Memantine is used to treat moderate to severe Alzheimer's disease. It acts on the glutamatergic system by blocking NMDA receptors.
Indications
Memantine is indicated for the treatment of patients with moderate to severe AD (i.e. - the MMSE score must be < 20).[1]
Mechanism of Action
Glutamate is the main excitatory neurotransmitter in the brain, and binds to the NMDA receptor in the brain.
Excessive glutamate release leads to excitotoxicity, which is thought to be a major mechanism of neurodegeneration in ischemia from stroke, trauma from traumatic brain injuries, and neurodegenerative disorders.
However, glutamatergic transmission also important for long-term potentiation, and this is a proposed cellular model for learning and memory
Memantine is a non-competitive NMDA receptor antagonist that is thought to help prevent excitotoxicity (mediated by Ca2+)
Memantine blocks NMDA receptors and so may reduce the negative effects of glutamate, namely the excitotoxicity pathway via NMDA receptor over-activation, which is thought to prevent cell death.
Memantine may also be neuroprotective.
Dosing
Week 1: 5 mg PO qAM
Week 2: 5 mg PO BID
Week 3: 10 mg PO qAM and 5mg PO qHS
Week 4: 10 mg PO BID
Renal
Dose should be halved in patients with renal impairment.[2]
Contraindications
Use with caution in patients with severe hepatic or renal impairment
Side Effects
Memantine is generally well tolerated. Most common side effects may include insomnia, diarrhea, urinary incontinence, confusion, dizziness, or agitation.