Pharmacokinetics of amoxicillin trihydrate in Thai swamp buffaloes (Bubalus bubalis): a pilot study

This study aimed to investigate the pharmacokinetic characteristics of amoxicillin (AMX) in Thai swamp buffaloes, Bubalus bubalis, following single intramuscular administration at two dosages of 10 and 20mg/kg body weight (b.w.). Blood samples were collected at assigned times up to 48h. The plasma concentrations of AMX were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The concentrations of AMX in the plasma were determined up to 24h after i.m. administration at both dosages. The C-max values of AMX were 3.39 +/- 0.18g/mL and 6.16 +/- 0.18g/mL at doses of 10 and 20mg/kg, respectively. The AUC(last) values increased in a dose-dependent fashion. The half-life values were 5.56 +/- 0.40h and 4.37 +/- 0.23h at doses of 10 and 20mg/kg b.w, respectively. Based on the pharmacokinetic data and PK-PD index (T > MIC), i.m. administration of AMX at a dose of 20mg/kg b.w might be appropriate for the treatment of susceptible Mannheimiahaemolytica infection in Thai swamp buffaloes.