Evaluation of the Antihypertensive Effect of Amlodipine Using 24-Hour Ambulatory Blood-Pressure Measurement

The antihypertensive effect of amlodipine was investigated in 20 patients (11 men and nine women) with essential hypertension using 24-hour monitoring of ambulatory blood pressure. The patients received placebo initially for 1 week followed by amlodipine 5 mg/day for 8 weeks. In three patients whose diastolic blood pressure did not fall below 90 mmHg after 4 weeks, the dosage was raised to 10 mg/day. All patients underwent ambulatory blood pressure monitoring at the end of the placebo period and at the end of 8 weeks of active treatment. Blood pressures and heart rate were measured and a physical examination was performed every 2 weeks during the treatment period. By the second week of treatment, systolic and diastolic blood pressures were significantly reduced with amlodipine therapy (P < 0.01). The reduction was more pronounced in the fourth week (P < 0.001). There were no significant changes in heart rate. Ambulatory investigations revealed a significant decrease in both systolic and diastolic blood pressures every hour of the day (P < 0.001). On the other hand, heart rate was significantly reduced only between 8 AM and 12 noon (P < 0.05). Changes at other hours of the day were not significant. Drug-related side effects disappeared quickly without the need for tapering off or discontinuing the drug. Amlodipine is an effective and well-tolerated drug for the treatment of hypertension.