Amantadine is a dopaminergic medication whose exact mechanism of action is not known.
On this page, we present some basic information about this medication. Other articles on this website with more advanced information and tips related to this medication are linked to under Related Pages below.
1. Treatment of Parkinson’s disease, parkinsonism due to other causes, and drug-induced extrapyramidal reactions.
2. Treatment of influenza type A.
In mental health, it has many other potential off-label uses.
Here are just a few clinically relevant things to know about the pharmacology of amantadine:
– The half-life is about 15 hours.
– It is largely excreted unchanged in the urine.
– Its excretion is increased when the urine is acidic (Note: this is the same as what happens with amphetamines)
Potential drug interactions
If amantadine and an anticholinergic are used together, significant anticholinergic side effects can occur, including CNS toxicity (confusion, hallucinations, nightmares).
Hydrochlorothiazide-triamterene combination (brand name Dyazide; fairly commonly used) decreases excretion of amantadine and CNS toxicity can occur (confusion, hallucinations, ataxia, myoclonus).
History of seizures: because an increased frequency of seizures has been reported after the addition of amantadine.
Congestive heart failure (CHF): because amantadine can cause peripheral edema due to local vascular effects.
Common side effects
Side effects that occur in more than 5% of patients are:
(Maybe “NIL” could be a mnemonic for these?)
Less common side effects
Side effects reported by 1% to 5% of patients may include:
– Depression, anxiety, nervousness irritability, agitation, abnormal dreams, somnolence.
– Hallucinations, confusion
– Headache, ataxia
– Anorexia, dry mouth, constipation, diarrhea
– Livedo reticularis, peripheral edema, orthostatic hypotension, dry nose, fatigue.
Dose (for antipsychotic-induced parkinsonism)
Usually, we start with 100 mg twice daily. If the symptoms are mild, we may even start with 100 mg once a day.
After at least 5 to 7 days, if symptoms are not adequately controlled, we can consider increasing the dose to 100 mg three times a day.
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