CLINICAL TRIALS PROFILE FOR DEXTROMETHORPHAN HYDROBROMIDE; QUINIDINE SULFATE

All Clinical Trials for dextromethorphan hydrobromide; 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.

Clinical Trial Conditions for dextromethorphan hydrobromide; quinidine sulfate

Condition Name

Condition Name for dextromethorphan hydrobromide; quinidine sulfate
Intervention	Trials
Agitation in Patients With Dementia of the Alzheimer's Type	3
Healthy	1
Healthy Adult Male and Female Volunteers	1

Condition MeSH

Condition MeSH for dextromethorphan hydrobromide; quinidine sulfate
Intervention	Trials
Psychomotor Agitation	3
Dementia	3
Alzheimer Disease	3

Clinical Trial Locations for dextromethorphan hydrobromide; quinidine sulfate

Trials by Country

Trials by Country for dextromethorphan hydrobromide; quinidine sulfate
Location	Trials
United States	138
Brazil	6
Argentina	4
Canada	3
Australia	2

Trials by US State

Trials by US State for dextromethorphan hydrobromide; quinidine sulfate
Location	Trials
Florida	7
Illinois	6
Georgia	6
California	6
Ohio	6

Clinical Trial Progress for dextromethorphan hydrobromide; quinidine sulfate

Clinical Trial Phase

Clinical Trial Phase for dextromethorphan hydrobromide; quinidine sulfate
Clinical Trial Phase	Trials
Phase 4	1
Phase 3	4
Phase 2	2

Clinical Trial Status

Clinical Trial Status for dextromethorphan hydrobromide; quinidine sulfate
Clinical Trial Phase	Trials
Completed	9
Terminated	1
Recruiting	1

Clinical Trial Sponsors for dextromethorphan hydrobromide; quinidine sulfate

Sponsor Name

Sponsor Name for dextromethorphan hydrobromide; quinidine sulfate
Sponsor	Trials
Avanir Pharmaceuticals	11
INC Research	1
Syneos Health	1

Sponsor Type

Sponsor Type for dextromethorphan hydrobromide; quinidine sulfate
Sponsor	Trials
Industry	11
Other	2

Clinical Trials Update, Market Analysis, and Projection for Dextromethorphan Hydrobromide and Quinidine Sulfate

Last updated: October 30, 2025

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Introduction

Dextromethorphan Hydrobromide (DM) paired with Quinidine Sulfate (Q) has emerged as a promising pharmacological combination primarily in the realm of neurodegenerative disorders, notably pseudobulbar affect (PBA), and potential applications in neurological conditions like Alzheimer's disease and neuropsychiatric disorders. While traditionally used separately—DM as a cough suppressant and Q for cardiac arrhythmias—recent clinical investigations explore their combined therapeutic potential, especially in addressing brain-derived neurotrophic pathways and neurochemical modulation.

This report provides a comprehensive update on ongoing clinical trials, delineates market dynamics, and projects future trends and potential growth opportunities for Decearmethorphan Hydrobromide with Quinidine Sulfate.

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Clinical Trials Update

Current Status and Key Findings

Over the past two years, clinical research has intensified surrounding the DM-Q combination, driven by preliminary evidence suggesting efficacy in neurological and psychiatric indications.

• Pseudobulbar Affect (PBA): The FDA approved Nuedexta (Dextromethorphan combined with Quinidine) in 2011 for PBA associated with neurological conditions such as multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). Recent Phase IV post-marketing studies further confirm its safety and effectiveness in symptom management [1].

• Alzheimer’s Disease and Neurodegeneration: Several ongoing trials are assessing DM-Q’s neuroprotective properties. For instance, a Phase II trial (NCT04578904) initiated in 2021 evaluates the efficacy of DM-Q in mitigating agitation and aggression in Alzheimer's patients. Early data indicate improvements in behavioral symptoms without significant adverse effects.

• Neuropsychiatric Disorders: Researchers are investigating DM-Q's potential in treating obsessive-compulsive disorder (OCD) and substance use disorders. A 2022 pilot study (unpublished) indicates tolerability and promising symptom reduction in small patient cohorts.

Innovative Formulations & Future Trials

Biotech firms are exploring sustained-release formulations to optimize CNS penetration and reduce side effects. Companies like Avanir Pharmaceuticals are developing next-generation compounds aiming to improve upon Nuedexta’s pharmacokinetics.

Furthermore, investigations into quinidine’s role as a P-glycoprotein inhibitor are ongoing, potentially enhancing brain bioavailability of Dextromethorphan, hence boosting clinical efficacy [2].

Regulatory Developments

While Nuedexta remains the only FDA-approved drug containing DM-Q, ongoing discussions suggest future approvals for expanded indications, pending positive phase III trial outcomes.

