- 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 extended-release 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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