Dextromethorphan-quinidine

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

Stop using this medicine and call your doctor at once if you have:

• headache with chest pain and severe dizziness or fainting;
• fast or pounding heartbeats, fluttering in your chest;
• easy bruising or bleeding (nosebleeds, bleeding gums);
• pain or burning when you urinate;
• lupus-like symptoms--joint pain or swelling with fever, headaches, confusion, chest pain, shortness of breath, skin sores, butterfly-shaped skin rash on your cheeks and nose, and numbness, cold feeling, or pale appearance of your fingers or toes;
• liver problems--nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or
• high levels of serotonin in the body--agitation, hallucinations, fever, fast heart rate, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination, fainting.

Common side effects may include:

• diarrhea, gas, vomiting;
• swelling in your hands or feet;
• dizziness, weakness; or
• flu symptoms, cough.

Side effects such as dry mouth, constipation, and confusion may be more likely in older adults.

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 FDA at 1-800-FDA-1088.

This medication may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert. Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall.

Grapefruit and grapefruit juice may interact with dextromethorphan and quinidine and lead to unwanted side effects. Discuss the use of grapefruit products with your doctor.

Ask a doctor or pharmacist before using any cough or cold medication. Dextromethorphan is contained in many combination medicines. Taking certain products together can cause you to get too much dextromethorphan. Check the label to see if a medicine contains dextromethorphan (Delsym, Robitussin Maximum Strength, Vicks 44, and others).

Many drugs can interact with dextromethorphan and quinidine. Not all possible interactions are listed here. Tell your doctor about all your medications and any you start or stop using during treatment with dextromethorphan and quinidine, especially:

• aprepitant;
• an antibiotic--azithromycin, clarithromycin, erythromycin, pentamidine, telithromycin;
• antifungal medicine--fluconazole, itraconazole, ketoconazole;
• anti-malaria medication--chloroquine, halofantrine;
• cancer medicine--arsenic trioxide, vandetanib;
• HIV or AIDS medicines--atazanavir, fosamprenavir, indinavir, nelfinavir, ritonavir, saquinavir,
• medicine to treat depression or mental illness--citalopram, escitalopram, nefazodone, pimozide, ziprasidone; or
• heart or blood pressure medication--diltiazem, disopyramide, dofetilide, ibutilide, sotalol, verapamil.

This list is not complete and many other drugs can interact with dextromethorphan and quinidine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Give a list of all your medicines to any healthcare provider who treats you.

Dosage Forms & Strengths

dextromethorphan/quinidine

capsule

• 20mg/10mg

Pseudobulbar Affect

Indicated for PBA and symptoms associated with a variety of neurological conditions (eg, MS, ALS) that result in involuntary, sudden, and frequent episodes of laughing and/or crying

PBA occurs secondary to a variety of otherwise unrelated neurologic conditions, and is characterized by involuntary, sudden, and frequent episodes of laughing and/or crying; episodes typically occur out of proportion or incongruent to the underlying emotional state

PBA is a specific condition, distinct from other types of emotional lability that may occur in patients with neurological disease or injury

1 capsule PO qDay for 7days, THEN 1 capsule q12h

Dosage Modifications

Renal impairment

• Mild or moderate: No dose adjustment required
• Severe: Safety and effaicacy not established

Hepatic impairment

• Mild or moderate: No dosage adjustment required; increase in adverse reactions possible with moderate impairment
• Severe: Safety and efficacy not established

Amyotrophic Lateral Sclerosis (Orphan)

Orphan designation for treatment of amyotrophic lateral sclerosis (ALS)

Sponsor

• Avanir Pharmaceuticals; 30 Enterprise, Suite 400; Aliso Viejo, California 92656

Safety and efficacy not established

Pregnancy Category: C

Lactation: unknown whether distributed in breast milk, caution advised

Pregnancy Categories

A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA:Information not available.

CYP2D6 is a protein in your body that is involved in the elimination of dextromethorphan/quinidine and other drugs from your body. Some patients have less of this protein in their bodies, affecting how much of the drug gets eliminated. Levels of CYP2D6 can vary greatly between individuals, and those having less of this protein are known as "poor metabolizers." 

CYP2D6 testing is done to determine whether you are a poor metabolizer. If you are a poor metabolizer, the levels of dextromethorphan/quinidine in your blood can become too high. As a result you may be at an increased risk of having more side effects from dextromethorphan/quinidine. 

Your doctor should use caution in treating you with dextromethorphan/quinidine or your doctor may adjust your dose if you are a poor metabolizer.

Tell your doctor if you are breastfeeding or plan to breastfeed.

It is not known if dextromethorphan/quinidine crosses into human milk. Because many medications can cross into human milk and because of the possibility for serious adverse reactions in nursing infants with use of this medication, a choice should be made whether to stop nursing or stop the use of this medication. Your doctor and you will decide if the benefits outweigh the risk of using this medication.

If you take too much of this medication, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away. 

The most important effects if acute quinidine overdose:

• changes in heartbeat
• low blood pressure
• vomiting
• diarrhea
• ringing in the ears
• dizziness/ fainting
• blurred or double vision
• headache
• confusion
• delirium

• nausea
• vomiting
• loss of consciousness
• difficulty breathing
• seizures
• unusual excitement
• abornmal thinking
• changes in muscle reflexes
• changes in heartbeat