THE NATRIURETIC EFFECT OF NIFEDIPINE GASTROINTESTINAL THERAPEUTIC SYSTEM REMAINS DESPITE THE PRESENCE OF MILD-TO-MODERATE RENAL-FAILURE

Background Calcium channel blockers facilitate the renal excretion of sodium and this effect is maintained during chronic administration of these drugs. However, it is unknown whether this natriuretic effect re mains despite the presence of a decreased renal function. Objective To compare the natriuretic capacity of nifedipine gastrointestinal thera peutic system (GITS) and lisinopril in patients with mild-to-moderate chronic renal failure. Methods An open-label, randomized, comparative study was conducted to compare the natriuretic capacity of nifedipine GITS and lisinopril in the presence of mild-to-moderate renal failure (creatinine clearance 30-80 ml/min). After a wash-out period of 4 week s an intravenous saline infusion (30 ml/kg of body weight of isotonic saline in 4 h) was performed and repeated after 4 weeks of active ther apy. Two sex-and age-matched groups of hypertensive patients (n = 25) were included in the study. Renal failure was diagnosed as secondary t o nephrosclerosis in all the patients. Results A significant increase in the renal capacity to excrete the sodium load was observed in patie nts receiving nifedipine GITS (n = 11) but not in those taking lisinop ril (n = 13). Both drugs controlled blood pressure to a similar extent . No changes were observed in body weight, glomerular filtration rate and renal plasma flow (measured as inulin and paraaminohippurate clear ances). A significant drop was observed in urinary albumin excretion a fter lisinopril, but not after nifedipine. Heart rate was higher in ni fedipine group. Conclusion The natriuretic capacity of nifedipine GITS remains despite the presence of mild-to-moderate chronic renal failur e. Such an effect takes place in the absence of changes in renal hemod ynamics, suggesting that it is caused by a direct tubular effect. (C) Rapid Science Publishers ISSN 0263-6352.