Reports of increased mortality associated with calcium-channel blockers have caused concerns among patients taking these drugs and their physicians.

Nicardipine (Cardene - Syntex), a dihydropyridine calcium-entry blocker structurally related to nifedipine (Procardia; Adalat), was recently approved by the US Food and Drug Administration for oral treatment of angina and hypertension. Advertisements for the drug claim that nicardipine is more vasoselective; than other calcium-channel blockers and does not depress myocardial contractility.

Candesartan cilexetil (Atacand - Astra) is the fourth angiotensin II receptor antagonist to become available in the USA for oral treatment of hypertension.

Hypertensive emergencies include hypertensive encephalopathy, intracranial hemorrhage with hypertension, aortic dissection, acute pulmonary edema with hypertension, acute cardiac ischemia with hypertension, malignant hypertension and severe hypertension after vascular surgery; hypertensive crisis due to pheochromocytoma or occurring during pregnancy is not discussed in this review. Although immediate reduction of blood pressure is necessary in hypertensive emergencies, an excessive decrease may cause stroke, myocardial infarction or visual changes. Most experienced clinicians aim...

Cerebral arterial spasm frequently causes ischemic neurological damage after subarachnoid hemorrhage from a ruptured intracranial aneurysm. Nimodipine (Nimotop - Miles), a 1,4-dihydropyridine calcium-entry blocker, was recently approved by the US Food and Drug Administration (FDA) for oral treatment of such patients; an intravenous preparation is available only for investigational use.

Nisoldipine (Sular -Zeneca), a dihydropyridine calcium-channel blocker structurally similar to nifedipine, has been approved for marketing by the US Food and Drug Administration. It is available in an oral extended-release formulation for treatment of hypertension.

In a study of the interaction between alcohol and the calcium-channel blocker felodipine (Plendil), the grapefruit juice vehicle for the alcohol appeared to increase felodipine plasma concentrations. Subsequent studies have found that grapefruit juice increases plasma concentrations of several calcium-channel blockers and of some other drugs as well (DG Bailey et al, Clin Pharmacokinet, 26:91, 1994).

Many fermented foods contain tyramine as a byproduct formed by the bacterial breakdown of the amino acid tyrosine; it can also be formed by para-hydroxylation of phenylethylamine or dehydroxylation of DOPA and dopamine. Tyramine and some other amines found in food can cause hypertensive reactions in patients taking monoamine oxidase (MAO)inhibitors.

Mibefradil dihydrochloride (Posicor - Roche), a chemically distinct nondihydropyridine calcium-channel blocker, has been approved by the US Food and Drug Administration (FDA) and is being heavily promoted as the first T-type calcium-channel blocker for treatment of hypertension and chronic stable angina.

Serious adverse interactions between drugs continue to be reported. Many of these are due to inhibition or induction of cytochrome P450 (CYP) enzymes, particularly CYP3A4. CYP3A is thought to be involved in the metabolism of more than 50 percent of currently prescribed drugs.2 CYP3A4, which is more abundantly expressed than CYP3A5, accounts for most CYP3A activity in vivo.