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Learn How Medications Work —
and Their Side Effects
The management of Alzheimer’s disease can be overwhelming, both to patients and caregivers. In addition, understanding the medications used to manage this disease can be very challenging, especially since there is a plethora of medications marketed today to help control this debilitating condition. Although there is no cure, Alzheimer’s disease medications have been proven to slow down the progression of the disease and improve patient’s quality of life. This article will concentrate on how these medications work and their side effects.
Medications for Alzheimer’s disease can be divided into two groups based on their mechanism of action or pharmacological effect. The first group is the acetylcholinesterase inhibitors. There are currently four FDA approved medications: Aricept®, Cognex®, Razadyne®, and Exelon®
Acetylcholinesterase Inhibitors and NMDA Receptor Blocker
| Brand |
Generic
|
Dosage Form |
Typical Dose* |
Most Common Side Effects |
| Acetylcholinesterase Inhibitors |
| Aricept® |
Donepezil |
5 mg and 10 mg tablets |
Initial dose is 5 mg daily, then increased to 10 mg daily after 4 weeks |
Nausea, vomiting, diarrhea, insomnia |
| Cognex® |
Tacrine |
10 mg, 20 mg, and 40 mg capsules |
Initial dose is 10 mg four times a day, and increased by 40 mg/day every 6 weeks
Maximum dose: 40 mg four times a day |
Liver toxicity, diarrhea, nausea, vomiting, dizziness and headache |
| Exelon® |
Rivastigmine |
Capsules:
1.5 mg capsule
3 mg capsule
4.5 mg capsule
6 mg capsule
Patches:
4.6 mg/24 hour patch
9.5 mg/24 hour patch
|
Initial dose: 1.5 mg capsule twice a day
Maintenance dose: 3 mg twice a day
Maximum: 6 mg twice a day
OR
Initial dose: 4.6 mg patch daily
Maintenance dose is 9.5 mg patch daily
Maximum dose: 9.5 mg/day |
Dizziness, headache, nausea, vomiting, diarrhea, anorexia, abdominal pain |
| Razadyne® |
Galantamine |
Extended Release Capsules:
8 mg
16 mg
24 mg
Immediate Release Tablets:
4 mg
8 mg
12 mg
Oral Solution:
4 mg per mL |
Extended Release Capsules: Initial dose is 8 mg once daily for 4 weeks, if tolerated increase to 16 mg once daily for 4 week, and if tolerated increase to 24 mg
Immediate Release Tablets or Oral Solution
Initial dose is 4 mg twice daily for 4 weeks, if tolerate increase to 8 mg twice daily for 4 weeks, if tolerated increase to 12 twice a day |
Nausea, vomiting, diarrhea, weight loss, anorexia |
| N-Methyl-D-Aspartate Receptor Blocker |
| Namenda® |
Memantine |
Tablets:
5 mg
10 mg
Oral Solution:
2 mg per mL |
Initial dose is 5 mg once daily, then increase by 5 mg twice daily, until target dose of 10 mg twice a day. |
Hypertension, dizziness, confusion, headache, hallucination, fatigue, pain, constipation, somnolence |
*These doses are based on normal kidney and liver functions. For patients with liver and/or kidney disease, doses may be different. Do not start these medications without discussing with your primary health care provider.
Patients who suffer from Alzheimer’s disease are found to have low levels of a chemical messenger in the brain called acetylcholine, which is involved in memory functions. Acetylcholine is broken down by an enzyme called acetylcholinesterase. Drugs that can impede the action of acetylcholinesterase can indirectly increase the levels of acetylcholine, thus preventing memory loss. This is how acetylcholinesterase inhibitors work to help manage Alzheimer’s disease.
