Aqueous Vascular Endothelial Growth Factor and Ranibizumab Concentrations after Monthly and Bimonthly Intravitreal Injections of Ranibizumab for Age-Related Macular Degeneration

Abstract

Purpose: To evaluate vascular endothelial growth factor (VEGF) and ranibizumab concentrations in eyes with age-related macular degeneration (AMD) after monthly and bimonthly intravitreal ranibizumab injections.

Methods: Aqueous humor samples were obtained from 19 eyes before and after treatment. Nine eyes received three monthly injections and 10 eyes received two bimonthly injections. The lower detectable limits of the VEGF and ranibizumab concentrations were 9.0 pg/ml and 0.156 ng/ml, respectively, measured by enzyme-linked immunosorbent assay.

Results: The aqueous VEGF concentrations with monthly injections decreased below the lower detectable limit in eight eyes at month 1 and seven eyes at month 2 from the mean baseline level of 94.7±32.0 pg/ml; with bimonthly injections, the concentrations decreased below the lower detectable limit in four eyes from the mean baseline level of 129.3±53.0 pg/ml at month 2. The aqueous VEGF concentrations with both regimens decreased significantly at month 2 (P<0.001, P<0.01, respectively). The mean aqueous ranibizumab concentrations with monthly injections were 71.2±48.6 ng/ml at month 1 and 96.3±65.4 ng/ml at month 2. The mean aqueous ranibizumab concentrations with bimonthly injections was 11.0 ± 27.1 ng/ml in eight eyes and decreased below the lower detectable limit in one eye at month 2.

Conclusions: The aqueous VEGF concentration was suppressed for 2 months after the initial intravitreal ranibizumab injection in some eyes with AMD. The aqueous ranibizumab concentration in these eyes may remain sufficiently high to suppress VEGF in some eyes 2 months after the initial injection.

Keywords: 412 age-related macular degeneration • 427 aqueous • 748 vascular endothelial growth factor