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Adamantane

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Adamantane, Amantadine, Symmetrel, Rimantadine, Flumadine

  • Indications
  1. Precaution: Do not use for Influenza management as of 2011 CDC Guidelines
    1. Due to resistance, these agents are not now routinely used for Influenza treatment and prophylaxis (use Neuraminidase Inhibitors)
    2. CDC no longer recommends Amantadine or Rimantadine for Influenza management
      1. Use Neuraminidase Inhibitors instead
  2. Prior indications for Influenza A management (no longer used)
    1. Influenza Prophylaxis
      1. Given if Vaccine contraindicated
      2. Can be given concurrently with Influenza Vaccine
        1. Covers 2 week period until immunity established
    2. Influenza A Treatment
      1. Shortens course by 1 day and lessens symptoms
      2. Start within 48 hours to be effective
  3. Influenza B is not covered by these antiviral agents
    1. See Neraminidase Inhibitors: Oseltamivir (Tamiflu) or Zanamivir (Relenza)
  • Contraindications
  1. Absolute Contraindications
    1. Seizure disorder
  2. Relative Contraindications for Amantadine
    1. Age over 65 years
    2. Renal Insufficiency
  • Supplied
  1. Tablets: 100 mg
  2. Syrup: 50 mg/5cc
  • Dosing
  1. General
    1. Prophylaxis and Treatment dosages are the same
    2. Rimantadine not indicated for treatment under age 14
    3. Dose: 4.4 - 8.8 mg/kg/day divided bid for 5 days
    4. May dose qd, but causes greater Nausea and Vomiting
  2. Age 1-9 years old or weight under 40 kg
    1. Amantadine 5mg/kg/day divided bid (up to 75 mg bid)
    2. Rimantadine 5mg/kg/day divided bid (up to 75 mg bid)
  3. Age 10 to 64 years old
    1. Amantadine 100 mg PO bid
    2. Rimantadine 100 mg PO bid
  4. Age over 65 years old
    1. Rimantadine 100 mg PO qd
    2. Amantadine 100 mg PO qd (avoid if possible)
  5. Renal Insufficiency (based on Creatinine Clearance)
    1. Consider avoiding Amantadine
    2. CrCl 30-50 ml/min: Amantadine 100 mg qd
    3. CrCl 15-29 ml/min
      1. Load: Amantadine 200 mg on Day 1
      2. Next: Amantadine 100 mg every other day
    4. CrCl <15 ml/min: Amantadine 200 mg q7 days
  • Adverse Effects
  • CNS Side effects
  1. Consider split dosing especially in elderly
  2. Rimantadine causes less adverse effects than Amantadine
  3. Amantadine and Rimantadine cross blood-brain barrier
    1. Antihistamines may block drugs crossing barrier
    2. Spector (1988) J Pharmacol Exp Ther 244:516-9 [PubMed]
  4. Related Symptoms
    1. Jitteriness
    2. Anxiety
    3. Insomnia
    4. Lightheadedness
    5. Irritability
    6. Difficulty concentrating (5-10%)
  • Adverse Effects
  • Gastrointestinal
  1. Amantadine and Rimantadine result in similar GI upset
  2. Nausea or Vomiting
  3. Dyspepsia
  • Precautions
  1. Adjust dosing in Renal Insufficiency
  • Resources
  1. CDC MMWR - ACIP Guidelines on antivirals in Influenza (2011)
    1. http://www.cdc.gov/mmwr/preview/mmwrhtml/rr6001a1.htm