Beta-adrenergic receptor blocking drugs in hypertension. With special reference to their use as initial therapy

Issues with antihypertensive therapy: safety perspectives

The benefits of treating hypertension have been documented by several long-term studies that have shown a decreased incidence of morbidity and mortality associated with stroke, left ventricular failure, and renal insufficiency. With the large number of antihypertensive drugs currently available, several safety factors need to be considered when initially choosing a regimen so as not to adversely influence the potential benefits of blood pressure control. Antihypertensive agents should be chosen based on their hemodynamic profile, the absence of adverse metabolic effects and subjective side effects, and the presence of beneficial effects on the patients' quality of life. Thiazide diuretics and beta-blocking agents have often been recommended as initial therapy in patients with mild to moderate hypertension. However, thiazide diuretics may be less desirable in certain patients because of their effects on lipids, potassium, and glucose tolerance; beta-blocking agents are not ideal for some patients because of their effects on lipids, exercise tolerance, and overall quality of life. The angiotensin-converting enzyme inhibitors, selective alpha 1-blocking agents, and calcium channel blocking agents may be more appropriate for initial therapy of hypertension in many patients.

Carvedilol for systemic hypertension

Twenty-four-hour profiles of intraarterial ambulatory blood pressure (BP) and heart rate were significantly reduced by administration of carvedilol, a new beta-blocking drug with vasodilating properties. Twelve patients were given carvedilol, 25 mg twice daily for 2 weeks; the dose was then increased to 50 mg twice daily if the target BP was not achieved. After 4 weeks of therapy, mean daytime reduction in BP was 25 +/- 3 mm Hg systolic and 19 +/- 3 mm Hg diastolic and mean reduction in heart rate was 22 +/- 3 beats/min. BP at the peak of isometric exercise and during dynamic exercise was also significantly reduced. Radionuclide measurements showed that left ventricular ejection fraction was not affected by treatment, but there was a significant reduction in systolic and diastolic volumes. The drug was well tolerated. This clinical trial suggests that carvedilol will be a useful first-line drug for treatment of essential hypertension, and its vasodilating action may have a more favorable effect on left ventricular function than conventional beta-blocking drugs.

Atenolol plus nifedipine for mild to moderate systemic hypertension after fixed doses of either agent alone

Three therapies were used to treat 35 patients with mild to moderate systemic hypertension: (1) the cardioselective beta-adrenoceptor blocker atenolol, (2) the calcium antagonist nifedipine and (3) combination therapy for those who failed to reach the target diastolic blood pressure (BP) of less than 90 mm Hg with monotherapy. After an initial run-in placebo period, when the mean supine diastolic BP was 102 +/- 1 mm Hg (mean +/- standard error of the mean), patients were randomized (double-blind) to atenolol, 100 mg as a single daily dose or nifedipine (slow-release form), 20 mg twice daily, then to a washout dummy placebo period before crossover. Each period lasted 4 weeks. Supine, erect and exercise BP were recorded. Atenolol and nifedipine, in the same fixed doses but in combination, were given to 20 patients in whom either supine or erect diastolic BP exceeded 90 mm Hg after the period of monotherapy. Atenolol monotherapy reduced the erect diastolic BP to less than 90 mm Hg in 14 patients (40%); of the remainder, 1 patient responded only to fixed-dose nifedipine and 11 to combination therapy, yielding a total success rate of 74%. The combination gave enhanced control, as shown by a further decrease in supine and erect BP and by better control of exercise BP; these effects were achieved without an increased incidence of adverse effects. The mean reductions in supine diastolic BP were: atenolol, 9 +/- 2 mm Hg; nifedipine, 6 +/- 2 mm Hg; and combination therapy, 16 +/- 2 mm Hg (p less than 0.05 vs atenolol or nifedipine).(ABSTRACT TRUNCATED AT 250 WORDS)