What are calcium channel blockers?
Calcium channel blockers are medicines that help relax the
pressure in blood vessel walls. Examples are diltiazem,
verapamil, nifedipine, and amlodipine. Which one is best
for you depends on your condition and health.
How do calcium channel blockers work?
Calcium channel blockers slow the movement of calcium from
the blood into the muscle cells of the heart. This relaxes
the vessels and blood flows more easily through them. This
helps lower blood pressure. Muscle cells need calcium to be
able to squeeze (contract). Muscle cells in other parts of
the body store their own calcium and don't depend on getting
calcium from the blood.
When are calcium channel blockers used?
The major use of these drugs is to treat high blood pressure
(hypertension). By partly blocking the transfer of calcium
to the blood vessel muscle cells, the blood vessels relax
and open up. This lowers blood pressure.
Calcium channel blockers are also used to treat angina
pectoris (chest pain caused by blockage of a coronary artery
in the heart), and some abnormal heart rhythms. They may be
prescribed to treat Raynaud's phenomenon (a blood vessel
problem) or to prevent migraine headaches.
When should I call my health care provider
Some calcium channel blockers may make angina worse or
cause the heart rate to slow too much. Talk with your
health care provider about this.
For most people, calcium channel blockers' good effect of
lowering blood pressure outweighs its bad effect of slightly
reducing the heart's pumping ability. In other people,
however, the reduced pumping of the heart causes heart
failure. Heart failure is a condition in which the heart
does not pump well enough to prevent the fluid buildup in
body tissues. If you are taking calcium blockers and notice
increasing shortness of breath or swelling in your legs or
ankles, call your doctor promptly. Other side effects to
report to your health care provider include constipation,
headache, rash, drowsiness, flushing, rapid heartbeat and
nausea.
Do not eat grapefruit or drink grapefruit juice while taking
a calcium channel blocker. Grapefruit affects the way this
medicine works and may increase the risk of side effects.


Disclaimer: This content is reviewed periodically and is subject to
change as new health information becomes available. The
information provided is intended to be informative and educational and is not a
replacement for professional medical evaluation, advice, diagnosis or
treatment by a healthcare professional.
HIA File MED4258F.HTM Release 9.0/2006. Copyright © 2006 McKesson Corporation and/or one of its subdiaries. All Rights Reserved.
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