Calcium channel blockade and renal function.

Since calcium channel blocking agents were introduced into the treatment of hypertension their influence on renal function has become an important issue. In animal experiments calcium channel blocking agents have been shown to increase renal blood flow and glomerular filtration rate and to augment urine flow and electrolyte excretion. In human acute studies the administration of calcium channel blocking agents have elicited similar renal hemodynamic and diuretic effects. Clinical studies on the renal effects of long-term treatment are however still lacking. Studies on the effect on renin release have given divergent results. In acute experiments renin release is increased by calcium channel blocking agents. In long-term treatment, however, no change in peripheral plasma levels of renin has been demonstrated. The influence of decreased renal function on the pharmacokinetics of calcium channel blocking agents has been studied in patients with renal disease. For verapamil the volume of distribution is smaller in uremic patients than in normals and both metabolic and renal clearances are decreased. For nifedipine, on the other hand, similar plasma levels, plasma half life and total plasma clearance are found in uremic patients and normal subjects.