Pharmacodynamics and pharmacokinetics of flumequine in pigs after single intravenous and intramuscular administration.
Authors: Villa R, Cagnardi P, Acocella F, Massi P, Anfossi P, Asta F, Carli S
Journal: Veterinary journal (London, England : 1997)
Summary
Flumequine, a quinolone antibiotic administered at 15 mg/kg, exhibits a two-phase elimination pattern in pigs with an initial half-life of 1.4 hours and terminal half-life of 6.35 hours, achieving peak serum concentrations of approximately 5 μg/mL between 2–3 hours after intramuscular injection. When researchers compared these pharmacokinetic parameters against bacterial susceptibility data from porcine isolates collected in northern Italy—including *Escherichia coli*, *Salmonella* spp., *Pasteurella* spp., and *Bordetella* spp.—a concerning pattern emerged: only *Pasteurella multocida* demonstrated reliable sensitivity (MIC₉₀ = 0.5 μg/mL), whilst other common respiratory and enteric pathogens showed markedly elevated minimum inhibitory concentrations, with some exceeding 64 μg/mL. The relatively large volume of distribution (753 mL/kg) and moderate systemic clearance observed suggest adequate tissue penetration, yet the documented resistance profiles in field isolates indicate that flumequine efficacy against Gram-negative pathogens may be substantially compromised, particularly in endemic areas where resistant strains are prevalent. For equine practitioners, whilst this study specifically addresses swine pharmacology, it reinforces the cautionary principle that fluoroquinolone susceptibility cannot be assumed without current local antimicrobial sensitivity testing, especially in conditions where cross-species pathogen resistance patterns are epidemiologically linked or where historical use has been intensive.
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Practical Takeaways
- •Not relevant to equine practice—this is a porcine pharmacokinetics study with no direct application to horses
- •The emergence of resistant Gram-negative bacteria noted in this pig population is a general concern for quinolone use across species, but species-specific data would be needed to inform equine prescribing
- •Equine practitioners should refer to equine-specific pharmacokinetic and susceptibility data before considering flumequine for any equine cases
Key Findings
- •Flumequine showed slow distribution and elimination in pigs with t1/2λ1 of 1.40±0.16 h and t1/2λ2 of 6.35±1.69 h after IV administration
- •Peak serum concentration of 4.99±0.92 μg/mL was achieved between 2-3 hours after IM administration of 15 mg/kg
- •Only Pasteurella multocida strains were susceptible with MIC90 of 0.5 μg/mL; other bacteria showed variable resistance (MIC 0.5 to >64 μg/mL)
- •Large distribution volume (Vdss 752.59±84.03 mL/kg) indicates extensive tissue penetration of flumequine