The objective of this study was to determine the pharmacokinetics and tolerance of tulathromycin (Draxxin®; 2.5 mg/kg once) after intramuscular (IM), subcutaneous (SC), and slow intravenous (IV) administration to six adult horses. A three-phase design and 4-week washout period were used. Drug concentrations in blood and bronchoalveolar lavage (BAL) samples were determined by ultra-performance liquid chromatography tandem mass spectrometry and pharmacokinetic parameters calculated using noncompartmental analysis. Following SC and IM administration, all horses exhibited sweating, discomfort, and periods of recumbency. As signs were more severe after SC administration this route was only used in 3/6 horses. Intravenous administration of tulathromycin was well tolerated in all horses. Mean bioavailability was 99.4% IM and 115% SC. Mean maximum plasma concentration was 645 ng/ml IM and 373 ng/ ml SC. Mean half-life was 59.8 h, 54.8 h, and 57.9 h for IV, IM, and SC administration, respectively. Mean clearance was 3.25 ml/kg/min, and mean volume of distribution was 16.8 L/kg following IV administration. Drug was detectable in plasma and BAL samples for 120 h following all routes; however, adverse effects may prevent IM use and SC use is not recommended. Tulathromycin may be a practical and affordable antibacterial for use in adult equine patients. / Master of Science / In human and veterinary medicine, antibacterial drugs are a mainstay of treatment. Antibacterials have been used for almost 100 years to prevent microbial organism infection, and as a treatment once there is an established infection. Although there are multiple "classes" of antibacterials that have different spectrums of activity and mechanisms of action, antibacterial resistance has become increasingly prevalent over time. The increasing rate of antimicrobial resistance has led to recommendations that medical practitioners be more judicious in the use of these drugs and to prescribe antibacterials to patients only when necessary. In equine medicine, once an antibacterial is deemed necessary, there are additional considerations, including administration method, frequency of administration, and availability and cost of antibacterial drugs. Tulathromycin, a long-acting semi-synthetic macrolide, is an antibacterial that is approved for use in cattle and swine and may have utility for equine patients for a variety of conditions. This study in healthy adult horses demonstrated that tulathromycin was detectable in plasma and the respiratory tract for up to 5 days after single dose administration. Thus, tulathromycin may be a practical and affordable antibacterial for use in equine patients.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/105382 |
| Date | 13 October 2021 |
| Creators | Leventhal, Hannah Rani |
| Contributors | Biomedical and Veterinary Sciences, Davis, Jennifer Lynn, Wilson, Katherine E., Estell, Krista Elise, Byron, Christopher R., McKenzie, Harold C. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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