The second group of medications is called n-methyl-d-aspartate (NMDA) receptor blockers. It is believed that the activation of NMDA receptors by glutamate, an excitatory brain chemical, causes neurons in the brain to die, leading to memory loss. Blocking of the NMDA receptors prevents glutamate from binding to them and ultimately stopping NMDA activation. There is currently only one drug that falls under this category, called Namenda®
NMDA receptor blockers and acetylcholine inhibitors are often prescribed together. Since these drugs work by affecting different brain chemicals, using them in combination can have a positive additive effect. Most patients who suffer from severe dementia can benefit from this combination therapy.
Both NMDA receptor blockers and acetylcholinesterase inhibitors are safe drugs if used appropriately. The most common side effects associated with acetylcholinesterase inhibitors include stomach upset, nausea, and vomiting. Therefore, it is best to take these drugs with food. Most serious, but rare side effects include syncope, slowed heart rate, and liver damage – associated mostly with Tacrine (Cognex®). On the other hand, NMDA receptor blocker Namenda’s side effects include dizziness, confusion, headache, constipation, and flu-like symptoms such as fatigue and muscle pains. When side effects from these drugs become intolerable or more serious side effects are experienced, it is best to contact your primary healthcare provider immediately.
NMDA receptor blockers and acetylcholinesterase inhibitors are available in different dosage forms. They come as extended release tablets that offer the benefit of once daily dosing, patches, for those who have difficulty swallowing, and liquid oral formulation, which is also an alternative for those who cannot swallow pills or require smaller than usual doses. The different dosage forms for these drugs are not interchangeable based on a milligram-to-milligram basis, therefore switching from one dosage form to another should not be self-initiated. Discuss with your primary healthcare provider before switching.
On occassion, Alzheimer’s disease patients are prescribed other drugs such as antipsychotics and antidepressants (Table 2). These drugs are used to management the behavioral symptoms associated with the disease, since Alzheimer’s disease patients sometimes present with psychiatric symptoms such as hallucinations, depression, and agitation. These drugs do not alter the progression of the disease, but instead manage its symptoms. Caution must be used when prescribing antipsychotic medications to treat the behavioral symptoms of patients with dementia, since there is an increased risk of death related to their use in this setting. The risks and benefits of using these drugs must be discussed with your healthcare provider before starting therapy.
Antipsychotics and Antidepressants
| Brand |
Generic |
Typical Daily Dose* (Range) |
Targeted Symptom(s) |
| Antipsychotics |
| Abilify® |
Aripiprazole |
10 mg (10 – 30 mg daily) |
Agitation and psychosis |
| Geodon® |
Ziprasidone |
40 mg (20 – 80 mg twice daily) |
| Risperdal® |
Risperidone |
1 mg (0.75 – 1.5 mg daily) |
| Seroquel® |
Quetiapine |
200 mg (50 – 150 mg twice daily) |
| Zyprexa® |
Olanzapine |
5 mg (5 – 10 mg daily) |
| Antidepressants |
| Celexa® |
Citalopram |
20 mg ( 20 – 40 mg daily) |
Depression, anxiety, psychosis, and agitation |
| Lexapro® |
Escitalopram |
10 mg (10 -1 20 mg daily) |
| Paxil® |
Paroxetine |
20 mg (10 – 40 mg daily) |
| Zoloft® |
Sertraline |
75 mg (75 – 100 mg daily) |
| Prozac® |
Fluoxetine |
10 mg (10 – 40 mg daily) |
| Pamelor® |
Nortriptyline |
50 mg (25 – 100 mg daily) |
Depression |
| Norpramin® |
Desipramine |
100 mg (50 – 200 mg daily) |
| Remeron® |
Mirtazapine |
15 mg (15 – 30 mg daily) |
*These doses are based on normal kidney and liver functions. For patients with liver and/or kidney disease, doses may be different. Do not start these medications without discussing with your primary health care provider.
There are many medications available in the market today that are approved for the management of Alzheimer’s disease. They differ in their mechanism of action, dosage form availability, and side effect profile. Antipsychotics and antidepressants are also used to manage the behavioral symptoms associated with this condition. It is important to discuss with your healthcare provider the different options available in order to better select the best treatment for you or your loved one.
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