A comparison of the serum level kinetics and biological half-life of oxytetracycline after long action preparations (Tetravet 20% LA inj. and Engemycin 10% LA inj.) in sheep and their tolerance

Blood serum concentrations and biological half-life of oxytetracycline afte r long action preparations were investigated in adult sheep of the Slovak M erino breed. Contemporarily their local tolerance has also been observed. I n the first group oxytetracycline was administered in form of the preparati on Tetravet 20% L.A. inj, a.u.v. (Sanofi, Ltd., France) and in the second g roup in form of the preparation Engemycin 10% L.A. inj. a.u.v. (Intervet, L td., The Netherlands). Oxytetracycline was administered intramuscularly at a single dose of 20 mg per kg of live weight. The blood serum concentration s of oxytetracycline were studied in the intervals of ist, 6th, 24th hours and 2nd, 3rd, 4th, 5th, 6th, 7th and 8th days after single administration o f preparations. Oxytetracycline was determined by high HPLC chromatography (Sokol and Matisova, 1994). The significantly higher serum concentrations o f oxytetracycline (p < 0.05) were recorded after preparation Tetravet L.A. from 24th hour to 5th day. Concentrations of oxytetracycline were detected on the 6th day after Tetravet L.A. preparation and in the case of Engemycin L.A. on the 5th day. Longer half-life was registered after Tetravet L.A. p reparation (40-42 hours). After Engemycin L.A, this time was registered as 37-39 hours. Tetravet L.A. does not induce any local reactions at the site of administration. In contrast to Tetravet L.A., Engemycin L.A, caused infl ammatory edematisation in 50% of animals which persisted 3 days only, witho ut other complications.