Pharmacokinetics of ceftiofur hydrochloride in pigs infected with porcine reproductive and respiratory syndrome virus.

: Objectives To compare the pharmacokinetic profile of ceftiofur hydrochloride (ceftiofur) administered intramuscularly at 3 mg/kg body weight (BW) in pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV) versus clinically healthy pigs. : Methods Sixteen 3- to 4-week-old PRRSV-negative pigs were randomly assigned to two groups (A and B), with eight pigs per group. Pigs in Group A were uninfected controls and pigs in Group B were intranasally challenged with a PRRSV isolate of Thai origin. Pigs in both groups were intramuscularly administered ceftiofur at 3 mg/kg BW at 7 days post-infection. Blood samples were serially collected up to 72 h post-injection. Plasma was analysed for ceftiofur and its related metabolites using HPLC. Pharmacokinetic parameters of ceftiofur were calculated based on non-compartmental analysis. : Results Pharmacokinetic parameters of ceftiofur revealed statistically significant differences (P < 0.01) in maximum concentration (C_max), AUC, volume of distribution at the terminal phase over bioavailability (V_z/F), clearance over bioavailability (CL/F) and the terminal half-life (t_1/2z) between Groups A and B. PRRSV-infected pigs had a V_z/F and CL/F of ceftiofur significantly higher than in the non-infected pigs (116% increase in V_z/F, 234% increase in CL/F). The C_max and AUC of the infected pigs decreased by 54% and 70%, respectively, compared with the non-infected pigs. The t_1/2z of the infected pigs and the non-infected pigs was 13.1 and 21.0 h, respectively. : Conclusions The pharmacokinetic profile of ceftiofur is altered in PRRSV-infected pigs due to the decreased plasma ceftiofur concentration compared with clinically healthy pigs. [ABSTRACT FROM AUTHOR]