Renal effects of calcium antagonists in hypertensive patients

This summary report of various clinical studies by our group describes the effects on renal excretion of water and sodium of several different calcium antagonists (verapamil, gallopamil, nifedipine and felodipine) which were administered for variable periods of time (from a single administration to repeated doses over up to 10 days) to hypertensive patients. All calcium antagonists tested displayed some diuretic and natriuretic action, despite profound differences in chemical nature and in pharmacodynamic properties. On single-dose administration the renal action of calcium antagonists was prompt, appearing during the first few hours, and decaying and ending after 6 h. When repeated doses were administered over several days the effect was at a maximum during the first 2 days and then disappeared in the following days, but the negative sodium balance which developed during the first 2 days was maintained for at least 7-10 days. The natriuretic effect was not accompanied by any change in the glomerular filtration rate, but with felodipine, a natriuretic effect observed at small doses reverted to an antinatriuretic effect at higher doses, at which the glomerular filtration rate was slightly decreased.