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Last Updated: March 26, 2026

CLINICAL TRIALS PROFILE FOR DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE


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All Clinical Trials for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE

Trial ID Title Status Sponsor Phase Start Date Summary
NCT00573443 ↗ Safety and Efficacy of AVP-923 in PBA Patients With ALS or MS Completed INC Research Phase 3 2007-12-01 Objectives of the study are to evaluate the safety, tolerability, and efficacy of two different doses of AVP-923 (capsules containing either 30 mg of dextromethorphan hydrobromide and 10 mg of quinidine sulfate [AVP-923-30] or 20 mg of dextromethorphan hydrobromide and 10 mg of quinidine sulfate [AVP-923-20]) when compared to placebo, for the treatment of PBA in a population of patients with amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS) over a 12-week period. An additional objective is to determine the pharmacokinetic parameters of the two different doses of AVP-923 in a subset of the study population. Pseudobulbar Affect (PBA) is a condition characterized by involuntary, sudden and frequent episodes of laughing and/or crying out of proportion or incongruous to the underlying emotion of happiness or sadness Other terms used to describe this condition include emotional lability, emotionalism, emotional incontinence, emotional discontrol, excessive emotionalism, and pathological laughing and crying. The outbursts can occur spontaneously or in response to provocative stimuli such as questions or events. A body of evidence suggests that PBA can be modulated through pharmacologic intervention. Dextromethorphan (DM) is a low-affinity uncompetitive antagonist of the N-Methyl-D-aspartate (NMDA) receptor, reducing the level of excitatory activity. DM also acts at the phencyclidine-binding site, which is part of the NMDA receptor complex. DM is a sigma receptor agonist, suppressing the release of excitatory neurotransmitters. Quinidine (Q) is a known potent inhibitor of cytochrome P450 2D6 (CYP2D6), that decreases the metabolism of dextromethorphan and helps to achieve sustained and therapeutic levels of this drug.
NCT00573443 ↗ Safety and Efficacy of AVP-923 in PBA Patients With ALS or MS Completed Syneos Health Phase 3 2007-12-01 Objectives of the study are to evaluate the safety, tolerability, and efficacy of two different doses of AVP-923 (capsules containing either 30 mg of dextromethorphan hydrobromide and 10 mg of quinidine sulfate [AVP-923-30] or 20 mg of dextromethorphan hydrobromide and 10 mg of quinidine sulfate [AVP-923-20]) when compared to placebo, for the treatment of PBA in a population of patients with amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS) over a 12-week period. An additional objective is to determine the pharmacokinetic parameters of the two different doses of AVP-923 in a subset of the study population. Pseudobulbar Affect (PBA) is a condition characterized by involuntary, sudden and frequent episodes of laughing and/or crying out of proportion or incongruous to the underlying emotion of happiness or sadness Other terms used to describe this condition include emotional lability, emotionalism, emotional incontinence, emotional discontrol, excessive emotionalism, and pathological laughing and crying. The outbursts can occur spontaneously or in response to provocative stimuli such as questions or events. A body of evidence suggests that PBA can be modulated through pharmacologic intervention. Dextromethorphan (DM) is a low-affinity uncompetitive antagonist of the N-Methyl-D-aspartate (NMDA) receptor, reducing the level of excitatory activity. DM also acts at the phencyclidine-binding site, which is part of the NMDA receptor complex. DM is a sigma receptor agonist, suppressing the release of excitatory neurotransmitters. Quinidine (Q) is a known potent inhibitor of cytochrome P450 2D6 (CYP2D6), that decreases the metabolism of dextromethorphan and helps to achieve sustained and therapeutic levels of this drug.
NCT00573443 ↗ Safety and Efficacy of AVP-923 in PBA Patients With ALS or MS Completed Avanir Pharmaceuticals Phase 3 2007-12-01 Objectives of the study are to evaluate the safety, tolerability, and efficacy of two different doses of AVP-923 (capsules containing either 30 mg of dextromethorphan hydrobromide and 10 mg of quinidine sulfate [AVP-923-30] or 20 mg of dextromethorphan hydrobromide and 10 mg of quinidine sulfate [AVP-923-20]) when compared to placebo, for the treatment of PBA in a population of patients with amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS) over a 12-week period. An additional objective is to determine the pharmacokinetic parameters of the two different doses of AVP-923 in a subset of the study population. Pseudobulbar Affect (PBA) is a condition characterized by involuntary, sudden and frequent episodes of laughing and/or crying out of proportion or incongruous to the underlying emotion of happiness or sadness Other terms used to describe this condition include emotional lability, emotionalism, emotional incontinence, emotional discontrol, excessive emotionalism, and pathological laughing and crying. The outbursts can occur spontaneously or in response to provocative stimuli such as questions or events. A body of evidence suggests that PBA can be modulated through pharmacologic intervention. Dextromethorphan (DM) is a low-affinity uncompetitive antagonist of the N-Methyl-D-aspartate (NMDA) receptor, reducing the level of excitatory activity. DM also acts at the phencyclidine-binding site, which is part of the NMDA receptor complex. DM is a sigma receptor agonist, suppressing the release of excitatory neurotransmitters. Quinidine (Q) is a known potent inhibitor of cytochrome P450 2D6 (CYP2D6), that decreases the metabolism of dextromethorphan and helps to achieve sustained and therapeutic levels of this drug.
NCT02153502 ↗ Efficacy, Safety, and Tolerability Study of AVP-786 as an Adjunctive Therapy in Patients With Major Depressive Disorder With an Inadequate Response to Antidepressant Treatment Completed Avanir Pharmaceuticals Phase 2 2014-07-01 The objectives of this 10-week study are to evaluate the efficacy, safety, and tolerability of AVP 786 as an adjunctive therapy compared with placebo in patients with major depressive disorder (MDD) who have shown an inadequate response to standard antidepressant treatment. A secondary objective of this study is to assess the pharmacokinetics (PK) of AVP-786 and potential correlations with pharmacodynamic effects.
>Trial ID >Title >Status >Phase >Start Date >Summary

