Renal electrolyte excretion pattern in response to bumetanide in healthy volunteers.

Renal electrolyte excretion patterns were determined in nonedematous healthy volunteers following bumetanide and furosemide in two separate clinical studies. In study 1, intravenous bumetanide was administered to 24 subjects at four dose levels. In study 2, bumetanide (1 or 2 mg) or furosemide (40 or 80 mg) was administered in a single oral dose to 32 subjects assigned at random to one of the four treatment groups. In study 1, there was a significant dose-related increase in urine volume and sodium, potassium, and chloride excretion, with chloride exceeding sodium at all dose levels, and the Na+/K+ ratios after bumetanide were greater than 3:1. In study 2, the Na+/K+ ratio increased significantly after treatment in all four treatment groups. The relative Na+/K+ ratios showed higher natriuretic potency and lower kaliuretic potency for bumetanide than for furosemide, but the differences were not statistically significant. Additionally, all four treatment groups demonstrated elevation in titratable acidity, ammonia formation, and total acid excretion. There was a significant degree of positive correlation in the bumetanide-treated groups between Na+/K+ and the three variables. In the furosemide-treated groups, this positive correlation was statistically significant between the Na+/K+ ratio and ammonia and total acid secretion but not for titratable acidity. The results support the view that increased H+ formation after the administration of loop diuretics has a relative potassium-sparing effect.