| Popis: |
To develop a spray of niclosamide ethanolamine salt for prevention of bovine from Schistosoma japonicum infection, and explore its characteristics and effect.The solubilizers, penetrating agents, emulsifiers were screened, and the spray of niclosamide ethanolamine salt was formulated according to the screening results. The niclosamide ethanolamine salt was determined by using a HPLC technique, and the stability was observed. The preventive effect of the spray was assessed by in-vitro trials against cercariae and protection trials in mice.The screened formulation was presented as following: 1% niclosamide ethanolamine salt was dissolved in 18% dimethyl sulfoxide, and then added with 1% azone and 2% span, together with 78% ethanol, to yield a 1% spray of niclosamide ethanolamine salt. The spray appeared golden flowing liquid, with 1% niclosamide ethanolamine salt in content (W/W), pH 7.4-7.8, and good thermal and cold stability. All cercariae died (100%) while exposed to the spray at a concentration of 1.00 mg/L for 2 min, and the similar effect was achieved while exposed to 0.50 mg/L of the spray for 5 min or 0.10 mg/L for 30 min. The spray at concentrations less than 0.05 mg/L had no evident toxicity to cercariae. A volume of 0.5 ml of the 1% spray was sprayed on the abdomen of mice, 1-3 d later, the mice were infected with S. japonicum cercariae on the spraying sites, no mice were infected, with a protection rate of 100%. Five days post-spraying, the protection rate was 40%, and the worm burden reduction rate was 65.87%. Ten days later, all the mice were infected, however, the worm burden reduction rate was 51.98%. The worm burdens on days 5 or 10 post-spraying were significantly lower than those of the control (P0.01). The spray exhibited a good preventive efficacy to mice from S. japonicum infection in lab.The spray of niclosamide ethanolamine salt has stable physical and chemical property, and is a novel liquid preventive agent against bovine schistosomiasis. In addition, it has a rapid activity against S. japonicum cercariae, so can prevent bovine from S. japonicum infection. |
