Calcium channel blockers prevention

Calcium channel blockers act to uncouple excitation-contraction coupling in myocardium and smooth muscle by inhibiting the influx of Ca2 +. Vasodilation [1, 16] and depression of atrial and ventricular activity [17, 18] occur as a direct result. The calcium channel blockers prevent contraction in response to depolarization of the cell membrane by electrical stimulation [ 17,19-21 ] or by agonists such as high potassium ion concentrations [22-33], noradrenaline [22-24,28,29,32,33], 5-hydroxytryptamine [21,24] or prostaglandin F2a [21,24]. 

Matsubara, M and Hasegawa, K, Benidipine, a dihydropyridine-calcium channel blocker, prevents lysophosphatidylcholine-induced injury and reactive oxygen species production in human aortic endothelial cells. Atherosclerosis 178 (2005) 57-66. 

Nakamura T, Obata J, Onitsuka M, et al Benidipine, a long-acting calcium-channel blocker, prevents the... 

ACE inhibitors can be administered with diuretics (qv), cardiac glycosides, -adrenoceptor blockers, and calcium channel blockers. Clinical trials indicate they are generally free from serious side effects. The effectiveness of enalapril, another ACE inhibitor, in preventing patient mortaUty in severe (Class IV) heart failure was investigated. In combination with conventional dmgs such as vasodilators and diuretics, a 40% reduction in mortaUty was observed after six months of treatment using 2.5—40 mg/d of enalapril (141). However, patients complain of cough, and occasionally rash and taste disturbances can occur. 

Calcium Channel Blockers. Because accumulation of calcium is one of the facets of the mote involved process leading to atherosclerosis, it would foUow that the antihypertensive calcium channel blockers might be effective in preventing atheroma. Both verapamil (Table 1) and nifedipine (Table 3) have been shown to stimulate the low density Upoprotein (LDL) receptor (159). This specific receptor-mediated pathway could theoretically improve Upid metaboUsm in the arterial wall, and thereby prove antiatherogenic. These effects have been proven in animals. 

The so-called calcium channel blockers constitute a class of cardiovascular agents that have gained prominence in the past few years. These drugs, which obtund contraction of arterial vessels by preventing the movement of calcium ions needed for those contractions, have proved especially useful in the treatment of angina and hypertension. Dihydropyridines such as nifedipine (30) are par-... 

In the treatment of hypertension, ACE inhibitors are as effective as diuretics, (3-adrenoceptor antagonists, or calcium channel blockers in lowering blood pressure. However, increased survival rates have only been demonstrated for diuretics and (3-adrenoceptor antagonists. ACE inhibitors are approved for monotherapy as well as for combinational regimes. ACE inhibitors are the dtugs of choice for the treatment of hypertension with renal diseases, particularly diabetic nephropathy, because they prevent the progression of renal failure and improve proteinuria more efficiently than the other diugs. 

Major outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs. diuretic The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). JAMA 2002 288(23) =2981-2997. 

In randomized, controlled, clinical trials, calcium channel blockers were as effective as p-blockers at preventing ischemic symptoms. Calcium channel blockers are recommended as initial treatment in IHD when /3-blockers are contraindicated or not tolerated. In addition, CCBs may be used in combination with /3-blockers when initial treatment is unsuccessful. However, the combination of a (1-blocker with either verapamil or diltiazem should be used with extreme caution since all of these drugs decrease AV nodal conduction, increasing the risk for severe bradycardia or AV block when used together. If combination therapy is warranted, a long-acting dihydropyridine CCB is preferred. (3-Blockers will prevent reflex increases in sympathetic tone and heart rate with the use of calcium channel blockers with potent vasodilatory effects. 

Although P-blockers should be avoided in patients with decompensated heart failure from left ventricular systolic dysfunction complicating an MI, clinical trial data suggest that it is safe to initiate P-blockers prior to hospital discharge in these patients once heart failure symptoms have resolved.64 These patients may actually benefit more than those without left ventricular dysfunction.65 In patients who cannot tolerate or have a contraindication to a P-blocker, a calcium channel blocker can be used to prevent anginal symptoms, but should not be used routinely in the absence of such symptoms.2,3,62... 

A calcium channel blocker can be used to prevent anginal symptoms in patients who cannot tolerate or have a contraindication to a /1-blocker but should not be used routinely in the absence of such symptoms. 

FIGURE 6-2. Algorithm for the treatment of acute (top portion) paroxysmal supraventricular tachycardia and chronic prevention of recurrences (bottom portion). Note For empiric bridge therapy prior to radiofrequency ablation procedures, calcium channel blockers (or other atrioventricular [AV] nodal blockers) should not be used if the patient has AV reentry with an accessory pathway. (AAD, antiarrhythmic drugs AF, atrial fibrillation AP, accessory pathway AVN, atrioventricular nodal AVNRT, atrioventricular nodal reentrant tachycardia AVRT, atrioventricular reentrant tachycardia DCC, direct-current cardioversion ECG, electrocardiographic monitoring EPS, electrophysiologic studies PRN, as needed VT, ventricular tachycardia.)... 

The cure for preeclampsia is delivery of the fetus if the pregnancy is at term. Drug therapy for hypertension in preeclampsia includes methyldopa, labetalol, and calcium channel blockers. Magnesium sulfate is used to prevent eclampsia and to treat eclamptic seizures. 

A pharmacist asked a clinical pharmacist for information about Cartia . Because an electronic drug reference listed the active ingredient as aspirin, the pharmacist was prepared to substitute an aspirin product for Cartia . The clinical pharmacist recognized the new product as Cartia XT (Diltiazem, a calcium channel blocker) and prevented the error. 

In addition to being used as antianginal and antiarrhythmic agents, calcium channel blockers are used to treat weak and moderate hypertension. These drugs prevent calcium ions from entering into the smooth muscle cells of peripheral vessels, and they cause relaxation of peripheral vessels, which leads to lowering of arterial blood pressure. In clinically used doses, calcium channel blockers relax smooth musculature of arteries and have little effect on veins. In doses that relax smooth musculature, calcium channel blockers have relatively little effect on cardiac contractility. 

Verdecchia P et al Angiotensin-converting enzyme inhibitors and calcium channel blockers for coronary heart disease and stroke prevention. Hypertension 2005 46 386. [PMID 16009786]... 

Nimodipine, a member of the dihydropyridine group of calcium channel blockers, has a high affinity for cerebral blood vessels and appears to reduce morbidity after a subarachnoid hemorrhage. Nimodipine was approved for use in patients who have had a hemorrhagic stroke, but it has recently been withdrawn. Nicardipine has similar effects and is used by intravenous and intracerebral arterial infusion to prevent cerebral vasospasm associated with stroke. Verapamil as well, despite its lack of vasoselectivity, is used by the intra-arterial route in stroke. Some evidence suggests that calcium channel blockers may also reduce cerebral damage after thromboembolic stroke. 

A significant body of evidence suggests that the calcium channel blockers may interfere with platelet aggregation in vitro and prevent or attenuate the development of atheromatous lesions in animals. Clinical studies have not established their role in human blood clotting and atherosclerosis. 

Iodinated radiographic contrast media can cause acute renal insufficiency, perhaps as a result of reduced renal blood flow, an intrarenal osmotic effect, or direct tubular toxicity (58). Diuretics, calcium channel blockers, adenosine receptor antagonists, acetylcysteine, low-dose dopamine, the dopamine Di receptor agonist fenoldopam, endothelin receptor antagonists, and captopril have all been used to prevent contrast nephropathy. 

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