Plasma disposition of enrofloxacin following intravenous and intramuscular administration in donkeys.
Authors: Sekkin S, Gokbulut C, Kum C, Karademir U
Journal: The Veterinary record
Summary
# Editorial Summary: Enrofloxacin Pharmacokinetics in Donkeys Enrofloxacin dosing protocols in equine practice are typically extrapolated from horse data, yet donkeys may require different approaches due to species-specific pharmacological differences. Sekkin and colleagues administered enrofloxacin (5 mg/kg) to six donkeys via both intravenous and intramuscular routes using a crossover design, with plasma sampling over 48 hours analysed by high-performance liquid chromatography. The intramuscular route produced a notably longer half-life (12.08 hours versus 9.54 hours intravenously) and extended mean residence time (17.85 versus 7.46 hours), indicating a flip-flop phenomenon where absorption becomes the rate-limiting step; additionally, intramuscular bioavailability was only 76.56 per cent with a prolonged absorption time of 10.39 hours. Significant metabolism to ciprofloxacin occurred via both routes (20–21 per cent conversion), and the lower resulting plasma concentrations suggest donkeys require higher doses than the standard equine protocol to achieve therapeutic drug levels. For practitioners treating donkey infections, these findings recommend reconsidering standard equine dosing regimens and potentially increasing enrofloxacin doses or adjusting dosing intervals to compensate for the slower, less complete absorption profile in this species.
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Practical Takeaways
- •Donkeys have slower and less complete absorption of intramuscular enrofloxacin compared to intravenous administration; veterinarians may need to increase doses or adjust dosing intervals for intramuscular treatment
- •The 76.56% bioavailability of intramuscular enrofloxacin is notably lower than in horses, indicating donkeys may require different dosing protocols than equine guidelines suggest
- •Monitor plasma concentrations or clinical response carefully when using intramuscular enrofloxacin in donkeys, as absorption is slow (10+ hours to peak) and variable
Key Findings
- •Enrofloxacin half-life was significantly longer after intramuscular (12.08 hours) versus intravenous (9.54 hours) administration in donkeys, demonstrating flip-flop phenomenon
- •Intramuscular bioavailability of enrofloxacin was 76.56% with mean absorption time of 10.39 hours in donkeys
- •20-21% of enrofloxacin was metabolized to ciprofloxacin via both administration routes
- •Plasma concentrations after intramuscular administration at 5 mg/kg may be insufficient in donkeys compared to horses, potentially requiring higher dosing