All studies suggesting a lower incidence of
edema on
lacidipine than on
amlodipine are based on subjective scoring. Therefore, we have compared
edema formation on two
dihydropyridine calcium channel blockers, using an accurate method for quantitative assessment of foot volume. In a randomized study, we treated 62 patients with
essential hypertension for 12 weeks starting with either
lacidipine 4 mg o.d. (
n = 30) or
amlodipine 5 mg o.d. (n = 32). At 6 weeks, the doses were increased to that maximally allowed (
lacidipine 6 mg, n = 18;
amlodipine 10 mg, n = 12) if trough diastolic blood pressure response was insufficient (>90 mmHg and decrease < 10 mmHg).
Edema, scored visually, occurred more frequently (p = 0.02) on
amlodipine (15/32) than on
lacidipine (6/30); this was confirmed by an increase of foot volume above the 95% upper limit of normal variation in 15 patients on
amlodipine and in only five patients on
lacidipine (p = 0.01). In the whole group of patients, both the increases of foot volume and the decreases of blood pressure just failed to be significantly different between
amlodipine and ]acidipine (foot volume, +3.3+/-1.0% on
amlodipine and +1.2+/-0.5% on
lacidipine, p = 0.08; mean arterial pressure, -11+/-1% on
amlodipine and -8+/-1% on
lacidipine, p = 0.052). In patients requiring dose increase, the increase of foot volume on
amlodipine was more pronounced (p < 0.05), and the
antihypertensive effect was larger (p < 0.05) than on
lacidipine. In conclusion, our data show a higher incidence of
edema on
amlodipine than on
lacidipine, which has to be explained at least partly by a comparably higher dose c.q. a larger
antihypertensive effect of
amlodipine. Other mechanisms might have contributed to these differences and need to be explored.