Pharmacokinetics of a single intravenous dose of marbofloxacin in adult donkeys.
Authors: González F, Rodríguez C, De Lucas J J, Waxman S, San Andrés M D, Serres C, Nieto J, San Andrés M I
Journal: The Veterinary record
Summary
Marbofloxacin is a fluoroquinolone antibiotic used in equine practice, but its pharmacokinetics in donkeys had not been characterised, prompting González and colleagues to administer a single 2 mg/kg intravenous dose to six donkeys and measure plasma concentrations to establish key parameters. The researchers found marbofloxacin demonstrated prolonged elimination kinetics in donkeys compared with horses, with a half-life of 9.24 hours and notably large volume of distribution (1.15 l/kg), reflecting extensive tissue penetration but slower clearance at 0.10 l/kg/hour. When the standard equine dose of 2 mg/kg was modelled against minimum inhibitory concentrations (MIC₉₀) for pathogenic bacteria, efficacy indicators proved adequate only for Enterobacteriaceae; infections caused by *Staphylococcus aureus* and Streptococci would require substantially higher doses—2.62 mg/kg and 20 mg/kg respectively—to achieve therapeutic targets. These findings have clear implications for donkey practitioners: dosing protocols cannot simply be extrapolated from horses, and the pronounced pharmacokinetic differences suggest that standard equine marbofloxacin regimens may be subtherapeutic for common gram-positive pathogens in donkeys, potentially leading to treatment failure and antimicrobial resistance. The authors' calculated dosing recommendations provide a rational basis for future clinical trials to establish evidence-based protocols specific to donkey medicine.
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Practical Takeaways
- •Marbofloxacin requires much higher doses (up to 20 mg/kg) in donkeys for Streptococcal infections compared to the standard 2 mg/kg dose used for Enterobacteriaceae
- •Donkeys have slower drug clearance than horses, allowing for potentially less frequent dosing intervals despite the long half-life
- •When treating bacterial infections in donkeys with marbofloxacin, select dosage based on specific pathogen type rather than using a fixed dose across all infections
Key Findings
- •Marbofloxacin in donkeys demonstrated a large volume of distribution (1.15 l/kg) and long elimination half-life of 9.24 hours, slower clearance than in horses at 0.10 l/kg/hour
- •At 2 mg/kg daily dose, marbofloxacin achieved adequate efficacy indices only for Enterobacteriaceae infections
- •Dosing recommendations calculated as 0.33 mg/kg for Enterobacteriaceae, 2.62 mg/kg for Staphylococcus aureus, and 20 mg/kg for Streptococci to achieve therapeutic efficacy