Preparation And Pharmcokinetics Studies Of α-cobrotoxin Loaded Liposomes Modified With Anti-transferrin Receptor Antibody

Objective To prepare an α-cobrotoin(αCT)loaded liposomes modified with transferrin receptor monoclonal antibody OX26(OX26-αCT-LP),and investigate their physicochemical properties and release feature in vitro,pharmacokinetics in vivo.Methods The α-cobrotoxin loaded liposomes(αCT-LP)was prepared by film dispersion-extrusion method.Based on the single factor experiment,the orthogonal design was adopted to optimized formulation and process of the preparation of aCT-LP,and the thiolated OX26 conjugated with the maleimides of DSPE-PEG2000-Mal on the liposomes surface covalently,OX26-αCT-LP was obtained at last.The transmission electron microscope(TEM)and Zeta sizer instrument were respectively utilized to investigate the morphology,particle size and Zeta potential of the liposomes.Entrapment efficiencies were evaluated by ultrafiltration,drug release behavior in vitro were studied by dialysis method.Plasma concentration of aCT was determined by fluorescence spectrophotometry after labeled with FITC.Pharmacokinetic behavior of OX26-αCT-LP was studied in comparison with FITC-αCT and aCT-LP after intravenous injection.Results Small particle size αCT-LP was prepared by film dispersion-extrusion method.Through ultrafiltration method the encapsulation efficiency was measured.Single factor investigation was carried out,and optimal formulation was decided.Chol/EPC was 1:3,FITC-αCT concentration was 11.67μg·mL-1,EPC concentration was 6.67 mg·mL-1.Then the thiolated OX26 conjugated with liposomes by the maleimides of DSPE-PEG20000-Mal.The prepared OX26-αCT-LP was spherical and uniform,with the average particle size of(106.3±5.36)nm,the polydispersity index of(0.094±0.006)the Zeta potential of(-23.17±1.14)mV and the encapsulation efficiency of(56.82±1.18)%.The release in vitro of OX26-αCT-LP in pH 7.4 PBS conformed to Weibull equation,which is lnln[1/(1-Q)]=0.5345lnt-1.452(R=0.9867).The main pharmacokinetic parameters of OX26-αCT-LP group after intravenous injection in rats was as follows:T1/2β was(263.75±10.05)min,1.29 times of FITC-αCT group;CL was(0.00045±0.00002)μg·kg-1/ng·mL-1/min,0.57 times of FITC-αCT group;AUC0→∞ was(155825.1±8009.8)ng·min·mL-1,1.73 times of FITC-αCT group.The results indicated that the T1/2β of OX26-αCT-LP was significantly prolonged.Conclusion OX26-αCT-LP prepared by film dispersion-extrusion method was smooth and round with well-distributed particle size as well as high entrapment efficiency.OX26-αCT-LP showed an obvious sustained-release characteristic in vitro and the circulation time was prolonged in vivo.