Symmetrel Drug Information

AMANTADINE (Systemic)

Some frequently used brand names are:

In the U.S.—

• Symmetrel

In Canada—

• Endantadine
• Gen-Amantadine
• Symmetrel

Generic medicine may be available in the U.S. and Canada.

Category

• Antidyskinetic
• Antifatigue, specifically in multiple sclerosis
• Antiviral, systemic

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 (RX medicine), in the dosage form provided belows:

• Oral
• Capsules (U.S. and Canada)
• Syrup (U.S. and Canada)
• Tablets (U.S.)

Before Using This Medicine

When deciding if it's worth using a medicine, the risk of taking it must be carefully weighed against the benifit it can do. This is the decision you and your doctor are to make together. Concerning amantadine, the following aspects should be taken into account:

Allergies—Inform your doctor if you have ever experienced any unusual or allergic reaction to amantadine. Also tell your doctor if you are allergic to any other substances, like foods, preservatives, dyes.

Pregnancy—No studies have been conducted in humans. However, there have been reports of birth defects, including birth defects of the heart, when women took amantadine during the first trimester of pregnancy. Also, a malformation involving the lower leg occurred in one infant. In addition, studies in some animals have shown that amantadine is harmful to the fetus and causes birth defects. Before taking this medicine, inform your doctor if you are pregnant or may become pregnant.

Breast-feeding—Amantadine passes into breast milk. However, the effects of amantadine in newborn babies and infants are not known. It may be necessary for you to take another medicine or to stop breast-feeding during treatment. Be sure you have discussed the risks and benefits of the medicine with your doctor.

Children—This medicine has been tested in children over 1 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 1 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 medicines—Although some medicines should not be used together at all, there are cases when 2 different medicines maybe used together even if an interaction might occur. In such cases, your doctor may advise you to change the dose, or other precautions may be required. When you are taking amantadine, it is essential to tell your health care professional 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

• Quinidine (e.g., Quinaglute Dura-tabs, Quinidex Extentabs) or
• Quinine or
• Trimethoprim and sulfamethoxazole (e.g., Bactrim, Septra)—These medicines may increase the amount of amantadine in the blood and increase the chance for side effects

Other medical problems—The existence of other medical problems may influence the use of /amantadine. You should tell your doctor if you have any other medical problems, in particular::

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

• Epilepsy or other seizure disorder (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

• Substance abuse (drug or alcohol abuse), history of—The chance of side effects from this medicine may be increased

Proper Use of This Medicine

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 two 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.

Dosing—The dose of amantadine will vary for different patients. Adhere to the orders of your doctor or the instructions on the label . The information below includes only the average doses of amantadine. Your dose may be different if you have kidney disease. If your dose differs, you should not change it unless your doctor tells you to do so. The number of capsules, tablets, 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 oral dosage forms (capsules, syrup, and tablets):
  • 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.
    • Children up to 1 year of age—Use and dose must be determined by your 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. Your doctor may increase this dose, if needed.
    • 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. You should not double doses.

Storage—To store this medicine properly, follow the instructions below:

• 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.

Precautions While Using 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 also may 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.

If amantadine causes you to feel very depressed or to have thoughts of suicide, check with your doctor immediately.

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, if they become worse, or you develop new symptoms, 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

Alongside with its expected effects, any medicine may be the cause of some unwanted effects. Although not all of these side effects may happen, if they do happen they may require medical attention.

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

Other side effects that may occur generally do not require any medical attention. These side effects may disappear in the course of treatment as your body gets used to the medicine. Nevertheless, inform your doctor if any of the side effects below persist or became annoying:

Other side effects not mentioned above may also happen in some patients. If you notice any other effects, tell your doctor about it.

Additional Information

Once a drug has been approved for marketing for certain cases, experience may show that it can also be applied to treatment of some 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.