【作者】 方桂杰；

【导师】 袁宗辉；

【作者基本信息】 华中农业大学 ， 农产品加工与贮藏工程， 2006， 博士

【摘要】 喹喔啉类药物作为饲料添加用抗菌促生长剂，曾在世界范围内广范应用，给人类社会带来了巨大的物质财富和社会经济效益。但由于特殊毒性问题，本类中的主要品种卡巴氧和喹乙醇已在很多国家和地区被禁止使用或严格限制使用。喹赛多为新一代喹喔啉类抗菌促生长剂，对食品动物具有良好的促生长效果。如其具有好的安全性，开发上市代替卡巴氧和喹乙醇，必将对畜牧业生产和人民生活水平的提高起到巨大的推动作用。为评价喹赛多的安全性，进行了系统的临床前毒性试验。测定喹赛多的急性毒性，致突变性，致畸和繁殖毒性，亚慢性毒性，对其致癌性进行预测，计算ADI（每日容许摄入量）和其在动物性食品中的安全浓度。为喹赛多作为新药审批提供毒理学资料，为其过渡到临床试验和应用提供剂量选择和毒副反应监测的依据。1急性毒性试验Wistar大鼠20只，雌雄各半，喹赛多用0.5％羧甲基纤维素钠（CMC）助溶制成混悬液，以1mL／100g b．w．的容量在24h内灌胃3次。观察28d内的中毒反应。结果表明仅给药后大鼠粪便呈黄色，为黄色的试药随粪便排出所致。大鼠未出现明显的中毒反应和死亡。喹赛多对Wistar大鼠的经口MTD＞13g／kg b．w．，按照急性毒性分级标准喹赛多属实际无毒物质。2遗传毒性研究鼠伤寒沙门氏菌回复突变（Ames）试验试验菌株为TA₉₇，TA₉₈，TA₁₀₀，TA₁₀₂。进行了2次试验，第1次试验剂量为5，10，25，50，100，250μg／皿，用已知的阳性物作阳性对照，同时设溶剂对照（二甲亚砜（DMSO））和空白对照（蒸馏水），加和不加S₉混合液的对照。每个处理作3个平行平皿，采用标准平皿掺入法，计数各皿回变菌落数，结果评价为计算各处理平均每皿诱发回变菌落数与相应的空白对照组的平均每皿自发回变菌落数的比值（MR），如MR大于2为阳性，小于2为阴性。第2次试验剂量为0.2，1，5，25，100μg／皿，同时设同类药物对照（喹乙醇25μg／皿），其余与第1次试验相同。两次试验结果基本一致，TA₉₇和TA₁₀₀加和不加S₉在剂量≥5μg／皿时均为阳性；TA₉₈不加S₉在剂量≥10μg／皿时为阳性，加S₉在剂量≥5μg／皿时为阳性；TA₁₀₂加和不加S₉在剂量≥100μg／皿时均为阳性。阳性反应呈现一定的剂量反应关系。喹赛多100μg／皿对TA₉₇有轻微抑菌作用，250μg／皿对TA₉₇，TA₉₈，TA₁₀₀均有不同程度的抑菌作用。喹乙醇25μg／皿除TA₁₀₂不加S₉为阴性（MR=1.73）外，其余均为阳性。在本试验条件下喹赛多Ames试验结果为阳性。喹乙醇在TA₁₀₂上的诱变性高于喹赛多。小鼠骨髓细胞微核试验第1次试验，取70只昆明种小鼠随机分为7组，雌雄各半，分别为空白对照组（蒸馏水），溶剂对照组（0.5％CMC），喹赛多组（0.016，0.16，1.6，16g／kg b.w．），阳性对照组（环磷酰胺（CP）40mg／kg b.w.）。第2次试验，取80只昆明种小鼠随机分为8组，雌雄各半，分别为溶剂对照组（0.5％CMC），喹赛多组（0.5，1，5，10，20g／kg b.w.），喹乙醇组（0.5g／kg b.w.），阳性对照组（CP 40mg／kgb.w.）。除阳性对照组外，其余各组均为每天灌胃给药1次，连续4d，第5d取胸骨骨髓制片。阳性对照组为腹腔注射给药2次，间隔24h，于末次给药后6h采样。每只小鼠计数1000个多染红细胞，计算含微核的嗜多染红细胞（MNPCE）数和含微核多染红细胞率，同时计数多染红细胞（PCE）和正染红细胞（NCE）的比例。两次试验结果均表明，溶剂对照组和喹赛多各剂量组含微核多染红细胞率与阴性对照组比较差异不显著（P＞0.05）。阳性对照组和喹乙醇组微核率与阴性对照组比较差异显著（P＜0.01）。各组小鼠的PCE／NCE均＞0.1，表明喹赛多对小鼠骨髓未呈明显的细胞毒性作用，红细胞的形成未受到抑制，不影响微核计数。阴性对照组含微核多染红细胞率＜3‰，符合一般自发率。喹赛多微核试验结果为阴性。喹乙醇的诱变性明显高于喹赛多。小鼠睾丸生殖细胞染色体畸变试验第1次试验取45只雄性昆明种小鼠随机分为9组，分别为阴性对照组（蒸馏水），溶剂对照组（0.5％CMC），喹赛多组（0.016，0.16，1.6，16g／kg b.w.），喹乙醇组（0.16，1.6g／kg b.w.），阳性对照组（CP 40mg／kg b.w.）。除阳性对照组为腹腔注射给药外，其余各组均为灌胃给药，每天1次，连续5d，于第11，12d再连续给药2d，第13d杀鼠。第1次试验给药5d后，1.6g／kg b.w.喹乙醇组小鼠在6d内陆续死亡。表明喹乙醇的毒性较强。第2次试验取45只雄性昆明种小鼠随机分为8组，分别为溶剂对照组（0.5％CMC），喹赛多组（0.5，1，5，10，20g／kg b.w.），喹乙醇组（0.5g／kg b.w.），阳性对照组（CP 40mg／kg b.w.）。给药方法和取样时间等与第1次试验相同。每只小鼠计数100个初级精母细胞中期相，进行染色体畸变分析。观察的染色体畸变的类型有断裂与断片、易位、性染色体早熟分离和常染色体早熟分离，并计算畸变细胞总数。两次试验结果均表明，除阳性对照组的断裂与断片（P＜0.01），畸变细胞总数（P＜0.01），阳性对照组的易位（P＜0.05）和喹乙醇组的畸变细胞总数（P＜0.05）与阴性对照组比较差异显著外，溶剂对照组和喹赛多组的各项指标与阴性对照组比较差异均不显著（P＞0.05）。喹赛多对小鼠睾丸生殖细胞无致突变作用，喹乙醇的致突变性高于喹赛多。3 90d喂养试验动物和分组SPF级Wistar大鼠雌性175只，雄性125只。随机分为5组，每组雌性35只，雄性25只。设喹赛多试验组，剂量为50、150、2500mg／kg饲料；药物对照喹乙醇组，剂量为150mg／kg饲料；空白对照组，饲以不添加药物的饲料。雌雄分笼饲养。各组均连续饲喂90d。观察项目和指标每周称量动物体重和饲料，计算平均摄食量、增重和饲料利用率。分别于用药后30d，60d，90d各组随机抽取10只大鼠，雌雄各半，取全血作血常规检验，血清作生化指标检验。并进行病理剖检和病理组织学检查，主要脏器称重，计算脏器系数。