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Influence of experimentally induced theileriosis ( Theileria annulata ) on the pharmacokinetics of a long‐acting formulation of oxytetracycline (OTC‐LA) in calves
Author(s) -
Rajiv Kumar,
Jitendra K. Malik
Publication year - 1999
Publication title -
journal of veterinary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.527
H-Index - 60
eISSN - 1365-2885
pISSN - 0140-7783
DOI - 10.1046/j.1365-2885.1999.00227.x
Subject(s) - oxytetracycline , pharmacokinetics , bioavailability , theileria , cmax , zoology , veterinary medicine , serum concentration , chemistry , biology , medicine , antibiotics , pharmacology , microbiology and biotechnology , parasite hosting , world wide web , computer science
The effects of experimental Theileria annulata infection on the i.m. (20 mg/kg) pharmacokinetics of oxytetracycline were investigated in crossbred calves. The serum concentration–time curves of oxytetracycline (OTC‐LA), before and after experimental infection, were best described by a one‐compartment open model. The experimental infection by subcutaneous administration of ground‐up tick supernate (GUTS), equivalent to 30 Hyalomma anatolicum anatolicum ticks infected with Theileria annulata , produced a clear temperature rise and signs of clinical disease in calves. Subsequently, haemoglobin, packed cell volume, total leucocyte count and serum Cu, Fe and Zn concentrations decreased after infection. The absorption and elimination half‐lives ( t ½ K a and t ½ K e ), mean absorbance time ( MAT ), time to peak concentration ( T max ), mean residence time ( MRT ), area under the serum concentration time curve ( AUC ∞ ) and the bioavailability ( F ) were significantly ( P < 0.05) decreased. The peak serum concentration ( C max ), however, remained unchanged after infection. These changes may necessitate alterations in the dosage regimen of oxytetracycline used to treat Theileria annulata infections in cattle under field conditions.