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NMDA Receptor Antagonist — Dementia

Memantine

Brand names: Ebixa, Namenda

Memantine is an NMDA-receptor antagonist used for moderate-to-severe Alzheimer's disease, and for moderate disease where a cholinesterase inhibitor is unsuitable.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

The recommended starting dose of memantine hydrochloride tablets is 5 mg once daily. The dose should be increased in 5 mg increments to 10 mg/day (5 mg twice daily), 15 mg/day (5 mg and 10 mg as separate doses), and 20 mg/day (10 mg twice daily). The minimum recommended interval between dose increases is one week. The dosage shown to be effective in controlled clinical trials is 20 mg/day. Memantine hydrochloride tablets can be taken with or without food. If a patient misses a single dose of memantine hydrochloride tablets, that patient should not double up on the next dose. The next dose should be taken as scheduled. If a patient fails to take memantine hydrochloride tablets for several …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2023-08-17. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It is an uncompetitive antagonist at N-methyl-D-aspartate (NMDA) glutamate receptors, reducing the effects of pathologically raised glutamate that may contribute to neuronal dysfunction.

Prescribing in practice

  • Reduce the dose in renal impairment according to creatinine clearance.
  • It is generally well tolerated; dizziness, headache, constipation and somnolence may occur.
  • It can be used alongside a cholinesterase inhibitor.

Monitoring

Review cognitive, functional and behavioural response periodically, and monitor renal function as it influences dosing. Reassess the continued benefit of treatment over time.

Counselling the patient

  • Take it regularly each day to get the most benefit.
  • Tell your prescriber if you develop dizziness or other new symptoms.
  • It may be used together with another dementia medicine.

Evidence & guidelines

Guideline-recommended for Alzheimer's disease (NICE NG97).

Reference: NICE NG97 (Dementia); Cochrane Review on Memantine; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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