NMDA Receptor Antagonist — Dementia Pregnancy: Memantine should not be used during pregnancy unless clearly necessary. There are no or limited data in pregnant women, and animal studies indicate a potential for reducing intrauterine growth at exposure levels identical to or slightly higher than human exposure. Women taking memantine should not breast-feed (excretion into human milk is not known but probable given the lipophilicity of the substance).

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.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 5 mg once daily in week 1 (days 1 to 7), 10 mg once daily in week 2 (days 8 to 14), 15 mg once daily in week 3 (days 15 to 21), then a maintenance dose of 20 mg once daily from week 4 onwards

Route: Oral — tablets may be taken with or without food

Frequency: Once a day, at the same time every day

Max: 20 mg per day

UK SPC (Memantine 20 mg film-coated tablets, eMC product 14496), Alzheimer's dementia. Treatment should be initiated and supervised by a physician experienced in the diagnosis and treatment of Alzheimer's dementia, and should only be started if a caregiver is available who will regularly monitor intake. The maintenance dose is reached by upward titration of 5 mg per week over the first 3 weeks to reduce the risk of undesirable effects. Tolerance and dosing should be reassessed regularly, preferably within three months of starting and thereafter according to current clinical guidelines; discontinuation should be considered when a therapeutic effect is no longer evident or the patient does not tolerate treatment. Elderly: on the basis of the clinical studies, the recommended dose for patients over 65 years is 20 mg per day, as described above. Hepatic impairment: no dose adjustment in mild or moderate impairment (Child-Pugh A and B); no data in severe hepatic impairment and administration is not recommended. Paediatric population: no data available. (US label, cross-check: starting dose 5 mg once daily, increased in 5 mg increments to 10 mg/day given as 5 mg twice daily, then 15 mg/day, then 20 mg/day given as 10 mg twice daily, with a minimum interval of one week between increases; if the patient fails to take memantine for several days, dosing may need to be resumed at lower doses and retitrated.)

Dose adjustments

Renal

Creatinine clearance 50 to 80 ml/min (mild impairment): no dose adjustment required. Creatinine clearance 30 to 49 ml/min (moderate impairment): daily dose should be 10 mg per day; if well tolerated after at least 7 days of treatment, the dose could be increased up to 20 mg/day according to the standard titration scheme. Creatinine clearance 5 to 29 ml/min (severe impairment): daily dose should be 10 mg per day. (US label: a target dose of 5 mg twice daily is recommended in severe renal impairment, creatinine clearance 5 to 29 ml/min by Cockcroft-Gault.)

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm 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.

Contraindications

Hypersensitivity to the active substance or to any of the excipients

Side effects

Dizziness (common; 6.3% versus 5.6% placebo)
Headache (common; 5.2% versus 3.9% placebo)
Constipation (common; 4.6% versus 2.6% placebo)
Hypertension (common; 4.1% versus 2.8% placebo)
Somnolence (common; 3.4% versus 2.2% placebo)
Also common: balance disorders, dyspnoea, drug hypersensitivity, elevated liver function tests, fatigue; uncommon: confusion, hallucinations (mainly in severe Alzheimer's disease), cardiac failure, venous thrombosis/thromboembolism; very rare: seizures

Interactions

Drugs and conditions that make the urine alkaline (e.g. carbonic anhydrase inhibitors, sodium bicarbonate; also renal tubular acidosis or severe urinary tract infection) — memantine clearance is reduced by about 80% at urine pH 8, risking accumulation and increased adverse effects; use with caution (US label)
Other NMDA antagonists — amantadine, ketamine and dextromethorphan; combined use has not been systematically evaluated and should be approached with caution (US label)

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. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Memantine · NMDA receptor antagonist — dementia

Pathways