1 Intravenous loading with 500 ml of 2.7% saline increased the clearance of PAH and inulin and urine sodium excretion in 14 healthy subjects. 2 Intravenous propranolol (0.075 and 0.15 mg/kg) did not alter PAH or inulin clearance at rest but abolished the increase expected during saline infusion. There was no consistent effect on urinary sodium excretion. 3 Intravenous nadolol (0.05 and 0.75 mg/kg) reduced resting PAH and inulin clearances by up to 25%. Both clearances fell significantly during saline infusion but natriuresis was not significantly reduced in spite of the changes in renal function. 4 There was no evidence from these studies in normal volunteers that nadolol confers any advantages over propranolol in its effects on renal function.

In an open crossover trial, 15 patients with evidence of renal impairment, defined by proteinuria, raised serum creatinine or impaired creatinine clearance, were randomly allocated to treatment with either 40 mg frusemide or 40 mg xipamide daily for 7 days. After a 3-day mid-point wash-out period, patients were changed the alternative drug for a further 7 days. Assessment measures involved a wide range of clinical and biochemical parameters. Whilst both drugs significantly reduced oedema, xipamide was more effective than frusemide, and this was associated with a significantly greater effect on sodium excretion with xipamide. With the exception of standing systolic blood pressure where the reduction was significantly more pronounced with xipamide, no significant changes in resting systolic, resting diastolic or standing diastolic pressure were observed to be associated with change of treatment. Three patients noticed minor side-effects during xipamide therapy. There were no adverse reactions inpatients taking frusemide.