Daytime-selective antihypertensive activity of celiprolol

Day-activity rhythms of heart rate and blood pressure are thought to be mediated mainly through the sympathetic nervous system and may have greater amplitudes in patients with hypertension owing to increased daytime and largely normal nighttime values. Drug-induced nighttime hypotension in patients with chronic hypertension has been associated with the precipitation of cardiac failure and a fall in cerebral flow. The authors examined the effects of a single dose and of a 4-week treatment with different classes of antihypertensive drugs on ambulatory blood pressure (ABP) in 10 patients with mild hypertension. Data were assessed by polynomial analysis (Harvard Graphics 3). A single oral dose of enalapril 10 mg, amlodipine 5 mg, carvedilol 25 mg, and celiprolol 200 mg produced a mean reduction of 24-hour ABP compared to placebo of, respectively, 24/11, 11/5, 13/6, and 12/5 mm Hg (p values between <0.02 and <0.001). With enalapril, amlodipine, and carvedilol, between-subject variability contributed significantly to the overall variability in the measurements (p values between 0.05 and 0.01 versus zero), whereas with celiprolol this was not so. Although the beta blockers reduced daytime blood pressures similarly to the ACE inhibitor or the calcium channel blocker, they did not reduce nighttime blood pressures. These results were confirmed by an 8-week crossover trial comparing enalapril 10 mg daily with celiprolol 200 mg daily in the same group of patients. The authors conclude (1) that beta blockers produce a more stable reduction of blood pressure in patients with mild hypertension less affected by pressor effects through the sympathetic nervous system; (2) that beta blockers, unlike ACE inhibitors and calcium channel blockers, do not give rise to nighttime hypotension in this category of patients; and (3) that the selective beta blocker celiprolol may even perform better in these respects than the nonselective beta blocker carvedilol.