The calcium antagonists (calcium entry blockers or slow channel inhibitors) are a heterogenous group of substances that inhibit the voltage-activated inward displacement of Ca2+. 2. These compounds can be subdivided according to their chemistry (organic and inorganic) and their preferred sites of action (myocardium, vascular or nodal tissue). 3. Some of the substances which inhibit slow channel transport exhibit other properties that may be of pharmacological significance.
