To prevent cardiovascular disease, targeting aldosterone synthesis and release may be clinically important. Aldosterone production in the adrenal gland is mediated mainly by the T-type calcium channel in vitro. Efonidipine inhibits both L- and T-type Ca channels. To compare the effects of efonidipine on neurohumoral factors with those of amlodipine, an L-type Ca channel blocker, we studied 40 essential hypertensive outpatients. Forty patients who had been administered amlodipine for more than 1 year were treated with efonidipine for 6 months in place of amlodipine. Substituting efonidipine for amlodipine had no significant effect on clinic systolic blood pressure or the plasma levels of brain natriuretic peptide, norepinephrine or active renin. However, the heart rate was significantly decreased (72.0+/-1.3 vs. 69.8+/-1.3 beats/min, p<0.01) and the plasma aldosterone level was also significantly decreased after efonidipine treatment (97.7+/-7.9 vs. 79.7+/-5.6 pg/mL, p<0.0001). Changes in the aldosterone level correlated with the baseline value before the replacement of amlodipine by efonidipine (r=-0.769, p<0.0001). These findings indicate that at the effective antihypertensive doses of efonidipine and amlodipine, efonidipine significantly decreases heart rate and plasma aldosterone level compared with those under amlodipine treatment in hypertensive patients.