AIM:To compare the concentration of Bevacizumab in serum and vitreous after bevacizumab administered by retrobulbar Tenon capsule perfusion and intravitreal injection in eyeballs of rabbits and observe the fluorescence of retinal, and to investigate the intraocular permeability of bevacizumab after retrobulbar Tenon capsule perfusion feasibility of extraocular administration route.

METHODS: Twenty healthy adult New Zealand rabbits were used in the study. The rabbits were randomly divided into two groups, group A received single administration of 1.25mg bevacizumab(1.25mg/0.05mL)by intravitreal injection, group B received single administration of 5mg bevacizumab(5mg/0.2mL)by retrobulbar Tenon capsule perfusion. Bevacizumab concentrations in serum and vitreous were determined by double antibody sandwich Elisa at 1 and 3d after administration. The changes of bevacizumab concentrations in serum and vitreous of two groups were compared, and the fluorescence of retinal was observed by laser confocal microscope.

RESULTS: One day after administration, intravitreal concentrations of bevacizumab in vitreous of group A and B were 254.40±13.65 and 1.60±0.32μg/mL respectively. Concentrations of bevacizumab in serum of group A and B were 0.55±0.15 and 0.63±0.05μg/mL respectively. The changes of bevacizumab concentrations in serum between two groups did not vary significantly(t=1.168, P=0.277). At 3d after administration, concentrations of bevacizumab in vitre-ous of group A and B were 236.80±8.70 and 1.40±0.23μg/mL respectively. Concentrations of bevacizumab in serum of group A and B were 0.66±0.17μg/mL and 0.64±0.14μg/mL respectively. The changes of bevacizumab concentrations in serum between two groups did not vary significantly(t=0.207, P=0.841). For two administration routes, the fluorescence distribution of retina layers could be clearly detected.

CONCLUSION: At 1 and 3d after intravitreal injection, intravitreal concentrations of bevacizumab of group A is much higher than that of group B. Intravitreal injection of bevacizumab is the more effective route of administration for intraocular tissue. But retrobulbar Tenon capsule perfusion can also achieve the minimum concentration which can completely blocks VEGF activity(>500ng/mL), and can remain for at least three days. Both intravitreal injection and retrobulbar Tenon capsule perfusion of bevacizumab results in high serum concentration, and the change of bevacizumab concentration in serum between two groups does not vary significantly. In both administration routes, the fluorescence distribution of retina layers can be clearly detected, and both two dosing ways can work on each layer of retina.