Effects of diltiazem hydrochloride on renal hemodynamics and urinary electrolyte excretion.

Dilitazem hydrochrolide, a potent coronary dilator, was administered in 18 patients to evaluate its effect on renal hemodynamics and urinary electrolyte excretion. Renal blood flow (RBF), glomerular filtration rate (GFR), and cardiac output were determined in 8 ambulatory patients by means of external counting of radioisotope dilution before and 3 or 4 weeks after the medication. Althoug RBF tended to increase after the therapy, there was no statistically significant change in RBF, GFR and cardiac output. Renal fraction of cardiac output (RBF/CO) showed a significant increase by 29.5% after the therapy, indicating that the renal vascular resistance decreased to a greater extent than the extrarenal vascular resistance. Standard renal clearance was performed in 10 inpatients whom 60 mg of dilitiazem was administered orally. Renal plasma flow (RPF) showed an average increase by 15% 3 hr after the administration of the drug, which was not, however, statistically significant. There was no certain trend for GFR and filtration fraction. Urinary sodium excretion (UNaV) began to increase one hr and reached its peak 2 hr after the medication in 9 out of the 10 patients. It may be concluded that diltiazem has a direct inhibitory action against the renal tubular reabsortion of sodium, although the participation of renal hemodynamics can not be denied.