Transcript CALCIUM CHANNEL BLOCKERS

- Calcium channel blockers decrease blood
pressure,cardiac workload, and myocardial
oxygen consumption.
- available in immediate-release and
sustained-release forms that are used in
treating hypertension include amlodipine
(Norvasc), felodipine (Plendil), isradipine
(DynaCirc, DynaCirc CR), and nicardipine
(Cardene, Cardene SR).
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- Other calcium channel blockers are
sustained- release or extendedrelease preparations.
- These include diltiazem (Cardizem,
Dilacor CR), nifedipine (Procardia XL),
nisoldipine (Sular), and verapamil
(Calan SR).
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- Calcium channel blockers inhibit the
movement of calcium ions across the
membranes of myocardial and arterial muscle
cells, altering the action potential and
blocking muscle cell contraction.
- This effect depresses myocardial
contractility, slows cardiac impulse formation
in the conductive tissues, and relaxes and
dilates arteries, causing a fall in blood
pressure and a decrease in venous return.
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- Calcium channel blockers are given orally and
are generally well absorbed, metabolized in
the liver, and excreted in the urine.
- These drugs cross the placenta and enter
breast milk .
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- are contraindicated in the presence of
allergy to any of these drugs .
- with heart block or sick sinus syndrome, and
with renal or hepatic dysfunction,
- should not be used during pregnancy unless
the benefit to the mother clearly outweighs
any potential risk to the fetus.
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- Central nervous system effects include
dizziness,light-headedness, headache, and
fatigue.
- GI problems include nausea and hepatic
injury related to direct toxic effects on
hepatic cells.
- Cardiovascular effects include hypotension,
bradycardia, peripheral edema, and heart
block. Skin flushing and rash may also occur.
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Drug–drug interactions vary with each of the
calcium channel blockers used to treat
hypertension.
A potentially serious effect to note is an
increase in serum levels and toxicity of
cyclosporine if taken with diltiazem.
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- The calcium channel blockers are a class of
drugs that interact with grapefruit juice.
- When grapefruit juice is present in the body,
the concentrations of calcium channel
blockers increase, sometimes to toxic levels.
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■ Monitor the patient’s blood pressure, cardiac
arrhythmia,rate and cardiac output closely .
■ Monitor blood pressure very carefully if the
patient is also taking nitrates because there is
an increased risk of hypotensive episodes.
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- Provide comfort measures to help the
patient tolerate drug effects. These include
small, frequent meals to alleviate
gastrointestinal (GI) upset;
- and taking safety precautions, such as
providing periodic rests and assisting with
ambulation if dizziness occurs.
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