ABSTRACT
Three types of calcium channels have been identified voltage-sensitive, receptor operated [cardiac muscle and vascular smooth muscle] and stretch operated [in some blood vessels] channels. Using electrophysiological and pharmacological techniques, three different types of voltage-gated calcium channels have been identified, namely, L-type [for long lasting, large channels], T-type [for transient, tiny channels] and N-type [for neuronal, neither L nor T]. Many compounds are known to have a calcium channel inhibitory effect. Calcium antagonists, based on the specificity of inhibition of the slow calcium current, can be classified into three groups: Group A: for 90 to 100 percent inhibition of calcium influx without change in the sodium current [verapamil, diltiazem and the dihydropyridines]; Group B: for 50 to 70 percent inhibition of calcium influx current without change in the sodium current [bepridil, cinnarizine and prenylamine] and Group C: for agents exhibiting some inhibition of calcium influx [phenytoin, indomethacin and propranolol]. There is now increasing evidence that, certain calcium channel blockers especially the dihydropyridines are more strongly associated with vasodilation of afferent arterioles than of efferent arterioles and also with increase intraglomerular pressure and albuminuria. Thus they have a beneficial effect in terms of reducing proteinuria and slowing the progression of diabetic renal failure
Subject(s)
Humans , Amlodipine/pharmacology , Diabetic Nephropathies/drug therapy , Ischemia , Diabetes Mellitus , Diltiazem/pharmacology , Calcium Channel Blockers/classification , Calcium Channel Blockers/historyABSTRACT
Constituyen un grupo importante de medicamentos ampliamente utilzados en la práctica diaria, que farmacológicamente se caracterizan por bloquear los canales lentos del calcio.
Subject(s)
Calcium Channel Blockers/classification , Dihydropyridines , Dihydropyridines/adverse effects , Dihydropyridines , Dihydropyridines/pharmacology , Diltiazem , Diltiazem/adverse effects , Diltiazem , Diltiazem/pharmacology , Verapamil , Verapamil/adverse effects , Verapamil , Verapamil/pharmacologySubject(s)
Humans , Adrenergic beta-Antagonists/classification , Adrenergic beta-Antagonists/pharmacokinetics , Antihypertensive Agents/classification , Calcium Channel Blockers/classification , Calcium Channel Blockers/metabolism , Diuretics/classification , Diuretics/adverse effects , Diuretics/pharmacology , Hypertension/drug therapy , Hypertension/physiopathologyABSTRACT
Neste artigo säo ilustradas as bases fisiológicas e farmacoclínicas das açöes dos agentes antagonistas de cálcio adotadas pela O.M.S. Da reuniäo que envolveu cardiologistas, neurologistas e farmacologistas, ficou assentada a possibilidade de classificaçäo clínica, dadas as análises dos efeitos através do emprego terapêutico e o número cada vez mais crescente de tais agentes adicionados no mercado médico