The combination of dextromethorphan and quinidine is used to treat pseudobulbar affect (PBA; a condition of sudden, frequent outbursts of crying or laughing that can not be controlled) in people with certain conditions such as amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease; condition in which the nerves that control muscle movement slowly die, causing the muscles to shrink and weaken) or multiple sclerosis (a disease in which the nerves do not function properly and patients may experience weakness, numbness, loss of muscle coordination and problems with vision, speech, and bladder control). Dextromethorphan is in a class of medications called central nervous system agents. The way it works in the brain to treat PBA is not known. Quinidine is in a class of medications called antiarrhythmics. When combined with dextromethorphan, quinidine works by increasing the amount of dextromethorphan in the body.
The combination of dextromethorphan and quinidine comes as a capsule to take by mouth. It is usually taken with or without food once a day for 7 days. After 7 days, it is taken every 12 hours. Do not take more than 2 doses in a 24-hour period. Be sure to allow about 12 hours between each dose. Take dextromethorphan and quinidine at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take the combination of dextromethorphan and quinidine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Your doctor may check from time to time to see if this medication is still needed to control your symptoms. Follow these directions carefully.
This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.
Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medication.
Unless your doctor tells you otherwise, continue your normal diet.
Skip the missed dose and take the next dose at the regular time. Do not take a double dose to make up for a missed one. Be sure to allow 12 hours between doses.
dry eyes or mouth
swelling of the hands, feet, ankles, or lower legs
frequent, painful, or difficult urination
cloudy or strong-smelling urine
unusual bleeding or bruising
muscle or joint pain
swelling of the face, throat, tongue, or lips
swollen lymph nodes
fast heart beat
The combination of dextromethorphan and quinidine may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.
If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at http://www.fda.gov/Safety/MedWatch] or by phone [1-800-332-1088].
Keep this medication in the container it came in, tightly closed, and out of reach of children and pets. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.
In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.
ringing in the ears
blurred or double vision
changes in heart beat
loss of consciousness
changes in muscle reflexes
loss of coordination
Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your body's response to dextromethorphan and quinidine. Your doctor may also order an electrocardiogram (ECG; test that measures the electrical activity in the heart) before and during your treatment.
Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.
It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.
Last Revised - 10/15/2011
AHFS® Consumer Medication Information. © Copyright, 2014. The American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.