Amlodipine ; 2-<(2-aminoepoxi)methyl>-4-(2-chlorophenyl)-3-ethoxycarbonyl-5-methoxycarbonyl-6-methyl-1,2, dihydropyridine) is a novel calcium channel antagonist of long half-life and steady state blood levels. However, its blood pressure lowering effect throughout the day has not been well documented especially in Korean patients with essectial hypertension. Therefore, antihypertensive effect of amlodipine in Korean patients with mild to moderate hypertension was evaluated with using 24 hour ambulatory blood pressure measurement(ABPM) as well as office blood pressure measurement.

Total 25 subjects(M;F=13:12, mean age;53.4±7.3 yrs) with mild-to-moderate essectial hypertension had completed the study. After 2 weeks of placebo, amlodipine was mediciated for 12 weeks. Initially, amlodipine was given as 5mg once a day and the daily dose was increased to 10mg/day if diastolic blood pressure in over 90mmHg at the 8th week of medication. The blood pressure level was measured every 4weeks during medication in sitting position('office blood pressure level') and 24 hour ambulatory blood pressure monitoring(ABPM) was done at the placebo run-in phase and at the 8th week of medication.

In the view of' office blood pressure lever', the blood pressure lowering effect of amlodipine was already impressive at 4 weeks after medication. The systolic(placebo; 165.3±16.9mmHg, arter 4 wk of medication; 136.1±16.0mmHg, 8 wk; 136.0±12.9mmHg, 12wk; 133.2±10.7mmHg) and diastolic blood pressure(placebo; 104.1±11.0mmHg,after 4 wk of medication; 87.4±6.8mmHg, 8 wk; 86.0±6.5mmHg, 12 wk; 84.7±5.4mmHg)fell significantly, and most patients had both satisfactory systolic(<160mmHg) and diastolic(<90mmHg) blood pressure levels. And such antihypertensive effects were main tained throughout study period. In contrast, the heart rate did not change significantly.

The blood pressure lowering effects assessed by 24 hour AVPM were slightly milder, but absolute systolic and diastolic blood pressures by ABPM after 8 weeks of meddication were as low as those of office measurement. The blood pressure lowering effect was maintained throughout the day including morning periods without either rebound blood pressure elevation or reflex tachycardia.

The percent reduction of systolc and diastolic vlood pressure with amlodipine were 17% in office blood pressure measurement and 10% in ABPM.

During medication, neither significant side effects nor discomforts that lead to discontinuation of the drug has not been observed. Mild edmatous feeling in 3 subjects, flushing in one and palpitation in one were reported.

Amlodipine is an effective antihypertensive drug that can control the elevated blood pressure in most patients with mild-to-moderate essential hypertension by monotherapy of once a day regimen without serious side effects.