Abstract
Purpose::
To determine the pharmacokinetics and serum bioavailability of intravitreal bevacizumab in the rabbit.
Methods::
12 albino rabbits were intravitreally injected to one eye with bevacizumab1.25mg/0.05ml. One rabbit served as intact control. Vitreous samples were taken 1, 2 ,4, 6 weeks after injection, 3 rabbits for each time point. Blood samples were taken 2 and 6 weeks after injection. Bevacizumab concentrations in the plasma and vitreous were determined by enzyme-linked immunosorbent assay (ELISA).
Results::
The mean vitreal concentration of bevacizumab decreased by 37%, 62%, 70% and 81% at the 1,2,4 and 6 weeks respectively. Mean vitreal concentration in the uninjected eye was 4.93 ng/ml, 4.36ng/ml, 1.06ng/ml and 0.41ng/ml at the 1,2,4,6 weeks respectively. Mean plasma concentrations of bevacizumab was 17.20 pg/ml, and 7.02 pg/ml at the 2 and 6 weeks respectively. Mean vitreal and plasma concentrations of the control rabbit were lower than the sensitivity of the assay.
Conclusions::
The mean half life of bevacizumab in the rabbit eye was 10 days. The high intravitreal concentrations observed after 6 weeks demonstrates a lower than expected turnover of bevacizumab. The concentration of bevacizumab in the plasma and uninjected eye indicates systemic circulation.
Keywords: age-related macular degeneration • vitreous • growth factors/growth factor receptors