Digitoxin-quinidine interaction: Pharmacokinetic evaluation

P. E. Fenster, J. R. Powell, P. E. Graves, K. A. Conrad, W. D. Hager, S. Goldman, F. I. Marcus

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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.

Original languageEnglish (US)
Pages (from-to)698-701
Number of pages4
JournalAnnals of internal medicine
Issue number5
StatePublished - Jan 1 1980


ASJC Scopus subject areas

  • Internal Medicine

Cite this

Fenster, P. E., Powell, J. R., Graves, P. E., Conrad, K. A., Hager, W. D., Goldman, S., & Marcus, F. I. (1980). Digitoxin-quinidine interaction: Pharmacokinetic evaluation. Annals of internal medicine, 93(5), 698-701. https://doi.org/10.7326/0003-4819-93-5-698