Amantadine

Overview

Amantadine is an antiviral drug that is used in the treatment and prevention of type A influenza infections. It may be used alone or given together with flu shots. This medication is not effective in treating common colds, other strains of flu, or other viral infections.

Amantadine is also used in the treatment of Parkinson’s disease. It is an antidyskinetic drug that may be used alone or in tandem with other Parkinson’s medications. The drug works by alleviating the symptomatic stiffness and loss of muscle control that are caused by the disease.

Amantadine can also be useful in the treatment of stiffness and tremors that can be a side effect of certain medication that is used to treat emotional, mental, and nervous conditions. These patients may benefit from the use of Amantadine, as it can help to improve their range of motion and ability to exercise. In the treatment of these conditions, Amantadine is believed to work by helping to restore the balance of neurotransmitters (natural chemicals) that are present in the brain.

Amantadine is only available on prescription from your doctor or other healthcare professional, and it comes in various oral dosage forms.

Conditions treated

  • Influenza virus (type A)
  • Parkinson’s disease

Type of medicine

  • liquid filled capsules
  • solution
  • tablet
  • syrup

Side effects

This medication is designed to treat and control the symptoms of your condition. However, you may experience some unwanted side effects when you begin using it. Before you commence treatment with Amantadine, always tell your doctor if you have ever experienced any side effects or allergic reactions to any form of medication. You should also mention any adverse reactions you have experienced when taking over-the-counter products, vitamin supplements or herbal preparations. You must also tell your doctor if you have any known allergies to particular food types (for example, lactose or shellfish), preservatives, dyes, or animals.

The side effects outlined below have been experienced by some patients taking Amantadine. However, please note that this list is not exhaustive, and if you notice anything unusual about your behavior or if you begin to feel unwell after starting your course of treatment with this medicine, you should consult your medical professional without delay.

Some of the more commonly experienced side effects seen in patients taking Amantadine include feelings of agitation, nervousness, or anxiety. You may find that you have difficulty in concentrating or that you feel more irritable than usual. Increased headaches can be experienced, and you may find that your appetite is reduced or that you feel nauseous. Some people find that their sleep patterns are disturbed and they suffer nightmares. You might also notice purplish-red, net-like patterns or blotches on your skin.

Less commonly, some patients experience feelings of confusion and may suffer hallucinations. Others may have a false sense of wellbeing or feel drowsy all the time. On a physical level, you may find that your vision becomes blurred, you have difficulty in urinating, or you feel faint, dizzy or lightheaded. You may find that you notice swelling in your feet, lower legs, and hands. You may also find that you are constipated more than usual or that you suffer from regular bouts of diarrhea or vomiting. Some patients report that their libido (sexual desire) has decreased. Others complain of dryness of the mouth, nose, and throat.

There are a number of rarely experienced side effects that you should be aware of, including:

  • convulsions
  • changes in your vision or loss of vision
  • problems with co-ordination
  • hypertension (increased blood pressure)
  • flu-like symptoms (fever, sore throat, chills)
  • increased body movements
  • swelling or irritation of the eyes
  • memory loss
  • depression, severe mental changes or mood swings
  • skin rash
  • slurred speech
  • shortness of breath
  • suicidal tendencies or thoughts

It is not uncommon for patients to experience some minor side effects when they first begin taking Amantadine, although many people find that these side effects resolve themselves within a few weeks as the body adjusts to the new medication. If you do begin to experience side effects after you commence your treatment with this medication, your doctor may be able to suggest ways in which these unwanted effects can be managed until your body acclimatises to the effects of the medication.

Amantadine can sometimes cause dryness of the mouth, nose, and throat. Continued dryness of the mouth can lead to dental disease, gum disease or fungal infections. You can combat mouth dryness by chewing sugarless gum, sucking on sugarless hard candy, or by melting small pieces of ice in your mouth. Your doctor or dentist may be able to provide you with a saliva substitute if the problem is particularly bothersome or if it persists for more than two weeks.

Not everyone who is prescribed Amantadine suffers from side effects when taking this medication. However, you should always consult your doctor if you have any questions or concerns about any side effects you may experience.

Dosage

The dose of this medicine will not necessarily be the same for every patient. Always take your medication as instructed by your healthcare professional, or refer to the directions on the product packaging.

The following dosage information is based on the average dose prescribed. The dose you are instructed to take will depend on the strength of the medication. The number of doses that you are required to take each day and the time that should elapse between doses may also vary. If you are prescribed a different dose, do not change it unless you are instructed to do so by your doctor.

