Antimicrobial dosing for common equine drugs: a content review and practical advice for veterinarians in Australia

Abstract

Background Appropriate dosing with antimicrobial agents is critical for effective treatment and to prevent the development of antimicrobial resistance. Methods A review was undertaken of equine journal articles (Equine Veterinary Journal, Equine Veterinary Education, Australian Veterinary Journal, Australian Equine Veterinarian, Journal of Veterinary Internal Medicine and Journal of Equine Veterinary Science) between January 2015 and August 2018. Those with dosing regimens for procaine penicillin G, gentamicin or trimethoprim‐sulfonamide in adult horses were examined and evaluated. Pharmacokinetics and ‐dynamics of these drugs were also reviewed. Results & Conclusion The most frequently reported doses for penicillin, gentamicin and trimethoprim‐sulfonamide were 20–25,000 IU/kg, 6.6 mg/kg and 30 mg/kg, respectively. Veterinarians treating equine patients in Australia should be aware of the current recommended doses and inter‐dosing intervals to ensure efficacy in therapy and to preserve the usefulness of these antimicrobials for the future.

Review: Water medication of growing pigs: sources of between-animal variability in systemic exposure to antimicrobials

“…While some classes of antimicrobial have time-dependent effects, others have concentration-dependent effects, and some are dependent on both time and concentration. These different effects determine the PK/pharmacodynamic (PD) index that best predicts efficacy (Lees et al, 2015;Hardefeldt et al, 2019) (Table 2 and Figure 3).…”

“…Colour online) Principal pharmacokinetic-pharmacodynamic (PK-PD) characteristics of antimicrobial drugs in animals (Adapted fromHardefeldt et al, 2019). C max = maximum plasma concentration, MIC = minimum inhibitory concentration of target pathogen.…”

Dosing equine antimicrobials: Ensuring clinical success and avoiding antimicrobial resistance

“…We undertook a content review of articles appearing in the major equine journals around the world (Equine Veterinary Journal, Equine Veterinary Education, Australian Veterinary Journal, Australian Equine Veterinarian, the Journal of Veterinary Internal Medicine and the Journal of Equine Veterinary Science) between January 2015 and August 2018 and searched for antimicrobial dosing regimens for the common equine antimicrobials (procaine penicillin G, gentamicin and trimethoprim sulphonamide) to assess the doses being used globally (Hardefeldt et al . ). In 83% of papers describing the use of penicillin, a dose of 20–25,000 IU/kg administered every 12 h was used (Hardefeldt et al .…”

“…In 93% of papers describing the use of gentamicin, a dose of 6.6 mg/kg administered every 24 hours was used (Hardefeldt et al . ), a dose used by 80% of respondents to an Australian survey (Hardefeldt et al . 2017a) but much higher than the labelled dose of 1.5–2 mg/kg (Australian Pesticides and Veterinary Medicines Authority ).…”

“…In all papers describing the use of trimethoprim sulphonamides a dose of 20–30 mg/kg administered every 12 h was used (Hardefeldt et al . ), a dose used by only 30% of respondents to an Australian survey (Hardefeldt et al . 2017a).…”