Influence of soft gelatin on digoxin absorption

Area of Science:

• Pharmacokinetics
• Drug Delivery Systems

Background:

• Digoxin absorption can be influenced by formulation, with soft gelatin capsules sometimes showing enhanced bioavailability.
• The specific solvent vehicle used in soft gelatin capsules may play a crucial role in drug absorption.

Purpose of the Study:

• To investigate the impact of soft gelatin encapsulation on digoxin absorption.
• To compare digoxin absorption from intact capsules, halved capsules, and solution forms.

Main Methods:

• Eight healthy volunteers received digoxin (0.6 mg) via four different routes: solution alone, intact soft gelatin capsules, halved soft gelatin capsules, and solution pre-dissolved in water.
• Plasma concentrations and cumulative urinary excretion of digoxin were monitored over time.

Main Results:

• No significant differences were observed in the area under the plasma concentration-time curve (AUC), peak plasma concentrations (Cmax), time to peak (Tmax), or cumulative urinary excretion among the four treatment groups.
• This suggests that the formulation method did not substantially alter digoxin's overall absorption profile.

Conclusions:

• The solvent composition, specifically polyethylene glycol 400, appears to be a more significant factor in digoxin absorption than the soft gelatin encapsulation itself.
• Encapsulation within soft gelatin may not be the primary driver for enhanced digoxin absorption when specific solvent systems are employed.