Amantril Capsule

The mechanism by which amantadine exerts its antiviral activity is not clearly understood. It appears to mainly prevent the release of infectious viral nucleic acid into the host cell by interfering with the function of the transmembrane domain of the viral M2 protein. In certain cases, amantadine is also known to prevent virus assembly during virus replication. It does not appear to interfere with the immunogenicity of inactivated influenza A virus vaccine.

Amantril inhibits the replication of influenza A virus isolates from each of the subtypes, i.e., H1N1, H2N2 and H3N2. It has very little or no activity against influenza B virus isolates. A quantitative relationship between the in vitrosusceptibility of influenza A virus to amantadine and the clinical response to therapy has not been established in man. Sensitivity test results, expressed as the concentration of amantadine required to inhibit by 50% the growth of virus (ED50) in tissue culture vary greatly (from 0.1 µg/mL to 25.0 µg/mL) depending upon the assay protocol used, size of virus inoculum, isolates of influenza A virus strains tested, and the cell type used. Host cells in tissue culture readily tolerated amantadine up to a concentration of 100 µg/mL.


Amantril Hydrochloride is used for-

  • Treatment of parkinsonism
  • Treatment of drug-induced extrapyramidal reactions
  • Prophylaxis and treatment of signs and symptoms of infection caused by various strains of influenza A virus

Amantril is also used to associated treatment for these conditions: Cerebral Arteriosclerosis, Chorea, Extrapyramidal disorder caused by neuroleptic drugs without Tardive dyskinesia, Fatigue, Influenza A Virus Infection, Parkinson's Disease (PD), Parkinsonism, Parkinsonism post encephalitic, Restless Legs Syndrome (RLS)

Trade Name Amantril
Generic Amantadine
Other Names Amantadina, Amantadine, Amantadinum, Amantidine, Aminoadamantane
Weight 100mg
Type Capsule
Formula C10H17N
Weight Average: 151.2487
Monoisotopic: 151.136099549
Protein binding

Approximately 67% bound to plasma proteins over a concentration range of 0.1 to 2.0 µg/mL.

Therapeutic Class Respiratory viral infections (Influenza)
Manufacturer ACI Limited
Available Country Bangladesh
Last Updated: June 23, 2021 at 11:16 am


Amantril dosage

Parkinson's disease:

  • Adult: Initially, 100 mg/day, increased to 100 mg bid after a wk or more. Max dose: 400 mg daily.
  • Elderly: >65 yr: Lowest effective dose.

Prophylaxis of influenza A:

  • Adult: 100 mg daily for up to 6 wk; when used with influenza vaccination: only up to 3 wk after vaccination.
  • Child: 10-15 yr: 100 mg daily.

Influenza A:

  • Adult: 100 mg daily for 5 days.
  • Elderly: >65 yr: Daily dose of 1 day.

Herpes zoster in immunocompromised patients:

  • Adult: 100 mg bid for 14 days, continued for another 14 days if pain persists.

Side Effects

The adverse effects of Amantril are generally mild and, when they occur, may diminish or cease after a week or more on the medication. The most commonly reported side effects include nausea, dizziness/ lightheadedness, and insomnia.

Other side effects may include edema of ankles, livedo reticularis; anxiety, elevation of mood, headache, lethargy, hallucinations, ataxia, slurred speech, blurred vision, loss of concentration, nervousness, depression, myalgia, palpitations, orthostatic hypotension, dry mouth, anorexia, constipation and diaphoresis.


Amantril should not be discontinued abruptly in patients with Parkinson's disease since a few patients have experienced a parkinsonian crisis, i.e., a sudden marked clinical deterioration, when this medication was suddenly stopped. The dose of anticholinergic drugs or of Amantril Hydrochloride should be reduced if atropine-like effects appear when these drugs are used concurrently. Abrupt discontinuation may also precipitate delirium, agitation, delusions, hallucinations, paranoid reaction, stupor, anxiety, depression and slurred speech.


Concurrent administration of Amantril and anticholinergic agents or levodopa may increase confusion, hallucinations, nightmares, gastro-intestinal disturbances, or other atropine-like side effects. Psychotic reactions have been observed in patients receiving Amantril and Levodopa.

Concurrent administration of Amantril and drugs or substances (e.g. alcohol) acting on the CNS may result in additive CNS toxicity. Close observation is recommended.

Food Interaction

  • Avoid alcohol.
  • Take with or without food. The absorption is unaffected by food.

Volume of Distribution

  • 3 to 8 L/kg [healthy subjects]

Half Life

Mean half-lives ranged from 10 to 14 hours, however renal function impairment causes a severe increase in half life to 7 to 10 days.


  • 0.2 - 0.3 L/hr/kg
  • 0.10 +/- 0.04 L/hr/kg [healthy, elderly male]

Pregnancy & Breastfeeding use

Pregnancy category C. No well-controlled studies have been done in pregnant women to evaluate Amantril's safety. Amantril may be used during pregnancy when the potential benefits outweigh the potential but unknown risks to the fetus.

Amantril is excreted into breast milk in low concentrations. As no information is available on the effects in infants, therefore amantadine should be used cautiously in women who are breastfeeding.


Amantril is contraindicated in patients with known hypersensitivity to the active substances or to any of the excipients.

Special Warning

Patients with renal impairment:  The dose should be reduced. This can be achieved by either reducing the total daily dose, or by increasing the dosage interval in accordance with the creatinine clearance. For example:

  • CrCl <15 ml/min: Contraindicated
  • CrCl 15-35 ml/min: 100 mg every 2 to 3 days
  • CrCl >35 ml/min: 100mg every day

Patients with hepatic impairment: Use with caution

Storage Condition

Store at 20-25°C in dry place. Protect from light.

Amantril contains Amantadine see full prescribing information from innovator Monograph