memantine NAMENDA
Class: NMDA Receptor AntagonistFDA Indications: Alzheimer's Dementia
Off-Label Use: OCD (augmenting W/ SSRI), Post-Traumatic Cognitive Impairment
Prescribing
Forms: 5, 10mg tablet; 7, 14, 21, 28mg extended release capsule; 2 mg/mL po solnDose Range: 5-20 mg/day
Starting: 5 mg qd. Increase dose in 5 mg increments to a maintenance dose of 10 mg bid. A minimum of 1 week of treatment with the previous dose should be observed before increasing the dose.
Precautions
Possible Risk of TdPSide Effects: dizziness, headache, confusion, constipation
Pharmacodynamics
1° MOA: NMDA receptor antagonist, works by preventing too much glutamate from damaging neuronsTarget: NMDA, 5HT3, σ (antagonism)
Pharmacokinetics
t½: 70 (60-80)° TMAX: 3-8°Substrate of: Primarily renal
Inhibits: 2B6; Induces: ∅
Active Metabolites: ∅
DDIs
- - Clearance is reduced by ~80% under alkaline urine conditions at pH 8 ∴ so use with caution when coadminstered with drugs that can alkalize urine (e.g. carbonic anhydrase inhibitors, sodium bicarbonate)
Misc
- - Can be used as monotherapy but is more commonly co-prescribed with a ChEI
- - Mildly augments the effects of donepezil in clinical trials
- - Probably less effective for mild dementia; this indication was rejected by the FDA in 2005
- - Per Cochrane review, slightly fewer patients with moderate to severe Alzheimer's dementia developed agitation while taking memantine than placebo (12% vs 18%)
- - Several case reports and two recent open-label case series suggest that the addition of memantine to standard medication therapy can benefit both children and adults with OCD
Special Populations
Category B—There are no adequate and well-controlled studies of memantine in pregnant women. NAMENDA should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
It is not known whether this drug is excreted in human milk.
There were no clinically meaningful differences in most adverse events reported by patient groups ≥65 and <65.
The terminal elimination half-life increased by 18%, 41%, and 95% in subjects with mild, moderate, and severe renal impairment, respectively, compared to healthy subjects. No dosage adjustment is needed in patients with mild or moderate renal impairment. Dosage should be reduced in patients with severe renal impairment.
Administer with caution to patients with severe hepatic impairment.