The Influence of Antihypertensive Agents on Circadian Rhythms of Blood Pressure and Heart Rate in Patients with Essential Hypertension.

The effects of once-daily administration of calcium (Ca) channel blockers, beta-blockers and and angiotensin-converting enzyme (ACE) inhibitors on circadian rhythms of blood pressure (BP) and heart rate (HR) were studied using the cosinor method. Sixty-two recruited patients with essential hypertension (WHO stage I or II) were divided into three groups based on the class of administered drugs. In the Ca channel blocker group (n = 37, age 54 +/- 9.0 years), 18 patients were given YM 730 at a mean dose of 11 +/- 4.0 mg/day (mean +/- S.D.), 8 were given nitrendipine (11 +/- 6.7 mg/day), and 11 were given nisoldipine (8 +/- 6.4 mg/day). In the beta-blocker group (n = 15, age 42 +/- 13.5 years), 13 patients were given atenolol (44 +/- 11.0 mg/day), 1 was given nadolol (30 mg/day), and 1 was given sustained-release propranolol (60 mg/day). In the ACE inhibitor group (n = 10, age 56 +/- 8.7 years), 7 patients were given enalapril (6 +/- 2.8 mg/day), and 3 were given lisinopril (20 mg/day). Ambulatory BP monitoring (ABPM) was performed before and during treatment. Mean arterial pressure (MAP) and HR were monitored under ambulatory conditions every five minutes for 24 hr with a finger volume oscillometric device. In all three groups, the mesor of MAP decreased significantly, while the amplitude and acrophase did not change during treatment. beta-Blockers reduced the amplitude as well as the mesor of HR. Ca channel blockers increased the amplitude of HR without influencing the mesor. ACE inhibitors had no effect on the circadian rhythm parameters of HR. These results suggest that Ca channel blockers, beta-blockers and ACE inhibitors lowered BP throughout the day without changing the circadian BP rhythm. However, the three drug classes may have different influences on the autonomic nervous system that regulates circadian cardiac rhythm.