|
What is
Memantine HCL?
|
Memantine
is the first in a novel class of Alzheimer's
disease medications acting on the glutamatergic
system by blocking NMDA glutamate receptors.
Glutamatergic (NMDA receptor)
A
dysfunction of glutamatergic neurotransmission,
manifested as neuronal excitotoxicity, is
hypothesized to be involved in the etiology of
Alzheimer's disease. Targeting the glutamatergic
system, specifically NMDA receptors, offers a
novel approach to treatment in view of the
limited efficacy of existing drugs targeting the
cholinergic system
Memantine is a low-affinity voltage-dependent
uncompetitive antagonist at glutamatergic NMDA
receptors By binding to the NMDA receptor with a
higher affinity than Mg2+ ions;
memantine is able to inhibit the prolonged
influx of Ca2+ ions which forms the
basis of neuronal excitotoxicity. The low
affinity and rapid off-rate kinetics of
memantine at the level of the NMDA
receptor-channel, however, preserves the
physiological function of the receptor as it can
still be activated by the relatively high
concentrations of glutamate released following
depolarization of the presynaptic neuron. This
unique molecular mechanism of action of
memantine was first discovered by the laboratory
of Stuart A. Lipton, MD, PhD, then at Harvard
Medical School and now at the Burnham Institute
for Medical Research in La Jolla, California.
The interaction of memantine with NMDA receptors
plays a major role in the symptomatic
improvement the drug produces in Alzheimer's
disease. Moreover, there is no evidence as yet
that the ability of memantine to protect against
NMDA receptor-mediated excitotoxicity has a
disease modifying effect in Alzheimer's,
although this has been suggested in animal
models.
Serotonergic (5-HT3 receptor)
Memantine acts as an uncompetitive antagonist at
the 5HT3 receptor, with a potency
similar to that for the NMDA receptor. The
clinical significance of this serotonergic
activity in the treatment of Alzheimer's disease
is unknown.
Cholinergic (Nicotinic acetylcholine receptor)
Memantine acts as an uncompetitive antagonist at
different neuronal nicotinic acetylcholine
receptors (nAChRs) at potencies possibly similar
to the NMDA and 5-HT3 receptors, but this is
difficult to ascertain with accuracy because of
the rapid desensitization of nAChR responses in
these experiments. It has been shown that the
number of nicotinic receptors in the brain are
reduced in Alzheimer's disease, even in the
absence of a general decrease in the number of
neurons, and nicotinic receptor agonists are
viewed as interesting targets for anti-Alzheimer
drugs.
|
|
|
|
How does
Memantine HCL work? |
|
Memantine is used to treat the symptoms of
Alzheimer's disease. Memantine is in a class of
medications called NMDA receptor antagonists. It
works by decreasing abnormal activity in the
brain. Memantine can help people with
Alzheimer's disease to think more clearly and
perform daily activities more easily, but it is
not a cure and does not stop the progression of
the disease. |
|
|
|
Who should not use Memantine HCL? |
|
You should not
use Memantine HCL if you:
 |
are allergic or sensitive to
or have had a reaction to any of the
ingredients in the medicine |
|
have a urinary tract
infection |
|
have epilepsy or have risk
factors for epilepsy |
|
have had raised blood
pressure |
|
have had seizures |
|
have heart problems |
|
have kidney problems |
|
have liver problems |
|
have recently had a heart
attack |
|
This medicine could affect
your ability to drive or operate machinery. |
|
|
|
|
How should I use Memantine HCL? |
|
Memantine comes as a tablet to
take by mouth. It is usually taken once or twice
a day with or without food. Follow the
directions on your prescription label carefully,
and ask your doctor or pharmacist to explain any
part you do not understand. To help you remember
to take memantine, take it at around the same
time(s) every day. Take memantine exactly as
directed. Do not take more or less of it or take
it more often than prescribed by your doctor.