结果喹赛多最高剂量组大鼠粪便呈淡黄色，可能是药物（黄色）经粪便排出所致。给药2周后开始直至实验结束，喹赛多2500mg／kg饲料组大鼠体重显著低于空白对照组，喹乙醇组雌性大鼠在给药的第3周和第4周体重显著低于空白对照组。其他组与空白对照组比较差异不显著。各期杀鼠病理组织学观察表明喹赛多剂量为2500mg／kg饲料可引起大鼠肝细胞和肾脏近曲小管上皮细胞肿胀、变性。喹乙醇150mg／kg饲料组也出现相近的结果。结论喹赛多对Wistar大鼠亚慢性毒作用的靶器官为肝脏和肾脏，与喹乙醇相同。高剂量喹赛多引起的肝脏和肾脏病变为首次发现。喹赛多亚慢性无不良作用剂量（NOAEL）为150mg／kg饲料。相当于15mg／kg b.w.，这与本实验室进行的喹赛多大鼠长期毒性试验的结果基本一致。4两代喂养繁殖与致畸试验方法90d喂养试验除用于剖杀检查的大鼠之外，每组剩余的雌性20只，雄性10只，在90d喂养试验之后，进行交配。1／2孕鼠于妊娠20d剖腹进行畸胎检查，另1／2自然分娩，产生F_1a。F_1a断奶后处死，进行系统病理剖检。母鼠再次交配产生F_1b。F_1b断奶后处死F₀，进行病理剖检并取其生殖器官进行病理组织学检查。F_1b各组分别选留雌性28只，雄性15只，分别饲喂与亲代相同的饲料。饲喂30d时每组随机抽取雌雄各5只，扑杀，进行血常规、血清生化指标测定，计算脏体比，并进行系统病理剖检。余下F_1b大鼠饲喂90d后进行交配，1／2孕鼠用于畸胎检查，另1／2自然分娩，产生F_2a。F_2a断奶后处死全部大鼠，进行系统病理剖检。畸胎检查包括测窝重、胎盘重、子宫重、黄体数、活胎数、死胎数、胎鼠体重、体长、尾长、性别，检查外观畸形，制作骨骼标本和内脏标本进行骨骼和内脏畸形检查。对所有子鼠在出生时检查外观畸形、体重、体长、尾长、活胎数、死胎数和性别比率等。出生4d时每窝随机选留8只，尽量雌雄各半，称5d重和21d重。F₀和F_1b在13周喂养期内每周称体重和饲料，计算平均摄食量、增重和饲料利用率。对亲代的影响喹赛多对孕鼠的健康状况，行为无明显不良影响，病理剖检未见明显的病变。组织病理学检查未见大鼠生殖器官受到损伤。体重：喹赛多2500mg／kg饲料组：雌雄F₀体重在13周的喂养期内均自第3周开始显著低于空白对照组；雌性F_1b在断奶后第2，5，11周显著低于空白对照组；雄F_1b在断奶后第1，2，4周显著低于空白对照组，在第8周显著高于空白对照组。其他各剂量组大鼠体重没有受到试药的明显影响。饲料利用率：与空白对照组比较，雄性F₀各剂量组均有所提高，雌性F₀各组无显著差异；F_1b各剂量组未出现明显的变化趋势。喹赛多2500mg／kg饲料组第2代致畸试验孕鼠体重显著低于空白对照组。病理组织学检查：F_1b喂养30d扑杀病理组织学观察表明喹赛多剂量为2500mg／kg饲料时引起大鼠肝细胞和肾近曲小管上皮细胞肿胀、变性。喹乙醇150mg／kg饲料组也出现相近的结果。其他组未发现与试药相关的变化。对子代的影响喹赛多2500mg／kg饲料组：第1代致畸试验胎鼠体重、体长、尾长和窝重显著低于空白对照组，吸收胎数显著高于空白对照组；第2代致畸试验窝重和活胎数显著低于空白对照组，吸收胎数显著高于空白对照组：F_1a，F_1b和F_2a出生活胎数显著低于空白对照组；F_2a出生后21d体重显著低于空白对照组。喹赛多150mg／kg饲料组：F_1b出生后5d体重和21d体重显著高于空白对照组。喹赛多50mg／kg饲料组：F_1b出生后21d体重显著高于空白对照组。各组均未出现明显的与药物相关的外观和内脏畸形。喹赛多2500mg／kg饲料组F_2a多肋变异显著增加；喹乙醇150mg／kg饲料组F_2a多肋变异也明显增加，但差异不显著。除此之外未发现明显的骨骼畸形。结论喹赛多在剂量为2500mg／kg饲料（临床剂量的50倍）时对大鼠胚胎发育有轻度抑制作用，对大鼠的生长发育和生殖机能有轻度抑制作用，无明显的繁殖毒性和致畸性。喹赛多的安全性较高。并初步判定同等剂量下喹乙醇对大鼠生殖发育的不良影响高于喹赛多。喹赛多对大鼠生殖发育毒性的NOAEL为150mg／kg饲料，相当于15mg／kg b.w.。5预测致癌性和计算每日容许摄入量（ADI）及安全浓度根据3项致突变试验的结果，运用致癌性预测和试验组合的选择（CPBS）法计算受试物的潜在致癌性概率。喹赛多可能是潜在致癌物的概率为16％，喹乙醇可能是潜在致癌物的概率为100％。根据目前通用的判别标准，θ⁺＜30％判为非致癌物；30％＜θ⁺＜70％，暂时无法下结论：θ⁺＞70％，判为潜在致癌物。喹赛多可预测为非致癌物。喹乙醇可预测为致癌物。根据上述各试验结果得到喹赛多的NOAEL=15mg／kg b.w.，按照FDA的ADI和安全浓度计算公式，计算其ADI=0.15mg／kg b.w.；在肌肉的安全浓度为30μg／g；在肝脏的安全浓度为90μg／g；在肾脏和脂肪的安全浓度为180μg／g。实际给药时动物组织中原药及代谢物的残留量远远低于安全浓度。所以，喹赛多的安全性很高。上述试验基本按照我国农业部颁布的《新兽药一般毒性试验技术要求》和《新兽药特殊毒性试验技术要求》进行试验设计，并参照兽药注册国际协调局（VICH）的新兽药安全性评价要求，食品安全性毒理学评价程序，动物毒理学试验方法和卫生毒理学试验方法等相应指南和试验技术要求进行规范和完善。在国内外首次对喹赛多的急性毒性、亚慢性毒性、致突变性、致畸性、繁殖毒性进行了系统评价，并与同类药物喹乙醇进行比较。试验结果与相关研究基本一致，喹赛多的毒性很低，且明显弱于喹乙醇，潜在致癌性预测结果为非致癌物。且其安全浓度远远高于实际给药时动物组织中的残留量。具有较好的安全性。可为喹赛多的临床使用提供相关的科学依据，也为喹赛多作为新兽药审评提供相关的资料。更多还原

