Calcium antagonists constitute a chemically \u2028and pharmacologically diverse group of drugs. Chemically, at least four major types of calcium antagonists can \u2028be distinguished; they include phenylalkylamines, dihydropyridines, benzothiazepines and piperazines. As a\u2028group they share the common property of slowing the \u2028transmembrane entry of calcium ions through either \u2028voltage-activated, or (probably) receptor operated, ion\u2028 selective channels. They differ from one another also in \u2028terms of their tissue specificity and selectivity. Different\u2028 types (L, T, N) of calcium channels have been identified \u2028and their distribution in different tissues is specific. The \u2028molecular properties and the differential binding characteristics of the subgroups of calcium antagonists have\u2028 been defined. At least one of calcium antagonists, diltiazem, has an intracellular action. All calcium antagonists\u2028 share the ability to dilate blood vessels, but there is a \u2028marked difference in potency and selectivity, even within \u2028individual subgroups. The dihydropyridines are relatively \u2028selective antagonists of vascular smooth muscle cell \u2028calcium uptake. Their ability to inhibit myogenic vascular\u2028 tone contributes to their predominant in vivo effect on\u2028 vascular beds characterized by a relatively high myogenic\u2028 tone, such as the coronary and skeletal muscle beds. Additional mechanisms contributing to the antihypertensive action of dihydropyridines include interference with \u2028neural control of circulation, as well as intrarenal actions \u2028to promote electrolyte and water excretion. In myocardium, the tissue protecting effects of calcium antagonists,\u2028 especially the dihydropyridine-based group, in the presence of hypertension involve not only reduction of hypertrophy, but they also reduce ischemia-induced injury and\u2028 the incidence of damage due to lipid peroxidation. Other \u2028possible therapeutic uses of calcium antagonist include\u2028 prevention of atherogenic changes, treatment and prevention of acute asthma, prevention of consequences of\u2028 cerebral ischemia and vasospasm, anticonvulsant therapy, prophylactic therapy of migraine, attenuation of acute \u2028renal failure and slowing of the progression of chronic \u2028renal failure, uterine relaxation, and treatment of some \u2028gastrointestinal disorders.<\/p>\n","protected":false},"excerpt":{"rendered":"
Calcium antagonists constitute a chemically \u2028and pharmacologically diverse group of drugs. Chemically, at least four major types of calcium antagonists can \u2028be distinguished; they include phenylalkylamines, dihydropyridines, benzothiazepines and piperazines. As a\u2028group they share the common property of slowing the \u2028transmembrane entry of calcium ions through either \u2028voltage-activated, or (probably) receptor operated, ion\u2028 selective channels. […]<\/p>\n","protected":false},"author":25,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[305,418],"tags":[],"class_list":["post-2713","post","type-post","status-publish","format-standard","hentry","category-1-1993-archive","category-pharmacology-and-experimental-toxicology"],"acf":[],"yoast_head":"\n