By blocking the inward transmembrane
calcium current and opposing the effects of increased intracellular ionised
calcium,
calcium antagonists exert vascular and myocardial effects which are useful therapeutic tools. Coronary and peripheral vascular relaxation results in an increase in coronary flow and a reduction of the afterload and, therefore, of myocardial oxygen consumption. In some cases, negative myocardial inotropic and chronotropic effects also reduce myocardial
oxygen requirements.
Spastic angina is the indication of choice of all
calcium antagonists whereas, to date,
verapamil and
diltiazem have been shown to be effective in
stable angina and, in the post-
infarction situation,
diltiazem and
verapamil decrease the number of cardiovascular events, and
verapamil alone has been shown to reduce mortality. All
calcium antagonists have been shown to be effective in
hypertension and most have a protective effect on the target organs. The main fields of research concern
atherosclerosis, the primary prevention of
myocardial infarction and the study of molecules which can be used in
heart failure.