SYMMETREL
General description

Symmetrel is the version of amantadine produced by Endo Pharmaceuticals. It is available in tablet and syrup form, both of which are taken orally. Amantadine acts as both an anti-Parkinson's and an antiviral drug, specifically for fighting against Influenza A, or the flu.

Mechanism

The primary mechanism of action is not clearly understood though it appears that amantadine will prevent release of infectious viral nucleic acids into the host cell and in some cases will prevent viral assembly.

Indications

Symmetrel is used for both prophylaxis and treatment of signs and symptoms of Influenza A infection. It is not a strain-specific drug. If early vaccination is not feasible, is contraindicated, or is unavailable, Symmetrel can serve as a chemoprophylaxis agent. It is also indicated for use in uncomplicated infections of the respiratory tract caused by Influenza A. It is not known to be effective against any strain but Influenza A strains.

Usage/Dosage

For adults, the recommended dosage is 200 mg once a day for both prophylaxis and treatment. If the patient complains of CNS effects, then splitting the dosage up through the course of the day can sometimes relieve symptoms. For patients 1-9 yrs of age, a daily dose should be calculated based on a 2 to 4 mg/lb/day scale. The total dosage should not exceed 150 mg. For patients 9-12 yrs of age, a dose of 200 mg per day can be administered as two 100 mg doses daily. Symmetrel adminstration should begin in anticipation of flu season and be continued at least 10 days after known exposure to Influenza A. As a treatment, adminstration should begin as soon after exposure as possible.

Precautions

Symmetrel overdose has been reported to cause death with a lethal dose as low as 2 grams. Symmetrel does not completely prevent host immune response to influenza A infection, and patients may develop immune response to natural disease or vaccination at a later date.

Contraindications

Symmetrel is contraindicated for patients with known sensitivity to amantadine chloride or any other ingredients of Symmetrel. Patients with history of CNS disorder, such as epilepsy or psychiatric illness should be observed carefully while under treatment with Symmetrel as well as patients with a history of congestive heart failure. No causal links have been proven, but Symmetrel could potentially be an agent in promoting epilepsy, heart failure, or even suicide attempts. Patients with untreated angle closure glaucoma should not receive Symmetrel.

Potential Adverse Effects

Aside from the potential dangers listed under contraindications, Symmetrel has most commonly been reported to cause nausea, dizziness, and light-headedness. It may be a cause of trembling when adminstered with thoridazine.