What is the recommended dosage of Namenda (memantine) for dementia?

Recommended Dosage of Namenda (Memantine) for Dementia

The recommended dosage of Namenda (memantine) for dementia is 5 mg once daily initially, with gradual titration to a target dose of 20 mg/day (10 mg twice daily), increasing by 5 mg increments weekly. 1

Dosing Schedule and Titration

The FDA-approved dosing regimen for memantine follows a specific titration schedule:

1. Initial dose: 5 mg once daily
2. Week 2: Increase to 10 mg/day (5 mg twice daily)
3. Week 3: Increase to 15 mg/day (5 mg and 10 mg as separate doses)
4. Week 4 and beyond: Reach target dose of 20 mg/day (10 mg twice daily)

The minimum recommended interval between dose increases is one week, allowing for better tolerability 1.

Administration Considerations

• Memantine can be taken with or without food
• If doses are missed for several days, restart at a lower dose and retitrate
• For oral solution formulation (2 mg/mL), use the provided dosing syringe and do not mix with other liquids 1

Special Populations

Renal Impairment

• For patients with severe renal impairment (creatinine clearance 5-29 mL/min), the recommended target dose is reduced to 10 mg/day (5 mg twice daily) 1

Hepatic Impairment

• Use with caution in patients with severe hepatic impairment 1

Extended-Release Formulation

An extended-release (ER) formulation is available as an alternative:

• Namenda XR 28 mg once daily
• Provides more convenient dosing and may improve adherence
• Capsules can be opened and sprinkled on applesauce for patients with swallowing difficulties 2

Efficacy Considerations

Memantine is indicated specifically for moderate to severe Alzheimer's dementia 1. It works as an N-methyl-D-aspartate (NMDA) receptor antagonist that partially blocks glutamatergic neurotransmission in the central nervous system 3.

Clinical evidence shows that:

• Memantine is not effective for mild Alzheimer's disease 4
• Combination therapy with memantine plus a cholinesterase inhibitor (e.g., donepezil) is recommended for moderate to severe Alzheimer's disease 4, 5
• Memantine should be deprescribed for individuals with mild cognitive impairment 6, 4

Monitoring and Discontinuation

Consider discontinuing memantine if:

• Clinically meaningful worsening of dementia occurs over 6 months
• No benefit is observed during treatment
• Patient develops severe or end-stage dementia
• Intolerable side effects develop (e.g., confusion, dizziness, falls)
• Poor medication adherence 6, 4

When discontinuing memantine:

• Reduce dose by 50% every 4 weeks until reaching the initial starting dose
• After 4 weeks at the starting dose, discontinue completely
• Monitor for worsening and consider reinitiating if clinically meaningful decline occurs 6, 4

Common Side Effects

The most common adverse events include:

• Dizziness
• Headache
• Confusion
• Constipation 1

Important Cautions

• Conditions that raise urine pH may decrease urinary elimination of memantine, resulting in increased plasma levels 1
• Do not discontinue memantine in patients with clinically meaningful psychotic symptoms, agitation, or aggression until these symptoms have stabilized 6, 4
• Continue treatment in patients who have had meaningful reduction in neuropsychiatric symptoms even with cognitive/functional decline 6, 4