Vasodilators are widely used for treatment of congestive heart failure (CHF) that has not responded adequately to diuretics and digitalis. Vasodilator drugs redistribute blood volume in patients with heart failure, lowering pressure and reducing volume in the failing left ventricle, which leads to increased cardiac output, decreased pulmonary capillary wedge pressure, and improved exercise tolerance. Since the last Medical Letter review of this subject (Volume 26, page 115, 1984), some additional data have become available.

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).

Amlodipine (am loe' di peen) besylate (Norvasc - Pfizer), a dihydropyridine calcium-channel blocker, has been approved by the US Food and Drug Administration for once-daily oral treatment of hypertension, chronic stable angina, and vasospastic (Prinzmetal's) angina.

Many nitrates, beta-blockers, and calcium-channel blockers have now been approved by the US Food and Drug Administration for treatment of stable angina pectoris. The table beginning on page 112 lists the individual drugs, their dosage, and their cost.

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.

Bosentan (Tracleer - Actelion), a non-peptide endothelin receptor antagonist, has been approved by the FDA for oral treatment of patients who have pulmonary arterial hypertension (PAH) with symptoms of dyspnea at rest or with minimal exertion.

View the Expanded Table: Some Drugs for Altitude Illness, Jet Lag, and Motion Sickness

Pantoprazole, the fourth benzimidazole proton pump inhibitor to become available in the United States, has been marketed for short-term oral treatment of erosive gastroesophageal reflux disease (GERD).

The ability of grapefruit juice to increase serum concentrations of drugs was first discovered during a study of the effect of ethanol on felodipine (Plendil) pharmacokinetics. Double-strength grapefruit juice used to disguise the taste of ethanol resulted in higher than expected serum concentrations of felodipine (DG Bailey et al, Clin Invest Med 1989; 12:357).