Alzheimer Disease Pharmacology: Acetylcholinesterase Inhibitors and NMDA Receptor Antagonists

Overview of Alzheimer Disease Treatment

• Alzheimer disease is the most common cause of dementia.

• There is currently no cure for Alzheimer disease.

• Medications are utilized to help mitigate specific symptoms and improve the client's quality of life.

• Pharmacological treatments are broadly categorized into two main classes:

  • Acetylolonsterase inhibitors.

  • NMDA receptor antagonists.

Acetylolonsterase Inhibitors

• Examples of Medications:

  • Rivastigamine.

  • Galantamine.

  • Donpazil.

• Routes of Administration:

  • Most are taken orally.

  • Rivastigamine can be administered both orally and in the form of a transdermal patch.

• Mechanism of Action (MOA):

  • Once absorbed, the medications travel to the brain via the bloodstream.

  • They inhibit the enzyme known as acetylolonsterase.

  • Normally, acetylolonsterase breaks down the neurotransmitter acetylcholine.

  • Inhibition leads to a buildup of acetylcholine in the synaptic cleft.

  • This results in increased and prolonged effects of the neurotransmitter.

• Therapeutic Rationale:

  • Evidence suggests Alzheimer disease is related to low levels of acetylcholine in the brain; therefore, these inhibitors help improve symptoms.

Side Effects and Adverse Reactions of Acetylolonsterase Inhibitors

• Conuric (Cholinergic) Side Effects:

  • Meiosis.

  • Blurred vision.

  • Headaches.

  • Dizziness.

  • Drowsiness.

• Respiratory System Impacts:

  • Acetylcholine triggers bronchoconstriction.

  • Increases bronchial secretions.

  • Manifests clinically as dispnnea and a persistent cough.

• Cardiovascular System Impacts:

  • Slows the heart rate.

  • Reduces blood pressure.

  • Potential complications include brada cardia, heart block, hypotension, and cardiac arrest.

• Gastrointestinal (GI) Tract Impacts:

  • Increased GI motility and secretions.

  • Nausea and vomiting.

  • Abdominal cramps.

  • Diarrhea.

  • Increased salivation.

  • Involuntary defecation.

  • Gastrointestinal bleeding.

• Urinary Tract Impacts:

  • Stimulates bladder muscles.

  • Relaxation of the sphincter.

  • May result in a sense of urinary urgency.

Contraindications and Precautions for Acetylolonsterase Inhibitors

• Cautions for use include clients with:

  • Brada cardia.

  • Intestinal or urinary obstruction.

  • Pregnancy or breastfeeding.

  • Epilepsy or a history of seizures.

  • Asthma.

  • Chronic obstructive pulmonary disease (COPD).

  • Arrhythmias.

  • Coronary artery disease.

  • Peptic ulcer disease.

  • Severe hippatic or renal impairment.

NMDA Receptor Antagonists

• Primary Example:

  • Mamantene.

• Route of Administration:

  • Taken orally.

• Mechanism of Action (MOA):

  • Works by blocking Nmethyl Daspartate (NMDA) receptors in the brain.

• Therapeutic Rationale:

  • In Alzheimer disease, there is an excess of the neurotransmitter glutamate.

  • Glutamate binds to NMDA receptors, causing an excessive influx of calcium.

  • High calcium levels lead to neuronal damage and cellular death.

  • NMDA receptor antagonists limit this calcium influx and prevent neuronal damage.

• Side Effects:

  • Drowsiness.

  • Headache.

  • Agitation.

  • Nausea and vomiting.

  • Constipation or diarrhea.

• Contraindications and Precautions:

  • Use with caution in pregnant or breastfeeding clients.

  • Use with caution in clients with epilepsy or a history of seizures.

  • Use with caution in those with severe hippatic or renal impairment.

Nursing Considerations and Baseline Assessment

• Baseline Assessment Requirements:

  • Weight.

  • Vital signs.

  • Hippatic and renal function.

  • Cardiac and respiratory function.

  • Cognitive and behavioral function: assess memory, reasoning, mood, and ability to perform activities of daily living (ADLs).

• General Client Education:

  • Explain why the medication is prescribed (to slow disease progression).

  • Stress the importance of taking the medication exactly as directed.

  • Instruct the client not to stop the medication abruptly.

  • Warn about common side effects of both classes: drowsiness and dizziness.

  • Advise the client to make position changes slowly.

  • Advise caution with ambulation.

Application-Specific Nursing Interventions

• For Acetylolonsterase Inhibitors:

  • Teach the client to take the medication with food to reduce gastric upset.

  • Advise the client to contact their healthcare provider immediately if they develop a cough, trouble breathing, diarrhea, or urinary urgency.

• For NMDA Receptor Antagonists (Mamantene):

  • Medication can be taken with or without food.

  • Liquid Form: Teach the use of the specific oral solution dispenser provided; do not mix with other liquids.

  • Storage: Store at room temperature in a dry place.

  • Diet and Urine pH: Clearance is reduced by alkaline urine. Stress the importance of a balanced diet with a variety of foods to maintain urine pH within normal limits.

• Ongoing Monitoring during Treatment:

  • Periodically monitor weight and vital signs.

  • Continue checking hippatic, renal, cardiac, and respiratory function.

  • Regularly assess mental and behavioral status to evaluate the effectiveness of the treatment.