Selective L-type, T-type, and nonspecific calcium-channel blockers for stable angina pectoris

Selection of optimal therapy for chronic stable angina

Patients with chronic stable angina (CSA) seek a medical opinion for relief of their symptoms and because of fear of having a heart attack. The underlying lesion responsible for CSA is often a severe narrowing of one or more coronary arteries. In addition, the coronary arteries of patients with CSA contain many more nonobstructive lesions, which progress at variable rates, and are prone to rupture and may manifest as acute coronary syndromes (myocardial infarction , unstable angina , or sudden ischemic death). Most patients with CSA can be managed with medical treatment. For angina relief, optimum doses of one of the antianginal drugs (beta blockers , long-acting organic nitrates, or calcium channel blockers ) should be used. If the patient remains symptomatic, combination treatment of BBs plus nitrates or BBs plus dihydropyridine CCBs, or nondihydropyridine CCBs plus nitrates should be tried. Triple therapy has not been shown to be more effective than treatment with two agents. To reduce the incidence of MI, UA, and sudden ischemic death, treatment strategies should include smoking cessation, daily aspirin, daily exercise, and pharmacologic therapy for dyslipidemias, and for elevated blood pressure. Patients who remain symptomatic despite medical therapy and those not willing to take or unable to tolerate antianginal drugs should be considered for percutaneous or surgical coronary revascularization. Patients who do not respond to medical therapy and are not candidates for a revascularization procedure may be considered for additional treatment with trimetazidine or nicorandil (these drugs are not available in the United States or approved by the US Food and Drug Administration, but are available in some other countries). Ranolazine also looks promising but is not yet available for clinical use. As a last resort, enhanced external counterpulsation, spinal cord stimulation, sympathectomy, or direct transmyocardial revascularization should be considered for symptom relief.

Current medical management of chronic stable angina

Severe atherosclerotic narrowing of one or more coronary arteries is responsible for myocardial ischemia and angina pectoris in most patients with stable angina. The coronary arteries of patients with stable angina also contain many more non-obstructive plaques, which are prone to rupture resulting in acute coronary syndrome (unstable angina, myocardial infarction, sudden ischemic death). Therefore, the medical management must use strategies which not only relieve symptoms and prolong angina free walking but also reduce the incidence of adverse clinical outcomes. Whether any of the approved antianginal drugs, nitrates, beta-blockers, and calcium channel blockers reduce the incidence of adverse clinical outcomes in patients with stable angina has not been studied to date. Published data shows that percutaneous coronary revascularization procedures and coronary bypass surgery are effective in relieving angina but these procedures do not reduce mortality or the incidence of myocardial infarction compared to anti-anginal drug therapy. From the available data, an initial trial of medical treatment with anti-anginal drugs and strategies to reduce adverse clinical outcomes (smoking cessation, daily aspirin, treatment of dyslipidemias and hypertension) is indicated in most patients with stable angina pectoris. The initial choice of drug will depend on the presence or absence of comorbid conditions. Patients who do not respond to medical therapy or do not wish to take anti-anginal drugs and whose life style is limited because of anginal symptoms should be offered percutaneous revascularization procedures with or without stent placement or coronary bypass surgery. New drug-coated stents hold promise but long-term data and large-scale trials assessing the continued long-term improvement in symptoms and reduction of adverse outcomes is needed before offering such devices to all patients with stable angina. Newer medical therapies such as metabolic modulators and sinus rate lowering drugs also hold promise but need further evaluation. Patients who have refractory angina despite optimal medical therapy and are not candidates for revascularization procedures may be candidates for some new techniques of enhanced external Counterpulsation, Spinal Cord Stimulation, sympathectomy or direct transmyocardial revascularization. The usefulness of these techniques, however, needs to be confirmed in large randomized trials.

Deadly pediatric poisons: nine common agents that kill at low doses

More than 97% of pediatric exposures reported to the AAPCC in 2001 had either no effect or mild clinical effects. Despite the large number of exposures, only 26 of the 1074 reported fatalities occurred in children younger than age 6. These findings reflect the fact that, in contrast to adolescent or adult ingestions, pediatric ingestions are unintentional events secondary to development of exploration behaviors and the tendency to place objects in the mouth. Ingested substances typically are nontoxic or ingested in such small quantities that toxicity would not be expected. As a result, it commonly is believed that ingestion of one or two tablets by a toddler is a benign act and not expected to produce any consequential toxicity. Select agents have the potential to produce profound toxicity and death, however, despite the ingestion of only one or two tablets or sips. Although proven antidotes are a valuable resource, their value is diminished if risk after ingestion is not adequately appreciated and assessed. Future research into low-dose, high-risk exposures should be directed toward further clarification of risk, improvements in overall management strategies,and, perhaps most importantly, prevention of toxic exposure through parental education and appropriate safety legislation.

Drug targets in the voltage-gated calcium channel family: why some are and some are not

The L-type calcium channel antagonists have been, and continue to be, a very successful group of therapeutic agents targeted at cardiovascular disorders, notably angina and hypertension. The discovery that the voltage-gated calcium channels are a large and widely distributed family with important roles in both the peripheral and central nervous systems has initiated a major search for drugs active at other calcium channel types directed at disorders of the central nervous system, including pain, epilepsy, and stroke. These efforts have not been therapeutically successful thus far, and small molecule equivalents of the L-type blockers nifedipine, diltiazem, and verapamil directed at non-L-type channels have not been found. The underlying reasons for this are discussed together with suggestions for new directions, including fertility control, oxygen-sensitive channels, and calcium channel activators.