Do not miss any doses of Amantadine. In the event that you do miss a dose, take it as soon as possible. If it is almost time for your next dose, you should skip the one that you have missed and revert to your regular dosing regimen. Do not double dose.

Amantadine can be taken with or without food. Do not chew or break the capsule or tablet.

Amantadine is formulated in oral dosage forms, including tablets, capsules, and syrup.

For the prevention and treatment of type A influenza

  • adults and teenagers: 200 mg or four teaspoonfuls, once daily in one single dose
  • elderly adults: 100 mg or two teaspoonfuls, once daily in one single dose
  • children nine to 12 years of age: 100 mg or two teaspoonfuls, twice daily
  • children one to nine years of age: the dose is based on the child’s bodyweight and must be determined by a doctor
  • children up to one year of age: the use and dose must be determined by a doctor

If you are intending to use Amantadine as a preventative measure to combat type A influenza, discuss the possibility of getting a flu shot if you have not already had one. Amantadine is most effective before you become exposed to people who have the flu, or as soon as practically possible afterwards. To prevent yourself from contracting the flu, you should take the full course of your prescribed treatment. If you are already suffering from the flu, take the full course of medication, even if you begin to feel better within a few days of starting the treatment. You should continue to take the medication for at least two days after all your flu symptoms have gone. If you stop taking the medication too soon, your flu symptoms may return.

For Amantadine to be most effective, you need to ensure that a constant amount of the medication remains in your blood. To be sure of this you must not miss any doses. It is also best to space the doses of your medication evenly across the day and night in order to ensure that the levels of the drug do not fluctuate. If you have been prescribed the oral liquid form of the medication, use a specially marked measuring device so that you can be sure the dose is accurate. Bear in mind that your household teaspoon may not hold the precise amount of liquid that constitutes your dose.

For the prevention and treatment of Parkinson’s disease or movement problems

  • adults: 100 mg, twice daily
  • older adults: initially, 100 mg, once daily in a single dose
  • children: the dose and use must be determined by a doctor

Your doctor may alter the dose and frequency as required.

If you are taking this medication to treat the symptoms of Parkinson’s disease or to combat the movement problems that can be caused by certain drugs that are used to treat emotional, mental or nervous disorders, you should always take the medication as prescribed for you by your doctor. Try not to miss any doses and do not exceed the prescribed amount.

You should notice an improvement in your symptoms within a couple of days, although in some patients this may take up to two weeks. If you find that this medication stops working as well after you have been using it for a few months, you should discuss the matter with your doctor. It could be that the dose needs adjusting.

If you have been instructed by your doctor to take this medication twice a day and consequently, you have problems sleeping, try taking your second dose a few hours before you go to bed.

In the case of an accidental overdose where serious side effects occur, such as losing consciousness or if the patient develops severe breathing difficulties, you should call 911. If an overdose occurs but no side effects are evident, consult your doctor immediately.

Drug interactions

Although some medicines should never be used at the same time, in other cases it may be appropriate to use two or more different drugs, even though an interaction could occur. In this case, your health care provider may choose to alter the dose or may advise that you take other precautions.

You should always tell your doctor immediately if you are prescribed Amantadine and you are also taking any other medication, including herbal preparations, vitamin supplements or over-the-counter medicines. You should not use some medications when you are eating certain types of foods, or if you are using tobacco or alcohol as this may cause interactions to occur. Under these circumstances, you should discuss the use of this medication with your health care provider before you start taking it.

If you have had a nasal flu vaccine (for example, live attenuated influenza vaccine, Flumist®) within the last two weeks, you must NOT take Amantadine. You must wait until at least 48 hours after taking this medication before having a nasal flu vaccine. These two drugs will produce a serious interaction if taken together.

Other drugs that may produce a serious interaction when used together with Amantadine include:

  • anticholinergics (for example, atropine)
  • antihistamines
  • some psychiatric medicines, including phenothiazines such as thioridazine
  • quinine
  • quinidine
  • caffeine
  • trimethoprim
  • sulfamethoxazole
  • potassium chloride
  • bupropion
  • donepezil
  • memantine
  • betel nut
  • bromperidol
  • triamterene

Warnings

It is very important that you have regular check-ups with your doctor or healthcare professional while you are taking this medication. These visits will give you the opportunity to discuss any concerns or unwanted side-effects that you are experiencing and will allow your doctor to adjust your dose if necessary.

Amantadine can cause some patients to experience abnormal behaviors, including agitation and irritability. In extreme cases, some people may feel suicidal and depressed. If you or your caregiver notice any of these effects, or if your child begins to exhibit them, you should inform your doctor or your child’s doctor immediately. Other behavioral changes that should be brought to your doctor’s attention include an increased interest in sex or in gambling.

