PAUL E. FENSTER, M.D.; J. ROBERT POWELL, Pharm. D.; PENELOPE E. GRAVES, Sc.D.; KENNETH A. CONRAD, M.D.; W. DAVID HAGER, M.D.; STEVEN GOLDMAN, M.D.; FRANK I. MARCUS, M.D.
The effect of quinidine on digitoxin single-dose pharmacokinetics was evaluated in five healthy adults. Blood was collected for 3 weeks, and a complete urine collection was obtained for 4 days, after a single intravenous dose of digitoxin. The protocol was conducted once while each subject was taking oral quinidine, for 3 weeks, and then repeated 10 days after discontinuing quinidine treatment. Quinidine induced the following changes in digitoxin pharmacokinetics: Elimination half-life was prolonged from 174 ± 25 to 261 ± 58 hours (p < 0.02); total body clearance decreased from 1.54 ± 0.40 to 1.09 ± 0.31 mL/h · kg (p < 0.05); renal clearance decreased from 0.65 ± 0.07 to 0.46 ± 0.17 mL/h kg (p < 0.05). Digitoxin volume of distribution and protein binding were unaltered by quinidine. Quinidine caused a rise in serum digitoxin levels. Digitoxin total body clearance was decreased by quinidine to an extent comparable to that reported for digoxin; however, the mechanism of the interaction with the two digitalis glycosides may, in part, be different.
PAUL E. FENSTER, J. ROBERT POWELL, PENELOPE E. GRAVES, KENNETH A. CONRAD, W. DAVID HAGER, STEVEN GOLDMAN, et al. Digitoxin-Quinidine Interaction: Pharmacokinetic Evaluation. Ann Intern Med. 1980;93:698–701. doi: 10.7326/0003-4819-93-5-698
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Published: Ann Intern Med. 1980;93(5):698-701.
Cardiology, Rhythm Disorders and Devices.
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