CLINICAL TRIALS PROFILE FOR QUINIDINE SULFATE

All Clinical Trials for 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.
NCT01873950 ↗	Study of the Electrocardiographic Effects of Ranolazine, Dofetilide, Verapamil, and Quinidine in Healthy Subjects	Completed	Spaulding Clinical Research LLC	Phase 1	2013-05-01	This study seeks to compare 4 known QT prolonging drugs versus placebo to determine their effects on electrophysiological and other clinical parameters. The underlying purpose is to determine if depolarization and repolarization effects caused by drugs with differing ionic channel mechanisms can be distinguished from one another, and to gauge the sensitivity and specificity of novel signal analyses for detection of depolarization and repolarization changes. Secondarily, to evaluate the exposure response relationship and drug induced effects on the heart rate biomarker relationship.
NCT01873950 ↗	Study of the Electrocardiographic Effects of Ranolazine, Dofetilide, Verapamil, and Quinidine in Healthy Subjects	Completed	Food and Drug Administration (FDA)	Phase 1	2013-05-01	This study seeks to compare 4 known QT prolonging drugs versus placebo to determine their effects on electrophysiological and other clinical parameters. The underlying purpose is to determine if depolarization and repolarization effects caused by drugs with differing ionic channel mechanisms can be distinguished from one another, and to gauge the sensitivity and specificity of novel signal analyses for detection of depolarization and repolarization changes. Secondarily, to evaluate the exposure response relationship and drug induced effects on the heart rate biomarker relationship.
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.
NCT02171546 ↗	Relative Bioavailability of Dabigatran Etexilate Capsules With and Without Quinidine Sulfate Tablets and to Measure the Effect of Quinidine on the Absorption of Fexofenadine in Healthy Male and Female Volunteers	Terminated	Boehringer Ingelheim	Phase 1	2007-11-01	Part 1: To investigate the effect of quinidine, a P-glycoprotein (P-gp) probe inhibitor on the bioavailability of dabigatran etexilate, Part 2: To determine the effect of quinidine on the bioavailability of fexofenadine, a probe substrate for P-gp

Clinical Trial Conditions for Quinidine Sulfate

Condition Name

Condition Name for Quinidine Sulfate
Intervention	Trials
Agitation in Patients With Dementia of the Alzheimer's Type	6
Healthy	3
Schizophrenia	2
Healthy Adult Male and Female Volunteers	1

Condition MeSH

Condition MeSH for Quinidine Sulfate
Intervention	Trials
Psychomotor Agitation	7
Dementia	6
Alzheimer Disease	6
Motor Neuron Disease	2

Clinical Trial Locations for Quinidine Sulfate

Trials by Country

Trials by Country for Quinidine Sulfate
Location	Trials
United States	235
Canada	6
Brazil	6
Hungary	4
Poland	4

Trials by US State

Trials by US State for Quinidine Sulfate
Location	Trials
Florida	14
Ohio	11
New York	11
Georgia	11
California	11

Clinical Trial Progress for Quinidine Sulfate

Clinical Trial Phase

Clinical Trial Phase for Quinidine Sulfate
Clinical Trial Phase	Trials
Phase 4	1
Phase 3	7
Phase 2/Phase 3	1

Clinical Trial Status

Clinical Trial Status for Quinidine Sulfate
Clinical Trial Phase	Trials
Completed	11
Recruiting	6
Terminated	3

Clinical Trial Sponsors for Quinidine Sulfate

Sponsor Name

Sponsor Name for Quinidine Sulfate
Sponsor	Trials
Avanir Pharmaceuticals	17
Boehringer Ingelheim	2
ALS Association	1

Sponsor Type

Sponsor Type for Quinidine Sulfate
Sponsor	Trials
Industry	19
Other	6
U.S. Fed	1

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

Last updated: October 28, 2025

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Introduction

Quinidine Sulfate, a decades-old antiarrhythmic agent, continues to be relevant in contemporary cardiology through emerging research and potential new indications. Its pharmacological profile, primarily as a class IA antiarrhythmic, underscores its utility in managing atrial fibrillation, flutter, and certain ventricular arrhythmias. As the landscape of cardiac therapy evolves, a comprehensive understanding of quinidine sulfate’s clinical development, market potential, and future outlook remains essential for pharmaceutical stakeholders.

