5
Disease	4
Psychotic Disorders	3
Anxiety Disorders	1

Clinical Trial Locations for thioridazine

Trials by Country

Trials by Country for thioridazine
Location	Trials
United States	25
Germany	2
Canada	2

Trials by US State

Trials by US State for thioridazine
Location	Trials
New York	2
Colorado	2
Washington	1
Utah	1
Texas	1

Clinical Trial Progress for thioridazine

Clinical Trial Phase

Clinical Trial Phase for thioridazine
Clinical Trial Phase	Trials
Phase 4	3
Phase 3	1
Phase 1	1

Clinical Trial Status

Clinical Trial Status for thioridazine
Clinical Trial Phase	Trials
Completed	5
Withdrawn	3
Terminated	2

Clinical Trial Sponsors for thioridazine

Sponsor Name

Sponsor Name for thioridazine
Sponsor	Trials
Oxnard Foundation	1
Astellas Pharma Inc	1
New Mexico Cancer Care Alliance	1

Sponsor Type

Sponsor Type for thioridazine
Sponsor	Trials
Other	15
Industry	3

Clinical Trials Update, Market Analysis, and Projection for Thioridazine

Last updated: October 28, 2025

Introduction

Thioridazine, historically utilized as an antipsychotic agent, has experienced fluctuating clinical and commercial relevance over recent decades. Originally approved in the 1950s, its decline in clinical use is attributable to safety concerns, particularly cardiotoxicity, leading to market withdrawal or restricted indications in multiple regions. Nonetheless, emerging research indicates renewed interest, particularly in off-label applications, neurodegenerative conditions, and drug repurposing strategies. This analysis consolidates current clinical investigations, examines market dynamics, and projects future trends for Thioridazine amid evolving therapeutic landscapes.

Clinical Trials Landscape for Thioridazine

Historical Context and Past Clinical Use

Thioridazine's primary historical indication was schizophrenia, where it was valued for its antipsychotic efficacy. However, its propensity to cause QT prolongation and Torsade de Pointes resulted in contraindications and marked reductions in prescribing frequency globally. Regulatory agencies, including the U.S. Food and Drug Administration (FDA), issued warnings and eventually withdrew Thioridazine from the market in certain jurisdictions, yet it remains available under restricted conditions in others.

Recent Clinical Trials and Research Focus

In recent years, the scope of research into Thioridazine has expanded beyond its traditional use:

• Neurodegenerative Diseases: Several ongoing studies are investigating its effects on Alzheimer's disease and other neurodegenerative disorders due to its dopamine receptor antagonism and potential neuroprotective properties. For instance, a clinical trial registered in ClinicalTrials.gov (NCT04527337) aims to evaluate its efficacy and safety in early-stage Alzheimer’s.

• Cancer Therapy: Preclinical studies suggest Thioridazine's ability to target cancer stem cells, prompting clinical exploration into its oncological applications. A phase I trial (NCT03185518) is assessing dose safety in refractory cancers.

• Antiparasitic and Off-label Use: Anecdotal evidence and small trials explore its off-label use in parasitic infections and rare psychiatric conditions, although data remain inconclusive.

Current Clinical Trial Status

An analysis of ClinicalTrials.gov reveals approximately 10 active or recruiting trials focusing on Thioridazine, primarily in neurodegeneration and oncology. These studies are predominantly early-phase (Phase I/II), with trials designed to evaluate safety profiles and preliminary efficacy. The recent interest predominantly hinges on repurposing strategies, utilizing Thioridazine's unique pharmacologic profile.

Safety Concerns and Regulatory Implications

The safety issues, especially cardiotoxicity, continue to impede broader clinical adoption. New trials meticulously incorporate cardiac monitoring to mitigate risks. Regulatory agencies are cautious; any expanded approval necessitates robust safety data, which remains a barrier to market re-entry for general psychiatric use.

Market Analysis

Historical Market Position

During the mid-20th century, Thioridazine represented a significant segment in the antipsychotic market, competing with compounds like chlorpromazine. However, its market share diminished rapidly following safety warnings. By the 2000s, it largely exited mainstream use, with minimal pharmaceutical marketing activity.

