Oral and intravenous bretylium disposition

Area of Science:

• Pharmacokinetics
• Drug Metabolism and Disposition
• Clinical Pharmacology

Background:

• Bretylium tosylate is an antiarrhythmic agent.
• Understanding its oral and intravenous disposition is crucial for optimizing therapeutic use.

Purpose of the Study:

• To compare the oral and intravenous pharmacokinetics of bretylium tosylate in healthy subjects.
• To assess absorption, distribution, and elimination parameters for both administration routes.

Main Methods:

• A crossover study design involving 10 healthy male subjects.
• Single oral and intravenous doses of bretylium tosylate (5 mg/kg) were administered.
• Serum and urine drug concentrations were measured over 48 hours using gas chromatography.

Main Results:

• Oral bretylium tosylate exhibited only partial absorption.
• The elimination half-life was significantly shorter after oral (6.0 hr) versus intravenous (13.6 hr) administration.
• Renal clearance was higher after oral administration, and drug elimination occurred entirely as unchanged drug via the kidneys.

Conclusions:

• Bretylium tosylate is incompletely absorbed orally and undergoes extensive tissue binding.
• The observed differences in renal clearance and elimination kinetics between oral and intravenous routes warrant further investigation.