Volume 20, Issue 3 p. 253-259
Article

Digoxin bioavailability: Formulations and rates of infusions

Frank I. Marcus M.D.

Frank I. Marcus M.D.

Cardiology Section, Department of Medicine and Department of Pharmacology, University of Arizona College of Medicine, Tucson, Ariz.

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Janet Dickerson R.N.

Janet Dickerson R.N.

Cardiology Section, Department of Medicine and Department of Pharmacology, University of Arizona College of Medicine, Tucson, Ariz.

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Susan Pippin M.S.

Susan Pippin M.S.

Cardiology Section, Department of Medicine and Department of Pharmacology, University of Arizona College of Medicine, Tucson, Ariz.

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Marvin Stafford M.S.

Marvin Stafford M.S.

Cardiology Section, Department of Medicine and Department of Pharmacology, University of Arizona College of Medicine, Tucson, Ariz.

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Rubin Bressler M.D.

Rubin Bressler M.D.

Cardiology Section, Department of Medicine and Department of Pharmacology, University of Arizona College of Medicine, Tucson, Ariz.

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First published: September 1976
Citations: 23
Supported in part by a grant-in-aid from the American Heart Association, No. 74-1085, and grants from the Burroughs-Wellcome Company and The Flinn Foundation.
Reprint requests to: Dr. F. I. Marcus, Cardiology Section, Department of Medicine, University of Arizona College of Medicine, Tucson, Ariz. 85724.

Abstract

The bioavailability of digoxin (Lanoxin) tablets, oral aqueous solution of digoxin, and capsules containing a solution of digoxin was compared with digoxin given intravenously over J and 3 hr. The mean peak serum concentration of digoxin after the 1-hr intravenous infusion was 5 nglml, after the 3-hr infusion, 3.5 nglml, and after the oral solution, 2.0 ng Iml. There was an equivalent bioavailability of the oral solution and reference tablets of digoxin. The digoxin in capsules tended to be better absorbed than the reference tablets. There was 21% more digoxin excreted over 6 days after the 3-hr iv i'lfusion than after the J hr iv infusion. This indicates that the calculated bioavailability of an orally administered dose of digoxin may vary with the rapidity of injection of the intravenous standard. It is estimated that an oral tablet of digoxin of 0.5 mg has about the same bioavailability as 0.35 mg of digoxin given by slow intravenous infusion (or 0.4 mg if calculated against a rapid intravenous injection).