Amantadine
SYMMETREL
What it isNMDA antagonist with additional uncertain actions; Parkinson disease and levodopa-induced dyskinesia.
Why this oneIt is the only oral drug specifically used to reduce levodopa-induced dyskinesia.
What limits itRenal accumulation causes confusion and hallucinations, especially in older adults. Livedo reticularis and edema occur; avoid abrupt withdrawal.
FDA-approved for
- influenza A (1966)
- Parkinson disease (1973)
- levodopa dyskinesia (ER) (2017)
Off-label
- MS fatigue
- SSRI sexual dysfunction
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Influenza A prophylaxis/treatment | Adult | 200 mg/day (QD or 100 mg BID) | 200 mg/day | 200 mg/day |
| Influenza A prophylaxis/treatment | ≥65 yr | 100 mg QD | 100 mg QD | 100 mg QD |
| Influenza A prophylaxis/treatment | Peds 1–9 yr | 4.4–8.8 mg/kg/day divided | — | 150 mg/day |
| Influenza A prophylaxis/treatment | Peds 9–12 yr | 100 mg BID | — | 200 mg/day |
| Parkinsonism | Adult | 100 mg BID (100 mg QD if serious illness/other antiparkinson drugs) | 200 mg/day | 400 mg/day divided |
| Drug-induced extrapyramidal reactions | Adult | 100 mg BID | 200 mg/day | 300 mg/day divided |
Titration Parkinsonism: after 1 to several weeks at 100 mg QD, may increase to 100 mg BID.
Renal CrCl 30–50: 200 mg day 1 then 100 mg QD; CrCl 15–29: 200 mg day 1 then 100 mg every other day; CrCl <15 or hemodialysis: 200 mg every 7 days.
Hepatic Undefined
Instructions
- Reduce dose in CHF, peripheral edema, orthostatic hypotension, or impaired renal function.
- Avoid abrupt discontinuation (may precipitate delirium, agitation, hallucinations, paranoid reaction).
Cautions
- CNS effects (dizziness, insomnia, confusion, hallucinations)
- Depression/suicidality reported
- CHF, peripheral edema, orthostatic hypotension
- Neuroleptic malignant syndrome, including with abrupt dose reduction/withdrawal
Adverse reactions
- Nausea
- Dizziness / lightheadedness
- Insomnia
- Depression, anxiety, irritability
- Hallucinations, confusion
- Orthostatic hypotension
- Livedo reticularis
- Peripheral edema
Pregnancy Animal embryotoxicity/teratogenicity; scarce human data with reported malformations—use only if benefit justifies risk.
Lactation Undefined
NO BOXED WARNINGS
Principal riskLivedo reticularis; confusion in renal impairment
Cost, est. cash$10–$500/month
Generic entry1986
Classes and tags
Clinical profile
Legacy pregnancy categoryUnknown / historical label unavailable
Defining liabilityOrthostasis, hallucinations, dyskinesia and impulse-control symptoms; abrupt withdrawal can be hazardous.
Mechanism of action: Amantadine ballicule
Open Amantadine in the interactive console ↗
Memory aids: mascots and interaction avatars
