Amantadine

Brand names

• Dom-Amantadine
• Endantadine
• Gen-Amantadine
• Med-Amantadine
• PMS-Amantadine
• Symadine
• Symmetrel

Usage

To prevent or treat type A influenza; to treat Parkinson's disease. It may also be used to minimize stiffness and shaking caused by certain other medicaments prescribed for treating nervous, mental, or emotional disorders.

How it works

The exact mechanism of action is unknown, though amantadine appears to prevent the influenza A virus from penetrating and entering healthy cells. In Parkinsonism, it increases the release and activity of dopamine, which plays a key role in the control of muscle movement. The increased availability of dopamine in the brain helps compensate for the reduction in the natural supply caused by the disease, and so eases symptoms of Parkinsonism.

Side effects

Serious

Skin rash, confusion, seizures, hallucinations, swollen feet or arms, difficulty breathing.

Common

Dizziness, irritability, distractibility, difficulty sleeping are common side effects of this medicament.

Less common

Mild skin rash, weakness, depression, fatigue, anxiety, headache, lightheadedness, loss of appetite, nausea, constipation, dry mouth. Seek medical advice if such symptoms persist.

Possible interactions

Other medicaments:

Amantadine may increase the effects of:

• atropinelike medicaments used to treat parkinsonism, especially benztropine (Cogentin), orphenadrine (Disipal) and trihexyphenidyl (Artane). Amantadine can increase results, but if doses are too large, these medicaments (taken with amantadine) may cause confusion, delirium, hallucinations and nightmares.
• levodopa (Dopar, Larodopa, Sinemet, etc.) and enhance results. Combination may cause acute mental disturbances.

The following medicaments may increase the effects of amantadine:



• amphetamine and amphetaminelike stimulant medicaments may cause excessive stimulation and adverse behavioral effects.
• hydrochlorothiazide with triamterene may increase the blood level of amantadine and cause toxicity.

Amantadine taken concurrently with:



• cotrimoxazole may increase risk of CNS stimulation or arrhythmias.
• hydrochlorothiazide (Dyazide, Esidrix, others) may increase risk of amantadine toxicity.
• sulfamethoxazole may increase risk of CNS stimulation or arrhythmia.
• triamterine may increase risk of CNS toxicity.
• trimethoprim may increase risk of CNS toxicity.
• zotepine (Nipolept) may decrease amantadine benefits.

Herbal medicines or minerals:

Calabar bean (chop nut, Fabia, ordeal nut, others) is unsafe when taken by mouth (physostigmine is the active ingredient) and should never be taken by people with Parkinson's disease. Echinacea purpurea should be avoided by those with multiple sclerosis.

Alcohol:

May impair mental function, lower blood pressure excessively.

Tobacco smoking:

No interactions expected.

Marijuana smoking:

Added drowsiness.

Exposure to cold:

Use caution. Excessive chilling may enhance the development of livedo reticularis.

Discontinuation:

When used to treat parkinsonism, this medicament should not be stopped abruptly (slowly tapering is prudent). Sudden discontinuation may cause an acute Parkinsonian crisis. When treating influenza A infections, medicament is continued for 48 hours after symptoms stop.