【Abstract】 (National Reference Laboratory of Veterinary Drug Residues, MO A Key Laboratory of Food Safety Evaluation, Huazhong Agricultural University, WuHan 430070, P. R. China) Quinoxalines were widely used as feed growth-promoting agent in the most areas of the world and produced large interests. However, the use of main quinoxalines drugs, carbadox and olaquindox, have been prohibited or limited attributing to their toxicity. Cyadox, a new member of the quinoxaline family, had the traits of obvious growth promotion in food-producing animals. If its safety is good it can be used to replace the old drugs and promote the development of animal husbandry, then improve people’s lives largely. To investigate the toxicity of cyadox, systematically preclinical toxicity tests were conducted and potential carcinogenicity was predicted with CPBS method. Acceptable daily intake （ADI） and safe concentration were caculated based on the results of toxicity tests.1 Acute toxicity test. To determine the maximum tolerated dose （MTD） of cyadox in rats, 10 adult Wstar rats/sex were orally given 1mL/100g b.w. cyadox suspended in 0.5% carboxymethylcellulose sodium （CMC） three times within 24h. Concentration of cyadox suspension is 43.34% （larger will make intubation very difficult）. After dosing the rats were fed with blank diet for 28 days. No death or obvious toxic effect related to cyadox was found other than yellow-colored feces in the first two days after dosing. The MTD of cyadox is above 13g/kg b.w. and cyadox belongs to practically nontoxic substance.2 Mutagenicity testsAmes assay. The mutagenicity of cyadox was evaluated in a reverse mutation assay using four histidine requiring strains of S. typhimurium (TA₉₇, TA₉₈, TA₁₀₀, and TA₁₀₂) with and without S9 from PCB-induced rats as activation systems using triplicate plates. The tests were conducted with doses 5, 10, 25, 50, 100, 250μg/plate cyadox for the first time and 0.2, 1, 5, 25, 100μg/plate cyadox and 25μg/plate olaquindox for the second time. The results of two times were consistent basically. 5μg/plate and higher dose cyadox induced mutagenic responses in TA₉₇ and TA₁₀₀ with and without S₉, and TA₉₈ with S₉; 10μg/plate and higher dose cyadox induced mutagenic responses in TA₉₈ without S₉; 100μg/plate and higher dose cyadox induced mutagenic responses in TA₁₀₂ with and without S₉. Mutagenic responses are dose related in all the four bacterial strains. 100μg/plate cyadox suppressed the growth of TA₉₇ slightly; 250μg/plate cyadox suppressed the growth of TA₉₇, TA₉₈ and TA₁₀₀ to a certain extent. 