Galantamine



Galantamine 1066
Photo by: mario beauregard

Definition

Galantamine belongs to a class of drugs called acetylcholinesterase inhibitors. In the United States galantamine is sold under brand name Reminyl.

Purpose

Galantamine is used to treat the symptoms of Alzheimer's disease . Galantamine is also being evaluated for the treatment of respiratory depression, mania, vascular dementia due to stroke or cardiac arrest that causes brain lesions, and reversal of side effects, such as blurred vision and mental changes caused by medications such as scopolamine.

Description

Alzheimer's disease develops when brain cells, called neurons, undergo an early, and selective death. It is believed that the premature death of these neurons may be prevented if stimulated by a brain chemical called acetylcholine. Acetylcholine is recycled by an enzyme called acetylcholinesterase. Galantamine works by inhibiting this enzyme. The inhibition of acetylcholinesterase increases the concentration of available acetylcholine.

Galantamine has only been studied, and is only used, in patients with mild-to-moderate Alzheimer's disease according to the Alzheimer's Disease Assessment Scale.

Galantamine is available in 4-mg, 8-mg, and 12-mg tablets.

Recommended dosage

The recommended initial dose of galantamine in adults is 4 mg twice daily. After a minimum of four weeks of treatment with galantamine, it may be increased to 8 mg twice daily. Further increases to 12 mg twice daily should be initiated only after a minimum of four weeks at the previous dose.

Increased side effects associated with higher doses may prevent the increase in dose in some patients. Patients with moderate liver or kidney problems should not exceed 16 mg of galantamine daily.

Precautions

Galantamine should not be used in patients with severe liver or kidney problems. Since there are no well-controlled studies for the use of galantamine in pregnancy, galantamine should only be used if the potential benefits justify the potential risks to the fetus.

Patients who are undergoing anesthesia or bladder or gastrointestinal surgery should take galantamine only after a discussion with their physician. Patients with gastrointestinal problems should be closely monitored if it is decided that they should take galantamine. Galantamine should be used under close physician supervision in patients who have Parkinson's disease, severe asthma, or obstructive pulmonary disease. Because galantamine may slow down the heart, patients with any heart condition, and especially patients taking other medications that slow down the heart, should be evaluated before starting galantamine.

Side effects

The most common side effects reported with the use of galantamine are nausea, vomiting, diarrhea, anorexia, and abdominal pain. These occur most often at dosage-escalation periods. The average duration of nausea is five to seven days. These side effects tend to be less frequent if the patient is taking a total daily dosage of 16 mg. Eleven percent of patients receiving 24 mg daily lose weight, while 6% of patients receiving 16 mg daily experience weight loss.

Other common side effects include dizziness, headache, tremor, fatigue , depression, agitation, irritation, and insomnia . These side effects have a higher incidence and severity if higher doses are used. If side effects become severe, the dosage should be adjusted downward under physician supervision.

Interactions

There is currently little data regarding potential drug interactions with galantamine. Medications that are known to increase levels of galantamine in the body include cimetidine, erythromycin, ketoconazole, and paroxetine .

Resources

BOOKS

Janssen Inc. Staff. Product Information Reminyl-Galantamine. Titusville, NJ: Janssen Inc., Reviewed 10/2001.

PERIODICALS

Davidsson, Pia. "Differential Increase in Cerebrospinal Fluid-Acetylcholinesterase After Treatment With Acetylcholinesterase Inhibitors in Patients With Alzheimer's Disease." Neuroscience Letters 300 (2001): 157-160.

Wilcock, Gordon. "Efficacy and Safety of Galantamine In Patients With Mild to Moderate Alzheimer's Disease: Multicentre Randomised Controlled Trial." British Medical Journal 321 (2000): 1445-1449.

Ajna Hamidovic, Pharm.D.



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