Diuretic Effects of Furosemide and Co-administration of Dopamine in Healthy Volunteers and Patients with Renal Impairment

Abstract

Diuretic effects of furosemide (FM) alone or combined with dopamine (DA) were inves-tigated in subjects with normal renal function and in patients with renal impairment. The renal excretion rate constant and the urinary recovery of FM were significantly decreased in the patients. However, there was no correlation between pharmacokinetic parameters and diuretic responses to FM in the patients. In contrast, linear regression line for urine flow rate vs.(Na⁺+K⁺) excretion rate (UV_Na+K), and that for Cl^- excretion rate vs. UV_Na+K showed high correlations, regardless of DA infusion, although diuretic responses and creatinine clearance in the patients were increased with DA. To clarify the variations of the sensitivity to FM, a urinary excretion-response curve, which was expressed by UV_Na+K vs. urinary excretion rate of FM, was analyzed. Increased apparent sensitivity to FM diuresis was observed in patients with renal failure, although the max imal and total diuretic responses were decreased. Therefore, highdose FM may not always be effective for patients with severe renal impairment. The sustained administration of FM or the co-administration of low-dose DA, by which the hemodynamics in the kidney are improved, may be a more effective treatment.