Nocturnal hypotension and ACE inhibitors

Thirty essential hypertensive subjects had their BP measured by 24h ambulatory monitoring before (first placebo period) and after exposure to antihypertensive therapy with either enalapril (four weeks) or nitrendipine (six weeks). Similar measures of BP were obtained during a second placebo period intercalated between the two active drugs. The 24h averages of systolic and diastolic pressures were higher during placebo (148 +/- 3/91 +/- 1 mmHg, respectively) than during treatment periods. Four weeks of treatment with enalapril reduced arterial pressure to a 24h average of 137 +/- 1/86 +/- 1 mmHg while nitrendipine given for six weeks lowered BP to an average of 135 +/- 1/84 +/- 1 mmHg. The antihypertensive effect of the drugs was of a comparable magnitude (P > 0.05). In addition both drugs produced analogous reductions in BP during the day (07.00 to 23.00 h). In contrast, the nocturnal fall in BP was significantly greater during treatment with nitrendipine. Average systolic and diastolic pressures between 23.00 h and 07.00 h were 133 +/- 1 mmHg and 82 +/- 2 mmHg with enalapril compared with 129 +/- 3 mmHg (P < 0.01) and 77 +/- 3 mmHg (P < 0.01) with nitrendipine, respectively. These data suggest that antihypertensive agents show important differences in terms of their action on the mechanisms that regulate BP during sleep. Medications that amplify the otherwise physiological fall in BP during sleep may add risk to patients with impaired coronary vasodilator reserve owing to ventricular hypertrophy, coronary atherosclerosis, or both.