PHARMACOKINETICS OF NORFLOXACIN IN HEMOLYMPH FROM WHITELEG SHRIMP,PENAEUS VANNAMEI FOLLOWING INTRAMUSCLE INJECTION AND ORAL ADMINISTRATION

The pharmacokinetics of norfloxacin were analyzed in whiteleg shrimp(Penaeus vannamei) following intramuscle injection and oral administration.The curvilinear trend of the hemolymph concentration versus time data were almost similar following intramuscle injection at salinities of 1 and 15.The hemolymph concentration versus time at the salinities of 1 ppt and 15 ppt were well described by a two-department model,and the pharmacokinetic models were C_0=35.422×e~(-9.778t)+4.363×e~(-0.165t) at salinity of 1 and C_0=35.144×e~(-13.335 t)+7.888×e~(-0.608t) at salinity of 15.There were significant differences in some pharmacokinetic parameters of norfloxacin in P. vannamei between at salinities of 1 and 15.The distribution half-life(t_(1/2α)),disposition half-life(t_(1/2β)),area under curve(AUC),total body clearance(CLs) and apparent volume of distribution(Vd)following intramuscle injection at salinity of 1 were 0.071h,4.208h,30.06μg·h/mL,332.7 mL/kg·h and 2016 mL/kg,respectively.The corresponding values at salinity of 15 were 0.052h,1.140h,15.61μg·h/mL,640.6 mL/kg·h and 1054mL/kg,respectively.Following oral administration at dose of 30(mg/kg),the hemolymph concentration-time profile of norfloxacin in whiteleg shrimp exhibited two peaks of hemolymph norfloxacin concentration,which occurred at 4h and 12h,and the hemolymph norfloxacin peak concentrations were 2.86μg/mL and 2.04μg/mL,respectively.The area under curve and total body clearance following oral administration were 43.50μg·h/mL and 689.7 mL/kg·h.The hemolymph concentration-time profile of norfloxacin following oral administration at dose of 15mg/kg also exhibited two peaks,which was similar to that at dose of 30mg/kg.But the second Cmax at dose of 15mg/kg occurred at 8h.There were no marked proportion between the dosage of norfloxacin and the hemolymph norfloxacin concentration.