Digoxin bioavailability: formulations and rates of infusions

Area of Science:

• Pharmacokinetics
• Drug Bioavailability
• Clinical Pharmacology

Background:

• Digoxin is a critical cardiac glycoside for heart failure and arrhythmias.
• Understanding digoxin bioavailability across different formulations is essential for therapeutic efficacy.
• Variability in intravenous administration may affect oral bioavailability estimations.

Purpose of the Study:

• To compare the bioavailability of oral digoxin formulations (tablets, oral solution, capsules) against intravenous digoxin.
• To assess the impact of intravenous infusion duration on digoxin bioavailability.
• To determine accurate oral digoxin dosage equivalents based on intravenous administration.

Main Methods:

• Comparative pharmacokinetic study involving oral and intravenous digoxin administration.
• Serum concentrations of digoxin were measured after various administration routes and durations.
• Urinary excretion of digoxin was monitored over six days to assess bioavailability.

Main Results:

• Oral solution and reference digoxin tablets demonstrated equivalent bioavailability.
• Digoxin capsules showed a trend towards better absorption compared to reference tablets.
• Intravenous infusion rate significantly influenced the calculated oral digoxin bioavailability, with slower infusion yielding lower estimates.

Conclusions:

• Oral digoxin formulations, particularly the solution, exhibit comparable bioavailability to reference tablets.
• The rate of intravenous digoxin administration is a critical factor in accurately calculating oral bioavailability.
• Adjusted oral digoxin dosages are recommended based on the intravenous administration rate for precise therapeutic management.