Preparation And Characterization Of Bevacizumab-encapsulated PLGA Microspheres For Intravitreal Administration

Objective: Bevacizumab (Avastin,Genentech/Roche ) is a synthetic monoclonal antibody against vascular endothelial growth factor with the molecular weight of 149 kd, indirectly blocking VEGF and its receptors to inhibit the binding angiogenesis, thus inhibiting the formation of new blood vessels and reducing the vascular permeability. Bevacizumab is a very effective drug in sever ocular diseases, but unfortunately its effect is shorted (its intravitreal half-life in different animal and human studies was measured at 3–5 days) and several intravitreal injections are needed for maintaining atherapeutic effect. The main concerns are difficulty of repeated injections and complication of these injections may be caused. To prepare and evaluate bevacizumab encapsulated in poly(L-lactic-co-glycolic acid)(PLGA) microsphere for intravitreal injection. For improvement of drug availability after intravitreal administration, in this study, bevacizumab-encapsulated PLGA microsphere as a novel drug delivery system was prepared and compared with conventional formulas in the market.Methods: Bevacizumab was encapsulated into PLGA microsphere via the S/O/hO ( Solid-in-oil-in-hydrophilic oil ) method. Then weigh the prepared PLGA microspheres bevacizumab 20mg, 1mL methylene chloride with dissolved vortex 5 min, centrifuged to discard the solution containing the polymer, after repeated five times and then adding 10mlPBS fully dissolved the bevacizumab, prepared the sample solution. And then we evaluate the drug encapsulation efficiency,drug loading and release rate by using ELISA, and the microsphere spherical and diameter by using scanning electron microscope(SEM)Results: The experiment results showed that the bevacizumab- encapsulated PLGA microspheres prepared by the S/O/hO method are spherical, smooth 2~7μm in diameter. The whole procedure is relatively simple, and biocompatible additives no threat to humans. Enzyme-linked immunosorbent assay (ELISA) determination of encapsulation efficiency of microspheres of about 49%, and the drug loading about 10% . And the bevacizumab in vitro release of microspheres showed very stable in vitro drug release process. Burst release on day 1 to 20.1% of bevacizumab, the first 3 days up to 34.6%, 63% on day 7, 87% on 14 days, the 28d up to 90%, that the microspheres in 14 days basically complete release of drug from the microspheres, these results can be proved by the microspheres in sustained effectConclusion:This study demonstrates that the appearance of microspheres meet the needs of intravitreal injection by S/O/hO method prepared. And we made applicable to the intravitreal injection of bevacizumab-PLGA controlled release microspheres, which may be ideal means of treating related diseases...