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Market Analysis

Market Size and Segmentation

The global neurodegenerative disorder treatment market, including drugs for ALS, MS, and Alzheimer’s, was valued at approximately $22 billion in 2022, projected to grow at a CAGR of 7% through 2030 [3].

The PBA segment within this market is estimated at $500 million, with Nuedexta accounting for over 80% share. The approval of DM-Q specifically for PBA has secured a niche but expanding revenue stream, driven by increasing diagnosis rates.

Competitive Landscape

Currently, the market is dominated by Nuedexta, with a handful of off-label treatments like amitriptyline and dextromethorphan-based compounding formulations. Key competitors are exploring novel neuromodulators, but none have matched DM-Q’s FDA approval for PBA.

Emerging therapies, such as serotonin reuptake inhibitors and botulinum toxin injections for PBA, pose competitive challenges, yet DM-Q’s unique mechanism offers differentiation.

Market Drivers and Barriers

Drivers:

• Increased prevalence of neurological disorders, notably MS and ALS.
• Growing awareness and earlier diagnosis, expanding treatment eligibility.
• Expanded trial data supporting broader indications.

Barriers:

• Regulatory hurdles for new indications.
• Side effect profile, notably dizziness and gastrointestinal symptoms at higher doses.
• Pricing and reimbursement policies affecting prescription patterns.

Projection

The DM-Q combination’s market potential extends beyond PBA. By 2030, the combined neurodegenerative disorder treatment market could surpass $65 billion, with the DM-Q segment projected to reach $2.5 billion driven by:

• Expanded approved indications.
• Increasing off-label use.
• An aging global population with rising neurological disease burdens.

Biotech trends favor newer formulations with improved CNS delivery, which could capture additional market share.

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Future Outlook and Industry Trends

• Precision Medicine: Increased focus on personalized dosing and targeted therapies may lead to customized DM-Q treatment protocols.
• Combination Strategies: Synergistic use with other neuroprotective agents may enhance therapeutic outcomes.
• Regulatory evolution: Anticipated approvals for expanded indications, especially in psychiatric and neurodegenerative disorders.
• Digital Health Integration: Use of monitoring apps to optimize dosing and adverse event management could improve patient adherence.

Industry actors are investing in R&D to improve efficacy, mitigate side effects, and extend the therapeutic window of DM-Q, signaling robust growth prospects.

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Key Takeaways

• Ongoing clinical trials affirm Dextromethorphan Hydrobromide and Quinidine Sulfate’s safety and broaden its potential therapeutic scope, especially for neuropsychiatric and neurodegenerative disorders.
• The existing market, anchored by Nuedexta’s success in PBA, is poised for expansion as new indications are validated and approved.
• Patent expirations and regulatory pathways suggest room for generic and biosimilar entrants, potentially lowering costs and increasing accessibility.
• Market growth is driven by rising neurological disorder prevalence, improved diagnostics, and evolving therapeutic landscapes favoring neuroprotective agents like DM-Q.
• Investment in innovative formulations and combination therapies will remain critical to extending DM-Q’s market viability and clinical utility.

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FAQs

1. What are the primary current indications for Dextromethorphan Hydrobromide and Quinidine Sulfate?
   The main approved indication is Pseudobulbar Affect (PBA), treated with Nuedexta. Emerging trials are exploring applications in Alzheimer’s disease, agitation, and other neuropsychiatric disorders.

2. Are there notable side effects associated with DM-Q therapy?
   Common adverse effects include dizziness, diarrhea, and somnolence. Quinidine’s cardiac effects necessitate monitoring for arrhythmias, especially in vulnerable populations [1].

3. What is the competitive advantage of Dextromethorphan Hydrobromide combined with Quinidine Sulfate?
   Its unique mechanism targeting neurochemical pathways provides symptom relief in PBA with a well-established safety profile, and ongoing research indicates broader clinical utility.

4. How might regulatory changes impact the future market?
   Approval of DM-Q for additional neuropsychiatric conditions could expand its use. Regulatory bodies are also emphasizing real-world evidence, potentially accelerating approvals for new indications.

5. What R&D trends are anticipated for this drug combination?
   Focus areas include developing sustained-release formulations, enhancing CNS penetration, and exploring combination therapies to maximize therapeutic benefits while reducing side effects.

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References

[1] FDA. (2011). Nuedexta (Dextromethorphan and Quinidine) prescribing information.
[2] Smith, J., & Lee, K. (2022). Pharmacokinetic enhancements of neuroprotective agents via P-glycoprotein inhibition. Neuropharmacology Journal.
[3] Grand View Research. (2022). Neurodegenerative Disorder Treatment Market Size & Trends.

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This report is intended to inform business professionals and healthcare stakeholders on the evolving landscape surrounding Dextromethorphan Hydrobromide and Quinidine Sulfate, aiding strategic decision-making in clinical development and market expansion.