Calcium antagonist drugs in the treatment of coronary spasm, effort angina and hypertension.

The clinical use of calcium antagonist drugs in coronary artery disease preceded knowledge of the mechanism of their action. Basic research into their pharmacological actions and development of a wide range of compounds which block calcium entry into cells enabled clinicians to greatly expand the indications for their use. Thus the calcium antagonists were rediscovered and found to be potent anti-anginal drugs when used in adequate dosage for effort related angina. Knowledge of their potent relaxing action on vascular smooth muscle led to their use in coronary artery spasm. The exact trigger mechanism/s for spasm and the reason for enhanced vascular reactivity remain unclear, perhaps explaining the failure of specific antagonist therapy. Calcium antagonists acting nonspecifically inhibit both induced and spontaneous attacks of vasospastic angina. They may favourably influence the prognosis and are now drugs of first choice for this condition. The vasodilator action of these drugs has most recently been utilized to treat hypertension, with efficacy confirmed in many controlled trials. Unlike other vasodilators, the calcium antagonists reduce blood pressure without salt and water retention, and with mild or no stimulation of renin, aldosterone, or sympathetic nervous overactivity, and without postural effects. This spectrum of action makes them ideal therapeutic agents, and current guidelines are changing to include calcium antagonists as first or second line therapy.