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E. Dib, M. E. Farah, M. Maia, I. M. Longomaugeri, E. F. Costa, F. M. Penha, B. A. Furlani, M. C. Martins; Subretinal Concentration of the Bevacizumab Two Hours After Intravitreal Injection. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1766.
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To evaluate subretinal detection of Bevacizumab - AvastinR (Genetech, USA) two hours after intravitreal injection of 1,25mg of bevacizumab in rabbits.
Seven female dutch-belted rabbits were submitted to anterior chamber paracentesis using a 30-gauge needle (Beckton-Dickson, USA) following by removal of 0.1 ml of aqueous humor. In all animals, transcleral retinal detachment was performed with a modified 25-gauge infusion cannula (Alcon, USA) connected to a bottle of Balanced Salt Solution (BSS) (Alcon, USA). Animals were divided in two groups: Group I) Four rabbits were submitted to intravitreal injection of 0,1ml of Bevacizumab 1,25mg using a 30-gauge needle (Beckton-Dickson, USA). Group II) Three rabbits were submitted to intravitreal injection of 0,1ml of BSS using a 30-gauge needle (Beckton-Dickson, USA). Two hours after intravitreal Bevacizumab injection (Group I) or intravitreal BSS injection (Group II), subretinal BSS was aspirated and submitted to immunoassay for Bevacizumab by ELISA method. Samples were also exposed to an anti-immunoglobuline (IGG) solution containing peroxidase followed by an absorbance dosage method. The rabbits were sacrificed by intravenous penthobarbital injection. Eyes were enucleated and fixated by 10% glutaraldehyde. The retinal site of the transcleral cannula introduction was analyzed by light microscopy to exclude iatrogenic retinal tears.
Subretinal Bevacizumab molecule was detected in the four eyes submitted to intravitreal Bevacizumab injection. No subretinal Bevacizumab was detected in the other three eyes used as control. The light microscopy showed no evidence of retinal tears in all the seven rabbits, excluding the possibility that bevacizumab could reach the subretinal space through iatrogenic holes. Bevacizumab dosage in subretinal space is under evaluation. These results demonstrate that Bevacizumab molecule reached the subretinal space by transretinal migration.
Bevacizumab molecule is able to diffuse through the retina into the subretinal space following intravitreal injection of 1.25 mg of AvastinR in rabbit model. Additional researches in different animal models comparable to human eyes (as primates) are necessary to define not only subretinal migration but also subretinal concentration of Bevacizumab after intravitreal injection.
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