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Memantine is an N-methyl-D-aspartate (NMDA) antagonist and is licensed for use in moderate-severe Alzheimer’s disease (AD).

Mechanism of Action

  • Memantine is an NMDA antagonist (AKA Glutamate receptor antagonist)
  • NMDA receptor found on post synaptic membrane
  • Prevents the binding of glutamate to NMDA receptor
  • Therefore, prevents excitotoxicity by preventing the influx of Ca2+ into the post synaptic membrane
  • By preventing excitotoxicity, memantine helps prevent neurodegeneration


Indication and dose

Moderate to severe Alzheimer’s Disease

  • Oral administration
  • Initially 5mg OD
  • Increase in increments of 5mg at weekly intervals
  • 20mg per day



Patients who have a history of convulsions



The interactions listed here are POTENTIALLY SERIOUS which is indicated by a black dot in the BNF. Further details of these interactions can be found in the BNF or Stockleys.

Furthermore, there are other interaction which are not potentially serious, nevertheless they should still be monitored and clinical judgement should be used.

  • Anaesthetics: Ketamine
  • Analgesics: Dextromethorphan
  • Dopaminergics: Amantadine


Side effects


Constipation, dizziness, drowsiness, dyspnoea, headache, hypertension

Hepatic Impairment

BNF states that is should be avoided in the severe hepatic impairment.


Renal Impairment

  • Reduce dose to 10mg OD, if eGFR 30-49ml/min/1.73m2. If well tolerated then after 7 days the dose can be increased in steps to 20mg OD
  • Reduce dose to 10mg OD, if eGFR 5-29ml/min/1.73m2
  • AVOID if eGFR is < 5ml/min/1.73m2




BNF 70, Joint Formulary Committee (2015) British National Formulary. 70th Ed., London: British Medical Association and Royal Pharmaceutical Society of Great Britain.

National Institute for Health and Clinical Excellence, NICE technology appraisal guidance [TA217], National Institute for Health and Clinical Excellence, March 2011



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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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