Pharmacokinetics Of Sulfadiazine And Trimethoprim In Mud Crab,Scylla Paramamosain

This paper established RP-HPLC simultaneous detecting method of sulfadiazine(SD) and trimethoprim(TMP) in the different tissues of Scylla Paramamosain.Researching on pharmacokinetics, tissue distribution and elimination of SD and TMP in Scylla paramamosain, following single dose oral administration. Comparing the effects of two aquatic environment stressors such as low dissolved oxygen and high ammonia on pharmacokinetics of SD/TMP in hemolymph, in order to provide scientific data to support rational drug use.1. RP-HPLC method for determination of sulfadiazine/trimethoprim residue in mud crab, Scylla paramamosainInfluence of different detection wavelengths and mobile phases on chromatographic behavior sulfadiazine and trimethoprim, and influence of different extraction methods on recovery of sulfadiazine and trimethoprim were carried out. The method of reversed-phase high performance liquid chromatography was developed to determine sulfadiazine and trimethoprim residue in carb. The mobile phase was acetonitrile and 0.01 mol/L ammonium acetate(p H was adjusted to be 3.80 with acetic acid). Aglient Zorbax SB-C18(4.6×150 mm, 5μm) was used with a mobile phase flow rate of 1.0 m L/min and column temperature of 35℃. Ultraviolet detection was used with wavelength of 245 nm. Sampling volume was of 10 μL. The method was found to be linear and reproducible in the concentration ranges of 0.05~10 μg/m L with the correlation coefficient of 0.995~0.999. Sulfadiazine and trimethoprim in Scylla paramamosain tissues were extracted by acetonitrile, and the average recoveries of sulfadiazine and trimethoprim from gill, hepatopancreas, hemolymph, muscle and were 82.26%~95.23% and 81.52%~98.59%, respectively. The relative standard deviations for intra-day and inter-day precisions of SD and TMP were 1.77%~2.53%, 1.75%~4.09% and 2.27%~3.30%, 1.95%~4.82%, respectively. The quantitative detection limits of SD and TMP both were 0.05 μg/m L, 0.05 μg/g, respectively. The method is simple, reproducible and suitable to determine sulfadiazine and trimethoprim in Scylla paramamosain.2. Pharmacokinetics of sulfadiazine/trimethoprim in Scylla paramamosainThis part studied pharmacokinetics, tissue distribution and elimination of SD and TMP in Scylla paramamosain following single dose oral administration at the temperature of 27±1 ℃, salinity 10 conditions, in order to provide scientific data to support its safe use. The results showed that after oral crab filling sulfadiazine/ trimethoprim, hemolymph sulfadiazine and trimethoprim drug concentration-time curves are in line with two-compartment model with first order absorption. Maximum concentrations(Cmax) of SD and TMP in hemolymph were 9.56 mg/L and 2.79 mg/L, respectively, and peak time(Tmax) were 4 h and 2 h, respectively, and the area under the curve(AUC) were 1417.65 mg/L·h and 82.76 mg/L·h, respectively. The peak time of SD and TMP in muscle were 4 h and 1 h, peak concentrations of the drug were 44.95 mg/kg and 10.09 mg/kg, respectively and elimination half- life was 25.09 h and 35.08 h.SD and TMP in hepatopancreas peak time was 4 h and 2 h, respectively, the peak concentration was 59.36 mg/kg, 74.82 mg/kg, elimination half- life was 32.39 h, 34.93 h, respectively. In gill tissue Tmax were 4 h and 2h, respectively, Cmax were 23.28 mg/kg and 25.29 mg/kg, elimination half- life was 32.39 h and 34.93 h, respectively. Drug concentrations in the hepatopancreas was highest level, significantly higher than other tissues, elimination half- life were longest, indicating that it is the main organ for the drug accumulation and metabolism, because of the high concentration of drug toxicity and metabolism saturated probably. Meanwhile gill tissue drug concentration is relatively high, and eliminate faster, may bear part of its role in drug metabolism.According to SD and TMP elimination in muscle and the maximum residue limit of 0.1mg/kg and 0.05 mg/kg in mud carb, the theoretical withdrawal time of SD/TMP in muscle and hepatopancreas were 290.6 h/302.8 h and 340.4 h/377.0 h.3. Comparative pharmacokinetics of sulfadiazine/trimethoprim in mud crab, Scylla paramamosain, at environment stressorsBy simulating low dissolved oxygen(2.5 ± 0.5 mg/L) and high ammonia(25 ± 2 mg/L) of aquatic environmental stressors to stress healthy mud crab, after 96 hours, oral administration sulfadiazine/trimethoprim, studied on comparative pharmaco-kinetics of drugs in different groups of crab hemolymph. The results show that Cmax of SD/TMP at low dissolved oxygen group and high ammonia group were 37.68 mg/L, 2.26 mg/L and 43.23 mg/L, 2.56 mg/L, the peak time 8 h, 4 h and 8 h, 4 h, AUC were 2416.08mg/L·h, 95.90 mg/L·h and 2029.36 mg/L·h, 95.56 mg/L·h, the MRT0-t were 54.60 h, 44.80 h and 45.17 h, 45.13 h, elimination half- life were 81.04 h, 33.55 h and 42.36 h, 40.24 h. Compared with the control group, absorption and elimination of drugs in low dissolved oxygen group were both depressed, inferred that crab have adjusted the metabolism level to adapt to low dissolved oxygen environment, leading to the ability to deal with the drug depressed. Crab in high ammonia groups may be in excited state, the elimination rate of drugs was higher than absorption in early stage after administration, leading to the peak time was advanced, furthermore with the prolonged stress, drugs elimination ability was depressed.