Interactions of dihydralazine with furosemide in hypertonic patients

In 9 hypertensive patients stage II we studied whether dihydralazine, which is known to increase the renal blood flow, influences the elimination of furosemide (40 mg i.v.) when given additionally over a period of 2 weeks (75 mg daily). The results were compared with data from 9 healthy volunteers. The most important alterations in hypertonics were significantly increased half-lives (28.0 +/- 3.7 and 35.1 +/- 5.7 min), distribution coefficients (0.105 +/- 0.017 and 0.132 +/- 0.028 ml/g) and unchanged plasma clearances (2.62 +/- 0.33 and 2.59 +/- 0.27 ml min-1 X kg-1). Pretreatment with dihydralazine resulted in normalization of distribution coefficients (0.134 +/- 0.027 and 0.102 +/- 0.020 ml/g), decrease in plasma clearance (2.55 +/- 0.29 and 2.08 +/- 0.23 ml min-1 X kg-1) without alterations in half-lives (36.3 +/- 6.0 and 34.2 +/- 7.0 min). The authors conclude that the effects after dihydralazine co-medication are only distribution mediated.