Pharmacodynamics and pharmacokinetics of flumequine in pigs after single intravenous and intramuscular administration

The pharmacokinetics and intramuscular (IM) bioavailability of flumequine (15 mg kg−1) were investigated in healthy pigs and the findings related to published minimal inhibitory concentrations (MICs) for susceptible bacteria of animal origin, and to experimentally determined MICs for susceptible strains of porcine origin. We found MICs for Escherichia coli, Salmonella spp., Pasteurella spp. and Bordetella spp. in the range 0.5 to >64 μg mL−1 isolated from infected pigs in the Forlı̀ area of Italy; only the Pasteurella multocida strains were sensitive (MIC90 = 0.5 μg mL−1). intravenous (IV) injection, flumequine was slowly distributed and eliminated (t1/2λ11.40 ± 0.16 h and t1/2λ26.35 ± 1.69 h). The distribution volume at steady state (Vdss) was 752.59 ± 84.03 mL kg−1 and clearance (ClB) was 237.19 ± 17.88 mL kg−1 h−1. After IM administration, peak serum concentration (4.99 ± 0.92 μg mL−1) was reached between the 2nd and the 3rd hour. The results on MIC of isolated bacteria, although only indicative, suggest that the efficacy of flumequine on Gram-negative bacteria may be impaired by the emergence of less sensitive or resistant strains.