Morysa (Memantine Hydrochloride)

Memantine hydrochloride is used in the management of neurodegenerative conditions that involve glutamate‑mediated excitotoxicity.

• Alzheimer’s disease (moderate to severe): helps maintain cognitive function and daily living activities.
• Behavioral symptoms of Alzheimer’s disease: may reduce agitation and aggression.
• Functional decline in Alzheimer’s disease: may slow progression of daily functional loss.

• Memantine hydrochloride acts as a non‑competitive antagonist at the NMDA (N‑methyl‑D‑aspartate) receptor. By binding to the receptor-associated ion channel, it reduces excessive calcium influx caused by prolonged glutamate activation, thereby decreasing neuronal excitotoxicity and supporting neuronal survival in Alzheimer’s disease.

Memantine is generally well tolerated, but a range of adverse reactions have been reported.

Common Side Effects

• Dizziness: sensation of light‑headedness or unsteadiness.
• Headache: mild to moderate cranial pain.
• Constipation: reduced bowel movements.
• Confusion: transient disorientation or difficulty concentrating.
• Fatigue: feeling unusually tired.
• Hypertension: elevated blood pressure readings.

Serious or Rare Side Effects

• Seizures: convulsive episodes requiring immediate medical attention.
• Allergic reactions: rash, itching, swelling, or anaphylaxis.
• Stevens‑Johnson syndrome: severe skin blistering and detachment.
• Hepatic dysfunction: abnormal liver enzyme elevations.
• Cardiac arrhythmias: irregular heart rhythms.
• Suicidal thoughts: emergence of suicidal ideation or behavior.

When prescribing memantine, clinicians should consider several safety factors.

• Renal impairment: dose adjustment may be required in patients with reduced kidney function.
• History of seizures: monitor closely for increased seizure activity.
• Cardiovascular disease: use cautiously in patients with uncontrolled hypertension or arrhythmias.
• Pregnancy: safety category unknown; avoid unless potential benefit justifies risk.
• Concomitant medications: review all drugs for possible interactions before initiating therapy.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Memantine may interact with other medications that affect the central nervous system or NMDA pathways.

Major Interactions (Avoid)

• Amantadine: combined use can increase neurotoxic risk.
• Ketamine: additive NMDA antagonism may cause excessive CNS depression.
• Other NMDA antagonists: heightened risk of dizziness, confusion, and sedation.

Moderate Interactions (Monitor Closely)

• Anticholinergics: may diminish memantine’s cognitive benefits.
• Diuretics: can raise plasma concentrations of memantine.
• CNS depressants (e.g., benzodiazepines): may enhance dizziness and sedation.