Pharmacokinetic model for predicting sulfamethazine disposition in pigs

Area of Science:

• Veterinary Pharmacology
• Pharmacokinetics
• Drug Metabolism

Background:

• Sulfamethazine is a widely used sulfonamide antibiotic in food-producing animals.
• Understanding its pharmacokinetic profile is crucial for establishing effective treatment protocols and ensuring food safety.

Purpose of the Study:

• To characterize the pharmacokinetics of sulfamethazine in pigs after intravenous and oral administration.
• To develop and validate a multi-compartment pharmacokinetic model for sulfamethazine disposition in pigs.
• To predict tissue residue depletion and assess withdrawal times.

Main Methods:

• Sulfamethazine concentrations were quantified in plasma and various tissues (fat, liver, kidney, spleen, lungs, skeletal muscle) of pigs.
• Intravenous (IV) and oral (PO) administration routes were used.
• A two-compartment model described plasma concentration-time data, and a multi-compartment model was developed for tissue disposition.
• Model predictions were compared against experimental data and results from other studies.

Main Results:

• The plasma concentration-time curve followed a two-compartment model with a distribution half-life of 0.46 hours and an elimination half-life of 16.9 hours.
• Oral bioavailability of sulfamethazine in pigs was determined to be 85.8 ± 5.3%.
• The developed pharmacokinetic model accurately predicted sulfamethazine concentrations in plasma and tissues over time, including residue depletion below the tolerated limit (0.1 ppm).

Conclusions:

• A robust pharmacokinetic model for sulfamethazine in pigs has been established, accurately predicting drug disposition in plasma and tissues.
• The model aids in determining appropriate dosing regimens and predicting withdrawal periods to ensure meat safety.
• This research provides valuable insights for the responsible use of sulfamethazine in swine production.