Pharmacokinetics of multiple doses of chloramphenicol in fed adult horses

Estell, Krista E.; Knych, Heather K.; Patel, Trishna; Edman, Judy M.; Magdesian, K. Gary

doi:10.1016/j.tvjl.2020.105446

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…Based upon pharmacokinetic studies in adult horses, as well as current CLSI recommendations, suggested equine‐specific susceptibility break points for orally administered antimicrobials in adult horses are as follows: Chloramphenicol: ≤1 µg/ml after a dose of 50 mg/kg PO, q 6–8 hr (Ref: Estell et al, 2020). Enrofloxacin: ≤0.12–0.25 µg/ml after oral dosing at 7.5 mg/kg once a day (Ref: CLSI, 2019 for ≤0.12 µg/ml, (0.25 µg/kg considered intermediate); Magdesian, 2019 for ≤0.25 µg/ml). Trimethoprim–sulfamethoxazole or trimethoprim–sulfadiazine: ≤0.5 µg/ml for the trimethoprim/≤ 9.5 µg/ml for the sulfonamide component (Magdesian, 2019).…”

Section: Introductionmentioning

confidence: 99%

Equine antimicrobial therapy: Current and past issues facing practitioners

Knych

Magdesian

2021

Vet Pharm & Therapeutics

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Equine antimicrobial therapy has advanced over time with the availability of increasing pharmacokinetic and pharmacodynamic studies in horses, allowing for greater evidence‐based clinical decision‐making. However, many challenges to optimal antimicrobial therapy remain and further research is needed to address these areas. There are a limited number of approved antimicrobials for use in horses, which creates a need for compounded preparations for clinicians. Extra‐label drug use is commonplace in equine practice, which warrants continual education of veterinarians about policies and updates. Performance and competitive horses have their own unique concerns when it comes to antimicrobial use and drug testing. In keeping with the use of a broader range of antimicrobials over time, antimicrobial resistance is emerging as an important issue facing veterinary medicine, including equine practice. Another challenge is that of drug interactions and adverse drug events for which there are little scientific data available for horses, especially for critically important diseases such as Rhodococcus equi infection. Finally, much progress has been made in the availability of equine‐specific antimicrobial susceptibility break points. These aid clinicians in interpreting culture and susceptibility results and antimicrobial selection. Even with these advances, continuing education and further research are needed in this area.

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Section: Introductionmentioning

confidence: 99%

Equine antimicrobial therapy: Current and past issues facing practitioners

Knych

Magdesian

2021

Vet Pharm & Therapeutics

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“…However, its use in equine neonates faces pharmacologic and practical limitations. In adult horses repeat oral dosing of chloramphenicol fails to achieve CLSI MIC targets for >50% of the conventional dosing interval 25 . Limited pharmacokinetic data is available on oral administration of chloramphenicol in foals, but the data available suggest mean peak plasma concentrations are highly variable among individuals and unlikely to consistently reach CLSI breakpoints 26 .…”

Section: Discussionmentioning

confidence: 99%

“…In adult horses repeat oral dosing of chloramphenicol fails to achieve CLSI MIC targets for >50% of the conventional dosing interval. 25 Limited pharmacokinetic data is available on oral administration of chloramphenicol in foals, but the data available suggest mean peak plasma concentrations are highly variable among individuals and unlikely to consistently reach CLSI breakpoints. 26 This could be related to reduced bioavailability associated with gastrointestinal dysfunction in sick foals, 27 though this finding is inconsistent.…”

Section: Discussionmentioning

confidence: 99%

Antibiograms of field and hospital acquired equine neonatal bacterial fluid cultures in the Midwestern United States: 149 samples (2007‐2018)

Bookbinder

Mani

Carr

2023

Veterinary Internal Medicne

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Background Contemporary data reflecting local pathogens and their antibiograms is necessary to select empirical antimicrobial therapy for equine neonates. Hypothesis/Objectives Describe bacterial isolates associated with equine neonatal infection and their antibiograms in the Midwestern United States. An increase in gram‐positive infection and antibiotic resistance compared to previous literature was expected. Animals Data from 149 fluid samples from 133 foals <30 days of age submitted for bacterial culture between January 2007 and December 2018. Methods A retrospective evaluation of equine neonatal fluid cultures was performed. Fluid submission type, bacterial culture and antibiogram, empirical antibiotic treatment, and foal outcome was included. Isolate susceptibility to individual antimicrobials and combination protocols relevant to equine practice were recorded. The effect of recorded variables on foal survival was evaluated using Fisher's exact or chi‐squared tests. Results Ninety bacterial isolates (78 aerobes and 12 anaerobes) were identified and gram‐positive organisms predominated (n = 50/90, 56%). Greater than 70% of aerobic isolates were susceptible to ampicillin, ceftiofur, chloramphenicol, trimethoprim/sulfamethoxazole, and all penicillin/aminopenicillin and aminoglycoside combinations. Seventy‐seven (n = 81/105) percent of foals survived. Survival was associated with a negative fluid culture and was not associated with empirical antimicrobial choice. Conclusions and Clinical Importance Gram positive and anaerobic isolates associated with equine neonatal fluid cultures exceed that of previous reports. Historical empirical antimicrobial choices for equine neonatal infection in the Midwestern United States are supported by local antibiogram results.

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Analytical advances in horseracing medication and doping control from 2018 to 2023

Gray,

Lubbock,

Love

et al. 2024

Drug Testing and Analysis

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The analytical approaches taken by laboratories to implement robust and efficient regulation of horseracing medication and doping control are complex and constantly evolving. Each laboratory's approach will be dictated by differences in regulatory, economic and scientific drivers specific to their local environment. However, in general, laboratories will all be undertaking developments and improvements to their screening strategies in order to meet new and emerging threats as well as provide improved service to their customers. In this paper, the published analytical advances in horseracing medication and doping control since the 22nd International Conference of Racing Analysts and Veterinarians will be reviewed. Due to the unprecedented impact of COVID‐19 on the worldwide economy, the normal 2‐year period of this review was extended to over 5 years. As such, there was considerable ground to cover, resulting in an increase in the number of relevant publications included from 107 to 307. Major trends in publications will be summarised and possible future directions highlighted. This will cover developments in the detection of ‘small’ and ‘large’ molecule drugs, sample preparation procedures and the use of alternative matrices, instrumental advances/applications, drug metabolism and pharmacokinetics, the detection and prevalence of ‘endogenous' compounds and biomarker and OMICs approaches. Particular emphasis will be given to research into the potential threat of gene doping, which is a significant area of new and continued research for many laboratories. Furthermore, developments in analytical instrumentation relevant to equine medication and doping control will be discussed.

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Pharmacokinetics of multiple doses of chloramphenicol in fed adult horses

Cited by 3 publications

References 9 publications

Equine antimicrobial therapy: Current and past issues facing practitioners

Equine antimicrobial therapy: Current and past issues facing practitioners

Antibiograms of field and hospital acquired equine neonatal bacterial fluid cultures in the Midwestern United States: 149 samples (2007‐2018)

Analytical advances in horseracing medication and doping control from 2018 to 2023

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