Effects Of Artemisinin On Pharmacokinetics And Elimination Regularity Of Enrofloxacin In Channel Catfish (Ictalurus Punetaus)

The combined use of antibiotics and Chinese herbal medicine can not only affect the curative effect,but also solve the problem of drug residue and drug resistance,so it has a good development prospect in aquatic medicine.In this study,we investigated the safety and pharmacokinetics of artemisinin（ART）and the effects of ART on the pharmacokinetics and elimination regularity of enrofloxacin（ENR）in channel catfish,so as to develop a reasonable administration and withdrawal regimen for the combined use of ART and ENR in aquaculture.Firstly,channel catfish was orally given to ART at different doses（20 50 and 100mg/kg body weight）for 5 consecutive times at 24 intervals.The potential side effects of ART on the body were determined by serum biochemical indices,tissue appearance and microstructure by observing the mental state and growth status of experimental fish.The results showed that the growth condition of fish in each group was good and their spirits were normal.Anatomical observation showed no obvious abnormality of tissues and organs.Serum biochemical indexes of each administration group were normal,and liver structures in ART group were not different from that in blank group.These results indicate the safety of artemisinin for channel catfish by oral administration of 20～100 mg/kg body weight for 5 consecutive times.Secondly,in order to research the pharmacokinetics of ART in channel catfish,the method of LC-MS/MS was established for detecting the concentration of ART in plasma.Fish was orally given to ART at different doses（20 and 50 mg/kg bw）for 5consecutive times at 24 intervals.Blood was collected and added to the anticoagulant tube at 0.5,1,2,4,6,8,10,12 and 16 h after the first administration and 0.5,1,2,4,6,8,10,12,16,24,48,72,120 and 168 h after the last administration.The concentration of ART in plasma was detected by LC-MS/MS.Curve fitting and bar charts were performed by Graph Pad Prism v5.0.Pharmacokinetic analysis of ENR in channel catfish was carried out using a non-compartmental model by the Phoenix Win Nonlin 8.1 software.The results showed that ART could induce metabolism of channel catfish by oral administration of 50 mg/kg body weight for 5 times.Subsequently,fish was divided into ENR group and ENR-ART group.Fish in ENR group was orally administered ENR with a single dose of 20 mg/kg body weight,and fish in the ENR-ART group was treated following a single oral administration of the mixture of ART（100 mg/kg body weight）and ENR（20 mg/kg body weight）.Plasma,muscle plus skin,liver and kidney of channel catfish were taken out from each group at each sampling time point including 0.5,1,2,4,6,8,10,12,24,48,72,96,120,and 168 h after administration.The concentrations of ENR and CIP in tissues of channel catfish were measured by UPLC-FLR.In ENR group,C_max of ENR in plasma,muscle plus skin,liver and liver were 13.78mg/m L,13.29mg/m L,21.40mg/m L,26.30mg/m L observed at 12 h,respectively;The values ofλ_z were 0.024 h^-1,0.011 h^-1,0.021 h^-1,0.005 h^-1,respectively;T_1/2 were found to be 28.79 h,63.93 h,32.70 h,139.76 h,respectively;The AUC_0-168were calculated to be 366.13mg×h/m L,746.56mg×h/m L,1016.42mg×h/m L,884.42mg×h/m L L,respectively;The values of V_zwere 2.20 L/kg,2.00 L/kg,0.88 L/kg,3.27 L/kg,respectively;The CL/F were 0.05L×h/kg,0.02 L×h/kg,0.02 L×h/kg,0.02 L×h/kg,respectively;The values of MRT_0-168of ENR were 45.36 h,102.14 h,50.27 h,140.55 h,respectively.For the ENR-ART group,C_max of ENR in plasma,muscle plus skin,liver and liver were 3.79mg/m L,8.23mg/m L,15.38mg/m L,15.56mg/m L observed at 12 h,12 h,16 h,12 h,respectively;The values ofλ_z were 0.006 h^-1,0.012 h^-1,0.015 h^-1,0.021 h^-1,respectively;T_1/2 were found to be 117.16 h,58.53 h,45.59 h,32.76 h,respectively;The AUC_0-168were calculated to be 95.71mg×h/m L,470.21mg×h/m L,614.03mg×h/m L,592.68mg×h/m L,respectively;The values of V_z were 27.89 L/kg,3.07 L/kg,2.02L/kg,1.53 L/kg,respectively;The CL/F were 43.08 L×h/kg,64.53 L×h/kg,43.97L×h/kg,44.19 L×h/kg,respectively;The values of MRT_0-168of ENR were 104.89 h,91.97 h,55.19 h,51.11 h,respectively.The results showed that ART inhibited absorption and distribution in channel catfish and enhanced ENR elimination.Finally,fish was divided into ENR group and ENR-ART group and orally administered 5 times according to dose conversion at an interval 24 h.ENR group was orally administered ENR with a dose of 20 mg/kg bw for 3 days,followed by vegetable oil for 2 days.Fish in ENR-ART group was given oral ENR（20 mg/kg body weight）for 3 days,followed by ART（100 mg/kg body weight）for 2 days.Plasma,skin muscle,liver and kidney were collected at 1,3,5,7,10,15,20,25 and30 d after administration.According to the concentration of ENR residual marker in tissues determined and the specified maximum residue limit（MRL=100mg/kg）,the withdrawal period（WT）needed to reduce the drug content in plasma and tissues to the required level（MRL）was fitted by using WT 1.4 withdrawal period software.The WT for ENR in ENR group in the following order:kidney（86.01 d）>muscle plus skin（59.70 d）>liver（52.40 d）>plasma（42.30 d）.As for ENR-ART group,the WT for ENR was as follows:kidney（62.80 d）>liver（50.20 d）>muscle plus skin（38.30d）>plasma（33.40 d）.The results showed that ART could reduce the residual concentration of ENR in channel catfish and shorten the WT of ENR.