Dextromethorphan and quinidine

Dextromethorphan and quinidine is a combination medicine that helps treat sudden outbursts of crying or laughing in people with specific neurological disorders, such as multiple sclerosis and amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease).

Dextromethorphan and quinidine may also be used for reasons not mentioned in this medication guide.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Dextromethorphan and quinidine is usually taken once per day for 7 days, and then once every 12 hours. Follow your doctor's dosing instructions very carefully.

You may take dextromethorphan and quinidine with or without food.

Your doctor will need to check your progress regularly. You may need medical tests to help your doctor decide how long to treat you with dextromethorphan and quinidine.

Store at room temperature away from moisture and heat.

You should not use this medicine if you have heart failure, a serious heart condition called "AV block" (unless you have a pacemaker), or a life-threatening heart rhythm disorder.

You also should not take dextromethorphan and quinidine if you are also taking mefloquine, quinidine, or quinine, or if you have ever had an allergic reaction or serious medical problem caused by taking any of these medications.

Tell your doctor about all your current medicines and any you start or stop using. Many drugs can interact, and some drugs should not be used together.

You should not take dextromethorphan and quinidine if you are allergic to dextromethorphan or quinidine, or if you have:

• heart failure;
• a history of life-threatening heart rhythm disorder;
• long QT syndrome (in you or a family member);
• a serious heart condition called "AV block" (unless you have a pacemaker); or
• if you also use mefloquine, quinidine, or quinine.

You also should not take dextromethorphan and quinidine if you have ever had any of the following problems caused by taking mefloquine, quinidine, or quinine:

• bruising or bleeding;
• hepatitis;
• an allergic reaction; or
• lupus-like symptoms (joint pain, fever, skin rash on your cheeks).

Do not use dextromethorphan and quinidine if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others. After you stop taking dextromethorphan and quinidine, you must wait at least 14 days before you start taking an MAOI.

Dextromethorphan and quinidine can cause a serious heart problem. You should not take dextromethorphan and quinidine if you also use certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria, or HIV.

Be sure your doctor knows if you also take stimulant medicine, opioid medicine, herbal products, or medicine for depression, mental illness, Parkinson's disease, migraine headaches, serious infections, or prevention of nausea and vomiting. These medicines may interact with dextromethorphan and quinidine and cause a serious condition called serotonin syndrome.

Tell your doctor if you have ever had:

• heart disease, high blood pressure, coronary artery disease;
• slow heartbeats or any type of heart rhythm disorder;
• an electrolyte imbalance (such as low levels of potassium or magnesium in your blood);
• myasthenia gravis; or
• trouble with balance or walking.

Tell your doctor if you are pregnant or breastfeeding.

Dextromethorphan and quinidine is not approved for use by anyone younger than 18 years old.

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

dextromethorphan and quinidine may cause serious side effects. Stop using dextromethorphan and quinidine and call your doctor immediately if you experience:

• fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness (feeling like you might faint);
• easy bruising or bleeding (such as nosebleeds or bleeding gums);
• pain or burning when you urinate;
• liver problems—fever, pain in the upper right side of your stomach, vomiting, loss of appetite, yellowing of your skin or eyes, and feeling unwell; or
• lupus-like symptoms—muscle or joint pain, flu-like symptoms, chest pain, and a rash or changes in skin color that worsen in sunlight.

Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, rapid heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.

Common side effects of dextromethorphan and quinidine may include:

• dizziness, weakness;
• diarrhea, gas, vomiting;
• swelling in your hands or feet;
• flu-like symptoms, cough; or
• abnormal liver function tests.

This is not a complete list of side effects, and others may occur. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Usual Adult Dose for Pseudobulbar Affect:

Initial dose (Days 1 to 7): Dextromethorphan 20 mg-quinidine 10 mg orally once a dayMaintenance dose (Day 8 and thereafter): Dextromethorphan 20 mg-quinidine 10 mg orally every 12 hoursMaximum dose: Dextromethorphan 40 mg-quinidine 20 mg/dayComments:-The need for continued treatment should be reassessed periodically as spontaneous improvement of pseudobulbar affect (PBA) occurs in some patients.Use: For the treatment of PBA

Take the medicine as soon as you can, but if it is almost time for your next dose, skip the missed dose. Do not take two doses at once.

Do not take more than 2 capsules in a 24-hour period.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose can cause severe dizziness, confusion, double vision, ringing in your ears, hearing loss, vomiting, fast or irregular heart rate, weak or shallow breathing, or seizure (convulsions).

Avoid driving or hazardous activity until you know how dextromethorphan and quinidine will affect you. Your reactions could be impaired. Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Dizziness can cause falls, accidents, or severe injuries.

Grapefruit may interact with dextromethorphan and quinidine and lead to unwanted side effects. Avoid the use of grapefruit products.

Ask a doctor or pharmacist before using any cough or cold medication that may contain dextromethorphan. Taking certain products together can cause you to get too much dextromethorphan. Check the label of medicines such as Delsym, Robitussin Maximum Strength, Vicks 44, and others.

Sometimes it is not safe to use certain medications together. Some drugs can change the levels of other drugs in your blood, which may increase side effects or make the medications less effective.

Dextromethorphan and quinidine can cause a serious heart problem. Your risk may be higher if you also take certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria, or HIV.

Many drugs can affect dextromethorphan and quinidine, and some drugs should not be used at the same time. Tell your doctor about all your current medicines and any medicine you start or stop using. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.