FU Berlin Digitale Dissertation
Ina Schmaedicke : Pharmacokinetics and residue behaviour of clenbuterol in calves fed with milk replacer Pharmakokinetik und Rückstandsverhalten von Clenbuterol bei Milchmastkälbern
|Abstract| |Table of Contents| |More Information|

Abstract 93 calves aged 14 - 18 weeks and weighing 118 -202 kg were fed with milk replacer, structural granola and calf muesli. In a cross-over design, 6 of these calves were administered doses of 2.5, 5 and 10 µg clenbuterol / kg b.w. orally and of 1, 2 and 3 µg clenbuterol / kg b.w. by the i.v. route. Per dose level, 22 blood and urine specimens each were sampled over a period of 72 h. After i.v. administration, the plasma curve followed a two-compartment model while after oral administration, it followed a single-compartment model. After oral dosage, the maximum plasma level was reached after 3 - 5 h and that in urine, after 2.5 - 7 h. Bioavailability was 89 % (SD 17.4 %). In the second experiment, 32 animals were administered orally 2 x 0.8 µg clenbuterol / kg b.w. over 10.5 days, 24 animals, 2 x 10 µg/kg and 12 animals, 10, 15 and 20 µg/kg, respectively, over 21 days. Thereafter, 3 animals each were slaughtered after periods of between 0 and 35 days. Specimens were taken from retina/uvea, liver, kidney, muscle, bile and plasma. Concentrations in retina/uvea exceeded those in all other matrices by 20 - 50 times. After all of the three courses of treatment, clenbuterol could be demonstrated in the retina/uvea over the entire withdrawal period. In all other matrices, clenbuterol that had been administered at a dose of 2 x 0.8 µg/kg b.w. could be detected for up to two days. At a dose of 2 x 10 µg/kg, it was no longer detectable in muscle and bile after 4 days, in kidney after 7 days, in plasma after 14 days, in liver after 21 days and at the highest dose, in muscle after 7 days and in bile after 14 days. From plasma specimens taken a different times before, during and after the treatment phase, it became evident that it had been impossible to fix any limit permitting a distinction between therapeutic (2 x 0.8 µg/kg b.w.) and higher doses. On the whole, the results have shown that an effective monitoring of a therapeutic use of clenbuterol on the basis of residue concentrations detected is impossible both at the side of animal production and at the abattoir.

Table of Contents Download the whole PhDthesis as a zip-tar file or as zip-File For download in PDF format click the chapter title Titelblatt, Widmung, Inhaltsverzeichnis, Tabellenverzeichnis, Abbildungsverzeichnis, Abkürzungsverzeichnis, Danksagung, Lebenslauf 1. Einleitung 2. Literaturübersicht 3. Matherial und Methoden 4. Ergebnisse 5. Diskussion 6. Zusammenfassung 7. Summary 8. Literaturverzeichnis 9. Anhang

More Information:
Online available:	http://www.diss.fu-berlin.de/1999/112/indexe.html
Language of PhDThesis:	german
Keywords:	clenbuterol; calves; cattle; pharmacology; pharmacokinetics; bioavailability; residues; monitoring
DNB-Sachgruppe:	34 Veterinärmedizin
Date of disputation:	26-Nov-1999
PhDThesis from:	Fachbereich Veterinärmedizin, Freie Universität Berlin
First Referee:	PD Dr. Rudi Scherkl
Second Referee:	Prof. Dr. Dr. Reinhard Kroker
Third Referee:	PD Dr. Claus-Christian Merck
Contact (Advisor):	i.schmaedicke@bgvv.de
Date created:	14-Dec-2000
Date available:	02-Feb-2001

 

---

|| DARWIN|| Digitale Dissertationen || Dissertation|| German Version|| FU Berlin|| Seitenanfang ||

---

	Fragen und Kommentare an: darwin@inf.fu-berlin.de
© Freie Universität Berlin 1999