Memantine
An NMDA receptor antagonist used alone or with donepezil when Alzheimer's disease is moderate to severe.
Drug card
- How it works
- Blocking the NMDA receptor channel to damp excess glutamate signaling
- Used for
- Moderate to severe Alzheimer's disease
- Alzheimer's disease, added to donepezil
- Known for
- Dizziness and balance problems
- Confusion
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does memantine work?
A low to moderate affinity, uncompetitive blocker that enters and plugs the open NMDA receptor channel, reducing the prolonged calcium entry driven by excess glutamate. It also blocks 5-HT3 and nicotinic receptors. About half leaves unchanged in the urine, so kidney function and urine pH change its levels.
Uses
What is memantine used for?
- Moderate to severe Alzheimer's disease
- Alzheimer's disease, added to donepezil
Side effects
Side effects of memantine
- Dizziness and balance problemsKnown for
- ConfusionKnown for
- Headache
- Constipation
- Drowsiness
- Raised blood pressure
- Hallucinations, mainly in severe diseaseSerious
- Shortness of breath
- Seizures (very rare)Serious
- Blood clots in the veinsSerious
- Pancreatitis (rare)Serious
- Hepatitis (rare)Serious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Alkaline urine (a sudden vegetarian diet, sodium bicarbonate, renal tubular acidosis) slows its excretion and raises levels.
- Severe kidney impairment calls for a lower dose.
- Amantadine, ketamine and dextromethorphan, which also block NMDA receptors, are best avoided with it.
- Care in epilepsy or past seizures.
Good to know: It works by a different route from the cholinesterase inhibitors, so it can be given with donepezil; a fixed combination of the two is licensed in the US.
Remember it
A way to remember it
Memantine mutes the glutamate noise.
It plugs the open NMDA channel, damping the steady excess glutamate signaling thought to damage neurons in Alzheimer's disease.
Written for biofideX
Its class
NMDA receptor antagonists
Memantine, the NMDA receptor antagonist used in dementia, blocks the open ion channel of the glutamate NMDA receptor with moderate affinity, in a voltage-dependent way. It damps the steady excess of glutamate signaling thought to harm neurons in Alzheimer's disease, limiting the calcium overload behind excitotoxicity. It eases symptoms but has not been shown to slow neurodegeneration.
Easily mixed up with cholinesterase inhibitors for dementia and intravenous anesthetics.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Memantine hydrochloride tablets: label (DailyMed)
- Memantine and donepezil capsules: label (DailyMed)
- Memantine (NCI Thesaurus)
- Memantine: product information (EMA)
- Memantine (NHS)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Parkinson's, dementia and migraine
Memantine is one of 9 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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