What is the recommended dosing for Namenda (memantine)?

Namenda (Memantine) Dosing

The recommended starting dose of memantine is 5 mg once daily, titrated weekly by 5 mg increments to a target maintenance dose of 20 mg daily (10 mg twice daily), with dose reductions required for severe renal impairment. 1

Standard Dosing Regimen

The FDA-approved titration schedule follows a structured 4-week escalation:

• Week 1: 5 mg once daily 1
• Week 2: 10 mg daily (5 mg twice daily) 1
• Week 3: 15 mg daily (5 mg and 10 mg as separate doses) 1
• Week 4 and beyond: 20 mg daily (10 mg twice daily) - this is the effective maintenance dose demonstrated in controlled trials 1

The minimum interval between dose increases must be one week to ensure tolerability 1.

Administration Guidelines

• Memantine can be taken with or without food 1
• The oral solution should not be mixed with any other liquid 1
• If a single dose is missed, do not double the next dose - simply resume the regular schedule 1
• If multiple doses are missed over several days, restart at a lower dose and retitrate upward to avoid adverse effects 1

Extended-Release Formulation

An extended-release formulation (Namenda XR) is available at 28 mg once daily, which provides higher total daily exposure than the immediate-release 20 mg/day regimen 2. The ER capsules can be opened and sprinkled on applesauce for patients with swallowing difficulties 2. This formulation offers improved convenience and may enhance adherence, though direct comparative efficacy trials between IR and ER formulations have not been conducted 2.

Renal Impairment Adjustments

For patients with severe renal impairment (creatinine clearance 5-29 mL/min), reduce the target dose to 5 mg twice daily (10 mg total daily). 1 No dose adjustment is needed for mild to moderate renal impairment 1.

Hepatic Impairment

Memantine should be administered with caution in patients with severe hepatic impairment, though specific dose reductions are not mandated by the FDA label 1.

Common Pitfalls to Avoid

• Do not escalate doses faster than weekly intervals - this increases the risk of adverse effects including headache, dizziness, and diarrhea 2, 3
• Do not restart at full dose after treatment interruption - patients who miss several days require retitration from lower doses 1
• Do not overlook renal function assessment - failure to dose-reduce in severe renal impairment can lead to drug accumulation 1

Combination Therapy Considerations

When memantine ER 28 mg is added to stable cholinesterase inhibitor therapy (particularly donepezil), it demonstrates superior efficacy on cognition, global status, and behavior compared to cholinesterase inhibitor monotherapy in moderate to severe Alzheimer's disease 3. The fixed-dose combination of memantine ER 28 mg/donepezil 10 mg is bioequivalent to coadministration of individual agents and may improve adherence 3.