Abstract
Purpose: :
To evaluate the pharmacokinetics of intravitreally injected bevacizumab in the systemic circulation and the aqueous humor and its effect on vascular endothelial growth factor (VEGF) in the aqueous humor.
Methods: :
Bevacizumab (1.25 mg/50 µl) was injected into the vitreous cavity of the right eyes of three cynomolgus macaques. Aqueous humor and serum were obtained from the macaques just before injection and on days 1, 3, and 7, and weeks 2, 4, 6, 8 after the injection. The bevacizumab and VEGF concentrations were measured using enzyme-linked immunosorbent assay.
Results: :
The aqueous VEGF concentrations ranged from 63.2 to 106 pg/ml (mean, 80.0 ± 22.6 pg/ml) before the injection; decreased to less than 31.2 pg/ml, the lower limit of detection, in all eyes between 1 and 28 days after the injection; and returned to the pre-injection level at 42 days. The aqueous VEGF concentrations in the fellow eyes did not change throughout the experiment. Aqueous bevacizumab concentrations in the treated eyes reached a mean peak concentration of 49,500 ± 10,900 ng/ml the day after the injection and gradually declined, while those in the untreated eyes peaked at 3 days with a mean concentration of 18.5 ± 25.5 ng/ml and declined to below 0.156 ng/ml, the limit of detection at 2 weeks. A maximum mean bevacizumab concentration of 1,430 ± 186 ng/ml was achieved in the serum 1 week after the injection. The half-life of 1.25 mg of intravitreally injected bevacizumab was 2.8±0.6 days(n=3;range2.3-3.5) in the aqueous humor and 12.3±2.6 days (n=3; range, 9.2-14.1) in the serum.
Conclusions: :
Intravitreal injection of bevacizumab decreased the VEGF concentration in the treated eyes for at least 4 weeks and had no or a minimal effect on the untreated fellow eyes.
Keywords: vascular endothelial growth factor • drug toxicity/drug effects