25μg/plate olaquindox induced mutagenic responses for all the four bacterial strains except TA₁₀₂ without S₉. Olaquindox exhibited higher mutagenicity in TA₁₀₂ than cyadox.In vivo mouse micronucleus assay. The test was performed to test the induction of micronuclei in polychromatic erythrocytes from sternal bone marrow of Kunming mice resulting from exposure to cyadox. The highest technically feasible dose for cyadox in 0.5% CMC was 20g/kg b.w. at a dose volume of 0.5mL/10g b.w.. Therefore, in the first test cyadox was administered to groups of five male and five female mice at a single dose level of 0.016, 0.16, 1.6, 16g/kg b.w. once a day in constantly four days. The same volum distilled water or 0.5% CMC was used as concurrent negative control or solvent control. In the second test dose levels for cyadox are 0.5, 1, 5, 10, 20g/kg b.w., and 0.5g/kg b.w. olaquindox and 0.5% CMC was used as drug control or concurrent solvent control, respectively. Dose route, dose times and dose interval was the same as those of the first test. In both tests mice were sacrificed and smear slides were made with sternal bone marrow after 24hs from the last dosing. Cyclophosphamide （CP） was used via intraperitoneal injection at a dose level of 40mg/kg b.w. as concurrent positive control and sampled on 6h after the second dosing. The slides were scored for micronuclei and for polychromatic （PCE） to normochromatic （NCE） cell ratio until 1000 cells （PCE and NCE） had been analyzed. Counting also continued until at least 1000 PCE had been observed. Cyadox is not mutagenic in all dose levels. 40mg/kg b.w. CP and 0.5g/kg b.w. olaquindox induced higher micronucleus rate relative to negative control. So cyadox is not mutagenic in mice bone marrow micronucleus assay, and olaquindox showed higher mutagenicity than cyadox. Mammalian spermatocyte of the first order chromosome aberration test. To investigate the potential germ cell mutagenicity of cyadox, groups of 5 male Kunming mice were given cyadox （0.016, 0.16, 1.6, 16g/kg b.w.） or olaquindox （0.16 and 1.6g/kg b.w.） by oral gavage once a day, both drugs suspended in 0.5% CMC, in concecutive five days. Mice were sacrificed in the thirteenth day from the first dosing and 100 metaphases of spermatocytes of the first order in each mouse were examined. In the testicle chromosome aberration test, cyadox did not cause any increase in aberrations. 1.6g/kg b.w. olaquindox group mice died within 6 days after 5 days dosing. A following study in male mice with cyadox （0.5, 1, 5, 10, 20g/kg b.w.） or olaquindox （0.5g/kg b.w.） with same sample times also did not reveal any increases of aberrations in cyadox group. 