Amantril^®

Amantril is the preparation of Amantadine Hydrochloride which has direct and indirect effects on dopamine neurons. 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 also prevents virus assembly during virus replication. It does not appear to interfere with the immunogenicity of inactivated influenza A virus vaccine.

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Amantril is indicated 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.

Route of administration: Amantril® should be taken in oral route.

Parkinson's disease

Adult: Initially, 100 mg/day, increased to 100 mg twice daily after a week or more. Maximum
dose is 400 mg daily.
Elderly (> 65 year): Lowest effective dose.

Prophylaxis of influenza A
Adult: 100 mg daily for up to 6 week; when used with influenza vaccination: only up to 3 week
after vaccination.
Child (10-15 year): 100 mg daily.

Influenza A
Adult: 100 mg daily for 5 days.
Elderly (> 65 year): Daily dose of 1 day.

Herpes zoster in immunocompromised patients
Adult: 100 mg twice daily for 14 days, continued for another 14 days if pain persists.

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

clearance. For example-

Patients with hepatic impairment: Use with caution.

Use in pregnancy and lactation
Pregnancy: Amantadine is a pregnancy category C drug. No well-controlled studies have been
done in pregnant women to evaluate amantadine’s safety. Amantadine may be used during
pregnancy when the potential benefits outweigh the potential but unknown risks to the fetus.

Lactation: Amantadine 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.

Use in children and adolescents
The safety and efficacy of amantadine in newborn infants and infants below the age of 1 year
have not been established.

Amantadine should not be discontinued abruptly in patients with Parkinson's disease since 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 amantadine 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.

The most common side effects of amantadine are 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.

Amantadine is contraindicated in patients with known hypersensitivity to amantadine or to components of this product.

Drug interaction with medication: Concurrent administration of amantadine 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 amantadine and levodopa. Concurrent administration of
amantadine and drugs or substances (e.g., alcohol) acting on the CNS may result in additive CNS toxicity. Close observation is recommended.

Drug interaction with food and others: Not applicable.

Deaths have been reported from overdose with amantadine hydrochloride. The lowest reported acute lethal dose was 1 gram. Because some patients have attempted suicide by overdosing
with amantadine, prescriptions should be written for the smallest quantity consistent with good patient management. Drug overdose has resulted in cardiac, respiratory, renal or central
nervous system toxicity. There is no specific antidote for an overdose of amantadine hydrochloride. However, slowly administered intravenous physostigmine in 1 and 2 mg doses in
an adult at 1 to 2 hour intervals and 0.5 mg doses in a child at 5 to 10 minute intervals up to a maximum of 2 mg/hour have been reported to be effective in the control of central nervous
system toxicity. For acute overdosing, general supportive measures should be taken and vitals should be monitored.

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