Medications
Dextromethorphan - Quinidine
NUEDEXTA is a combination product containing dextromethorphan hydrobromide (an uncompetitive NMDA receptor antagonist and sigma-1 agonist) and quinidine sulfate (a CYP450 2D6 inhibitor) indicated for the treatment of pseudobulbar affect (PBA). Studies to support the effectiveness of NUEDEXTA were performed in patients with underlying amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS). NUEDEXTA has not been shown to be safe or effective in other types of emotional lability that can commonly occur, for example, in Alzheimer’s disease and other dementias.
The most common adverse reactions (incidence of ≥ 3% and two-fold greater than placebo) in patients taking NUEDEXTA are diarrhea, dizziness, cough, vomiting, asthenia, peripheral edema, urinary tract infection, influenza, increased gamma-glutamyltransferase, and flatulence.
- Desipramine: Exposure increases 8-fold. Reduce desipramine dose and adjust based on clinical response.
- Paroxetine: Exposure increases 2-fold. Reduce paroxetine dose and adjust based on clinical response.
- Digoxin: Increased digoxin substrate plasma concentration may occur.
- Thrombocytopenia or other hypersensitivity reactions: Discontinue if occurs.
- Hepatitis: Discontinue if occurs.
- QT Prolongation: Monitor ECG if concomitant use of drugs that prolong QT interval cannot be avoided or if concomitant CYP3A4 inhibitors used.
- Left ventricular hypertrophy (LVH) or left ventricular dysfunction (LVD): Monitor ECG in patients with LVH or LVD.
- CYP2D6 substrate: Nuedexta inhibits CYP2D6. Accumulation of parent drug and/or failure of metabolite formation may decrease safety and/or efficacy of concomitant CYP2D6 metabolized drugs. Adjust dose of CYP2D6 substrate or use alternative treatment when clinically indicated.
- Dizziness: Take precautions to reduce falls.
- Serotonin syndrome: Use of NUEDEXTA with selective serotonin reuptake inhibitor (SSRI)’s or tricyclic antidepressants increases the risk. Discontinue if occurs.
- Anticholinergic effects of quinidine: Monitor for worsening in myasthenia gravis and other sensitive conditions.