0.16 and 0.5g/kg olaquindox produced mild mutagenic effect.3 90-day feeding test. To investigate the potential subchronic toxicity of cyadox, groups of 15 male and 15 female Wistar rats were fed with the diets containing cyadox （0, 50, 150 or 2500mg/kg） or olaquindox （150mg/kg）, approximately equivalent to cyadox 5, 15, 250 or olaquindox 15mg/kg b.w./d, for 13 wk. 5 rats/sex/group were sacrificed on days 30, 60 and 90. No test-material-related changes were seen in mortality, clinical signs, hematology, clinical chemistry, organ weight data and macroscopic examinations. Except that body weights of both sexes of 2500mg/kg cyadox group were significantly lower than controls beginning from the second week of treatment. Body weights of females of 150mg/kg olaquindox group were significantly lower than those of the control group at weeks 3 and 4. Body weights of other groups were unaffected by treatments. Histopathological observations revealed that 2500mg/kg cyadox or 150mg/kg olaquindox induced swelling and fatty degeneration of the hepatocytes and proximal renal tubular epithelial cells. It is the first time that the changes of liver and kidneys were found in rats given high level of cyadox. The subchronic no-observed-adverse-effect level （NOAEL） of cyadox for rats was estimated to be 150mg/kg dietary dose level based on this study, which was equivalent to approximately 15mg/kg b.w./d and is significantly higher than that of olaquindox.4 Two generation feeding reproduction test and teratogenicity test. Method: To investigate the potential teratogenic and reproductive toxicity of cyadox, groups of 10 male and 20 female Wistar rats （F₀） were fed with the diets containing cyadox （0, 50, 150 or 2500mg/kg） or olaquindox （150mg/kg） through a 13-week prebreed period as well as during mating, gestation, parturition and lactation. Half pregnant rats were subjected to caesarean section on gestational day （GD） 20 for teratogenic examination and another half produced the young (F_1a). F_1a were euthanized on day 21 after birth and autopsied. F₀ rats were mated again after 10 days following weaning of the F_1a generation to produce an F_1b generation. At weaning, 10 males and 25 females of F_1b weanlings per group were selected randomly as parents for the F₂ generation. Selected F_1b weanlings were exposed to the same diet and treatment as their parents. More than 12 pregnant rats were used to teratogenic examination and the rest produced the young (F_2a). F_2a were autopsied on day 21 after birth as well as their parents. Fetuses were examined for external, visceral, and skeletal abnormalities. The young were randomly selected on day 4 after birth and only 8 of each litter preferring equal number for female and male were kept. Body weights of the young on days 5 and 21 after birth were recorded. Body weight and feed intake of F₀ and F_1b throughtout 13wk feeding