Advances in calcium blocker therapy.

Calcium blockers are drugs that interfere with the entry of calcium ions into cells of a variety of tissues. Three calcium blockers, verapamil, nifedipine, and diltiazem, are currently approved for clinical use in the United States and many others are undergoing clinical trials. All calcium blockers share the effect of dilating blood vessels, although some agents are selective dilators of certain vascular beds, such as the coronary or cerebral circulation. There exist major differences among these drugs in their ability to depress myocardial contraction and inhibit cardiac impulse conduction, as well as other properties. The therapeutic actions of the agents in use, as well as the actions of the investigational calcium blockers, have been reviewed. Although calcium blockers are generally well tolerated and have fewer side effects than many alternative drugs, serious adverse effects are possible in certain clinical settings. The clinical indications for these drugs continue to expand and will likely find many uses in surgical patients, especially in the areas of cardiac surgery, neurosurgery, vascular surgery, and general surgery.