Memantina Sun (Memantine Hydrochloride)

• Memantine is an NMDA receptor antagonist that modulates glutamatergic activity and is indicated for the treatment of cognitive decline associated with neurodegenerative conditions, most notably Alzheimer’s disease.
• Alzheimer's disease (moderate to severe): Improves cognition, behavior, and functional abilities in patients with moderate to severe disease.
• Behavioral symptoms of Alzheimer’s disease: Reduces agitation and aggression in affected individuals.
• Functional impairment in Alzheimer’s disease: Supports activities of daily living and slows functional decline.

• Memantine binds to the phencyclidine site of the NMDA (N‑methyl‑D‑aspartate) receptor as a non‑competitive antagonist. By blocking excessive calcium influx caused by overstimulation of glutamate, it reduces excitotoxic neuronal injury while preserving normal synaptic transmission. The drug’s low‑affinity, voltage‑dependent binding allows it to dissociate during physiological activity, maintaining essential neurotransmission. This modulation helps to protect cortical and hippocampal neurons implicated in memory processes.

Memantine may be associated with several adverse reactions, ranging from mild to serious.

Common Side Effects

• Dizziness: transient sensation of light‑headedness.
• Headache: mild to moderate intensity.
• Constipation: reduced bowel movements.
• Confusion: occasional disorientation.
• Hypertension: modest increase in blood pressure.
• Insomnia: difficulty falling or staying asleep.

Serious or Rare Side Effects

• Seizures: potential for convulsive episodes.
• Hallucinations: visual or auditory disturbances.
• Cardiac arrhythmia: irregular heart rhythm.
• Severe skin reactions: such as Stevens‑Johnson syndrome.
• Hepatic dysfunction: elevated liver enzymes or jaundice.

Before initiating therapy, consider the following precautions.

• Renal impairment: dose adjustment may be required in patients with reduced kidney function.
• Hepatic impairment: use with caution in severe liver disease.
• Concomitant NMDA antagonists: avoid combining with other NMDA‑blocking agents.
• History of seizures: monitor closely for increased seizure risk.
• Pregnancy and lactation: safety not established; prescribe only if benefit outweighs potential risk.
• Store below 25°C: keep in the original pack, protect from moisture.

Memantine can interact with several medicines; interactions are categorized by clinical significance.

Major Interactions (Avoid)

• Amantadine: combined NMDA antagonism may increase toxicity.
• Strong CYP3A4 inhibitors: may raise memantine plasma concentrations.
• Probenecid: reduces renal clearance, leading to higher exposure.

Moderate Interactions (Monitor Closely)

• NSAIDs: may increase risk of edema.
• Anticholinergic agents: additive cognitive impairment.
• Antihypertensives: potential enhancement of blood‑pressure‑lowering effect.
• Diuretics: monitor electrolyte balance.
• SSRIs: possible increase in serotonergic side effects.