Amantadine

Description—Amantadine (a-MAN-ta-deen) is an antiviral. It is used to prevent or treat certain influenza (flu) infections (type A). It may be given alone or along with flu shots. Amantadine will not work for colds, other types of flu, or other virus infections.

Amantadine also is an antidyskinetic. It is used to treat Parkinson’s disease, sometimes called paralysis agitans or shaking palsy. It may be given alone or with other medicines for Parkinson’s disease. By improving muscle control and reducing stiffness, this medicine allows more normal movements of the body as the disease symptoms are reduced. Amantadine is also used to treat stiffness and shaking caused by certain medicines used to treat nervous, mental, and emotional conditions.

Amantadine may be used for other conditions as determined by your doctor.

Amantadine is available only with your doctor’s prescription, in the following dosage forms:

Oral

•Capsules (U.S. and Canada)

•Syrup (U.S. and Canada)

Before Using this Medicine—In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For amantadine, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to amantadine. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Studies have not been done in humans. However, studies in some animals have shown that amantadine is harmful to the fetus and causes birth defects.

Breast-feeding—Amantadine passes into breast milk. However, the effects of amantadine in newborn babies and infants are not known.

Children—This medicine has been tested in children over one year of age and has not been shown to cause different side effects or problems in these children than it does in adults. There is no specific information comparing the use of amantadine in children under one year of age with use in other age groups.

Older adults—Elderly people are especially sensitive to the effects of amantadine. Confusion, difficult urination, blurred vision, constipation, and dry mouth, nose, and throat may be especially likely to occur.

Other medical problems—The presence of other medical problems may affect the use of amantadine. Make sure you tell your doctor if you have any other medical problems, especially:

•Eczema (recurring) — Amantadine may cause or worsen eczema

•Epilepsy or other seizures (history of) — Amantadine may increase the frequency of convulsions (seizures) in patients with a seizure disorder

•Heart disease or other circulation problems or

•Swelling of feet and ankles

— Amantadine may increase the chance of swelling of the feet and ankles, and may worsen heart disease or circulation problems

•Kidney disease — Amantadine is removed from the body by the kidneys; patients with kidney disease will need to receive a lower dose of amantadine

•Mental or emotional illness — Higher doses of amantadine may cause confusion, hallucinations, and nightmares

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking amantadine, it is especially important that your health care professional know if you are taking any of the following:

•Amphetamines or

•Appetite suppressants (diet pills), except fenfluramine (e.g., Pondimin), or

•Caffeine (e.g., NoDoz) or

•Chlophedianol (e.g., Ulone) or

•Cocaine or

•Medicine for asthma or other breathing problems or

•Medicine for colds, sinus problems, or hay fever or other allergies (including nose drops or sprays) or

•Methylphenidate (e.g., Ritalin) or

•Nabilone (e.g., Cesamet) or

•Pemoline (e.g., Cylert) — The use of amantadine with these medicines may increase the chance of unwanted effects such as nervousness, irritability, trouble in sleeping, and possibly seizures or irregular heartbeat

•Anticholinergics (medicine for abdominal or stomach spasms or cramps) — The use of amantadine with these medicines may increase the chance of unwanted effects such as blurred vision, dryness of the mouth, confusion, hallucinations, and nightmares

Proper Use/Preparation of this Medicine/Test—For patients taking amantadine to prevent or treat flu infections:

•Talk to your doctor about the possibility of getting a flu shot if you have not had one yet.

•This medicine is best taken before exposure, or as soon as possible after exposure, to people who have the flu.

•To help keep yourself from getting the flu, keep taking this medicine for the full time of treatment. Or if you already have the flu, continue taking this medicine for the full time of treatment even if you begin to feel better after a few days. This will help to clear up your infection completely. If you stop taking this medicine too soon, your symptoms may return. This medicine should be taken for at least 2 days after all your flu symptoms have disappeared.

•This medicine works best when there is a constant amount in the blood. To help keep the amount constant, do not miss any doses. Also, it is best to take the doses at evenly spaced times day and night. For example, if you are to take 2 doses a day, the doses should be spaced about 12 hours apart. If this interferes with your sleep or other daily activities, or if you need help in planning the best times to take your medicine, check with your health care professional.

•If you are using the oral liquid form of amantadine, use a specially marked measuring spoon or other device to measure each dose accurately. The average household teaspoon may not hold the right amount of liquid.

