Studies On Pharmacoknetics Of Enroflxacin And Its Withdrawal Time In Chinese Mitten-Handed Crab, Eriocheir Sinensis

It was more than 10 billion yuan/year of Chinese mitten-handed crab,Eriocheir sinens can be sold from the lakes and rivers in Jiangsu.At the same time,Quality safety of Eriocheir sinens about sickness,drug residues and specie deterioration becomes a more and more serious problem.Usage of Enrofloxaxin in Eriocheir sinens has been studied in this paper,including(1) RP-HPLC detecting method of Enrofloxacin,ciprofloxacin and norfloxacin in Eriocheir sinens;(2) Pharmacoknetics of enroflxacin in Eriocheir sinensis after intramuscular injection at 17±2℃;(3) Pharmacoknetics of enroflxacin in Eriocheir sinensis after intramuscular injection at 17,23 and 29℃water temperatures;(4) Study on protein binding data of enrofloxacin with plasma protein in Eriocheir sinens;(5)Study on withdrawal time of enrofloxacin in Eriocheir sinen.1.A RP-HPLC method was developed for the determination of residues of norfloxacin, ciprofloxacin and enrofloxacin in the liver of Eriocheir sinensis.The effect of composition, pH value of the mobile phase on the separation of the above said quinolone mixtures was studied and the chromatographic conditions were thus optimized.The pre-treatment steps as vibration extraction,concentration and centrifugation were carefully improved to minimize the interferences caused by the complicated compositions,high content of lipid and pigments etc.in the liver of Eriocheir sinensis.The developed method is with required accuracy and precision as well as a good linearity in the interested concentration range of 0.01 to 1.0μg·mL^-1.The recovery at spiking levels of 0.01,0.02 and 0.05μg·mL^-1 is.73 -86%,respectively,with a relative standard deviation(n=5) of 2.01%～4.29%from the liver sample.The limit of detection of the method as estimated by 3 times of signal to noise ratio is 10μg·kg^-1.The low residue levels of enrofloxacin and its major metabolites ciprofloxacin could be identified in the liver of Chinese mitten-handed crab 72h after intramuscular injection by the method developed in this work.This should be helpful for the future study on the distribution and metabolism of quinolones in Eriocheir sinensis.2 This is first report about pharmacoknetics of enroflxacin and its activated metabolite ciprofloxacin in Eriocheir sinensis after intramuscular injection at 17±2℃was reported. The concentration of medicament was determined by HPLC.The data were analyzed with the pharmacokinetics computer program 3P97.The pharmacyoknetic results showed that the concentration-time curve of enrofloxacin in plasma after intramuscular injection could be described by a two-compartment open model.The main pharmacokinetics parameters are as follows:T_1/2α 5.29h,T_1/2β 92.42h,K₂₁0.078h^-1,K₁₂0.048 h^-1,K₁₀0.012h^-1, AUC304.80μg·ml^-1h^-1,CLs0.016 L·kg^-1hour^-1.The theoretical equation was C_blood= 6.68e^0.49t+3.38e^-0.013t.The concentration-time course of enrofloxacin in muscle and liver can be described by a two-compartment open model,too.The main pharmacokinetics parameters are as follows:Ciprofloxacin,the metabolite of enrofloxacin at concentration level as low as 10μg·kg^-1 can be indentified in all three tissues.3 Study on pharmacokinetic of enrofloxacin and its metabolite ciprofloxacin following a single intramuscular administration(3.0 mg.kg^-1) was carried out in the Chinese mitten-handed crab at 17,23 and 29℃water temperatures.Hemolymph,muscular and liver samples were collected at 1,10 min and 0.5,1,2,8,16,24,48,72 and 168 h post-injection.The concentration of ENR and CIP were simultaneously determined by HPLC method.The ENR level in hemolymph and muscular reached maximum momentarily,while those in liver appeared to be a maximum then declined.The liver data was analyzed with Practical Pharmacokinetics Program(3P97).The kinetic profile of ENR in liver was conformed to a two-compartment model.The absorption half-life(1.81,0.97 and 0.14 h,respectively),elimination half-life(240.27,60.57 and 37.59 h,respectively) and the area under the concentration-time curve from zero to infinity(2148.65,324.16 and 264.47μg·mL^-1·h^-1,respectively) of ENR in liver was found to have a negative relationship with temperature.Whereas total body clearance had a positive relationship with temperature,and were 0.0014,0.0093 and 0.011 L·kg^-1·h^-1,respectively.4 Protein binding data of enrofloxacin with plasma protein in Chinese Mitten-Handed Crab,Eriocheir sinensis were determined in this paper.Results showed that:percent of enrofloxacin binding to bovine serum albumin(BSA) was 13%～28.95%.In the test,it was found that the concentration of plasma proteins in Chinese Mitten-Handed Crab,Eriocheir sinensis was 63.95±0.29mg/mL.And molecular weight of these proteins were mainly between 66.2KDa～97.1KDa.Protein binding level of enrofloxacin and crab plasma proteins was 49.97～78.81%,which showed more than 50%of the drug could be bound to the proteins.Above all,it could come into the conclusion that enrofloxacin bound with plasma proteins tightly,which assured the efficient utilizing of drug in the crab.It seemed that enrofloxacin could be used in Chinese Mitten-Handed Crab,Eriocheir sinensis.5 The tissue concentration of enrofloxacin and ciprofloxacin were determined simultaneously by a HPLC method.The data were analyzed with Practical Pharmacokinetic Program 3P97(Mathpharmacology Committee,Chinese Academy of Pharmacology, Beijing,China) on a personal computer to automatically determine the type of compartment model and pharmacokinetic parameters.The model was selected on the basis of the residual sum of squares and the minimum Akaike's information criterion(AIC) value.Finally,it can be concluded that the WDT in Eriocheir sinens is 600 day*℃.Generally speaking,this paper totally studied enrofloxacin residual detecting method, pharmaeokinetics,protein bingd data in Chinese mitten-handed crab,Eriocheir sinens,including,And at the end,withdrawal time of enrofloxaein was assured,which is very useful in safe crab producing.