1 Calcium antagonists with long us short elimination half‐life may show marked differences in their antihypertensive effect during short interruptions of therapy by missed doses. 2 In the present study we evaluated the blood pressure lowering effect of amlodipine us diltiazem both on active maintenance treatment and after active treatment was interrupted for 2 days by placebo using a double‐blind randomized design. After a single blind placebo run‐in period, hypertensive patients were randomized to amlodipine 5 mg once daily or diltiazem 90 mg twice daily. After 4–6 weeks, doses were increased to 10 mg once daily or 180 mg twice daily, if necessary for control of diastolic blood pressure. During week 9 or 10 on active treatment blisterpacks contained 2 days of placebo. Twenty‐four hour blood pressure monitoring was performed at the end of run‐in period and during week 9 and 10 on active us interrupted therapy. 3 Active therapy by amlodipine ( n = 20 ) lowered day systolic blood pressure by 17 ± 2 mmHg and diastolic blood pressure by 12 ± 2 mmHg and did not change heart rate. In second day of interrupted therapy most of these responses were still present. Diltiazem (n = 14) lowered day systolic blood pressure by 13 ± 2 mmHg, diastolic blood pressure by 11 ± 2 mmHg and heart rate by 10 ± 2 beats min ‐1 . Most of these responses had disappeared during the second day of interrupted therapy. 4 We conclude that amlodipine and diltiazem are fairly similar in lowering blood pressure from an efficacy point of view. However, during short periods of non‐compliance blood pressure control will persist markedly better with the agent with a long vs the one with a short elimination half‐life.
1,4-Dihydropyridine calcium antagonists, which have a rapid onset and short duration of action, tend to increase sympathetic activity, which may limit the regression of left ventricular hypertrophy when used for the treatment of hypertension. This study compares the effects of the shorter-acting formulation of nifedipine (PA) with longer-acting felodipine (ER) on 24-h blood pressure and left ventricular mass in patients with uncomplicated essential hypertension. Subjects were randomly allocated to receive nifedipine (n = 52) or felodipine (n = 56) over 8 weeks at increasing doses until the sitting office diastolic blood pressure (DBP) was < 90 mm Hg. An ambulatory blood pressure (ABP) recording and echocardiogram were performed at baseline and upon completion of the study. At the end of the dosing interval, felodipine lowered office DBP (mm Hg) by−18 ± 12/14 ± 1 compared to −14 ± 2/11 ± 1 for nifedipine (P ≤ .05). Mean 24-h ABP was reduced (P < .001) by felodipine (−15 ± 1/−10 ± 1 mm Hg) and nifedipine (−15 ± 1/−9 ± 2 mm Hg). However, nifedipine caused an apparent biphasic response with felodipine reducing (P < .05) blood pressure more in the early afternoon compared to nifedipine. Left ventricular mass index was significantly reduced (P < .01) by felodipine (-6 ± 1 g/m2), but not by nifedipine. Once-daily administration of felodipine achieves a more consistent control of blood pressure compared to twice-daily nifedipine and may be associated with a greater reduction in left ventricular mass. Am J Hypertens 1995;8:712–718