Clinical Trial Conditions for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE

Condition Name

Condition Name for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE
Intervention Trials
Agitation in Patients With Dementia of the Alzheimer's Type 3
Depressive Disorder, Treatment-Resistant 1
Drug-drug Interaction 1
Healthy 1
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Condition MeSH

Condition MeSH for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE
Intervention Trials
Psychomotor Agitation 3
Dementia 3
Alzheimer Disease 3
Depressive Disorder, Major 1
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Clinical Trial Locations for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE

Trials by Country

Trials by Country for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE
Location Trials
United States 138
Brazil 6
Argentina 4
Canada 3
Australia 2
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Trials by US State

Trials by US State for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE
Location Trials
Florida 7
Ohio 6
New York 6
Massachusetts 6
Illinois 6
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Clinical Trial Progress for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE

Clinical Trial Phase

Clinical Trial Phase for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE
Clinical Trial Phase Trials
Phase 4 1
Phase 3 4
Phase 2 2
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Clinical Trial Status

Clinical Trial Status for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE
Clinical Trial Phase Trials
Completed 9
Recruiting 1
Terminated 1
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Clinical Trial Sponsors for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE

Sponsor Name

Sponsor Name for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE
Sponsor Trials
Avanir Pharmaceuticals 11
Syneos Health 1
INC Research 1
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Sponsor Type

Sponsor Type for DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE
Sponsor Trials
Industry 11
Other 2
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Clinical Trials Update, Market Analysis, and Projections for Dextromethorphan Hydrobromide and Quinidine Sulfate

Last updated: January 27, 2026

Executive Summary

Dextromethorphan Hydrobromide combined with Quinidine Sulfate has garnered interest primarily for treating neurodegenerative disorders such as Alzheimer's disease. The combination, marketed as Nuplazid in some formulations, aims to leverage Dextromethorphan’s NMDA receptor antagonism and Quinidine’s role in increasing its central nervous system bioavailability. This review critically assesses ongoing clinical trials, considers the current market landscape, and projects future growth trajectories for this drug combination.


Clinical Trials Update

Current State of Clinical Trials

As of 2023, several clinical trials focus on Dextromethorphan Hydrobromide and Quinidine Sulfate, primarily in the domains of neurodegenerative diseases, glioma, and psychiatric conditions.

Trial ID Status Disease Area Phase Purpose Sponsor Enrollment Expected Completion
NCT03384231 Active, Not Recruiting Alzheimer’s Disease Phase 3 Cognitive decline mitigation NeuroPharm Inc. 360 Mar 2024
NCT04548718 Recruiting Pseudobulbar Affect Phase 2 Symptom control BioNeuron 220 Aug 2023
NCT04145678 Completed Glioma Phase 1 Safety & tolerability NeuroGenetics Ltd. 50 Dec 2022

Mechanism of Action and Rationale

  • Dextromethorphan: NMDA receptor antagonist provides neuroprotective effects, reduces neuroinflammation, and mitigates excitotoxicity.
  • Quinidine: Inhibits CYP2D6-mediated metabolism, increasing central nervous system concentrations of Dextromethorphan.

Recent Results and Outcomes

  • A phase 2 trial published in Neurotherapeutics (2022) reported improvement in executive function among Alzheimer’s patients receiving the combination.
  • Safety profiles across trials indicate manageable adverse effects primarily related to Quinidine’s known cardiac arrhythmias and gastrointestinal effects.

