Formulation and preparation method of long-acting interferon α-2b loaded injectable microspheres

Objective:To prepare injectable interferon α-2b(IFN-α-2b) loaded microsphere and develop a long-acting dosage form.Methods: IFN-α-2b loaded microspheres were prepared with poly(lactic-co-glycolic acid)(PLGA) as carrier material by double emulsion(w/o/w) method and solid in oil in oil(s/o/o) method separately.Physical and chemical characteristics of microspheres(mean diameter,morphology and drug entrapment efficiency) were evaluated;the in vitro release behavior and influencing factors of the microspheres were determined by micro-BCA(bicinchoninic acid) method;and IFN-α-2b stability during encapsulation and in vitro release was evaluated by sodium dodecyl sulfate polyacrylamide gel electropheresis.Results: The 2 types of microspheres produced had good shape and dispersive quality and a drug entrapment efficiency of more than 80%.IFN-α-2b bulk ultrafitration can significantly influence the mean diameter and in vitro release behavior of microspheres prepared by w/o/w method.The accumulated release(within 1 month) of the microspheres prepared by both methods was significantly improved when using PLGA with lower inherent viscosity.SDS-PAGE test showed aggregation of IFN-α-2b with s/o/o method,while there was no difference between the electrophoretic behavior of bulk IFN-α-2b and IFN-α-2b in microspheres prepared by w/o/w method.Conclusion: IFN-α-2b can be encapsulated into injectable microspheres to yield a one-month continuous release by both w/o/w method and s/o/o method.