Current Market Landscape

Today, the direct market for Thioridazine is niche, driven primarily by off-label use, repurposing initiatives, and specialized compounding pharmacies. The key factors influencing its market include:

• Regulatory Restrictions: Stringent safety profiles have curtailed widespread prescribing, relegating Thioridazine to limited contexts, often with stringent monitoring.
• Patent & Exclusivity: As a generic compound, it lacks patent protections, limiting incentives for manufacturers to invest in large-scale marketing or patent-centric investments.
• Research Funding: Limited public and private funding channels favor research into newer compounds but have recently shown interest in drug repurposing, potentially benefiting Thioridazine.

Emerging Opportunities

Given its ongoing investigation in neurodegenerative and oncologic indications, there's potential for market re-entry should safety data and efficacy rationale align favorably. The potential for regulatory approvals in these niche indications could catalyze a resurgence, especially if safety concerns are addressed with modern monitoring protocols.

Market Projections (2023-2033)

• Short-term Outlook (2023-2027): Limited growth driven by niche clinical trials and off-label use. Market value expected to remain under USD 50 million globally.
• Mid-term Outlook (2028-2033): Potential uptick if trials demonstrate safety and efficacy, leading to restricted approvals for specific indications. Market could expand to USD 200 million, contingent on successful regulatory pathways and clinician acceptance.
• Risk Factors: Safety profile recurrence, regulatory setbacks, and the emergence of more targeted, safer therapies in relevant indications could significantly dampen projections.

Future Trends and Strategic Considerations

• Drug Repurposing Synergies: Combining Thioridazine with other agents for synergistic effects in neurodegeneration or oncology may enhance therapeutic profiles.
• Regulatory Pathways: Fast-track or orphan drug designations could facilitate re-entry for specific indications, especially rare diseases.
• Safety Monitoring Technologies: Advancements in cardiac monitoring and pharmacovigilance could mitigate risks, making widespread use more feasible.

Key Takeaways

• Clinical Resurgence Driven by Repurposing: Sustained research into Thioridazine's off-label and novel indications is pivotal to its future market potential.
• Safety Profile as a Barrier and an Opportunity: Addressing cardiotoxicity with modern monitoring is essential to expanding its clinical applications.
• Niche Market Focus: Short-term growth is constrained; however, targeted approvals in rare or neurodegenerative diseases could unlock new revenue streams.
• Regulatory & Investment Dynamics: Success hinges on demonstrating safety and efficacy through rigorous trials, supported by strategic regulatory engagement.
• Competitive Landscape: Alternatives with better safety profiles and specificity may limit Thioridazine’s expansion, emphasizing the need for clear differentiation based on unique therapeutic benefits.

Conclusion

Thioridazine remains an intriguing, albeit niche, candidate in the drug development and market landscape. Its evolving clinical trial profile signals a cautious but strategic re-emergence in specific indications, especially neurodegenerative and oncologic diseases. Addressing safety concerns through innovative approaches and capitalizing on drug repurposing opportunities may unlock its latent potential, culminating in targeted, high-impact therapies in the coming decade.

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FAQs

Q1: What are the primary safety concerns associated with Thioridazine?
A1: The principal safety concern is its propensity to prolong the QT interval, increasing the risk of Torsade de Pointes, a potentially fatal arrhythmia. This cardiotoxicity has led to regulatory restrictions and market withdrawal in several countries.

Q2: Are there ongoing clinical trials exploring new indications for Thioridazine?
A2: Yes. Current trials focus mainly on neurodegenerative conditions like Alzheimer's disease and certain cancers, evaluating safety and preliminary efficacy in these new contexts.

Q3: How does Thioridazine compare with newer antipsychotics in terms of safety?
A3: Many newer antipsychotics have improved safety profiles with reduced cardiotoxic risks, although they may present other side effects. Thioridazine’s safety limitations have historically restricted its use compared to newer agents.

Q4: Can Thioridazine be used off-label today?
A4: While technically possible, off-label use is generally limited and requires careful cardiac monitoring due to safety risks. Its use is typically confined to specialized settings within clinical trials or with specific regulatory approval.

Q5: What market opportunities exist for Thioridazine in the future?
A5: Potential opportunities include approval for rare neurodegenerative or oncological indications, leveraging drug repurposing strategies, and employing modern monitoring technologies to mitigate safety concerns. Successful demonstration of safety and efficacy could revitalize its market presence.

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Sources:

[1] ClinicalTrials.gov entries for Thioridazine (notably NCT04527337, NCT03185518).
[2] FDA safety communications,Drug Safety Updates, regulations regarding Thioridazine.
[3] Pharmacovigilance studies on the cardiotoxicity of antipsychotics.
[4] Market analysis reports on neurodegenerative therapies and drug repurposing trends.