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

Abstract

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. 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. 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. The pharmacokinetic profile of ceftiofur is altered in PRRSV-infected pigs due to the decreased plasma ceftiofur concentration compared with clinically healthy pigs.