NMDA Receptor Antagonist

NMDA receptor antagonists help treat moderate to severe Alzheimer’s disease. They slow the decline of cognitive and physical functioning in clients. Clients may take NMDA receptor antagonists in conjunction with cholinesterase inhibitors.

Prototype and Other Medications

Medication Classification – NMDA Receptor Antagonist

Currently, there is only one NMDA receptor antagonist on the market for the treatment of Alzheimer’s disease, called memantine.

Expected Pharmacologic Action

NMDA receptor antagonists block excess glutamate from stimulating NMDA receptors, decreasing the influx of calcium into neurons in the brain. By reducing levels of intracellular calcium, they restore normal nerve transmissions. NMDA receptor antagonists may slow the progression of Alzheimer’s disease by preventing neuronal damage from high levels of calcium.

Adverse Drug Reactions

NMDA receptor antagonists can cause CNS effects such as headaches, dizziness, and increased confusion. Some clients may also have constipation. Memantine seems to be better tolerated than the cholinesterase inhibitors.

Interventions

When caring for clients taking an NMDA receptor antagonist, monitor for CNS effects such as dizziness, headache, and increased confusion. Keep them safe if dizziness or increased confusion occurs. Monitor for constipation and provide fiber supplements, stool softeners, and laxatives as needed.

Administration

Memantine is available in oral tablet form or as a liquid solution. Give it with or without food.

Client Instructions

Memantine cause constipation or diarrhea. Instruct clients to monitor diet as needed. Instruct clients to report to the provider CNS effects such as dizziness, headache, or increased confusion.

Safety Alert

Clients with Alzheimer’s disease might not recognize when they are experiencing dizziness and confusion. Instruct caregivers to watch for these side effects and to report them to the provider should they occur.

Contraindications and Precautions

Do not administer memantine to clients who have renal failure. Use it with caution for clients who have liver or renal disorders. Due to a decrease in metabolism and excretion, memantine may need a lower dosage. Exercise caution with clients who have a history of seizure disorders and with older adults.

Interactions

Memantine can interact with over-the-counter antacids, such as sodium bicarbonate, and other medications that increase the pH of the urine. This can increase levels of memantine and lead to possible toxicity.