[Comparative bioavailability of three pharmaceutical forms of digoxin]

Area of Science:

• Pharmacokinetics
• Drug Bioavailability
• Clinical Pharmacology

Background:

• Digoxin is a crucial medication for heart conditions.
• Understanding the bioavailability of different digoxin formulations is essential for therapeutic efficacy.
• Variations in drug release kinetics can impact absorption and clinical outcomes.

Purpose of the Study:

• To compare the bioavailability of single digoxin doses from three different pharmaceutical preparations.
• To assess plasma digoxin concentrations and urinary excretion over time.
• To investigate potential discrepancies in bioavailability assessment based on statistical methods.

Main Methods:

• A crossover study involving nine healthy volunteers.
• Administration of single 0.5 mg doses of three digoxin preparations.
• Measurement of plasma digoxin concentrations (0-72 hours) and urinary glycoside excretion (0-96 hours) using radioimmunoassay.
• Statistical analysis of areas under the plasma concentration-time curves using two methods: preparation comparison and subject comparison.

Main Results:

• Bioavailability assessments differed significantly depending on the statistical method employed.
• Analysis comparing preparations indicated similar bioavailabilities.
• Analysis comparing subjects revealed significant differences in bioavailability.
• Urinary digoxin excretion did not differ significantly across the preparations.
• Areas under the plasma concentration-time curves showed variability based on statistical approach.

Conclusions:

• Despite differing release kinetics from pharmaceutical preparations, the total absorbed amount of digoxin appears equivalent.
• Statistical methodology significantly influences the interpretation of digoxin bioavailability data.
• Further investigation into drug release kinetics is warranted to reconcile bioavailability discrepancies.