Metabolic Studies (Minocycine In Carp, Albendazole Sulfoxide In Crucian Carp) And Preliminary Study Of Microsomal CYP450in Carp

China is a big fishing country. Due to the prevalence of fish disease, various drugs have been used extensively to control it. The abuse of fishery drugs leads to disposition of residues in the edible parts of treated fish. However, Chinese climate shows significant seasonal variations. So the studies of pharmacokinetics and residues of drugs in fish at different seasons could provide theoretical basis for the formulation of dosage regimen and withdrawal time.Pharmacokinetics and residues elimination of minocycline(MINO) in carp (Cyprinus carpio) and albendazole sulfoxide(ABZSO) in crucian carp (Carassius auratus) were studied kept at winter water temperature(10℃) and summer water temperature (25℃). The drug concentrations in biological samples were analyzed by means of high-performance liquid chromatography (HPLC) after sample pretreatment steps. The correlation of calibration curves (correlation coeffcients were above0.9997) was all good. The average of experimental drug extraction recoveries were more than88%from plasma and more than73%from other tissues. The coefficients of variation (inter-day and intra-day) were less than10%and5%, respectively.Fish were administration orally (a single dose of10mg/kg·bw) in the pharmacokinetics group (MINO in carp and ABZSO in crucian carp). The results revealed that the influence of water temperature on the drug metabolism was significant. There were higher absorption rate and shorter elimination half-lives (t1/2ke) compared with those at winter water temperature. The plasma concentration-time data (MINO in carp, ABZSO and ABZSO2in crucian carp) conformed to one-compartment open model at two water temperatures. At winter water temperature(10℃), the pharmacokinetics parameters of MINO:the absorption half-lives(t1/2ka) was2.65h, the peak time(Tmax) was7.21h, the peak concentration (Cmax) was2.34μg/mL, the elimination half-lives(t1/2ke) was11.16h, the distribution volumes(Vd/F) was4.09L/kg, the total body clearances(CLb) was0.25L/(h-kg), the areas under the concentration-time curve(AUC) was59.07μg·h/mL; the pharmacokinetics parameters of ABZSO:t1/2ka was3.89h, Tmax was10.58h, Cmax was3.20μg/mL, t1/2ke was16.34h, Vd/F was1.99L/kg, CLb was0.08L/(h·kg), AUC118.21μg·h/mL; the pharmacokinetics parameters of ABZSO2:t1/2ka was6.39h, Tmax was12.82h, Cmax was0.78μg/mL, t1/2kewas12.86h, Vd/F was6.43L/kg,CLb was0.34L/(h-kg), AUC28.86μg·h/mL. At summer water temperature(25℃), the pharmacokinetics parameters of MINO:t1/2ka was1.65h, Tmax was3.50h, Cmax was2.97μg/mL, t1/2ke was3.78h, Vd/F was2.66L/kg,CLb was0.49L/(h·kg), AUC30.77μg·h/mL; the pharmacokinetics parameters of ABZSO:t1/2ka was1.29h, Tmax was3.80h, Cmax was4.39μg/mL, t1/2ke was6.72h, Vd/F was1.53L/kg, CLb was0.19L/(h·kg), AUC63.21μg·h/mL; the pharmacokinetics parameters of ABZSO2:t1/2ka was3.73h, Tmax was7.04h, Cmax was1.03μg/mL, t1/2ke was6.56h, Vd/F was4.61L/kg, CLb was0.49L/(h·kg), AUC20.52μg·h/mL.In the residues study, fish were given a multi-dose of10mg/kg·bw (MINO in carp and ABZSO in crucian carp) for3consecutive days by oral gavages. The results showed that the influence of water temperature on the elimination rate (MINO in carp, ABZSO and its metabolites in crucian carp) was significant and the drug metabolic rate in skin was relatively slower than that in other tissues. So the elimination of MINO and ABZSO in skin could be behaved as a reservoir. If fish were administered MINO and ABZSO orally with a single dose(10mg/kg·bw) for several days, the withdrawal periods of MINO could be not less than19d at winter water temperature(10℃) and8d at summer water temperature(25℃), which of ABZSO could be not less than17d and10d, respectively. Cytochrome P450(CYP450) enzymes represent a superfamily of monooxygenases that play a pivotal role in metabolism of endogenous and exogenous compounds, which have great research significance in pharmacology. The research on CYP450only focused on the experimental animal and human, although it plays an important in animal drug metabolism. The research of CYP450in edible animal was relatively fewer. As China is a big consuming country in fish food, rational use of fishery drug relates closely to human health and experimental safety. The experiment(with carp as object) studied on the influence of water temperature and3sulfonamides(SD, SM2, SMM) on the CYP450biochemical indicators; studied on the influence of reaction temperature(5℃,10℃,15℃,20℃,25℃,30℃) on the CYP2E1-like isoform activity with Chorzoxazone (CZX) as substrate. This experiment provided theoretical basis for further research of fish CYP450and the rational use of fish drug. Detail results are as follows.1. The influence of water temperature on CYP450biochemical indicatorsSome biochemical indicators at winter water temperature(10℃) were lower compared to those at summer water temperature(25℃), which provided theoretical basis for it that fish metabolic rate at summer water temperature(25℃) is higher than that at winter water temperature(10℃). These results laid the foundation for the future research in relationship between temperature and CYP450isoform.2The influence of3sulfonamides on CYP450biochemical indicatorsThese results showed that sulfonamides (SD, SM2, SMM) could make the content of liver microsomal protein decreased and make the activity (AND and AH) inhibited significantly (P<0.01); these sulfonamides have no effect on the content of CYPb5or the activity of ERND. Those provided directive significance on the rational use of sulfonamides in fish.3The influence of temperature on CYP2El-like isoform activityThese results revealed that the Michaelis constant (Km) value of CYP2El-like isoform(with CZX as probe) was minimal and Maximum reaction velocity (Vmax) was maximal at25℃compared with those at other temperatures. The influence of reaction temperature on CYP450activity could reflect the influence of water temperature on drug metabolism in fish indirectly. So variations of fish pharmacokinetic parameters at different water temperatures could be due to the variation of CYP450activity at different temperatures.