Calcium channel blocker: A drug that blocks the entry of calcium into the muscle cells of the heart and the arteries. It is the entry of calcium into these cells that causes the heart to contract and arteries to narrow. By blocking the entry of calcium, calcium channel blocker (CCBs) decrease the contraction of the heart and dilate (widen) the arteries. By dilating the arteries, CCBs reduce the pressure in the arteries. This makes it easier for the heart to pump blood, and, as a result, the heart needs less oxygen. By reducing the heart’s need for oxygen, CCBs prevent or relieve angina. CCBs also are used for treating high blood pressure because of their blood pressure-lowering effects. CCBs also slow the rate at which the heart beats and are therefore used for treating certain abnormal heart rhythms such as atrial fibrillation.
The most common side effects of CCBs are constipation, nausea, headache, rash, edema (swelling of the legs with fluid), low blood pressure, drowsiness, and dizziness. When diltiazem or verapamil are given to individuals with heart failure, symptoms of heart failure may worsen because these drugs reduce the ability of the heart to pump blood.
Most of the interactions of CCBs occur with verapamil or diltiazem. The interaction occurs because verapamil and diltiazem decrease the elimination of a number of drugs by the liver. Through this mechanism, verapamil and diltiazem may reduce the elimination and increase the blood levels of carbamazepine (Tegretol), simvastatin (Zocor), atorvastatin (Lipitor), and lovastatin (Mevacor). This can lead to toxicity from these drugs.
The CCBS that have been approved for use in the US include nisoldipine (Sular), nifedipine (Adalat, Procardia), nicardipine (Cardene), bepridil (Vascor), isradipine (Dynacirc), nimodipine (Nimotop), felodipine (Plendil), amlodipine (Norvasc), diltiazem (Cardizem), and verapamil (Calan, Isoptin).
- Calcium deficiency
Calcium deficiency: A low blood level of calcium (hypocalcemia), which can make the nervous system highly irritable, causing spasms of the hands and feet (tetany), muscle cramps, abdominal cramps, overly active reflexes, and so on. Chronic calcium deficiency contributes to poor mineralization of bones, soft bones (osteomalacia) and osteoporosis, and, in children, rickets and impaired […]
- Calcium excess
Calcium excess: An elevated blood calcium level (hypercalcemia), which can cause muscle weakness and constipation, affect the conduction of electrical impulses in the heart (heart block), lead to calcium stones in the urinary tract, impair kidney function through nephrocalcinosis, and interfere with the absorption of iron, predisposing the person to iron deficiency.
Calculi: The plural of calculus. Medically, a calculus is a stone, for example, a kidney stone.
- Calculi, renal
Calculi, renal: Kidney stones, by another name. A common cause of blood in the urine and pain in the abdomen, flank, or groin. Occurs in 1 in 20 people at some time in their life. Development of the stones is related to decreased urine volume or increased excretion of stone-forming components such as calcium, oxalate, […]
Calculus: A stone, as in the urinary tract, or calcium salt deposits on the teeth. In Latin, the word calculus means ‘a pebble.’ Pebbles were once used for counting, from which came the mathematical field of calculus.