period were recorded and feed efficiency were caculated. Result: No test-material-related changes were seen in mortality, clinical signs, and macroscopic examinations throughout the study. Relative to concurrent control group, body weights of prebreed period for rats of 2500mg/kg cyadox group were significantly lower in both sexes of F₀ beginning from the third week of treatment, and in female F_1b at weeks 2, 5, 11 and male F_1b at weeks 1, 2, 4 after weaning. However, it is significantly higher in male F_1b at week 8. Body weights of other groups were not affected by treatment obviously. Feed efficiency of male F₀ increased to a certain extent in all the treatment groups and that of female F₀ showed no obvious drug-related effect. However, Feed efficiency in both sexes of F_1b showed no clear or obvious trend. Body weights of pregnant rats of 2500mg/kg cyadox group in F_1b were significantly lower relative to concurrent control group. Histopathological observations revealed that 2500mg/kg cyadox or 150mg/kg olaquindox induced swelling and degeneration of the hepatocytes and proximal renal tubular epithelial cells in F_1b rats on day 30. No test-material-related changes were found in other groups. On 2500mg/kg cyadox group, relative to those of blank controls, body weight, body length and tail length of fetus and litter weight decreased and number of resorption fetus increased significantly in the first generation teratogenicity test; litter weight, number of viable fetus decreased and number of resorption fetus increased significantly in the second generation teratogenicity test; number of viable fetus of F_1a, F_1b and F_2a decreased in the reproduction test; Body weights of F_2a on day 21 after birth decreased significantly. On 150mg/kg cyadox group, body weights of F_1b on days 5 and 21 after birth increased significantly relative to those of blank controls. On 50mg/kg cyadox group, body weights of F_1b on day 21 after birth increased significantly relative to those of blank controls. No obvious external and visceral abnormalities were found in all the groups in both two generation teratogenic tests. Except that extra little rib in neck or waist significantly increased in the fetus of 2500mg/kg cyadox group in F_2a, and obviously increased in those of 150mg/kg olaquindox group, but no significant difference. No obvious skeleton abnormalities were observed. Conclusion: 2500mg/kg cyadox depressed mildly the development of fetus and fertility of rats. No obvious teratogenicity or reproductive toxicity was revealed, and results indicated that olaquindox produced higher adverse effect on the reproduction