Effect of Long-Term, Once-Daily Administration of Atenolol, Metoprolol, Pindolol and Slow-Release Propranolol on Ambulatory Blood Pressure and its Variability

1. Twenty-four-hour intra-arterial blood pressure recordings were made before and after chronic β-receptor blockade in 34 patients with essential hypertension. 2. Subjects were randomized in double blind fashion to either atenolol, metoprolol, pindolol or slow-release propranolol. 3. Drugs were administered in a once-daily variable dose regimen for a period of 3–8 months (mean 5.0 ± sd 1.4). 4. All four drugs reduced blood pressure significantly 24 h after the last dose but there were considerable differences in control when each intervening hour was assessed separately. 5. Not all β-receptor blockers in conventional formulations are equally effective as antihypertensive agents over 24 h when taken once daily.