Memantine Eg (Memantine)

Memantine is an NMDA receptor antagonist used in the management of Alzheimer’s disease and related cognitive disorders.

• Moderate to severe Alzheimer’s disease: improves cognition, functional abilities and global clinical status in adult patients.
• Alzheimer’s disease with behavioral disturbances: may reduce agitation, aggression and psychotic symptoms.
• Dementia associated with Alzheimer’s pathology: supports maintenance of daily living activities and slows functional decline.
• Patients with progressive neurodegeneration due to Alzheimer’s: provides symptomatic benefit in memory and attention.
• Adjunct to cholinesterase inhibitors: can be combined to enhance overall therapeutic effect in Alzheimer’s management.

• Memantine binds to the phencyclidine site of the N‑methyl‑D‑aspartate (NMDA) receptor as a non‑competitive antagonist. By blocking excessive calcium influx caused by overstimulation of glutamate, it reduces excitotoxic neuronal injury. This modulation of glutamatergic transmission helps to preserve neuronal function and slows the progression of cognitive decline associated with Alzheimer’s disease. The drug’s voltage‑dependent blocking properties allow normal synaptic activity while preventing pathological activation.

Memantine may be associated with a range of adverse reactions, varying in frequency and severity.

Common Side Effects

• Dizziness: transient sensation of light‑headedness or imbalance.
• Headache: mild to moderate intensity, often resolves without intervention.
• Constipation: reduced bowel movements, may require dietary adjustment.
• Fatigue: feeling of tiredness or reduced energy levels.

Serious or Rare Side Effects

• Seizures: rare occurrence of convulsive episodes requiring immediate medical attention.
• Severe allergic reaction: rash, swelling, or difficulty breathing indicating possible anaphylaxis.
• Hallucinations or psychosis: rare emergence of visual or auditory disturbances.
• Suicidal thoughts: rare emergence of depressive ideation, necessitating prompt evaluation.
• Liver toxicity: abnormal liver function tests indicating potential hepatic injury.

When prescribing memantine, clinicians should consider several safety factors to minimize risk.

• Renal impairment: monitor kidney function and adjust therapy as needed.
• Hepatic impairment: use with caution and observe liver enzymes regularly.
• History of seizures: monitor closely for increased seizure activity.
• Concurrent use with other NMDA antagonists: avoid combined use due to additive neurotoxicity.
• Pregnancy and lactation: safety not established; weigh potential benefits against risks.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Memantine can interact with other medicines, affecting its safety or effectiveness.

Major Interactions (Avoid)

• Amantadine: combined use may increase neurotoxic risk.
• Ketamine: additive NMDA antagonism can lead to excessive central nervous system depression.

Moderate Interactions (Monitor Closely)

• Anticholinergic agents: may diminish memantine’s cognitive benefits.
• Diuretics: can influence blood pressure and electrolyte balance.
• CNS depressants (e.g., benzodiazepines): may enhance sedation and dizziness.