amantadine (Symmetrel - Discontinued) (cont.)

Pharmacy Author:
Medical and Pharmacy Editor:

GENERIC AVAILABLE: No

PRESCRIPTION: Yes

PREPARATIONS: Capsule: 100 mg. Syrup: 50 mg/5 ml (teaspoon).

STORAGE: Amantadine should be stored at room temperature between 15 C - 30 C (59 F - 86 F).

DOSING: Amantadine is taken once or twice daily with or without food. If it causes an upset stomach, it can be taken with food. The dosage for prevention and treatment of influenza A infections in adults is 200 mg daily. For treatment of influenza, amantadine should be started within 24 to 48 hours after the onset of signs or symptoms and should be continued for 24 to 48 hours after the disappearance of signs or symptoms. To prevent influenza, amantadine should be started as soon as possible after exposure to the influenza virus and continued for at least 10 days. Persons with reduced kidney function and elderly persons may need lower doses (or less frequent doses).

The dosage for treating Parkinson's or extrapyramidal symptoms is 100 mg twice daily.

DRUG INTERACTIONS: Amantadine adds to the sedating effects of alcohol and other sedating drugs such as:

Such combinations can cause dizziness, confusion, lightheadedness, fainting, or dizziness upon standing (orthostatic hypotension).

Since amantadine amplifies the actions of dopamine in the brain, drugs which block the effects of dopamine should be avoided in persons taking amantadine when amantadine is used for the treatment of Parkinson's disease. Such drugs include haloperidol (Haldol), metoclopramide (Reglan), and phenothiazines, for example, thioridazine (Mellaril) or triflupromazine (Stelazine).

The use of the diuretics hydrochlorothiazide or triamterene (Dyazide; Maxzide) with amantadine can reduce the kidney's ability to eliminate amantadine. This can lead to high levels of amantadine in the blood and amantadine-associated toxicity.

PREGNANCY: No well-controlled studies have been done in pregnant women to evaluate amantadine's safety. Physicians may choose to use amantadine during pregnancy when the potential benefits outweigh the potential but unknown risks to the fetus.

NURSING MOTHERS: Amantadine is excreted into breast milk in low concentrations. Although no information is available on the effects in infants, the manufacturer recommends that amantadine be used cautiously in women who are breastfeeding.

Medically reviewed by Eni Williams, PharmD

Reference: FDA Prescribing Information


Medically Reviewed by a Doctor on 12/22/2015


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