Comparative Pharmacokinetics and Preliminary Pharmacodynamics Evaluation of Piscidin 1 Against PRV and PEDV in Rats

Antimicrobial peptide (Piscidin-1) is an effective natural polypeptide, which has great influence and potential on porcine epidemic diarrhea virus (PEDV) and pseudorabies virus (PRV). As an alternative antibiotic substitute, Piscidin-1 was subjected for pharmacokinetics study with three administration routes (i.v, i.m, and p.o) after a single dose of 2 mg/kg in rats and preliminary pharmacodynamics including antiviral activity in cell against PEDV and PRV. Based on 50 percent tissue culture infective dose (TCID(50)), there were about 2 and 10% virus survived ratios for Piscidin-1 against PRV and PEDV, respectively. The plaque test showed 1 and 2 μg/ml Piscidin-1 could eliminate 95% PRV and 85% PEDV, respectively. The main pharmacokinetics parameters of C(max), AUC(0−∞), Ke, t(1/2), T(max), MRT, and Cl(b) in plasma were not applicable value, 25.9 μg(*)h/ml, 0.041 h(−1), 16.97 h, not available value, 22.77 h, 0.067 L/h(*)kg after i.v administration, 2.37 μg/ml, 18.95 μg(*)h/ml, 0.029 h(−1), 23.50 h, 0.33 h, 30.12 h, 0.095 L/h(*)kg after i.m administration and 0.73 μg/ml, 9.63 μg(*)h/ml, 0.036 h(−1), 19.46 h, 0.50 h, 26.76 h, 0.171 L/h(*)kg after p.o administration. The bioavailability values after i.m and p.o administrations were calculated as 73.17 and 37.18%, respectively. The i.m administration was selected for pharmacokinetics study in ileum content against PEDV. The main pharmacokinetic parameters of C(max), AUC(0−∞), Ke, t(1/2), T(max), MRT, and Cl(b) in ileum content were 1.67 μg/ml, 78.40 μg(*)h/ml, 0.034 h(−1), 20.16 h, 8.12 h, 36.45 h, 0.026 L/h(*)kg. The C(max) values in plasma (2.37 μg/ml) and ileum content (1.67 μg/ml) were higher than the effective inhibitory concentration determined in the plaque test, and this indicates that Piscidin-1 might have effective inhibition effect against PRV and PEDV after administration of 2 mg/kg i.m. The results of this study represent the first investigations toward the pharmacokinetic characteristics of piscidin-1 in plasma upon three different administration routes, among which i.m. resulted in the highest bioavailability (73.17%). Furthermore, the pharmacokinetics study of ileum content indicated Piscidin-1 might have good effect against PEDV and could be regarded as an alternative antibiotic in clinical veterinary in the future study.