Hormonal effects of the diuretic xipamide in healthy men.

The effect of xipamide on plasma alpha-atrial natriuretic peptide and the renin-aldosterone-kallikrein system have been studied in 12 healthy men, using a double-blind cross-over design. After a run-in period on placebo of 1 week, the subjects were treated with either placebo (n = 6) or xipamide 20 mg once daily (n = 6) for 16 weeks and were then switched to the alternative medication for another 16 weeks. The plasma concentration of alpha-atrial natriuretic peptide fell after 1 week of xipamide administration and increased during prolonged xipamide administration but remained reduced. The changes in plasma alpha-ANP observed after 1 week of xipamide were negatively correlated with the changes in hematocrit and hemoglobin. Plasma renin activity (PRA), aldosterone concentration (PAC), and urinary excretion of aldosterone and kallikrein increased after 1 week of xipamide administration, levelled off during the second and fourth weeks, but remained elevated during further prolonged xipamide administration for 16 weeks. The xipamide-induced changes in PRA and PAC were positively correlated with the changes in the hematocrit and hemoglobin. The changes in plasma renin, aldosterone, and alpha-atrial natriuretic peptide during xipamide administration may be related to diuretic-induced volume contraction.