Effect of quinidine on the renal clearance of digoxin in the presence of low and high serum digoxin concentrations

DR Clohisy, AP Quintanilla and TP Gibson

The effect of an infusion of quinidine, 180 micrograms/kg/Min (base) on the fractional clearance of digoxin (CDIG/Cin) was studied in saline volume-expanded dogs given a constant infusion of digoxin of either 0.0067 micrograms/kg/min (low dose) or 0.120 micrograms/kg/min (high dose). CDIG/CIN decreased 28% from 1.42 +/- 0.36 during control periods to 1.01 +/- 0.03 (P less than .05) with quinidine in dogs given the low dose. In dogs given the high dose of digoxin, CDIG/CIN decreased 22% from 0.76 +/- 0.17 to 0.59 +/- 0.05 (p less than .05) with quinidine. It is concluded that quinidine reduces CDIG/CIN. High doses of digoxin also reduce CDIG/CIN. Inasmuch as quinidine reduces CDIG/CIN to the same extent in the presence of low or high dose digoxin, the effect of quinidine would appear to be mediated through a mechanism different from that of digoxin.

Volume 222, Issue 1, pp. 49-51, 07/01/1982
Copyright © 1982 by American Society for Pharmacology and Experimental Therapeutics