Product Information

Registration Status: Active

SYMMETREL 100 CAPSULE 100mg is approved to be sold in Singapore with effective from 1988-05-23. It is marketed by NOVARTIS (SINGAPORE) PTE LTD, with the registration number of SIN01481P.

This product contains Amantadine 100mg in the form of CAPSULE. It is approved for ORAL use.

This product is manufactured by Catalent Germany Eberbach GmbH in SLOVENIA, andLek Pharmaceuticals d.d (Pri & sec packaging) in GERMANY.

It is a Prescription Only Medicine that can only be obtained from a doctor or a dentist, or a pharmacist with a prescription from a Singapore-registered doctor or dentist.



An antiviral that is used in the prophylactic or symptomatic treatment of influenza A. It is also used as an antiparkinsonian agent, to treat extrapyramidal reactions, and for postherpetic neuralgia. The mechanisms of its effects in movement disorders are not well understood but probably reflect an increase in synthesis and release of dopamine, with perhaps some inhibition of dopamine uptake. [PubChem]


For the chemoprophylaxis, prophylaxis, and treatment of signs and symptoms of infection caused by various strains of influenza A virus. Also for the treatment of parkinsonism and drug-induced extrapyramidal reactions.

Mechanism of Action

The mechanism of its antiparkinsonic effect is not fully understood, but it appears to be releasing dopamine from the nerve endings of the brain cells, together with stimulation of norepinephrine response. It also has NMDA receptor antagonistic effects. The antiviral mechanism seems to be unrelated. The drug interferes with a viral protein, M2 (an ion channel), which is needed for the viral particle to become "uncoated" once it is taken inside the cell by endocytosis.


Amantadine is well absorbed orally from the gastrointestinal tract.
* 3 to 8 L/kg [healthy subjects]
No appreciable metabolism, although negligible amounts of an acetyl metabolite have been identified.


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


Deaths have been reported from overdose with amantadine. The lowest reported acute lethal dose was 2 grams. Drug overdose has resulted in cardiac, respiratory, renal or central nervous system toxicity. Cardiac dysfunction includes arrhythmia, tachycardia and hypertension. Pulmonary edema and respiratory distress (including ARDS) have been reported. Renal dysfunction including increased BUN, decreased creatinine clearance and renal insufficiency can occur. Central nervous system effects that have been reported include insomnia, anxiety, aggressive behavior, hypertonia, hyperkinesia, tremor, confusion, disorientation, depersonalization, fear, delirium, hallucination, psychotic reactions, lethargy, somnolence and coma. Seizures may be exacerbated in patients with prior history of seizure disorders. Hyperthermia has also been observed in cases where a drug overdose has occurred.

Active Ingredient/Synonyms

1-adamantanamine | 1-adamantylamine | 1-aminoadamantane | Amantadina | Amantadine | Amantadinum | Amantidine | Aminoadamantane | Tricyclo[,7)]decan-1-amine | Tricyclo[,7)]decan-1-ylamine | Tricyclo[,7)]decane-1-amine | Viregyt | Virosol | Amantadine |

Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.


  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank