- 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). 2

- 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). 3

- 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. 4

- 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. 5

- 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. 6

- 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. 7

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. 8

- 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. 9

■ 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. 10

- 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. 11