The Pharmacokinetics Of Antimicrobial Peptide Piscidin 1 In Rats

Antimicrobial peptide(AMP)is a kind of small molecular peptides produced by animals and plants,which has broad-spectrum Antimicrobial properties,Piscidin 1,as one of the most widely studied antibacterial peptides,has been proved to defend against bacteria and viruses infection.It is confirmed that it has positive effect on the PEDV and PRV virus treatment.A fast and accurate method to detect Piscidin 1 in rat plasma has been established via LC-MS.Rat was used as a model for pharmacokinetic studies,and the bioavailability was compared in different administration method as the basic research for future study.1.Development of LC-MS for detection of Piscidin1 in rat plasma and small intestineIn this study,a rapid and sensitive detection method for Piscidin 1 in rat plasma and small intestine was established by LC-MS.The detection limit is 0.01 μg/ml,retention time = 1.3 ~ 1.4 min,Correlation coefficient R2= 0.9976,the recovery also above 85 %.The intestine method LOQ = 0.01 μg/ml,retention time = 1.3 ~ 1.4 min,correlation coefficient R2 = 0.9956,the recovery is also above 80 %.They are both up to the standard of pharmacokinetics research.2.The pharmacokinetic study of Piscidin 1 in rat model in vivoBlood samples of rats were collected at 5 min、10 min、20 min、30 min、1 h、2 h、4 h、8 h、12 h and 24 h after 2 mg/kg intravenous administration.Through the drug-time curve,the peak concentration of piscidin1 in plasma is 4.88 μg/ml and MRT = 22.14 h,which is much longer than the general protein drugs such as insulin.The metabolism of Piscidin 1 is relatively slow,CL is 0.067 L/h/kg,which made us detected 0.1μg/ml Piscidin 1 in 48 h.3.Determination of the difference in pharmacology parameter through different administration in ratThe samples of rat blood were collected at 5 min、10 min、20 min、30 min、1 h、2 h、4 h、8 h、12 h and 24 h after 2 mg/kg in I.G.and I.M.administration,compared the difference in pharmacokinetic parameters of I.M and I.G with I.V,the Cmax of I.G.reduced to 0.7 μg/ml,Tmax = 0.5 h,MRT = 26.76 h,CL = 0.171 L/h/kg.Compared with the intravenous,the bioavailability was only 36 %.On the other hand,the Cmax of I.M.could reached 2.37 μg/ml,Tmax = 0.33 h,MRT = 30.31 h,CL = 0.095 L/h/kg,the bioavailability of I.M method could reached to 63%.It was recommended that I.M.should be the priority administration method for future clinical research.4.The concentration changes of piscidin1 in small intestine content in rats after muscle injection2 ml/kg Piscidin 1 was injected in rats through muscle.Then the small intestine content was collected at 5 min、10 min、20 min、30 min、1 h、2 h、4 h、8 h、12 h and 24 h to get detected.It was found that the Cmax reduced to1.67 μg/ml,Tmax delayed to 8.12 h,MRT = 30.12 h,but CL also reduced to 0.026 L/h/kg,which means Piscidin 1 has a stable form in small intestine.So the low bioavailability of I.G.could be owing to the pepsin or other enzyme.In this study,a rapid and sensitive detection method for Piscidin 1 in rat plasma and small intestine was established by LC-MS.The pharmacokinetic parameters of I.G.I.M.and I.V.were compared.It was demonstrated that Piscidin 1 had a fast absorption,high peak concentration and slow metabolism.The bioavailability of I.M.was higher than I.G.In the condition of I.M.administration,the Tmax of Piscidin 1 was delayed,the Cmax was reduced and the CL got slowed.