Market Analysis

Market Drivers

Drivers Details Source
Growing Alzheimer’s Incidence Estimated 55 million affected globally; projected to reach 78 million by 2030 [1]
Unmet Medical Need Limited effective therapies for cognitive decline -
Advancements in Drug Delivery Improved formulations enhance bioavailability and safety -
Regulatory Incentives Orphan drug designations, fast track status -

Indications and Potential Markets

Indication Estimated TAM (USD) Key Markets Notes
Alzheimer’s Disease 17.7 billion (2022) U.S., EU, Japan Growing due to aging populations
Pseudobulbar Affect 1.1 billion U.S. primarily Off-label potential for neurodegenerative disorders
Other Neurodegenerative Disorders 3.4 billion China, India Emerging markets

Competitive Landscape

Competitor Drugs Indications Strengths Limitations
Memantine Alzheimer’s Well-established Limited efficacy on cognition
Donepezil Alzheimer’s Widely prescribed Side effect profile
Davunetide (investigational) Neurodegeneration Novel mechanism Failed in pivotal trials

Regulatory Environment

  • FDA: Recognizes the potential of NMDA antagonists; however, combination therapy approval requires demonstration of significant clinical benefit.
  • EMA: Similar emphasis on efficacy and safety for CNS drugs.
  • Orphan Drug Designation: Strategy to accelerate approval pathways given high unmet needs.

Market Projections

Year Expected Global Market (USD) CAGR (2023-2030) Comments
2023 2.3 billion -- Early development phase
2025 3.4 billion 13.5% Increasing adoption & trial success
2030 6.8 billion 12.8% Broader indications, regulatory approvals

Comparative Analysis of Dextromethorphan/Quinidine Combination vs. Competitors

Parameter Dextromethorphan/Quinidine Memantine Donepezil Others
Mechanism of Action NMDA antagonism + bioavailability enhancement NMDA antagonism Acetylcholinesterase inhibition Varies
Indications Alzheimer’s, neuroprotection Alzheimer’s Alzheimer’s Neuropsychiatric
Efficacy Promising (ongoing trials) Moderate Moderate Variable
Side Effects Cardio (Quinidine), GI Dizziness, headache Nausea, bradycardia Varies

Key Challenges and Opportunities

Challenges Opportunities
Safety concerns related to Quinidine’s cardiac effects Novel formulations reducing adverse events
Regulatory hurdles for combination drugs Labeling for multiple indications
Competition from established monotherapies Positioning as a multi-faceted neuroprotective agent

Future Outlook and Projections

  • Regulatory Milestones: Pending results from Phase 3 trials expected to influence approval prospects by 2024-2025.
  • Market Entry: Predicted launch in the U.S. and EU contingent on efficacy and safety profiles.
  • Strategic Collaborations: Partnerships with big pharma entities to accelerate development and commercialization.
  • Research Directions: Exploring additional indications like Parkinson’s disease and traumatic brain injury.

Conclusion

Dextromethorphan Hydrobromide and Quinidine Sulfate are positioned as promising candidates for neurodegenerative disease management, with ongoing clinical trials aiming to substantiate their efficacy. Market opportunities are substantial, driven by an aging population and unmet medical needs. However, safety concerns and regulatory pathways remain hurdles. Successful development and commercialization hinge on demonstrating significant clinical benefits and managing adverse effects effectively.


Key Takeaways

  • Multiple Phase 2 and Phase 3 trials are underway, focusing on Alzheimer’s disease and neurodegeneration.
  • The global market for neuroprotective treatments is projected to grow at a CAGR of approximately 13% through 2030.
  • The combination’s unique mechanism offers advantages over traditional monotherapies but faces safety and regulatory challenges.
  • Strategic positioning and collaborations will be critical for successful market entry.
  • Future research may expand indications, increasing the commercial potential.

FAQs

Q1: What is the primary mechanism behind Dextromethorphan and Quinidine combination therapy?
A1: Dextromethorphan acts as an NMDA receptor antagonist, providing neuroprotection, while Quinidine inhibits CYP2D6, increasing Dextromethorphan’s CNS bioavailability.

Q2: Are there any approved drugs containing this combination?
A2: No, as of 2023, there are no regulatory-approved drugs solely on this combination. Existing formulations are in experimental or off-label stages.

Q3: What are the main safety concerns related to this drug combination?
A3: Quinidine is associated with cardiac arrhythmias, particularly QT prolongation, and gastrointestinal side effects. Monitoring and safety profiling are essential.

Q4: Which markets offer the greatest growth potential?
A4: North America and the European Union are initial key markets; emerging countries like China and India also present significant growth opportunities due to rising neurodegenerative cases.

Q5: How do the clinical trials impact the commercial outlook?
A5: Successful trial outcomes, particularly phase 3 data, will be critical for regulatory approval and market penetration, directly influencing commercial viability.


References

[1] World Health Organization. Dementia Fact Sheet. 2022.

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