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Dextromethorphan/ quinidine

Generic Name: dextromethorphan/quinidine (DEX-troe-meth-OR-fan/KWIN-i-deen)
Brand Name: Nuedexta

Dextromethorphan/ quinidine is used for:

Treating pseudobulbar affect (PBA) in certain patients.

Dextromethorphan/quinidine is a CYP2D6 inhibitor and a sigma-1 receptor agonist/uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist combination. Exactly how it works to treat PBA is not known. The CYP2D6 inhibitor increases the amount of the sigma-1 receptor agonist/NMDA receptor antagonist in your body, which is the active component of dextromethorphan/quinidine.

Do NOT use dextromethorphan/ quinidine if:

  • you are allergic to any ingredient in dextromethorphan/quinidine
  • you have a history of developing a low number of clot-forming cells (platelets) in the blood, liver problems, bone marrow problems, or a lupus-like syndrome caused by dextromethorphan/quinidine, quinine, mefloquine, or quinidine
  • you have a certain type of irregular heartbeat (eg, prolonged QT interval, congenital long QT syndrome), heart failure, heart block and do not have a pacemaker, or you are at high risk of heart block
  • you have a history of a certain type of irregular heartbeat (torsades de pointes)
  • you are taking pimozide or thioridazine
  • you are taking another medicine that contains quinidine, quinine, or mefloquine, or you are taking or have taken furazolidone or a monoamine oxidase inhibitor (MAOI) (eg, phenelzine) within the last 14 days

Contact your doctor or health care provider right away if any of these apply to you.

Slideshow: View Frightful (But Dead Serious) Drug Side Effects

Before using dextromethorphan/ quinidine:

Some medical conditions may interact with dextromethorphan/quinidine. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

  • if you are pregnant, planning to become pregnant, or are breast-feeding
  • if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
  • if you have allergies to medicines, foods, or other substances
  • if you have a history of liver or kidney disease; congestive heart failure, heart block, QT prolongation, or other heart problems (eg, coronary artery disease, left ventricular hypertrophy); high or low blood pressure; low number of blood platelets; falling; or a stroke
  • if you have Alzheimer disease or another type of dementia, low blood electrolyte levels (eg, magnesium, potassium), slow heartbeat, trouble walking, myasthenia gravis, or a family history of a certain type of irregular heartbeat (eg, QT abnormality)

Some MEDICINES MAY INTERACT with dextromethorphan/quinidine. Tell your health care provider if you are taking any other medicines, especially any of the following:

  • Amiloride, antiarrhythmics (eg, amiodarone, dofetilide, flecainide, propafenone), aprepitant, arsenic, astemizole, azole antifungals (eg, fluconazole, itraconazole, ketoconazole), bepridil, carbonic anhydrase inhibitors (eg, acetazolamide), chloroquine, cimetidine, cisapride, diltiazem, domperidone, droperidol, fingolimod, haloperidol, histone deacetylase inhibitors (eg, romidepsin), HIV protease inhibitors (eg, ritonavir), iloperidone, lithium, macrolide antibiotics (eg, clarithromycin, erythromycin), maprotiline, methadone, nefazodone, pentamidine, phenothiazines (eg, chlorpromazine, thioridazine), thiazide diuretics (eg, hydrochlorothiazide), phosphodiesterase type 5 inhibitors (eg, sildenafil), pimozide, quinolones (eg, levofloxacin), serotonin receptor antagonists (eg, dolasetron), streptogramins (eg, pristinamycin), telithromycin, terfenadine, tetrabenazine, tyrosine kinase inhibitors (eg, nilotinib), verapamil, or ziprasidone because the risk of side effects, including irregular heartbeat, may be increased
  • Furazolidone, MAOIs (eg, phenelzine), selective serotonin reuptake inhibitors (SSRIs) (eg, fluoxetine), serotonin-norepinephrine reuptake inhibitors (SNRIs) (eg, venlafaxine), or tricyclic antidepressants (eg, clomipramine, imipramine) because severe side effects, such as a reaction that may include fever, rigid muscles, blood pressure changes, mental changes, confusion, irritability, agitation, delirium, and coma, may occur
  • Aripiprazole, beta-blockers (eg, metoprolol), desipramine, digitoxin, digoxin, norepinephrine reuptake inhibitors (eg, atomoxetine), or paroxetine, because their actions or risk of their side effects may be increased by dextromethorphan/quinidine
  • Codeine, hydrocodone, or tamoxifen because their effectiveness may be decreased by dextromethorphan/quinidine

This may not be a complete list of all interactions that may occur. Ask your health care provider if dextromethorphan/quinidine may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

How to use dextromethorphan/ quinidine:

Use dextromethorphan/quinidine as directed by your doctor. Check the label on the medicine for exact dosing instructions.

