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Patients with renal insufficiency often undergo therapy with large doses of loop diuretics. We tested the hypotheses that remaining nephrons respond normally to amounts of diuretic reaching them, and that more limited doses than are commonly used are sufficient to reach effective portions of the dose-response curve. In eight patients with creatinine clearance less than 20 ml/min/1.73 m2, the amount of diuretic causing half-maximal response was identical to that in normal subjects, but the maximal response expressed as fractional excretion of sodium was increased approximately 60%. The upper plateau of the dose-response curve was attained with single intravenous doses of furosemide, 120 to 160 mg. In conclusion, remnant nephrons appear to demonstrate an exaggerated response to furosemide. Because maximal response was attained with single intravenous doses of furosemide of 120 to 160 mg, there appears to be no need to administer larger single doses in such patients.

Administration of nonsteroidal anti-inflammatory drugs (NSAIDs) to patients with chronically impaired renal function has been reported to cause abrupt and sustained reductions in renal plasma flow (RPF), glomerular filtration rate (GFR), and solute and water excretion in association with decreased renal prostanoid production. However, the time course of these acute effects and whether they are sustained during chronic exposure to the NSAIDs are unknown. Accordingly, using standard clearance and balance techniques, we investigated the effects of acute (zero to four hours) and chronic (five days) oral administration of two different NSAIDs on renal function in patients with stable, mild to moderate chronic renal insufficiency (CRI) and in normal subjects. In patients, acute oral administration of ketoprofen (K) and indomethacin (I) resulted in significant decreases in GFR (K: from 36 +/- 3 to 20 +/- 4 ml/min, P = 0.001; I: from 37 +/- 6 to 30 +/- 7 ml/min, P = 0.032; in RPF (K: from 194 +/- 21 to 146 +/- 21 ml/min, P = 0.002; I: from 222 +/- 33 to 147 +/- 18 ml/min, P = 0.016); and in urinary PGE2 excretion (K: from 0.60 +/- 0.25 to 0.08 +/- 0.02 ng/min, P = 0.05; I: from 0.34 +/- 0.06 to 0.18 +/- 0.06 ng/min, P = 0.042). Fractional excretion of sodium chloride and fractional free water clearance (CH2O/CIn) also decreased significantly after both agents. In normal subjects, GFR and RPF were not significantly decreased after acute dosing, whereas urinary PGE2 and fractional excretions of NaCl and free water decreased significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

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