Effects of atenolol and propranolol on platelet aggregation in moderate essential hypertension: randomized crossover trial.

AIM To compare the effects of a selective beta-blocker atenolol and a nonselective beta-blocker propranolol on platelet aggregation. METHODS Twenty successive outpatients with moderate essential hypertension (6 women and 14 men, mean age-/+standard deviation 42.6-/+8.5 years) were randomized to either propranolol (40 mg three times a day) or atenolol (100 mg once a day) for the first two weeks, followed by a one-day washout period, and then a two-week administration of the alternative drug. Along with standard examinations and tests, circulating platelet aggregates were measured. RESULTS There were no significant differences in creatinine, blood glucose, potassium, total cholesterol, hemoglobin, red blood cells (RBC), or platelets in three periods: baseline, atenolol, and propranolol period. Significant and comparable reductions in systolic and diastolic arterial pressure, body weight, heart rate, and HDL-cholesterol were recorded in both patient groups. The LDL-cholesterol concentration increased significantly in propranolol compared with both baseline and atenolol period. Serum triglycerides increased significantly with both medications. The number of circulating platelet aggregates decreased significantly with propranolol (0.99-/+0.19) in comparison with both atenolol (1.41-/+0.70; P=0.004, Wilcoxon matched pairs test) and baseline (1.59-/+0.94; P=0.002, Wilcoxon matched pairs test). CONCLUSION Propranolol inhibits platelet aggregation more than atenolol and may have a favorable effect on the management of hypertension especially in patients with increased cardiovascular risk.