amantadine, Symmetrel (Discontinued)

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Pharmacy Author:

Omudhome Ogbru, PharmD

Omudhome Ogbru, PharmD

Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

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Medical and Pharmacy Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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GENERIC NAME: amantadine

BRAND NAME: Symmetrel (Discontinued)

DRUG CLASS AND MECHANISM: Amantadine is a synthetic (man-made) anti-viral drug that can inhibit the replication of viruses in cells. To prevent a viral infection, the drug should be present before exposure to the virus. Clearly, this is not practical for most viral infections. It was initially used to prevent influenza A during flu season, and, if given within 24 to 48 hours of the onset of flu symptoms, to decrease the severity of the flu. Later amantadine was found to cause improvement in the symptoms of Parkinson's disease. Amantadine's mechanism of action in Parkinson's disease is not fully understood. Its effects may be related to its ability to augment (amplify) the effects of dopamine, a neurotransmitter in the brain, that is reduced in Parkinson's disease. Amantadine is less effective than levodopa in Parkinson's disease but can offer additional benefit when taken with levodopa. Amantadine was approved by the FDA in 1966.

GENERIC AVAILABLE: Yes

PRESCRIPTION: Yes

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

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

PRESCRIBED FOR: Amantadine is used for the prevention or treatment of infections with influenza A, especially for individuals at high-risk such as immunosuppressed patients and nursing home residents. It should not be used as a substitute for vaccination for influenza. Amantadine also is used for control of the symptoms of Parkinson's disease and for treatment of drug-induced extrapyramidal symptoms.

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 the benzodiazepine class of anti-anxiety drugs (for example, diazepam [Valium], lorazepam [Ativan], clonazepam [Klonopin], alprazolam [Xanax, Xanax XR, Niravam], zolpidem [Ambien, Ambien CR, Zolpimist, Edluar]), the tricyclic class of antidepressants (for example, amitriptyline [Elavil, Endep], imipramine [Tofranil, Tofranil-PM], desipramine [Norpramin]), dicyclomine (Bentyl), certain antihistamines (diphenhydramine [Benadryl], hydroxyzine [Vistaril, Atarax], clemastine), opiate agonists (for example, Dilaudid, hydrocodone/acetaminophen [Vicodin, Vicodin ES, Lorcet, Lorcet Plus, Norco], oxycodone and acetaminophen [Percocet, Roxicet, Tylox, Oxycet] codeine) and certain antihypertensive medications (for example, clonidine [Catapres, Catapres-TTS, Jenloga], propranolol [Inderal, Inderal LA, Innopran XL]). Such combinations can cause dizziness, confusion, lightheadedness, fainting, or dizziness upon standing (orthostatic hypotension).

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