Do not drink alcohol while taking this medication. Alcohol in combination with Amantadine can cause fainting, dizziness, and confusion. Circulatory problems may also occur. If you begin to notice any of these effects, do not drive or operate machinery.

You may find that feelings of lightheadedness and dizziness can be managed by sitting up or getting up slowly. These symptoms usually manifest themselves when the dose is increased. If the problem does not resolve or begins to get worse, check with your doctor.

If you suffer from Parkinson’s disease, you should be careful not to overdo physical activities as your condition begins to improve. It is best to gradually increase your activity levels in order to allow your body the time it needs to adjust to changes in balance, co-ordination, and circulation.

Amantadine can cause side effects that include convulsions, a rapid heartbeat, fever, increased sweating, breathing difficulties, severe muscle stiffness, and feelings of extreme tiredness. These symptoms can all be indicative of a serious medical condition called neuroleptic malignant syndrome (NMS). If you experience any of these symptoms, consult your doctor immediately.

If you are taking Amantadine for Parkinson’s disease, you should ask your doctor to check your skin regularly for signs of melanoma (skin cancer). If you see any unusual black, brown, or red spots on your skin anywhere on your body, mention it to your doctor without delay.

Elderly people can suffer from a decline in kidney function, meaning that this medication is not removed as efficiently from the body. This can mean that elderly patients may have a greater risk of side effects while taking Amantadine.

Tell your doctor if you have glaucoma before you begin taking this medication.

Amantadine should only be used by pregnant women if absolutely necessary. There have been reports of babies that have been born with heart defects because their mothers were taking this medication during their pregnancy. If you are pregnant, or if you are planning on becoming pregnant while taking Amantadine, you should discuss the risks and benefits of this drug with your doctor. Amantadine passes into the breast milk and can have unpleasant effects on a nursing infant. If you are taking this medication, always consult your doctor before you begin breastfeeding. You should also note that expressed breast milk may also contain the medication, so it may be best to feed your baby with an appropriate formula instead.

Amantadine should not be given to patients who have a history of heart failure or heart transplant.

Some other existing medical problems can affect the use of this medicine. Be sure to tell your treating physician if you suffer from any of the following medical problems:

  • a recurrent history of congestive heart failure
  • a recurrent history of eczema
  • a history of epilepsy, seizures, or convulsions
  • liver disease, including liver cirrhosis
  • hypotension (low blood pressure)
  • a history of neuroleptic malignant syndrome (NMS)
  • swelling of the feet, ankles or hands (peripheral oedema)
  • a history of mental illness or psychosis

It has been shown that using Amantadine in patients suffering from any of the above listed conditions can make their symptoms and side effects worse. Your doctor will therefore suggest an alternative.

If you have a history of kidney disease, this drug should be used with extreme caution and a reduced dosage strategy may be applicable.

Patients who have a history of untreated narrow-angle glaucoma, glaucoma, or angle-closure glaucoma should never be treated with this medication.

Storage

Your medicine should be kept in a sealed, airtight container and at room temperature.

Do not freeze the medication.

Do not place the medication where it will be exposed to direct sunlight. Store the medication well away from sources of heat and moisture.

Keep the medication away from children and pets. In the event that a pet consumes Amantadine, you should seek veterinary advice immediately.

Never use any medication that has exceeded its use-by date or if the packaging appears to be damaged.

Ask your doctor or pharmacist for advice on how to dispose of any unwanted or out-of-date medication. Do not flush the leftover medicines down the toilet, put them down the drain, or throw them out with your trash where they could be found by children or animals.

Summary

Amantadine is an antiviral drug that is used in the treatment and prevention of type A influenza infections. It may be used alone or given together with flu shots. Amantadine is also used in the treatment of Parkinson’s disease and in combating some of the tremors and shaking that can be caused by certain medication that is used for the treatment of some mental, nervous, or psychiatric conditions.

As the medication can cause feelings of drowsiness, dizziness and confusion in some patients, it is important that sufferers do not drive or operate machinery until these side effects are addressed.

Amantadine is a highly beneficial drug, although it can pose a risk to patients who do not communicate effectively with their doctor or other healthcare professional. Amantadine helps to reduce the symptoms of flu and Parkinson’s disease. In some cases where a person’s mobility has been affected, this medication can mean that a patient can return to much improved levels of physical activity and an improved quality of life. To achieve these results it is important that the patient and clinician work closely together to find the correct dose and frequency of use.

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Last Reviewed:
December 10, 2017
Last Updated:
December 22, 2017
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