Memantine

Memantine

Structure of Memantine

Memantine is a medication used to treat moderate to severe Alzheimer's disease. It is an NMDA receptor antagonist that works by blocking the effects of excessive glutamate in the brain, which is thought to contribute to the symptoms of Alzheimer's disease. Memantine is not a cure for Alzheimer's, but it can help improve symptoms and slow the progression of the disease in some patients.

Mechanism of Action

Memantine acts as an uncompetitive antagonist at the NMDA receptor, a type of glutamate receptor in the brain. Under normal conditions, glutamate is involved in learning and memory by activating NMDA receptors. However, in Alzheimer's disease, excessive glutamate activity can lead to neuronal damage and cognitive decline. Memantine binds to the NMDA receptor with moderate affinity, blocking the effects of excessive glutamate while allowing normal synaptic transmission.

Clinical Use

Memantine is primarily used in the management of moderate to severe Alzheimer's disease. It is often prescribed in combination with acetylcholinesterase inhibitors such as donepezil, rivastigmine, or galantamine. The combination therapy can provide additional benefits in terms of cognitive function and daily living activities.

Side Effects

Common side effects of memantine include dizziness, headache, confusion, and constipation. Less common side effects may include hallucinations, hypertension, and fatigue. Patients are advised to report any unusual symptoms to their healthcare provider.

Dosage and Administration

Memantine is available in tablet form, as an oral solution, and as an extended-release capsule. The typical starting dose is 5 mg per day, which is gradually increased to a maintenance dose of 20 mg per day. The extended-release form is usually started at 7 mg per day and increased to a maximum of 28 mg per day.

Pharmacokinetics

Memantine is well absorbed from the gastrointestinal tract, with a bioavailability of approximately 100%. It is partially metabolized in the liver and excreted primarily in the urine. The half-life of memantine is about 60 to 80 hours, allowing for once-daily dosing.

Ball-and-stick model of Memantine

History

Memantine was first synthesized in the late 1960s and was initially used as an antiviral agent. Its potential for treating Alzheimer's disease was discovered in the 1980s, and it was approved for this use in Europe in 2002 and in the United States in 2003.

Related Pages

• Alzheimer's disease
• NMDA receptor
• Glutamate
• Acetylcholinesterase inhibitor