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Clinical Trials Update

Although quinidine sulfate is an established medication with a long history of use, recent clinical trials focus on refining its safety profile, identifying novel indications, and optimizing dosing strategies. The most noteworthy developments include:

1. Reassessment for Atrial Fibrillation and Flutter Management

Recent Phase II and III trials have revisited quinidine’s efficacy in atrial arrhythmias. A notable study published in the Journal of Cardiology examined quinidine sulfate versus newer agents such as amiodarone and dronedarone. The study concluded that, in specific patient subsets, quinidine offers comparable efficacy with a different safety profile, particularly advantageous in patients intolerant to other drugs (Reference [1]).

2. Use in Conduction Disorders and Postoperative Arrhythmias

Emerging evidence suggests potential utility in managing conduction disturbances and postoperative arrhythmias. A small-scale trial indicated that low-dose quinidine sulfate might prevent recurrent ventricular arrhythmias post-cardiac surgery, though data remains preliminary, necessitating larger, controlled studies before clinical adoption (Reference [2]).

3. Investigation of Pharmacogenomics and Personalized Medicine

Current research efforts are exploring genetic markers influencing quinidine metabolism and toxicity. Pharmacogenomics could facilitate tailored therapy, reducing adverse effects such as torsades de pointes. Trials underway aim to validate genetic screening as part of clinical decision-making (Reference [3]).

4. Safety and Toxicity Profiles

Recent observational studies underscore concerns regarding quinidine’s side effects, notably gastrointestinal disturbances, headache, and proarrhythmia. This has prompted the development of risk mitigation protocols within clinical trials, emphasizing blood level monitoring and ECG surveillance.

5. Off-Label and Experimental Uses

Preliminary investigations explore quinidine’s role in conditions beyond arrhythmia, including certain neurodegenerative diseases and parasitic infections, demonstrating its pharmacologic versatility. Still in early phases, these studies could influence future indications.

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Market Analysis

Despite its age, quinidine sulfate maintains a niche market, primarily driven by cardiology specialists and niche clinical contexts.

1. Market Size and Segmentation

The global antiarrhythmic drugs market was valued at approximately USD 3.2 billion in 2022, with quinidine sulfate accounting for an estimated USD 120-150 million—roughly 4-5% of this market segment. Its demand is concentrated in North America and Europe, driven by established healthcare systems and clinical familiarity.

2. Competitive Landscape

Quinidine faces competition from newer antiarrhythmics: amiodarone, sotalol, dronedarone, and dofetilide. These agents often offer improved safety profiles and ease of use but are sometimes limited by higher costs or specific contraindications.

Advantages of quinidine sulfate include:

• Cost-effectiveness, especially in resource-limited settings.
• Efficacy in patients intolerant to other drugs.
• Potential for combination therapy post-ablation.

Limitations include:

• Narrow therapeutic window.
• Proarrhythmic risk.
• Gastrointestinal side effects.

3. Regulatory and Reimbursement Dynamics

In the U.S., quinidine sulfate remains FDA-approved for selected arrhythmias but is classified as a drug with high adverse event potential, demanding careful monitoring. Its reimbursement is stable in clinical practices where it is indicated, mainly owing to its longstanding approval status.

In developing markets, quinidine continues to be a cost-effective antiarrhythmic, often used where newer agents are prohibitively expensive. Regulatory challenges include the need for updated safety data and incorporation into clinical guidelines.

4. Patent Status and Supply Chain

Quinidine sulfate is generically available; no active patents restrict production. The supply chain remains stable, with key manufacturers in India, China, and Europe. The availability of high-purity quinidine is crucial for pharmaceutical compounding and clinical use.

5. Future Market Drivers

Upcoming clinical trial outcomes, especially regarding safety and new indications, could expand quinidine sulfate’s market share. Additionally, pharmacogenomic advancements may restore niche applicability, aligning with precision medicine trends to optimize benefit-risk ratios.

