Continuous monitoring of penicillin G and gentamicin in allantoic fluid of pregnant pony mares by in vivo microdialysis

Continuous monitoring of penicillin G and gentamicin in allantoic fluid of pregnant pony mares by... Summary Reasons for performing study: Most current treatments for placentitis in mares are empirical with few control studies to evaluate their effectiveness. Objective: To monitor drug concentrations in allantoic fluid of pregnant pony mares using in vivo microdialysis and establish if this method would be useful for determining allantoic concentrations of drugs in normal mares and those with placentitis. Methods: Five late gestational pony mares had microdialysis probes inserted into the allantoic fluid using transabdominal ultrasound‐guided allantocentesis. Single injections of penicillin G (22,000 u/kg), gentamicin (6.6 mg/kg bwt) and flunixin meglumine (1 mg/kg bwt) were administered i.v. and dialysate samples collected continuously for 24 h. In a separate study, drug concentrations were monitored in allantoic fluid of 2 mares with experimental placentitis induced by intracervical inoculation with Streptococcus equi ssp. zooepidemicus. Drug concentrations were measured by high performance liquid chromatography (penicillin G, flunixin meglumine) or enzyme‐linked immunosorbent assay (gentamicin). Results: Penicillin G and gentamicin achieved average peak concentrations of 9.8 ± 2.2 and 8.5 ± 3.1 μg/ml, respectively, in allantoic fluid of noninfected mares. Pharmacokinetic comparisons indicate that penicillin G persists much longer in allantoic fluid than blood, whereas gentamicin exhibited similar profiles in the 2 compartments. Flunixin meglumine was not detected in allantoic fluid. In infected mares, penicillin G achieved a similar peak concentration in allantoic fluid (11.2 μg/ml) whereas peak gentamicin concentration (3.9 μg/ml) appeared to be reduced relative to drug concentrations in noninfected mares. Conclusions: Microdialysis is a useful technique for continuous in vivo monitoring of drugs in equine allantoic fluid. Our results indicate that penicillin G and gentamicin undergo effective placental transfer in pregnant mares and in 2 mares that transplacental drug transfer may be altered selectively if active placental infection is present. Potential relevance: Further studies are needed to evaluate the feasibility of using increased dose intervals for penicillin G and an increased dose rate of gentamicin to effectively combat placental infections in mares. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Equine Veterinary Journal Wiley

Continuous monitoring of penicillin G and gentamicin in allantoic fluid of pregnant pony mares by in vivo microdialysis

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Publisher
Wiley
Copyright
2006 EVJ Ltd
ISSN
0425-1644
eISSN
2042-3306
DOI
10.2746/042516406X156136
Publisher site
See Article on Publisher Site

Abstract

Summary Reasons for performing study: Most current treatments for placentitis in mares are empirical with few control studies to evaluate their effectiveness. Objective: To monitor drug concentrations in allantoic fluid of pregnant pony mares using in vivo microdialysis and establish if this method would be useful for determining allantoic concentrations of drugs in normal mares and those with placentitis. Methods: Five late gestational pony mares had microdialysis probes inserted into the allantoic fluid using transabdominal ultrasound‐guided allantocentesis. Single injections of penicillin G (22,000 u/kg), gentamicin (6.6 mg/kg bwt) and flunixin meglumine (1 mg/kg bwt) were administered i.v. and dialysate samples collected continuously for 24 h. In a separate study, drug concentrations were monitored in allantoic fluid of 2 mares with experimental placentitis induced by intracervical inoculation with Streptococcus equi ssp. zooepidemicus. Drug concentrations were measured by high performance liquid chromatography (penicillin G, flunixin meglumine) or enzyme‐linked immunosorbent assay (gentamicin). Results: Penicillin G and gentamicin achieved average peak concentrations of 9.8 ± 2.2 and 8.5 ± 3.1 μg/ml, respectively, in allantoic fluid of noninfected mares. Pharmacokinetic comparisons indicate that penicillin G persists much longer in allantoic fluid than blood, whereas gentamicin exhibited similar profiles in the 2 compartments. Flunixin meglumine was not detected in allantoic fluid. In infected mares, penicillin G achieved a similar peak concentration in allantoic fluid (11.2 μg/ml) whereas peak gentamicin concentration (3.9 μg/ml) appeared to be reduced relative to drug concentrations in noninfected mares. Conclusions: Microdialysis is a useful technique for continuous in vivo monitoring of drugs in equine allantoic fluid. Our results indicate that penicillin G and gentamicin undergo effective placental transfer in pregnant mares and in 2 mares that transplacental drug transfer may be altered selectively if active placental infection is present. Potential relevance: Further studies are needed to evaluate the feasibility of using increased dose intervals for penicillin G and an increased dose rate of gentamicin to effectively combat placental infections in mares.

Journal

Equine Veterinary JournalWiley

Published: Nov 1, 2006

References

  • Application of microdialysis in pharmacokinetic studies
    Elmquist, Elmquist; Sawchuck, Sawchuck
  • In‐vitro susceptibility to antimicrobial drugs of bacterial isolates from horses in The Netherlands
    Ensink, Ensink; Vanklingeren, Vanklingeren; Houwers, Houwers; Klein, Klein; Vulto, Vulto
  • Ultrasonographic assessment of fetal well‐being during late gestation: Development of an equine biophysical profile
    Reef, Reef; Vaala, Vaala; Worth, Worth; Sertich, Sertich; Spencer, Spencer
  • Pharmacokinetics of gentamicin in mares in late pregnancy and early lactation
    Santschi, Santschi; Papich, Papich

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