- Flu Slideshow: 10 Foods to Eat When You Have the Flu
- Natural Cold & Flu Remedies Slideshow
- Take the Cold & Flu Quiz
- What is amantadine, and how does it work (mechanism of action)?
- Is amantadine available as a generic drug?
- Do I need a prescription for amantadine?
- What are the side effects of amantadine?
- What is the dosage for amantadine?
- Which drugs or supplements interact with amantadine?
- Is amantadine safe to take if I'm pregnant or breastfeeding?
- What else should I know about amantadine?
What is amantadine, and how does it work (mechanism of action)?
Amantadine is a synthetic (man-made) anti-viral drug that can inhibit the replication of viruses in cells. To prevent a viral infection, the drug should be present before exposure to the virus. Clearly, this is not practical for most viral infections. It was initially used to prevent influenza A during flu season, and, if given within 24 to 48 hours of the onset of flu symptoms, to decrease the severity of the flu. Later amantadine was found to cause improvement in the symptoms of Parkinson's disease. Amantadine's mechanism of action in Parkinson's disease is not fully understood. Its effects may be related to its ability to augment (amplify) the effects of dopamine, a neurotransmitter in the brain, that is reduced in Parkinson's disease. Amantadine is less effective than levodopa in Parkinson's disease but can offer additional benefit when taken with levodopa. Amantadine was approved by the FDA in 1966.
What are the side effects of amantadine?
The most frequent side effects associated with amantadine that can appear after a few hours or several days of therapy include:
Less common side effects include:
What is the dosage for amantadine?
Amantadine is taken once or twice daily with or without food. If it causes an upset stomach, it can be taken with food. The dosage for prevention and treatment of influenza A infections in adults is 200 mg daily. For treatment of influenza, amantadine should be started within 24 to 48 hours after the onset of signs or symptoms and should be continued for 24 to 48 hours after the disappearance of signs or symptoms. To prevent influenza, amantadine should be started as soon as possible after exposure to the influenza virus and continued for at least 10 days. Persons with reduced kidney function and elderly persons may need lower doses (or less frequent doses).
The dosage for treating Parkinson's or extrapyramidal symptoms is 100 mg twice daily.
Which drugs or supplements interact with amantadine?
- The benzodiazepine class of anti-anxiety drugs, for example:
- The tricyclic class of antidepressants, for example:
- dicyclomine (Bentyl)
- Certain antihistamines, for example:
- Opiate agonists, for example:
- Certain antihypertensive medications, for example:
Since amantadine amplifies the actions of dopamine in the brain, drugs which block the effects of dopamine should be avoided in persons taking amantadine when amantadine is used for the treatment of Parkinson's disease. Such drugs include haloperidol (Haldol), metoclopramide (Reglan), and phenothiazines, for example, thioridazine (Mellaril) or triflupromazine (Stelazine).
The use of the diuretics hydrochlorothiazide or triamterene (Dyazide; Maxzide) with amantadine can reduce the kidney's ability to eliminate amantadine. This can lead to high levels of amantadine in the blood and amantadine-associated toxicity.
Is amantadine safe to take if I'm pregnant or breastfeeding?
No well-controlled studies have been done in pregnant women to evaluate amantadine's safety. Physicians may choose to use amantadine during pregnancy when the potential benefits outweigh the potential but unknown risks to the fetus.
Amantadine is excreted into breast milk in low concentrations. Although no information is available on the effects in infants, the manufacturer recommends that amantadine be used cautiously in women who are breastfeeding.
Multimedia: Slideshows, Images & Quizzes
Related Disease Conditions
Influenza (flu) is a respiratory illness caused by a virus. Flu symptoms include fever, cough, sore throat, runny nose, headache,...
Parkinson's disease is a slowly progressive neurological disease characterized by a fixed inexpressive face, a tremor at rest,...
Post-polio syndrome (PPS) is a group of signs and symptoms that show up two to four decades after the initial polio infection....
Bird Flu (Avian Influenza, Avian Flu)
Bird flu (avian flu, avian influenza) infection in humans may result from contact with infected poultry. There is a vaccine to...
Fragile X Syndrome
Fragile X syndrome is the most common inherited form of mental retardation. It's caused by a mutation on the X chromosome. People...
Multiple Sclerosis Early Symptoms and Signs (Early, Body Areas Affected)
Multiple sclerosis (MS) symptoms vary from person to person, and can last for days to months without periods of remission....
Treatment & Diagnosis
- Parkinsons Disease FAQs
- Medication Disposal
- Dangers of Mixing Medications
- How To Reduce Your Medication Costs
- Pharmacy Visit, How To Get The Most Out of Your Visit
- Indications for Drugs: Approved vs. Non-approved
- Drugs: Buying Prescription Drugs Online Safely
- Drugs: The Most Common Medication Errors
- Flu: What to Do if You Get the Flu
- Generic Drugs, Are They as Good as Brand-Names?
Medications & Supplements
Prevention & Wellness
Cold and Flu Resources
Health Solutions From Our Sponsors
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.