Examples
| Brand Name | Chemical Name |
| Symadine, Symmetrel | amantadine hydrochloride |
| Flumadine | rimantadine hydrochloride |
How It Works
These antiviral medications prevent the spread of type A influenza by interfering with the production of the virus inside the body. They do not treat or protect you against influenza B.
Why It Is Used
These antiviral medications reduce the severity of influenza (flu) symptoms and shorten the course of the illness of influenza A.1 They need to be started within 48 hours of the first symptoms and continued, usually, for 7 days.
For the past few years, the U.S. Centers for Disease Control and Prevention (CDC) has advised doctors not to use amantadine (Symadine or Symmetrel) or rimantadine (Flumadine) to treat or prevent the flu. These medicines have not worked against most types of the flu virus. Talk to your doctor about the medicine that is best to use for the current type of flu.
When used to protect people during a flu outbreak, antiviral medications usually are used for 7 days but may be continued for 5 to 7 weeks.
How Well It Works
In healthy young adults and children, antiviral medications are 70% to 90% effective in preventing influenza A during an outbreak.2 However, these antiviral medicines do not always treat or prevent the flu.3
When given within 48 hours after symptoms begin, they may reduce symptoms, shorten the length of influenza A illness by 1 or 2 days, and allow for a faster return to usual activities.
Side Effects
In one study, approximately 13% of healthy adults taking amantadine and 6% of those taking rimantadine reported minor side effects, which can include:2
- Sleeplessness (insomnia), dizziness, headache, nervousness, or an inability to concentrate. These side effects occur less often with rimantadine than amantadine. They are more common in people who are also taking antihistamines.
- Nausea, vomiting, loss of appetite (1% to 3%).
More serious but less frequent side effects (seizures, confusion) have been reported in older adults and, most commonly, in adults who have seizure disorders. Lowering the dose reduces these side effects without reducing the effectiveness of the medication.
Side effects decrease after about 1 week of use and reverse as soon as treatment stops.
See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
What To Think About
Amantadine and rimantadine are effective only against some type A influenza viruses.
Amantadine usually should not be taken at the same time as antihistamines or other medications that stimulate the central nervous system. These may increase the risk of side effects such as insomnia, anxiety and, at high doses, seizures.
Amantadine is removed from the body by the kidneys; rimantadine by the liver. This difference may have an impact on which medication is used to treat people who have diseases affecting the kidneys or liver. Because side effects occur less often with rimantadine, it may be a better choice. However, rimantadine costs more than amantadine.
Little information exists regarding the effectiveness of antiviral medications in treating children who have influenza A.
- Amantadine is used to prevent and treat type A influenza in adults and in children older than age 1.
- Rimantadine is used to prevent and treat type A influenza in adults. However, in children, it is used only to prevent influenza A.
Antiviral medications may prevent complications of type A influenza illness in high-risk people; the evidence is not conclusive.4
Antiviral medications may need to be given only once a day in older adults.
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References
Citations
Hansen L (2003). Influenza. Clinical Evidence (10): 867–874.
Centers for Disease Control and Prevention (2004). Prevention and control of influenza: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR, 53(RR-6): 1–44. Also available online: http://www.cdc.gov/mmwr/PDF/RR/RR5306.pdf. [Erratum: (2004). MMWR, 53(RR-6): 743. Also available online: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5332a8.htm.]
Centers for Disease Control and Prevention (2006). CDC Health Alert: CDC Recommends Against the Use of Amantadine and Rimantadine for the Treatment or Prophylaxis of Influenza in the United States During the 2005–06 Influenza Season. Available online: http://www.cdc.gov/flu/han011406.htm.
Uyeki T, Winquist A (2001). Influenza. Clinical Evidence (6): 550–556.
Credits
| Author | Sydney Youngerman-Cole, RN, BSN, RNC |
| Editor | Susan Van Houten, RN, BSN, MBA |
| Associate Editor | Tracy Landauer |
| Associate Editor | Terrina Vail |
| Primary Medical Reviewer | Adam Husney, MD - Family Medicine |
| Specialist Medical Reviewer | W. David Colby IV, MSc, MD, FRCPC - Infectious Disease |
| Last Updated | September 29, 2006 |
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