Single-Dose Pharmacokinetics of Piperacillin/Tazobactam in Hispaniolan Amazon Parrots ( Amazona ventralis )

Abstract

To determine the pharmacokinetics of piperacillin/tazobactam in Hispaniolan Amazon parrots ( Amazona ventralis ), 8 healthy adult parrots of both sexes were used in a 2-part study. In a pilot study, piperacillin (87 mg/kg) in combination with tazobactam (11 mg/kg) was administered intramuscularly (IM) to 2 birds, and blood samples were obtained at 0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, and 10 hours after administration. Based on the results obtained, a main study was done in which piperacillin/tazobactam was administered at 2 different doses. In 3 birds, the initial dose of piperacillin (87 mg/kg)/tazobactam (11 mg/kg) IM was administered, and in 3 birds, the dose was doubled to piperacillin (174 mg/kg)/tazobactam (22 mg/kg) IM. In all 6 birds, blood samples were obtained at 0, 5, 15, and 30 minutes and at 1, 1.5, 2, 2.5, 3, and 4 hours after administration. Quantification of plasma piperacillin and tazobactam concentrations was determined by validated liquid chromatography-mass spectrometry assay. Pharmacokinetic parameters were determined by noncompartmental analysis. After intramuscular administration, the mean ± standard error values of T1/2 (h) was 0.52 ± 0.05 and 0.32 ± 0.07, Tmax (h) was 0.28 ± 0.09 and 0.25 ± 0.10, Cmax (μg/mL) was 86.34 ± 20.62 and 9.03 ± 2.88, and Cmax/dose was 0.99 ± 0.24 and 0.83 ± 0.26 for piperacillin (87 mg/kg) and tazobactam (11 mg/kg), respectively. When the doses were doubled, the T1/2 (h) was 0.65 ± 0.08 and 0.34 ± 0.02, Tmax (h) was 0.28 ± 0.12 and 0.14 ± 0.06, Cmax (μg/mL) was 233.0 ± 6.08 and 22.13 ± 2.35, and Cmax/dose was 1.34 ± 0.03 and 1.02 ± 0.11 for piperacillin and tazobactam, respectively. Results indicate that piperacillin is rapidly absorbed and reaches high initial concentrations; however, it is also rapidly eliminated in the Hispaniolan Amazon parrot, and tazobactam has similar pharmacokinetics as piperacillin. Administration of piperacillin at 87 mg/kg IM q3-4h is recommended for this species to control infections attributed to susceptible bacteria with a minimum inhibitory concentration of ≤4 μg/mL.