Memantine belongs to the group of medications known as NMDA receptor antagonists. It is used alone or with other medications to treat people with moderate-to-severe Alzheimer's disease. Memantine does not cure Alzheimer's disease, but it is used to decrease the symptoms. It works in the brain to block the effect of some chemicals that cause symptoms of Alzheimer's disease such as decreased memory and other mental functions.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The usual starting dose of memantine is 5 mg once daily. This dose is gradually increased, usually over a one-month period, to 10 mg twice daily. By gradually increasing the dose, the side effects of this medication are less severe.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

Memantine tablets can be taken with or without food. The tablets should be swallowed whole with a glass of water and should not be chewed.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature in a dry place and keep it out of the reach of children.

Do not take this medication if you are allergic to memantine or any ingredients of the medication.

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• anxiety
• behavior changes (e.g., aggression, rage, agitation, anxiety, paranoia)
• change in frequency of urination
• confusion
• change in balance and coordination especially when walking
• fungal infection
• hallucinations (seeing, hearing, or feeling things that are not actually there)
• high blood pressure
• signs of an allergic skin reaction (e.g., rash, itchiness, skin redness)
• signs of a blood clot in the arm or leg (tenderness, pain, swelling, warmth, or redness in the arm or leg) or lungs (difficulty breathing, sharp chest pain that is worst when breathing in, coughing, coughing up blood, sweating, or passing out)
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of heart failure (e.g., decreased heart rate, difficulty breathing, build up of fluid in the legs and ankles)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
• trouble walking
• vision changes

Stop taking the medication and seek immediate medical attention if any of the following occur:

• seizures
• signs of a severe allergic reaction (hives; difficulty breathing; swelling of the mouth, lips, or throat)
• signs of a severe skin reaction (e.g., blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Drowsiness/decreased alertness: Memantine may cause drowsiness or dizziness, affecting your ability to drive or operate machinery. Avoid driving, operating machinery, or performing other potentially hazardous tasks until you have determined how you are affected by this medication.

Eyes: Memantine may build up in the tear fluid and contribute to changes in the eyes and possible changes in vision. People taking memantine should have regular check-ups from their eye doctor. If you notice any changes to your vision, contact your doctor as soon as possible.

Heart disease: Memantine may cause increased blood pressure, slowed heartbeat and occasionally, heart failure. If you have heart problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: The kidneys remove memantine from the body. When the kidneys aren't working properly, the medication can build up in the body and cause side effects. Memantine is not recommended for people with severe kidney disease.

If you have reduced kidney function or moderate kidney disease you may need a lower dose of memantine. Discuss with your doctor how this medication may affect your medical condition and whether any special monitoring is needed.

Liver function: The safety of memantine when given to someone with severely reduced liver function has not been studied and is not recommended. If you have reduced liver function or liver disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Reduced elimination from the body: The elimination of memantine from the body can be reduced in certain situations. These include changing from a normal diet to a strict vegetarian diet, taking certain medications (e.g., sodium bicarbonate, acetazolamide), having a kidney condition called renal tubular acidosis, or having a urinary tract infection. Your doctor will monitor your condition closely in these situations.

Seizures: Memantine has not been studied for use by people who have seizure disorders (such as epilepsy). If you have a history of seizure disorder, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if memantine passes into breast milk. If you are breast-feeding and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

Seniors: There is limited information about the safety of memantine for people over the age of 85.

There may be an interaction between memantine and any of the following:

• amantidine
• carbonic anhydrase inhibitors (e.g., acetazolamide, topiramate)
• cimetidine
• dextromethorphan
• dopamine agonists (e.g., bromocriptine, pramipexole, ropinirole)
• esketamine
• hydrochlorothiazide
• ketamine
• levodopa
• potassium citrate
• procainamide
• quinidine
• quinine
• sodium bicarbonate
• trimethoprim
• warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications.