The influence of gastrointestinal parasitism on fecal elimination of doramectin, in lambs

摘要

A study was done to investigate the effect of parasitism on patterns of doramectin (DRM) fecal elimination in lambs. Fourteen Suffolk Down parasitized lambs (26.9 + 1.5 kg body weight: bw) were purposely selected for the study. Seven pairs of lambs were allocated into two experimental groups. Group I (non-parasitized) was pre-treated with 3 repeated administrations of 5mg/kgbw of fenbendazole to maintain a non-parasitized condition. In Group 11 (parasitized), the lambs did not receive any anthelmintic treatment. After 85 d of the pre-treatment period, both groups were treated with a subcutaneous injection of 200 ng/kg bw of DRM. Fecal samples were collected at different times between -85 d before and 60 d after the DRM treatment, for both parasitological and chromatographic analysis. Samples were analyzed by high-performance liquid chromatography (HPLC) with fluorescence detection. Data of DRM concentrations were expressed as wet weight. A non-linear pharmacokinetic analysis was performed and results were compared using the Mann Whitney test. Fecal maximum concentrations (C_(max)) of DRM were 1.37 + 0.19 μg/g (parasitized group) and 0.86 + 0.15 μg/g (non-parasitized group) observed at the time of the maximum concentration (T_(max)) of 2.1 + 0.4 and 3.1+0.3 d, respectively. Differences in C_(max) values were significant (P<0.05). The accumulated elimination of DRM in feces, expressed as the percentage of DRM total dose, was 67.1% in the parasitized group, whereas in the non-parasitized group it was 56.5%. Our results showed that gastrointestinal parasitic diseases can modify the patterns of DRM fecal elimination, when the drug is administered by subcutaneous route in lambs.