Residue Analysis Of Methyltestostrone And Pharmacokinetic Study Of Tilapia And Its Metabolites

Tilapia, commonly known as African crucian, belonging to perciformes order, perciformes suborder,Cichlidae,tilapia genus. Tilapia are euryhaline fish,can survive in both sea and freshwater, their diet is broad, and grow rapidly. Because of its delicious meat, easy breeding, has become the world major farming fish. In this paper, we conducted the methyltestostrone study in tilapia from three different aspects, which are residue analysis of methyltestostrone in tilapia fry, Pharmacokinetics and elimination of methyltestosterone in tilapia and Pharmacokinetics of metabolism of methyltestostrone in tilapia. Provide theoretical basis and technology support for the healthy development of tilapia aquaculture and quality and safety of aquatic products.Pharmacokinetics and elimination research of methyltestosterone in tilapia using High performance liquid chromatography (HPLC) method. After orally administered at a dose of 20mg/kg or 2mg/kg fish, Take plasma, muscles and liver tissue samples. Extracted samples with ethyl acetate,and purified with florisil column. The data of drug-time were processed by 3p97 software. The C-T curves of both groups are in accordance with two compartment open model with the first order absorption. The pharmacokinetic parameters of MET in two groups are as follows: the absorbtion half-life are respectively 0.29h, 0.28 h; distribution half-life are respectively and 0.65h, 0.57 h; the peak time are 0.78h, 0.60 h; the elimination half life are 18.40h, 5.98h. Group 20mg/kg could be detected out MET in plasma and mussel until 144h, and MET is negative at the 216h; the concertration in liver is higher than plasma and mussel, and MET can be detected out in 24h, and is negative at the 48h. The results indicated that: after oral administration, the assimilation and distribution of MET was fast, the elimitation was slow, and MET was mainly absorbed and metabolized by the liver. Therefore, the conduct of MET supervision and inspection, in addition to the conventional detection of muscle sample, it should also increase the test of blood samples.Pharmacokinetics of 17α-methyl-5β-androstane-3α, 17β-diol (MeAD) were investigated using GC-MS method. After orally administrated MET at a dose of 20mg/kg to Tilapia, take the plasma samples. Adding acetic acid buffer solution which the PH value is 5.2, hydrolysis withβ-glucuronidase at a condition of 55℃and 3h. Extracted samples with ethyl acetate,and purified with Waters HLB column,derivatized with MSTFA, and then determined the concentration of MeAD in the plasma using GC-MS method. The data was analysted with 3P97 software, the result is The C-T curves of MeAD is in accordance with two compartment open model with the first order absorption, the main pharmacokinetic parameters are as follows: T1/2(ka) is 0.586h, T1/2(alpha) is 4.164h, T1/2(beta) is 362.740h, C(max) is 5604.883ng/ml, T(peak) is 1.920h. The result shows that: the elimination of MeAD in tilapia is extremely slow, and the residues is high. So, in addition to strengthen supervision and inspection of MET, the detection of MET metabolites should be increased, and establish a standard detection method of its metabolites as soon as possible.Conducted MET residues research in tilapia fries, which was just hatched and fed feed adding with different concentrations of methyltestosterone (MET). After feeding for 30 days, MET residue was detected using HPLC method, and then continuing to feed feed without MET, 30 days later, detected MET residues again. The results showed, feeding tilapia fry for 30 days, MET residues were not detected in the controlled group, but were detected in the groups adding different concentrations of MET, and the amounts of residues increased with the increasing of adding concentrations. To continue feeding eel feed without MET for 30 days, MET residues were not detected out in all the experimental groups.