Neurology
Memantine
An NMDA-receptor antagonist — Used in moderate-to-severe Alzheimer's disease — a different mechanism from the cholinergic drugs.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
What it is
Memantine treats moderate-to-severe Alzheimer's disease. It can be used on its own or alongside a cholinesterase inhibitor, and works through a completely different mechanism.
How it works
In Alzheimer's disease, over-activity of a brain messenger system (glutamate acting at NMDA receptors) is thought to contribute to nerve-cell damage and to disrupt the signalling needed for memory. Memantine gently dampens this excess activity without blocking normal signalling, which is thought to protect function.
In practice
In practice memantine is used in moderate-to-severe Alzheimer's disease, either when the cholinesterase inhibitors are not suitable or tolerated, or added to them in more advanced disease. It is generally better tolerated than the cholinergic drugs and does not cause their nausea or slow pulse; the points to watch are that it is cleared by the kidneys, so the dose is reduced when renal function is poor, and that it can occasionally cause dizziness, headache or confusion. As with the other dementia drugs the goal is symptom support — maintaining function and easing some behavioural symptoms — rather than changing the disease itself, and benefit is reviewed over time.
Examples
Practical use
How to take it & use it well
- Take memantine once a day as prescribed, with or without food, at about the same time each day.
- Expect a gradual build-up from a low starting dose, as increasing slowly helps your body adjust and reduces side effects.
- Swallow tablets with water, and if you use a liquid form, measure it carefully with the device provided.
- Do not stop suddenly without advice; speak to your team first if you have concerns about side effects.
- Tell your prescriber if you have kidney problems, as the dose may need to be lower.
- Make sure carers understand the routine so the person with dementia takes it reliably each day.
Common uses
- Moderate-to-severe Alzheimer's disease
- Where cholinesterase inhibitors are unsuitable or not tolerated
- Add-on in more advanced disease
Monitoring
- Cognitive and functional benefit at review
- Renal function (for dosing)
- Tolerability (dizziness, confusion)
Weighing it up
Advantages & disadvantages
Advantages
- Can help with symptoms of moderate to severe Alzheimer's disease, supporting memory, thinking and daily function.
- Works in a different way from the donepezil group, so it can be used when those are not suitable or alongside them in some cases.
- Generally well tolerated, with fewer stomach side effects than the donepezil group.
- Simple once-daily dosing makes it easier to fit into a routine.
Disadvantages
- Treats symptoms rather than curing the disease, and the benefit can lessen as dementia progresses.
- May cause side effects such as dizziness, headache, constipation, drowsiness or raised blood pressure.
- Needs a lower dose in people with reduced kidney function, so kidney health must be checked.
- Can occasionally cause confusion or hallucinations, which should be reported to your team.
Key safety principles
What to watch for
- Generally well tolerated; can cause dizziness, headache or confusion.
- Reduce the dose in significant renal impairment (it is renally cleared).
- Symptom support, not a cure — benefit is reviewed.
Key interactions
What to avoid or check alongside
- Combining memantine with other medicines that act on the same brain pathway, such as amantadine or ketamine, may add to side effects and is avoided.
- Medicines that make the urine more alkaline, such as some antacids and carbonic anhydrase inhibitors, can raise memantine levels.
- Memantine may alter the effect of some Parkinson's medicines and muscle relaxants, so report new symptoms.
- Using it with other sedating medicines can add to drowsiness.
- Tell your pharmacist about all your medicines so any overlap can be checked.
Patient & carer advice
- It supports symptoms rather than curing the condition
- It is usually well tolerated and can be combined with other dementia treatment
- Tell us about kidney problems, as the dose may need adjusting
Use with
Related clinical calculators
Dose and risk decisions for this class often depend on renal function, weight or bleeding/stroke risk. These tools help:
Answers
Memantine: frequently asked questions
When is memantine used?
Memantine is mainly used for moderate to severe Alzheimer's disease. It works differently from the donepezil group and can be used when those are unsuitable or, in some cases, alongside them.
Is memantine well tolerated?
It is generally well tolerated, often with fewer stomach side effects than the donepezil group. Some people get dizziness, headache or constipation, which usually settle as the body adjusts.
Does kidney function affect memantine?
Yes. Memantine is cleared by the kidneys, so people with reduced kidney function usually need a lower dose. Your team will check your kidneys before and during treatment.
Does memantine cure dementia?
No. It can ease symptoms and support daily function for a time, but it does not cure or halt Alzheimer's disease, which continues to progress.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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