Furosemide kinetics and dynamics after kidney transplant.

We examined differences between responder (R) (40 to 80 mg/day) and nonresponder (NR) (greater than or equal to 120 mg/day) patients after kidney transplant with respect to furosemide kinetics and dynamics. Nonresponders had reduced plasma clearance (NR 64 +/- 21.4 and R 105 +/- 23 ml/min, two-sample t test; p less than 0.05), renal clearance (NR 18.4 +/- 8.1 and R 47.1 +/- 11.0 ml/min; p less than 0.005), and renal clearance to creatinine clearance ratio (NR 0.43 +/- 0.15 and R 0.80 +/- 0.07; p less than 0.005). Half-life rose in the nonresponders (NR 130 +/- 13 and R 87.6 +/- 16.3 min; p less than 0.005). There was no difference between groups with respect to nonrenal clearance, extent of availability, volume of distribution steady state, and the fraction of the dose excreted unchanged in the urine after intravenous administration. These results suggest that nonresponders have less ability to secrete furosemide into tubular fluid as well as less ability to respond to drug.