Dextromethorphan Quinidine (Nuedexta) For Pseudobulbar Affect is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
| Property |
Value |
| Drug Name |
Dextromethorphan/Quinidine |
| Brand Name |
Nuedexta |
| Drug Class |
NMDA Receptor Antagonist / CYP2D6 Inhibitor |
| Target |
NMDA Receptors, Sigma-1 Receptors |
| Route of Administration |
Oral |
| FDA Approval |
2010 |
| Company |
Axsome Therapeutics |
Nuedexta is a fixed-dose combination of dextromethorphan and quinidine, specifically developed for the treatment of pseudobulbar affect (PBA), also known as emotional lability or pathological laughing and crying. PBA is a neurological condition characterized by involuntary episodes of crying, laughing, or other emotional expressions that are disproportionate or inappropriate to the situation.
- NMDA Receptor Antagonism: Blocks NMDA receptors in the brain, reducing glutamatergic excitotoxicity
- Sigma-1 Receptor Agonism: Modulates calcium signaling and may provide neuroprotective effects
- Serotonin/Norepinephrine Effects: Mild reuptake inhibition may contribute to mood stabilization
- CYP2D6 Inhibition: Primarily serves to inhibit CYP2D6, which metabolizes dextromethorphan
- Plasma Level Enhancement: Increases dextromethorphan plasma levels 30-fold, enabling therapeutic effect
- Antiarrhythmic Properties: Historically used for cardiac arrhythmias (not relevant to PBA indication)
The combination allows dextromethorphan to achieve therapeutic concentrations in the CNS without requiring doses that would cause quinidine-related cardiac effects.
- Primary PBA: Associated with neurological diseases including:
- Amyotrophic lateral sclerosis (ALS)
- Multiple sclerosis (MS)
- Stroke
- Traumatic brain injury
- Parkinson's disease
- Alzheimer's disease
- Primary Endpoint: Reduce the frequency and severity of PBA episodes
- Study Results:
- Phase 3 trials showed 49% reduction in PBA episode frequency vs placebo
- Clinically meaningful improvement in ≥80% of patients
- Onset of action within 1-2 weeks
- Initial Dose: 20/10 mg (dextromethorphan/quinidine) once daily
- Target Dose: 20/10 mg twice daily after 1 week
- Administration: With or without food
| Target |
Mechanism |
Clinical Effect |
| NMDA Receptors |
Antagonism |
Reduce glutamatergic excitotoxicity |
| Sigma-1 Receptors |
Agonism |
Modulate stress responses |
| CYP2D6 |
Substrate |
Increase dextromethorphan bioavailability |
- Absorption: Rapid oral absorption
- Onset: 30-60 minutes
- Duration: 6-12 hours
- Metabolism: Extensive first-pass metabolism (CYP2D6, CYP3A4)
- Excretion: Renal
- Absorption: Near complete
- Half-life: 6-8 hours (therapeutic doses)
- Metabolism: Hepatic (CYP3A4)
- Excretion: Renal (20% unchanged)
¶ Side Effects and Safety
- Nausea
- Dizziness
- Headache
- Somnolence
- Diarrhea
- QT Prolongation: Quinidine can prolong QT interval
- Hepatic Effects: Elevated liver enzymes (rare)
- Serotonin Syndrome: Risk when combined with serotonergic drugs
- Known hypersensitivity to dextromethorphan or quinidine
- Concomitant use with MAO inhibitors
- History of quinidine-induced thrombocytopenia
- Severe cardiac conduction abnormalities
- Concurrent use of other QT-prolonging drugs
| Interacting Drug |
Effect |
| MAO Inhibitors |
Serotonin syndrome risk |
| SSRIs/SNRIs |
Serotonin syndrome risk |
| CYP2D6 Substrates |
Increased levels |
| QT-prolonging drugs |
Additive QT effect |
- Prevalence: PBA affects ~50% of ALS patients
- Impact: Significant quality of life impairment
- Evidence: Nuedexta approved based on ALS subgroup data
- Prevalence: PBA affects ~10% of MS patients
- Impact: Social embarrassment, isolation
- Evidence: Clinical trials included MS patients
- Prevalence: Less common than in ALS/MS
- Consideration: May co-exist with dysarthria
- Prevalence: Variable, often underdiagnosed
- Consideration: May improve caregiver burden
¶ Advantages and Limitations
- Targeted therapy specifically for PBA
- Rapid onset of action (1-2 weeks)
- Well-studied in neurodegenerative disease populations
- Oral administration
- Requires twice-daily dosing
- Drug interaction concerns
- Cost considerations
- Not suitable for all patients (cardiac, hepatic issues)
- Formulation Development: Once-daily formulations under development
- Combination Therapy: Studies evaluating combination with antidepressants
- Expanded Indications: Potential for use in other neurological conditions
- Biomarker Development: Identifying predictors of response
The study of Dextromethorphan Quinidine (Nuedexta) For Pseudobulbar Affect has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- {{cite journal | author=Schiffer R et al. | title=Dextromethorphan/quinidine for pseudobulbar affect | journal=CNS Drugs | year=2009 }}
- {{cite journal | author=Brooks BR et al. | title=Nuedexta for pseudobulbar affect in ALS | journal=Amyotroph Lateral Scler | year=2012 }}
- {{cite journal | author=Patel GK et al. | title=Pseudobulbar affect: review and treatment options | journal=Ther Clin Risk Manag | year=2019 }}