Hydralazine and furosemide kinetics.

Fursosemide kinetics were studied in 25 patients with congestive heart failure. The elimination half-life (t1/2) was longer and the elimination rate constant and the plasma clearance smaller in patients with advanced (n = 15) than in those with moderate (n = 10) failure. Furosemide kinetics with and without hydralazine were compared in eight patients with advanced heart failure. Furosemide t1/2 patients receiving both drugs fell from 96 +/- 16 to 81 +/- 15 min (P less than 0.02), elimination rate constant increased from 0.0186 +/- 0.0056 to 0.0214 +/- 0.0068 min -1 (P less than 0.05), and plasma clearance rose from 72.6 +/- 18.5 to 88.1 +/- 26.9 ml/min (P less than 0.01). Renal clearance rose from 45.4 +/- 12.0 to 60.9 +/- 19.0 ml/min (P less than 0.01) and creatinine clearance was unchanged. We conclude that hydralazine affects furosemide kinetics.