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

 

Cautions

Patients who have a history of convulsions

 

Interactions

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

Common:

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

 

 

References

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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