For patients taking amantadine for Parkinson’s disease or movement problems caused by certain medicines used to treat nervous, mental, and emotional conditions:

•Take this medicine exactly as directed by your doctor. Do not miss any doses and do not take more medicine than your doctor ordered.

•Improvement in the symptoms of Parkinson’s disease usually occurs in about 2 days. However, in some patients this medicine must be taken for up to 2 weeks before full benefit is seen.

Storage—To store this medicine:

•Keep out of the reach of children.

•Store away from heat and direct light.

•Do not store the capsule form of this medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down. •Keep the oral liquid form of this medicine from freezing.

•Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Dosing—The dose of amantadine will be different for different patients. Follow your doctor’s orders or the directions on the label. The following information includes only the average doses of amantadine. Your dose may be different if you have kidney disease. If your dose is different, do not change it unless your doctor tells you to do so.

•The number of capsules or teaspoonfuls of suspension that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking amantadine.

•For the treatment or prevention of flu:

— Older adults: 100 milligrams once a day.

— Adults and children 12 years of age and older: 200 milligrams once a day, or 100 milligrams two times a day.

— Children 9 to 12 years of age: 100 milligrams two times a day.

— Children 1 to 9 years of age: Dose is based on body weight and must be determined by the doctor.

•For the treatment of Parkinson’s disease or movement problems:

— Older adults: 100 milligrams once a day to start. The dose may be increased slowly over time, if needed.

— Adults: 100 milligrams one or two times a day.

— Children: Dose has not been determined.

Missed dose—If you miss a dose of this medicine, take it as soon as possible. This will help to keep a constant amount of medicine in the blood. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Precautions While/After Using Receiving this Medicine—Drinking alcoholic beverages while taking this medicine may cause increased side effects such as circulation problems, dizziness, lightheadedness, fainting, or confusion. Therefore, do not drink alcoholic beverages while you are taking this medicine.

This medicine may cause some people to become dizzy, confused, or lightheaded, or to have blurred vision or trouble concentrating. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert or able to see well. If these reactions are especially bothersome, check with your doctor.

Getting up suddenly from a lying or sitting position may also be a problem because of the dizziness, lightheadedness, or fainting that may be caused by this medicine. Getting up slowly may help. If this problem continues or gets worse, check with your doctor.

Amantadine may cause dryness of the mouth, nose, and throat. For temporary relief of mouth dryness, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if your mouth continues to feel dry for more than 2 weeks, check with your doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

This medicine may cause purplish red, net-like, blotchy spots on the skin.. This problem occurs more often in females and usually occurs on the legs and/or feet after this medicine has been taken regularly for a month or more. Although the blotchy spots may remain as long as you are taking this medicine, they usually go away gradually within 2 to 12 weeks after you stop taking the medicine. If you have any questions about this, check with your doctor.

For patients taking amantadine to prevent or treat flu infections:

•If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

For patients taking amantadine for Parkinson’s disease or movement problems caused by certain medicines used to treat nervous, mental, and emotional conditions:

•Patients with Parkinson’s disease must be careful not to overdo physical activities as their condition improves and body movements become easier since injuries resulting from falls may occur. Such activities must be gradually increased to give your body time to adjust to changing balance, circulation, and coordination.

•Some patients may notice that this medicine gradually loses its effect while they are taking it regularly for a few months. If you notice this, check with your doctor. Your doctor may want to adjust the dose or stop the medicine for a while and then restart it to restore its effect.

•Do not suddenly stop taking this medicine without first checking with your doctor since your Parkinson’s disease may get worse very quickly. Your doctor may want you to reduce your dose gradually before stopping the medicine completely.

Side Effects of this Medicine—Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Unwanted Effects—Check with your doctor immediately if any of the following side effects occur:

Less common

Blurred vision; confusion (especially in elderly patients); difficult urination (especially in elderly patients); fainting; hallucinations (seeing, hearing, or feeling things that are not there)

Rare

Convulsions (seizures); decreased vision or any change in vision; difficulty in coordination; irritation and swelling of the eye; mental depression; skin rash; swelling of feet or lower legs; unexplained shortness of breath

Other Side Effects

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

More common

Difficulty concentrating; dizziness or lightheadedness; headache; irritability; loss of appetite; nausea; nervousness; purplish red, net-like, blotchy spots on skin; trouble in sleeping or nightmares

Less common or rare

Constipation; dryness of the mouth, nose, and throat; vomiting

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Additional Information — Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although this use is not included in product labeling, amantadine is used in certain patients with the following medical condition:

•Unusual tiredness or weakness associated with multiple sclerosis

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for this use.