Acute diuretic/natriuretic properties of felodipine in man

The natriuretic/diuretic effect of felodipine was investigated in 2 studies. The first was performed as an open study using intravenous and oral felodipine in healthy male subjects. The second was a double-blind study where a high and a low dose of oral felodipine were given to hypertensive patients on long term treatment with beta-blockers; the different doses of felodipine were chosen to decrease and to have no effect on the blood pressure, respectively. In both studies an oral placebo solution was used as a reference. Felodipine caused a significant increase in natriuresis. Compared with placebo and corrected for total 24-hour excretion, the sodium output during the first 4 hours after drug administration was increased by 219 +/- 53% (mean +/- SEM) after intravenous administration in healthy subjects (p less than 0.01) and by 80 +/- 43% in the first 3 hours after the high dose in hypertensive patients (p less than 0.05). For the same period, the urine excretion was increased by 114 +/- 38% (p less than 0.05) in the healthy subjects and by 36 +/- 22% in the hypertensive patients (not significant). However, the 24-hour excretion of urine, Na+ and K+ was not significantly changed from placebo. A significantly lower blood pressure was recorded after the higher dose (0.10 mg/kg) when given to hypertensive patients, but no such effect was seen after the lower dose (0.01 mg/kg) or in healthy subjects. The changes in diastolic blood pressure seem to be negatively correlated with the diuretic but not with the natriuretic effect.