Your doctor will probably start
you on a low dose of memantine and gradually
increase your dose, not more than once every
week.
Memantine controls Alzheimer's
disease but does not cure it. Continue to take
memantine even if you feel well. Do not stop
taking memantine without talking to your doctor. |
|
What happens if I miss a
Memantine HCL dose?
|
|
Take the missed
Memantine HCL dose as soon as you remember it.
However, if it is almost time for the next dose,
skip the missed dose and continue your regular
dosing schedule. Do not take a double dose to
make up for a missed one. |
|
|
What happens if I overdose?
|
|
In
case of overdose, call your local poison control
center at 1-800-222-1222. If the victim has
collapsed or is not breathing, call local
emergency services at 911.
Symptoms of overdose may include:
|
restlessness
|
|
hallucination (seeing things
or hearing voices that do not exist)
|
|
sleepiness
|
|
loss of consciousness
|
|
|
|
|
What should I avoid while using Memantine HCL? |
|
This medicine could affect your ability to drive or operate machinery.
It is best to avoid drinking alcohol while you
are taking this medicine.
Tell
your doctor if you are a vegetarian or if you
usually eat large amounts of citrus fruits,
vegetables, beans, or peas. Your doctor will
tell you if you need to change your diet. If you
do not regularly eat these foods, continue your
normal diet. |
|
|
|
What are the possible side effects of Memantine HCL? |
|
Memantine may cause side effects. Tell your
doctor if any of these symptoms are severe or do
not go away:
|
extreme tiredness
|
|
dizziness |
|
confusion |
|
headache |
|
sleepiness
|
|
constipation
|
|
vomiting |
|
pain anywhere in your body,
especially your back |
|
coughing |
Some
side effects can be serious. The following
symptoms are uncommon, but if you experience any
of them, call your doctor immediately:
|
shortness of breath
|
|
hallucination (seeing things
or hearing voices that do not exist)
|
|
|
|
|
What other drugs will affect Memantine HCL? |
|
The following
medicines may interact with Memantine
hydrochloride:
|
amantadine |
|
baclofen |
|
cimetidine |
|
dantrolene |
|
dextromethorphan |
|
donepezil |
|
galantamine |
|
glyburide |
|
hydrochlorothiazide |
|
ketamine |
|
levodopa |
|
metformin |
|
nicotine |
|
phenytoin |
|
procainamide |
|
quinidine |
|
quinine |
|
ranitidine |
|
warfarin |
The following
types of medicine may interact with Memantine
hydrochloride:
|
anticholinergics |
|
antipsychotics |
|
barbiturates |
|
dopaminergics |
|
NMDA-antagonists |
|
oral anticoagulants |
If you are
taking Memantine hydrochloride and one of the
above medicines or types of medicines, make sure
your prescriber knows about it. |
|
|
|
Where can I get more information? |
|
If
you have questions about the medicine you are
taking or would like more information, check
with your doctor, pharmacist, or other health
care provider |
|
|
|
Memantine HCL
Storage |
|
Keep
this medication in the container it came in,
tightly closed, and out of reach of children.
Store it at room temperature and away from
excess heat and moisture (not in the bathroom).
Throw away any medication that is outdated or no
longer needed. Talk to your pharmacist about the
proper disposal of your medication. |
|
|
|
Nursing Mothers use of Memantine HCL |
|
Women who are
taking Memantine hydrochloride should not
breast-feed |
|
|
|
Pregnancy
and use of Memantine HCL |
|
You should only
take this medicine during pregnancy if your
doctor thinks that you need it. |
|
|
|
Disclaimer:
|
|
|
Information
on this page is provided for general information
purposes. You should not make a clinical
treatment decision based on information
contained in this page without consulting other
references including the package insert of the
drug, textbooks and where relevant, expert
opinion. We cannot be held responsible for any
errors you make in administering drugs mentioned
on this page, nor for use of any erroneous
information contained on this page. |
|
