Calcium antagonists were introduced for the treatment of hypertension
in the 1980s. Their use was subsequently expanded to additional disorders,
such as angina pectoris, paroxysmal supraventricular tachycardias,
hypertrophic cardiomyopathy, Raynaud phenomenon, pulmonary hypertension,
diffuse esophageal spasms, and migraine. Calcium antagonists as a group
are heterogeneous and include 3 main classes-phenylalkylamines, benzothiazepines,
and dihydropyridines-that differ in their molecular structure, sites
and modes of action, and effects on various other cardiovascular functions.
Calcium antagonists lower blood pressure mainly through vasodilation
and reduction of peripheral resistance. They maintain blood flow to
vital organs, and are safe in patients with renal impairment. Unlike
diuretics and beta-blockers, calcium antagonists do not impair glucose
metabolism or lipid profile and may even attenuate the development
of arteriosclerotic lesions. In long-term follow-up, patients treated
with calcium antagonists had development of less overt diabetes mellitus
than those who were treated with diuretics and beta-blockers. Moreover,
calcium antagonists are able to reduce left ventricular mass and are
effective in improving anginal pain. Recent prospective randomized
studies attested to the beneficial effects of calcium antagonists in
hypertensive patients. In comparison with placebo, calcium antagonist-based
therapy reduced major cardiovascular events and cardiovascular death
significantly in elderly hypertensive patients and in diabetic patients.
In several comparative studies in hypertensive patients, treatment
with calcium antagonists was equally effective as treatment with diuretics,
beta-blockers, or angiotensin-converting enzyme inhibitors. From these
studies, it seems that a calcium antagonist-based regimen is superior
to other regimens in preventing stroke, equivalent in preventing ischemic
heart disease, and inferior in preventing congestive heart failure.
Calcium antagonists are also safe and effective as first-line or add-on
therapy in diabetic hypertensive patients. Heart rate-lowering calcium
antagonists (verapamil, diltiazem) may have an edge over the dihydropyridines
in post-myocardial infarction patients and in diabetic nephropathy.
Thus, calcium antagonists may be safely used in the management of hypertension
and angina pectoris.
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