Quinidine and Related Drugs

NUEDEXTA contains quinidine; do not use concomitantly in patients taking other drugs containing quinidine, quinine, or mefloquine.



Patients with a history of NUEDEXTA, quinine, mefloquine or quinidine-induced thrombocytopenia, hepatitis, bone marrow depression or lupus-like syndrome or known hypersensitivity to dextromethorphan (e.g. rash, hives).



Patients currently taking monoamine oxidase inhibitors (MAOIs), or within 14 days of starting or stopping an MAOI, due to the risk of serious and possibly fatal drug interactions.



Patients with a prolonged QT interval, congenital long QT syndrome, history suggestive of torsades de pointes, heart failure, patients receiving drugs that both prolong QT interval and are metabolized by CYP2D6 (e.g., thioridazine and pimozide), patients with complete atrioventricular (AV) block without implanted pacemaker or at high risk of complete AV block.

Warnings and Precautions

Thrombocytopenia and Other Hypersensitivity Reactions:

Quinidine can cause immune-mediated thrombocytopenia that can be severe or fatal. Discontinue if this or other hypersensitivity reaction occurs. 



Hepatitis, has been reported in persons receiving quinidine, generally during the first few weeks of therapy. Discontinue immediately if this occurs. 


Cardiac Effects:

NUEDEXTA causes dose-dependent QTc prolongation. When initiating NUEDEXTA in patients at risk for QT prolongation and torsades de pointes, electrocardiographic (ECG) evaluation should be conducted at baseline and 3-4 hours after the first dose. Some risk factors include use with CYP3A4 inhibitors or drugs that prolong QT interval, electrolyte abnormalities, bradycardia, or left ventricular hypertrophy or dysfunction. 


Concomitant Use of CYP2D6 Substrates:

NUEDEXTA inhibits CYP2D6 and may interact with other drugs metabolized by CYP2D6; adjust dose of CYP2D6 substrates as needed. 



NUEDEXTA may cause dizziness. Take precautions to reduce the risk of falls. 


Serotonin Syndrome:

Use of NUEDEXTA with selective serotonin reuptake inhibitor (SSRI) or tricyclic antidepressants increases risk for “serotonin syndrome”. 


Anticholinergic Effects of Quinidine:

Monitor for worsening in myasthenia gravis.


Adverse Drug Reactions (Incidence of ≥5% of Patients and ≥2x Placebo):

The most common adverse reactions are diarrhea, dizziness, cough, vomiting, asthenia, and peripheral edema.


Pregnancy (Category C):

No adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus.