Electrolyte excretion patterns. Intravenous and oral doses of bumetanide compared to furosemide.

The response to bumetanide and furosemide administered orally and intravenously was compared in normal subjects. Doses of bumetanide were 0.5 and 1 mg intravenously and 0.5, 1 and 2 mg orally. Doses of furosemide were 20 and 40 mg intravenously and 20, 40, and 80 mg orally. After intravenous doses of both drugs, peak natriuresis occurred during the first collection period of 30 minutes and the response returned to baseline by 3.5 hours. After oral dosing, peak effect occurred at 75 minutes and returned to baseline within 4 hours. Cumulative response was assessed for volume, sodium, potassium, and chloride excretion. The response did not differ substantially between drugs. On a milligram basis, bumetanide was approximately 50 times as potent as furosemide. For both drugs, the intravenous dose was approximately three times as potent as the oral preparation. The time course of response shows that the curves are virtually superimposable. The diuretic effect was short-lived for both diuretics. The urine volume and sodium and chloride excretion were parallel. The sodium/potassium ratio was calculated as follows: for every 200 mEq sodium excreted in 4 hours, bumetanide caused about 35 mEq and furosemide caused about 50 mEq potassium to be eliminated. Even if statistically significant, this difference does not appear to be clinically remarkable. If bumetanide offers therapeutic advantages in this regard, studies in patients with various disease states would have to be performed.