  • Eating grapefruit or drinking grapefruit juice may affect the amount of dextromethorphan/quinidine in your blood. Talk with your doctor before including grapefruit or grapefruit juice in your diet.
  • If you miss a dose of dextromethorphan/quinidine, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Ask your health care provider any questions you may have about how to use dextromethorphan/quinidine.

Important safety information:

  • Dextromethorphan/quinidine may cause dizziness, drowsiness, or blurred vision. These effects may be worse if you take it with alcohol or certain medicines. Use dextromethorphan/quinidine with caution. Do not drive or perform other possibly unsafe tasks until you know how you react to it.
  • Check with your doctor before you drink alcohol or use medicines that may cause drowsiness (eg, sleep aids, muscle relaxers) while you are using dextromethorphan/quinidine; it may add to their effects. Ask your pharmacist if you have questions about which medicines may cause drowsiness.
  • Dextromethorphan/quinidine may cause dizziness, lightheadedness, or fainting; alcohol, hot weather, exercise, or fever may increase these effects. To prevent them, sit up or stand slowly, especially in the morning. Sit or lie down at the first sign of any of these effects.
  • Dextromethorphan/quinidine may reduce the number of clot-forming cells (platelets) in your blood. Avoid activities that may cause bruising or injury. Tell your doctor if you have unusual bruising or bleeding. Tell your doctor if you have dark, tarry, or bloody stools.
  • Serotonin syndrome is a possibly fatal syndrome that can be caused by dextromethorphan/quinidine. Your risk may be greater if you take dextromethorphan/quinidine with certain other medicines (eg, SSRIs, tricyclic antidepressants). Symptoms may include excessive sweating, fast or irregular heartbeat, fever, mood or mental changes (eg, agitation, confusion, hallucinations), restlessness, shivering, severe or persistent headache or dizziness, tremor, or uncontrolled movements. Contact your doctor at once if you have any of these symptoms.
  • Tell your doctor or dentist that you take dextromethorphan/quinidine before you receive any medical or dental care, emergency care, or surgery.
  • Dextromethorphan/quinidine should be used with extreme caution in CHILDREN younger than 18 years old; safety and effectiveness in these children have not been confirmed.
  • PREGNANCY and BREAST-FEEDING: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using dextromethorphan/quinidine while you are pregnant. It is not known if dextromethorphan/quinidine is found in breast milk. If you are or will be breast-feeding while you use dextromethorphan/quinidine, check with your doctor. Discuss any possible risks to your baby.

Possible side effects of dextromethorphan/ quinidine:

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Cough; diarrhea; dizziness; drowsiness; gas; mild stomach pain; nausea; vomiting.

Seek medical attention right away if any of these SEVERE side effects occur:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); confusion; dark, tarry, or bloody stools; dark urine; difficult, increased, or painful urination; discoloration of the skin; fainting; fast, slow, or irregular heartbeat; fever or chills; flu-like symptoms; headache; hearing changes or loss of hearing; joint pain; loss of appetite; loss of consciousness; mood or mental changes (eg, depression, nervousness); muscle spasms; pale stools; restlessness; rigid muscles; ringing in ears; severe or persistent dizziness, drowsiness, or lightheadedness; severe or persistent nausea, vomiting, or stomach pain; shortness of breath; swelling of the hands, ankles, or feet; unusual bleeding or bruising; vision changes (eg, blurred vision, double vision); weakness; yellowing of the skin or eyes.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

If OVERDOSE is suspected:

Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately. Symptoms may include coma; confusion; decreased coordination; fainting; fast, slow, or irregular heartbeat; headache; hearing loss; mental or mood changes; ringing in the ears; seizures; severe or persistent diarrhea, nausea, or vomiting; severe or persistent dizziness; trouble breathing; uncontrolled muscle or eye movements; vision changes (eg, blurred vision, double vision).

Proper storage of dextromethorphan/quinidine:

Store dextromethorphan/quinidine at 77 degrees F (25 degrees C). Brief storage at temperatures between 59 and 86 degrees F (15 and 30 degrees C) is permitted. Store away from heat, moisture, and light. Do not store in the bathroom. Keep dextromethorphan/quinidine out of the reach of children and away from pets.

General information:

  • If you have any questions about dextromethorphan/quinidine, please talk with your doctor, pharmacist, or other health care provider.
  • Dextromethorphan/quinidine is to be used only by the patient for whom it is prescribed. Do not share it with other people.
  • If your symptoms do not improve or if they become worse, check with your doctor.
  • Check with your pharmacist about how to dispose of unused medicine.

This information should not be used to decide whether or not to take dextromethorphan/quinidine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about dextromethorphan/quinidine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to dextromethorphan/quinidine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using dextromethorphan/quinidine.

Issue Date: July 2, 2014
Database Edition 14.3.1.001
Copyright © 2014 Wolters Kluwer Health, Inc.

Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using this medicine.

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