Pharmacokinetics and bioavailability of digitoxin by a specific assay

R. T. MacFarland, F. I. Marcus, P. E. Fenster, P. E. Graves, D. Perrier

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


The pharmacokinetics and bioavailability of digitoxin were examined in six normal human subjects using an assay that separates digitoxin from its metabolites. After intravenous administration, the mean systemic clearance was 2.44 ml/min; the volume of distribution was 0.47 l/kg; and the elimination half-life was 6.5 days. After oral administration, the elimination half-life was 5.8 days. The bioavailability was 81.5% using the specific assay. Using a non-specific, direct serum digitoxin radioimmunoassay the bioavailability was 98.0%. Assay of aqueous fractions from extracted serum samples indicated higher levels of water-soluble metabolites following oral compared to intravenous digitoxin administration. These findings suggest that previously reported values for digitoxin bioavailability using non-specific methods may be falsely elevated due to the presence of digitoxin metabolites in serum.

Original languageEnglish (US)
Pages (from-to)85-89
Number of pages5
JournalEuropean Journal of Clinical Pharmacology
Issue number1
StatePublished - Jan 1984


  • bioavailability
  • digitoxin
  • digitoxin metabolites
  • pharmacokinetics
  • radioimmunoassay

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)


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