Pharmacokinetics of Amoxicillin-Clavulanic Acid in Domestic Chickens After Multiple-day Oral Dosing of Two Different Formulations

heryl Greenacre, DVM, DABVP (Avian), DABVP (Exotic Companion Mammal) - Professor Emeritus, University of Tennessee

Individual (pet, companion, backyard, small flock) chickens are being presented to avian veterinarians frequently, and there are few antibiotics that are labeled or can be used in an extra-label manner in chickens, meaning it is all the more important to have confidence the appropriate dose is being given based on a PK study. A previous pharmacokinetic (PK) study in domestic chickens showed that after 9 doses of the pill form of amoxicillin-clavulanic acid administered at 150 mg/kg every 12 hours, therapeutic plasma concentrations (0.5 µg/ ml) were never reached, and no amoxicillin was detectable in the plasma after 2 hours.1 The results of this previous PK study caused avian veterinarians to question the efficacy of this long standing published dose. Some practitioners are now using 250 mg/kg q12h with no evidence-based data to prove efficacy at this dose. We plan to repeat the study in domestic chickens using a higher dose (250 mg/ kg orally every 12 hours for 9 doses) and comparing the plasma concentrations of amoxicillin after being administered the pill or liquid formulation of commercially available Clavamox. The study will be conducted in collaboration with East Tennessee Clinical Research, Inc. and the University of Tennessee Pharmacology Laboratory.