Nuedexta® is a combination product containing dextromethorphan and quinidine. The quinidine has been added because it is a CYP450 2D6 inhibitor and markedly increases the serum levels of dextromethorphan (see Related Pages below).
Here is basic information about this medication. Other articles on this website with more advanced information and tips related to this medication are linked to under Related Pages below..
FDA-approved indications
For the treatment of pseudobulbar affect (PBA).
Dosage
Starting dose: One capsule daily by mouth for 7 days
Maintenance dose: After 7 days, one capsule two times daily.
Dosage forms and strengths
Capsules: Containing dextromethorphan 20 mg/quinidine sulfate 10 mg
Pharmacodynamics
Dextromethorphan has multiple effects in the CNS.
1. Blocks N-methyl-D-aspartate (NMDA) receptors
2. Agonist at sigma-1 receptors
3. Inhibits serotonin reuptake
4. Antagonist at voltage-gated calcium channels
5. Inhibits norepinephrine reuptake
6. May block nicotinic acetylcholine receptors, especially those with α3β4 subunits.
Contraindications
Source: Prescribing Information.
Besides hypersensitivity:
1. With an MAOI or within 14 days after stopping an MAOI.
2. Prolonged QT interval, congenital long QT syndrome, history suggestive of torsades de pointes, or heart failure.
3. Complete atrioventricular (AV) block without an implanted pacemaker, or patients at high risk of complete AV block.
4. On a medication that is metabolized by CYP2D6 AND can prolong the QT interval, e.g., thioridazine or pimozide.
Potentially serious side effects
Thrombocytopenia
Hepatitis
QT prolongation
Dizziness/ risk of fall
Other potential side effects
Adverse events that occurred at least twice as often as on placebo are considered here to be “side effects” of the drug. Percentage differences in the incidence of each adverse event on the drug and on placebo are in parentheses.
Diarrhea (7%)
Dizziness (5%)
Vomiting (4%)
Peripheral edema (4%)
Cough (3%) — isn’t that surprising?
Asthenia (3%)
Urinary tract infection (3%)
Influenza (3%)
Increased gammaglutamyltransferase (GGT; 3%)
Flatulence (2%)
Drug interactions
Serotonin syndrome can occur if dextromethorphan/ quinidine is used with a serotoninergic antidepressant
Important! Please refer to Prescribing Information (see link below) for a complete discussion of dosage, administration, warnings and precautions, contraindications, etc.
Related Pages
Why is dextromethorphan being combined with a CYP 2D6 inhibitor?
Dextromethorphan / quinidine (Nuedexta®) for dementia (major neurocognitive disorder)
References
Nuedexta Prescribing Information
Copyright 2019, Rajnish Mago, MD. All rights reserved. May not be reproduced in any form without express written permission. Disclaimer: The content on this website is provided as general education for medical professionals. It is not intended or recommended for patients or other laypersons or as a substitute for medical advice, diagnosis, or treatment. Patients must always consult a qualified health care professional regarding their diagnosis and treatment. Healthcare professionals should always check this website for the most recently updated information.
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