Pharmacokinetics and residues of a new oral amoxicillin formulation in piglets: A preliminary study

The pharmacokinetics of amoxicillin (Amx) were determined in pigs following intravenous (IV) administration of a single dose of 15 mg/kg and a single dose of 15 mg/kg of a new oral formulation (Amx-FP containing 10% amoxicillin). Residue studies were performed to determine residues in edible tissues of healthy pigs after chronic oral administration of Amx-FP at a daily dose of 15 mg/kg for five consecutive days. IV administration, the plasma concentration was characteristic of a two-compartment open model. The main pharmacokinetic variables were: t 1 / 2 λ n = 82.5 min , MRT = 90.1 min, Vdarea = 0.81 L/kg and Clb = 3.9 mL/kg/min. After single oral administration the main pharmacokinetic variables were: Cmax = 758 μg/L, tmax = 347 min and Clb/f = 3.7 mL/kg/min for Amx-FP. The oral bioavailability (F) was calculated at 11% for Amx-FP. Based on maximum residue levels (MRL) for AMX in pigs established at 50 μg/kg for all tissues, the withdrawal times of AMX in muscle and skin plus fat were estimated (95% tolerance limit and 95% confidence) to fall below the MRL after a withdrawal period of seven days. Levels of AMX in the liver and kidneys were estimated to fall below the MRL after a withdrawal period of four days.