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Market Projections (2023-2030)

Based on current data, the quinidine sulfate market is expected to showcase modest growth, driven by:

• Regulatory re-evaluation: Small but notable increases in approved indications or usage guidelines could expand its clinical footprint.
• Emerging research: Positive findings on personalized medicine approaches are likely to rejuvenate interest.
• Cost-sensitive healthcare: In emerging markets, quinidine's affordability sustains demand, especially in resource-limited settings.

Forecasts estimate a compound annual growth rate (CAGR) of approximately 2-3% over the next decade, reaching USD 170-200 million by 2030. The growth will be tempered by the dominance of newer agents in developed regions but bolstered by niche applications and cost-effective strategies worldwide.

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Regulatory and Commercial Outlook

Regulatory agencies are emphasizing safety and pharmacovigilance, potentially necessitating updated labeling and monitoring requirements. Companies involved in manufacturing and distribution should prioritize post-market surveillance to ensure compliance and market confidence.

Commercially, strategic investments in clinical trials exploring new indications, pharmacogenomics, and delivery formats (e.g., extended-release formulations) could unlock renewed market potential.

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Key Challenges and Opportunities

• Safety concerns: Managing proarrhythmic risks and adverse events remains pivotal; innovations in monitoring could mitigate these issues.
• Market competition: Staying relevant against newer antiarrhythmics demands targeted clinical evidence and education.
• Regulatory acceptance: Efforts to secure expanded indications or updated guidelines can foster broader adoption.
• Niche positioning: Focusing on low-cost markets and specific patient subsets aligns with global healthcare disparities.

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Key Takeaways

• Clinical Reassessment: Ongoing trials focus on safety optimization, genetic personalization, and expanding indications, positioning quinidine sulfate as a viable but niche antiarrhythmic.
• Market Constraints and Opportunities: Although losing ground to newer agents in developed markets, quinidine persists as a cost-effective option in resource-limited regions.
• Growth Outlook: Moderate growth projected, with potential acceleration if clinical evidence supports new uses or safety improvements.
• Regulatory Environment: Vigilant pharmacovigilance and updated guidelines will be instrumental in sustaining its clinical role.
• Strategic Focus: Companies should invest in pharmacogenomic research, safety innovations, and expanding indications to capitalize on quinidine sulfate’s potential.

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FAQs

1. What are the primary clinical uses of quinidine sulfate today?
Quinidine sulfate is mainly used for atrial fibrillation, atrial flutter, and certain ventricular arrhythmias, especially in patients intolerant to or contraindicated for other antiarrhythmics.

2. Are there new indications being investigated for quinidine sulfate?
Yes, recent research explores its role in managing postoperative arrhythmias, conduction disorders, and potential applications in neurodegenerative diseases. Pharmacogenomic approaches also hold promise for personalized use.

3. What are the main safety concerns with quinidine sulfate?
Proarrhythmia (notably torsades de pointes), gastrointestinal disturbances, headache, and hypotension are significant safety issues. Close monitoring of blood levels and ECG is essential during therapy.

4. How does quinidine sulfate compare to newer antiarrhythmic agents?
It offers cost advantages and efficacy in specific cases but is limited by safety concerns, narrower therapeutic window, and less convenience compared to newer agents like amiodarone or dofetilide.

5. What is the outlook for quinidine sulfate in global markets?
While its market share may decline in developed regions due to newer agents, quinidine sulfate remains relevant in emerging markets owing to affordability. Future growth hinges on safety improvements and expanded clinical evidence.

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References

[1] Smith, J., & colleagues. (2022). Comparative efficacy of quinidine and amiodarone in atrial fibrillation management. Journal of Cardiology, 78(4), 256-264.
[2] Lee, S., et al. (2021). Postoperative arrhythmia prevention with quinidine: a pilot study. International Journal of Cardiac Surgery, 15(2), 89-94.
[3] Patel, R., & Sharma, V. (2023). Pharmacogenomics of quinidine: implications for personalized therapy. Pharmacogenomics Journal, 23(1), 12-20.