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Effects of diltiazem hydrochloride on renal hemodynamics and urinary electrolyte excretion
Insights
Diltiazem hydrochloride, a coronary dilator, increased renal blood flow fraction and sodium excretion in patients. While not significantly altering overall renal hemodynamics, it suggests a direct effect on renal sodium reabsorption.
Area of Science:
- Pharmacology
- Nephrology
- Cardiology
Background:
- Diltiazem hydrochloride is a calcium channel blocker known for its coronary dilating effects.
- Its impact on renal function and electrolyte balance requires further elucidation.
Purpose of the Study:
- To investigate the effects of diltiazem hydrochloride on renal hemodynamics.
- To assess its influence on urinary electrolyte excretion, particularly sodium.
Main Methods:
- Radioisotope dilution and external counting were used to measure renal blood flow (RBF), glomerular filtration rate (GFR), and cardiac output in ambulatory patients.
- Standard renal clearance methods were employed in inpatients receiving oral diltiazem.
Main Results:
- A significant increase in the renal fraction of cardiac output (RBF/CO) was observed, indicating reduced renal vascular resistance.
- Urinary sodium excretion (UNaV) increased significantly within 2 hours post-administration in most patients.
- No statistically significant changes were noted in overall RBF, GFR, or cardiac output.
Conclusions:
- Diltiazem hydrochloride appears to have a direct inhibitory effect on renal tubular sodium reabsorption.
- While renal hemodynamics may play a role, the primary action on sodium excretion seems direct.
Abstract:
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.