Disposition and Residue Depletion of Metronidazole in Pigs and Broilers

Area of Science:

• Veterinary Pharmacology
• Food Safety Analysis
• Analytical Chemistry

Background:

• Metronidazole (MNZ) is a key veterinary antimicrobial for anaerobic infections and protozoal/parasitic diseases.
• Understanding MNZ disposition and residue depletion in food-producing animals is crucial for safety.
• Current data on MNZ residue kinetics in pigs and broilers requires further investigation.

Purpose of the Study:

• To investigate the disposition and residue depletion of Metronidazole (MNZ) and its primary metabolites in pigs and broilers.
• To identify appropriate target tissues and withdrawal times for MNZ residue monitoring.
• To inform regulatory surveillance of MNZ in animal-derived food products.

Main Methods:

• Single oral administration of Metronidazole (MNZ) to pigs and broilers.
• Quantification of MNZ and its metabolites (MNZ-OH, MAA) in excreta and tissues using LC-MS/MS.
• Analysis of residue concentrations and elimination half-lives in various tissues up to 14 days post-administration.

Main Results:

• Over 75% of administered MNZ was recovered within 14 days, with MNZ comprising ~40%, MNZ-OH 20-25%, and MAA <10%.
• Metronidazole (MNZ) was the predominant residue in liver, kidney, and muscle, detectable up to the 14-day withdrawal period.
• The metabolite MNZ-OH showed lower concentrations but a similar elimination half-life to MNZ in tissues.

Conclusions:

• Kidney and muscle are proposed as suitable target tissues for MNZ residue monitoring in food animals.
• Routine surveillance should include monitoring of both Metronidazole (MNZ) and its hydroxylated metabolite (MNZ-OH).
• The findings support the established 14-day withdrawal period for MNZ in pigs and broilers, emphasizing the need for continued monitoring.