Nuedexta
Combination product
Pronunciation: dex-troe-meth-OR-fan and KWIN-i-deen
What it isNMDA antagonist/sigma-1 agonist dextromethorphan with CYP2D6-blocking quinidine; pseudobulbar affect.
Why this oneThe only drug approved for pseudobulbar affect; quinidine dose is far below antiarrhythmic range.
What limits itQuinidine's CYP2D6 block raises levels of other 2D6 substrates; dizziness, falls and diarrhea occur.
Pearls
- Off-label: modestly reduces Alzheimer agitation and aggression.
- Avoid with MAOIs; serotonergic.
Nude Dexter
Components (2)
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Pseudobulbar affect (PBA) | Adults | 1 capsule (20 mg/10 mg) QD for 7 days | 1 capsule q12h (BID) from day 8 | 2 capsules/day |
Titration After 7 days at once daily, increase to one capsule every 12 hours
Renal No adjustment for mild-to-moderate impairment; not studied in severe (levels likely increased)
Hepatic No adjustment for mild-to-moderate impairment (additional adverse-reaction monitoring advised); not evaluated in severe
Starting dose is once daily for 7 days, then every 12 hours; reassess need for continued treatment periodically
Instructions
- May be taken without regard to meals
- Correct hypokalemia/hypomagnesemia before initiating; monitor ECG if QT risk factors present
Available strengths
- cap 20/10 mg
Contraindications
- Concomitant use with quinidine, quinine, or mefloquine
- History of quinidine/quinine/mefloquine-induced thrombocytopenia, hepatitis, or other hypersensitivity reactions
- Use with an MAOI, or within 14 days of stopping an MAOI (risk of serious drug interactions including serotonin syndrome)
- Prolonged QT interval, congenital long QT syndrome, history suggestive of torsades de pointes, or heart failure
- Complete AV block without implanted pacemaker, or high risk of complete AV block
- Concomitant use with drugs that both prolong QT and are metabolized by CYP2D6 (e.g., thioridazine, pimozide)
Cautions
- Thrombocytopenia and other hypersensitivity reactions (quinidine)
- Hepatotoxicity (quinidine)
- Dose-dependent QTc prolongation; monitor ECG in LVH/LVD or with QT-prolonging/CYP3A4-inhibitor coadministration
- Inhibits CYP2D6 (affects CYP2D6-metabolized drugs)
- Dizziness (fall risk)
- Serotonin syndrome with SSRIs/TCAs
- Anticholinergic effects of quinidine
Adverse reactions
- Diarrhea, dizziness, cough, vomiting, asthenia, peripheral edema, urinary tract infection, influenza, increased gamma-glutamyltransferase, flatulence
Pregnancy No adequate human data; animal studies show developmental toxicity including teratogenicity (rabbits) and embryolethality; may cause fetal harm
Lactation Quinidine excreted in human milk; unknown whether dextromethorphan is excreted; no data on effects on breastfed infant
Cost
| Strength | #/mo | generic $/mo | brand $/mo | CostPlus | |
|---|---|---|---|---|---|
| 20/10 mg | cap | 30 qd | — | $799.06 | offered |
Clinical profile
Defining liabilityQT prolongation and CYP2D6-mediated interactions
Part D rank #600.
Self-check
- Which syndrome is dextromethorphan–quinidine indicated for?
Pseudobulbar affect. - Why combine quinidine with dextromethorphan?
CYP2D6 inhibition slows dextromethorphan metabolism.