Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.
Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
DRUG CLASS AND MECHANISM: Memantine is an oral medication for treating
patients with Alzheimer's disease. Other medications used for Alzheimer's
disease affect acetylcholine, one of the neurotransmitter chemicals that nerve
cells in the brain use to communicate with one another. These drugs -
galantamine (Razadyne - formerly known as Reminyl), donezepil (Aricept),
rivastigmine (Exelon), and tacrine (Cognex)-- inhibit the enzyme
acetylcholinesterase that destroys acetylcholine and thereby increase the
effects of acetylcholine. Memantine's effects are independent of acetylcholine
and acetylcholinesterase. Glutamate is the main excitatory neurotransmitter in
the brain. It is believed that too much stimulation of nerve cells by glutamate
may be responsible for the degeneration of nerves that occurs in some
neurological diseases such as Alzheimer's disease. Like other neurotransmitters,
glutamate is produced and released by nerve cells in the brain. The released
glutamate then travels to nearby nerve cells where it attaches to a receptor on
the surface of the cells called the N-methyl-D-aspartate (NMDA) receptor.
Memantine blocks this receptor and thereby decreases the effects of glutamate.
It is thought that by blocking the NMDA receptor and the effects of glutamate,
memantine may protect nerve cells from excess stimulation by glutamate.
Memantine was approved by the FDA in October 2003.
PRESCRIPTION: Yes.
GENERIC AVAILABLE: Yes.
PREPARATIONS: Tablets: 5 and 10 mg. Capsule (extended release): 7, 14,
21 and 28 mg. Solution: 2 mg/ml.
STORAGE: Tablets should be stored at room temperature, 15-30 C (59-86
F).
PRESCRIBED FOR: Memantine is used for the treatment of moderate to
severe dementia associated with Alzheimer's. Dementia can be categorized into
three levels of severity: mild in which patients are alert and sociable, but
forgetfulness begins to interfere with daily living, moderate which often is the
longest stage of the disease with deterioration of intellect, logic, behavior,
and function, and severe, in which there is loss of long-term memory and
language skills. Patients with severe Alzheimer's may require 24-hour care and
can no longer complete basic self-care tasks including washing, eating, and
using the bathroom.
DOSING: The usual starting dose of memantine tablets is 5 mg once
daily. The dose usually is increased to 5 mg twice daily, then 5 mg and 10 mg as
separate doses daily, and finally 10 mg twice daily. Memantine can be taken with
or without food. The initial recommended dose of memantine capsules is 7 mg
daily. The dose may be increased weekly by 7 mg daily and the maximum dose is 28
mg daily. Capsules may be swallowed whole or opened and sprinkled on spoonsful
of applesauce. Capsules should not be crushed or chewed.
DRUG INTERACTIONS: Medicines that make the urine more alkaline (for
example, carbonic anhydrase inhibitors such as acetazolamide (Diamox) and sodium
bicarbonate would be expected to reduce the elimination of memantine by the
kidneys and might increase the blood levels and the risk of side effects of
memantine. Combining memantine with other NMDA receptor antagonists (for
example, amantadine
[Symmetrel], ketamine, and dextromethorphan) has not been
evaluated and should be done cautiously.
PREGNANCY: Memantine given in high doses to pregnant rats and rabbits
did not affect the offspring. However, studies have not been conducted in
pregnant women. Memantine should only be used during
pregnancy if the potential
benefit justifies the potential risk to the fetus.
impairment in another area of thinking such as the ability to organize thoughts and reason, the ability to use language, or the ability to see accurately the visual world (not because of eye disease), and
these impairments are severe
enough to cause a decline in the patient's usual level of functioning.
Although
some kinds of memory loss are normal parts of aging, the changes due to aging
are not severe enough to interfere with the level of function. Many different
diseases can cause dementia, but Alzheimer's disease is by far the most common
cause for dementia in the United States and in most countries in the world.
What is Alzheimer's disease?
Alzheimer's disease (AD) is a slowly progressive disease of the brain that is
characterized by impairment of memory and eventually by dist...
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