Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2019 Publisher: Fontus Health Ltd, 60 Lichfield Street, Walsall, WS4 2BX, United Kingdom
Trilasym is indicated in patients suffering from clinical influenza in which complications might be expected to occur.
Additionally, amantadine is recommended prophylactically in cases particularly at risk, including:
Trilasym does not completely prevent the host immune response to influenza A infection, so individuals who take this drug still develop immune responses to the natural disease or vaccination and may be protected when later exposed to antigenically related viruses.
Trilasym is also indicated in post-exposure prophylaxis in conjunction with inactivated vaccine during an outbreak until protective antibodies develop, or in patients who are not expected to have a substantial antibody response (immunosuppression).
Trilasym is indicated in elderly or debilitated patients in whom the physician suspects that a severe and painful rash could occur. Trilasym can significantly reduce the proportion of patients experiencing pain of long duration.
When treating influenza, the treatment should start as early as possible and to continue for 4 to 5 days. When amantadine is started within 48 hours of symptoms appearing, the duration of fever and other effects is reduced by one or two days and the inflammatory reaction of the bronchial tree that usually accompanies influenza resolves more quickly.
Treat daily while the protection from infection is required. In most of the cases this is expected to be for 6 weeks. When used with inactivated influenza A vaccine, amantadine is continued for 2 to 3 weeks following inoculation.
Adults: 10 ml (100 mg) daily for the recommended period.
Children aged 10-15 years: 10 ml (100 mg) daily for the recommended period.
Children under 10 years of age: Dosage not established.
This medicine should not be used in children under the age of 3 years old.
Adults over 65 years of age: A daily dose of less than 10 ml (100 mg), or 10 ml (100 mg) given at intervals of greater than one day, may be appropriate, dependent on the renal function.
Plasma amantadine concentrations are influenced by renal function. In elderly patients, the elimination half-life is longer and renal clearance of the compound is diminished in comparison to young people.
Initially 10 ml (100 mg) daily for the first week, increasing to 10 ml (100 mg) twice daily.
The dose can be titrated against signs and symptoms.
Doses exceeding 200 mg daily may provide some additional relief, but may also be associated with increasing toxicity.
A dose of 400 mg/day should not be exceeded.
The dose should be increased gradually, at intervals of not less than 1 week.
Adults over 65 years of age: Since patients over 65 years of age tend to show lower renal clearance and consequently higher plasma concentrations, the lowest effective dose should be used.
Trilasym acts within a few days, but may appear to lose efficacy within a few months of continuous treatment. Its effectiveness may be prolonged by withdrawal for three to four weeks, which seems to restore activity. During this time, existing concomitant antiparkinsonian therapy should be continued, or low dose L-dopa treatment initiated if clinically necessary.
Trilasym withdrawal should be gradual, e.g. half the dose at weekly intervals. Abrupt discontinuation may exacerbate Parkinsonism, regardless of the patient’s response to therapy (see section 4.4).
Any antiparkinson drug already in use should be continued during initial amantadine treatment. It may then be possible to reduce the other drug gradually. If increased side effects occur, the dosage should be reduced more quickly. In patients receiving large doses of anticholinergic agents or L-dopa, the initial phase of amantadine treatment should be extended to 15 days.
10 ml (100 mg) twice daily for 14 days. Treatment should be started as soon as possible after diagnosis. If post-herpetic pain persists treatment can be continued for a further 14 days.
In patients with renal impairment, the dose of amantadine 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,
| Creatinine clearance ml/(min) | Dose |
|---|---|
| <15 | Trilasym contraindicated |
| 15–35 | 10 ml (100 mg) every 2 to 3 days |
| >35 | 10 ml (100 mg) every day |
The above recommendations are for guidance only and physicians should continue to monitor their patients for signs of unwanted effects.
Overdose with amantadine can lead to a fatal outcome.
Neuromuscular: disturbances and symptoms of acute psychosis are prominent.
Central nervous system: hyperreflexia, motor restlessness, convulsions, extrapyramidal signs, torsion spasms, dystonic posturing, dilated pupils, dysphagia, confusion, disorientation, delirium, visual hallucinations, myoclonus.
Respiratory system: hyperventilation, pulmonary oedema, respiratory distress, including adult respiratory distress syndrome.
Cardiovascular system: cardiac arrest and sudden cardiac death have been reported. Sinus tachycardia, arrhythmia, hypertension.
Gastrointestinal system: nausea, vomiting, dry mouth.
Renal function: urine retention, renal dysfunction, including increase in BUN and decreased creatinine clearance.
The effects of anticholinergic drugs are increased by amantadine. Acute psychotic reactions (which may be identical to those of atropine poisoning) may occur when large doses of anticholinergic agents are used. Where alcohol or central nervous stimulants have been taken at the same time, the signs and symptoms of acute poisoning with amantadine may be aggravated and/or modified.
There is no specific antidote. Induction of vomiting and/or gastric aspiration (and lavage if patient is conscious), activated charcoal or saline cathartic may be used if judged appropriate.
Since amantadine is excreted mainly unchanged in the urine, maintenance of renal function and copious diuresis (forced diuresis if necessary) are effective ways to remove it from the blood stream. Acidification of the urine favours its excretion.
Haemodialysis does not remove significant amounts of amantadine.
Monitor the blood pressure, heart rate, ECG, respiration and body temperature, and treat for possible hypotension and cardiac arrhythmias, as necessary.
Convulsions and excessive motor restlessness: administer anticonvulsants such as diazepam iv, paraldehyde im or per rectum, or phenobarbital im.
Acute psychotic symptoms, delirium, dystonic posturing, myoclonic manifestations: physostigmine by slow iv infusion (1mg doses in adults, 0.5mg in children) repeated administration according to the initial response and the subsequent need, has been reported. Retention of urine: bladder should be catheterised; an indwelling catheter can be left in place for the time required.
Shelf life: 24 months.
After first opening the bottle: 1 month.
Store below 25°C.
Store in the original bottle, in order to protect from light.
Type III amber glass bottle with a tamper evident polypropylene child-resistant screw cap with a polyethylene inner liner containing 150ml of solution with a polypropylene dosing cup.
Pack size: 150 ml.
The box containing this medicine contains a plastic measuring cup. The cup is marked in ml (millilitres) to help measuring out the correct amount. This medicine should be taken using the measuring cup and the cup should be rinsed out with water after each use.
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