Combined subcutaneous administration of ivermectin and nitroxynil in sheep:

MORENO, L; CEBALLOS, L; LIFSCHITZ, A; BISTOLETTI, M; ALVAREZ, L; LANUSSE, C

RESEARCH IN VETERINARY SCIENCE

ELSEVIER SCI LTD

Año: 2010 p. 315 - 320

0034-5288

The effect of body weight in the plasma disposition kinetics of ivermectin (IVM) 2424 and nitroxynil (NTX) after co-administration as a combined formulation to lambs was 2525 studied. Sixteen (16) lambs were allocated into a high body weight (high bw) group 2626 (n=8) and a low body weight (low bw) group (n=8). Animals on both groups were 2727 subcutaneously (sc) treated with IVM (200 µg/kg) and NTX (10 mg/kg) using a 2828 commercially available combined formulation (Nitromectin, Lab. Ovejero, Spain) Blood 29Nitromectin, Lab. Ovejero, Spain) Blood 29 samples were taken by jugular venopuncture before (time 0) and at 2, 4, 8, 12, h and 1, 3030 2, 3, 5, 7, 10, 15, 20, 25, 35, 40, 50 and 60 days after administration. Recovered plasma 3131 was analysed to quantify IVM and NTX by HPLC. Higher IVM plasma concentrations 3232 were measured until 20 days post-administration in “low bw” compared to “high bw” 3333 lambs, where IVM was recovered up 35 days post-treatment. The IVM absorption 3434 process greatly differs according to the animals’ body weight. A significantly higher 3535 (p<0.01) Cmax (36.7±7.52 ng/ml) value was obtained at a later (p<0.05) Tmax (48.0±0.0) 36max (36.7±7.52 ng/ml) value was obtained at a later (p<0.05) Tmax (48.0±0.0) 36 in light compared to heavy body weight (Cmax: 8.0±0.80 ng/ml; at 34.0 h) lambs. IVM 37max: 8.0±0.80 ng/ml; at 34.0 h) lambs. IVM 37 elimination half life and mean residence time was significantly shorter in light 3838 compared to heavy bw lambs. NTX mean plasma concentrations were lower in “low 3939 bw” lambs with elimination phases declining in parallel in both experimental groups up 4040 to 60 d post-administration. The NTX AUC value in “low bw” (1188.5±122.6 4141 µg·day/ml) was significantly lower (p<0.05) than in “high bw” (1735.0±155.8 4242 µg·day/ml) lambs. Shorter NTX T½el and MRT (p<0.01) were observed in “low bw” 43½el and MRT (p<0.01) were observed in “low bw” 43 compared to the heavier lambs. The work reported here assesses for the first time the 4444 disposition of IVM and NTX after their combinated injection to lambs, demonstrated 4545 that animal body weight/development greatly affect the kinetic behaviour of both 4646 antelmintic drugs. 47 48 48 48 48 48 48 48 48 48 47 48