- Neurologic
-
Parkinsonism
- Second-line agent (less effective than Levodopa), but more effective than AnticholinergicParkinsonism agents
- Levodopa-Associated Dyskinesia in Parkinsonism
- Extrapyramidal Side Effect
- Influenza (Listed for historical reasons only)
- Precautions: Do not use for Influenza management as of 2011 CDC Guidelines
- Due to resistance, these agents are not now routinely used for Influenza treatment and prophylaxis (use Neuraminidase Inhibitors)
- CDC no longer recommends Amantadine or Rimantadine for Influenza prophylaxis or treatment
- Use Neuraminidase Inhibitors instead
- Prior indications for Influenza A management (no longer used)
- Influenza Prophylaxis
- Given if Vaccine contraindicated
- Can be given concurrently with Influenza Vaccine
- Covers 2 week period until Immunity established
- Influenza A Treatment
- Shortens course by 1 day and lessens symptoms
- Start within 48 hours to be effective
- Influenza Prophylaxis
-
Influenza B is not covered by these Antiviral Agents
- See Neraminidase Inhibitors: Oseltamivir (Tamiflu) or Zanamivir (Relenza)
- Absolute Contraindications
- Relative Contraindications for Amantadine
- Age over 65 years
- Renal Insufficiency
- Antiviral Agent derived from Adamantane (a diamond-like molecule originally discovered in petroleum)
- Releases Dopamine from intact nerve terminals
- Weak non-competitive NMDA receptor Antagonist
- Tablets: 100 mg
- Syrup: 50 mg/5cc
- Neurologic
- Renal Dosing adjustment needed for GFR <60 ml/min
- Amantadine Immediate Release Tablets (for Parkinsonism, Extrapyramidal Side Effects)
- Start 100 mg orally twice daily
- Titrate to 300 to 400 mg/day orally divided three to four times daily
- Amandatine Extended Release
- Osmolex ER (for Parkinsonism with Extrapyramidal Side Effects)
- Start 129 mg orally daily in morning
- May increase dose on a weekly basis as needed to maximum dose 322 mg/day
- Gocovri (for Levodopa-Associated Dyskinesia in Parkinsonism)
- Start 137 mg orally at bedtime
- May increase dose to 274 mg orally daily after one week
- Osmolex ER (for Parkinsonism with Extrapyramidal Side Effects)
- Influenza (Historical)
-
General
- CDC no longer recommends Amantadine or Rimantadine for Influenza prophylaxis or treatment
- Prophylaxis and Treatment dosages are the same
- Dose: 4.4 - 8.8 mg/kg/day divided bid for 5 days
- May dose daily, but causes greater Nausea and Vomiting
- Age 1-9 years old or weight under 40 kg
- Amantadine 5mg/kg/day orally divided twice daily (up to 75 mg twice daily )
- Age 10 to 64 years old
- Amantadine 100 mg orally twice daily
- Age over 65 years old
- Amantadine 100 mg orally daily (avoid if possible)
- Renal Insufficiency (based on Creatinine Clearance)
- Consider split dosing especially in elderly
- Rimantadine causes less adverse effects than Amantadine
- QTc Prolongation (risk of Torsades de Pointes) in the elderly
- Amantadine and Rimantadine cross blood-brain barrier
- Antihistamines may block drugs crossing barrier
- Spector (1988) J Pharmacol Exp Ther 244:516-9 [PubMed]
- Related Symptoms
- Jitteriness
- Anxiety
- Insomnia
- Anticholinergic effects (Dry Mouth)
- Orthostatic Hypotension or Lightheadedness
- Irritability
- Difficulty concentrating (5-10%)
- Suicidality
- Hallucinations, Confusion or Nightmares at high dose (severe Psychosis may occur in the elderly)
- Abrupt medication stoppage may precipitate withdrawal, Delirium and risk of Neuroleptic Malignant Syndrome
- Gastrointestinal
- Amantadine and Rimantadine result in similar GI upset
- Nausea or Vomiting
- Dyspepsia
- Constipation
- Pregnancy Category C
- Unknown safety in Lactation
- Anticholinergic Agents (increased Anticholinergic effects)
-
Prolonged QT Interval due to Medication
- Avoid combining Amantadine with other agents that prolong QTc
- Agents that alkalinize the urine (e.g. carbonic anhydrase inhibitors)
- Increase Amantadine levels
-
Alcohol
- May increase Amantadine related CNS effects
- Adjust dosing in Renal Insufficiency if GFR <60 ml/min
- Unknown safety in pregnancy and Lactation
- (2021) Med Lett Drugs Ther 63(1618): 25-32
- Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 46-7
- Hamilton (2020) Tarascon Pocket Pharmacopoeia