Indications
Memantine is used to treat the symptoms of moderate to severe dementia caused by Alzheimer’s disease. It can help with memory, attention, thinking and the ability to carry out daily activities. It does not cure the disease or stop it from progressing. It may be used on its own or together with Donepezil.
How It Works
In Alzheimer’s disease, too much of a brain chemical called glutamate can overstimulate NMDA receptors and damage nerve cells. Memantine partly blocks these receptors, reducing the harmful effect of excess glutamate while still allowing normal signals for learning and memory.
Dosage and Administration
Adults: the dose is increased slowly to reduce side effects, as prescribed. A common plan is 5 mg once a day in week 1, 10 mg a day in week 2, 15 mg a day in week 3, and then 20 mg once a day from week 4 onwards. In severe kidney disease, the usual maximum is 10 mg a day. Take it at the same time each day, with or without food. Some products are taken twice a day; follow the doctor’s instructions. Do not stop it suddenly without speaking to the doctor.
Interactions
Avoid using with Amantadine, Ketamine or Dextromethorphan, which act in a similar way and can cause confusion or hallucinations. Medicines or diets that make urine less acidic (such as Acetazolamide, sodium bicarbonate or a sudden change to a mainly vegetarian diet) can raise memantine levels. Cimetidine, Ranitidine, Quinine, Hydrochlorothiazide and nicotine can change levels. It may increase the effect of Levodopa and anticholinergic medicines, and people taking Warfarin should have their INR checked.
Contraindications
Allergy to memantine or any ingredient of the product.
Side Effects
Common: dizziness, headache, drowsiness, constipation, raised blood pressure, breathlessness and problems with balance. Less common: confusion, hallucinations, tiredness, vomiting, abnormal walking, fungal infections and blood clots. Fits (seizures) are rare.
Get urgent medical help if the person has a fit, sudden severe confusion or hallucinations, chest pain, sudden breathlessness, pain or swelling in one leg, or signs of a serious allergic reaction such as swelling of the face or throat.
Pregnancy and Lactation
There is little information on use in pregnancy; it should be used only if clearly needed and the doctor advises it. It is not known whether it passes into breast milk, so breastfeeding is not recommended during treatment.
Precautions and Warnings
Tell the doctor about epilepsy or past fits, a recent heart attack, heart failure, uncontrolled high blood pressure, kidney problems or a recent change in diet. Dizziness and drowsiness can affect driving and using machinery. Carers should watch for changes in behaviour and keep a list of all medicines the person takes.
Overdose
Too much may cause restlessness, drowsiness, dizziness, confusion, hallucinations, vomiting, slow movements, weakness or fits. Seek urgent medical help.
Therapeutic Class
NMDA receptor antagonist; anti-dementia medicine.
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.