Pharmacokinetics of sulphamethoxazole in calves and cows |
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| Authors: | J F M Nouws T B Vree M Degen D Mevius |
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| Institution: | 1. RVV‐District 6, P.O. Box 40010, Nijmegen, 6504 AA, The Netherlands;2. Clinical Pharmacy , St. Radboud Hospital , Nijmegen, The Netherlands;3. Department of Large Animal Medicine, Faculty of Veterinary Medicine , University of Utrecht , Utrecht, The Netherlands |
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| Abstract: | Summary The kinetics of sulphamethoxazole (SMZ) in plasma and milk, and its metabolism, protein binding and renal clearance were studied in three newborn calves and two dairy cows after intravenous administration. SMZ was predominantly acetylated; no hydroxy and glucuronide derivatives could be detected in plasma and urine. Age‐dependent pharmacokinetics and metabolism of SMZ were observed. The plasma concentration‐time curves of the N4‐acetyl metabolite in the elimination phase were parallel to those of the parent drug; the N4‐acetyl metabolite plasma percentage depended on age and ranged between 100% (new‐born) to 24.5% (cow). SMZ was rapidly eliminated (elimination half‐lives: 2.0–4.7 h) and exhibited a relatively small distribution volume (VDarea: 0.44–0.57 l/kg). SMZ was excreted predominantly by glomerular filtration, while its N4‐acetyl metabolite was actively eliminated by tubular secretion. |
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