and development of rats than cyadox at the same dose. The NOAEL for reproduction/development of cyadox for rats was estimated to be 150mg/kg dietary dose level based on this study, which was equivalent to approximately 15mg/kg b.w./day and significantly higher than that of olaquindox.5 Preclinical safety evaluation for cyadox.Predicting potential carcinogenicity. Based on the results of the above three mutagenicity tests probability of potential carcinogenicity for cyadox is 16% and that of olaquindox is 100% predicted with carcinogenicity prediction and battery selection （CPBS） method, and cyadox can be predicted to be non-carcinogen and olaquindox to be carcinogen.Caeulating ADI （acceptable daily intake） and safe concentration. With NOAEL （15mg/kg b.w.） of the above subchronic toxicity test and two generation feeding reproduction test and teratogenic test, ADI was calculated to be 0.15mg/kg b.w. according to method of FDA. Safe concentration of cyadox for muscle is 30μg/g, and that for liver is 90μg/g and both that for kidney and fat are 180μg/g. The safe concentrations of all the above tissues were much larger than residues of cyadox or its metabolites detected in tissues of animals given cyadox in diet. Therefore, cyadox possess very good safety.Brief summary. All the above tests were designed and conducted according to "the Technological Requirement for General Toxicity Test of New Veterinary Drug" and "the Technological Requirement for Special Toxicity Test of New Veterinary Drug" published by MOA in 1991 basically, and were standarded and improved by refering to "Guidance for Industry: Studies to Evaluate the Safety of Residues of Veterinary Drugs in Human Food" published by International Cooperation on Harmonization of Technical Requirements for Registration of Veterinary Medicinal Products （VICH）, "Toxicological Principles for the Safety Evaluation of New drug （western medicine）" published by Hygeian administration, "Toxicological Principles for the Safety Evaluation of Food", animal and hygeian toxicological test methods. The acute toxicity, subchronic toxicity, mutagenicity, teratogenicity and reproductive toxicity of cyadox were systematically evaluated firstly. All the above tests revealed that the toxicity of cyadox was mild, which was much milder than that of olaquindox. Results of these tests were consistent with other studies basically and provided valuable toxicological information of cyadox, which demonstrated the good safety profile of cyadox and can be used as scientific evidence for approvement and application of cyadox in food-producing animals as a growth-promoting agent.更多还原