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A. R. Shah, L. V. Del Priore; Duration of Action of Intravitreal Ranibizumab and Bevacizumab in Exudative AMD Eyes Based on Macular Volume Measurements. Invest. Ophthalmol. Vis. Sci. 2008;49(13):305.
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Ranibizumab and bevacizumab are monoclonal antibodies targeting vascular endothelial growth factor (VEGF) that are used to control the exudative complications of age-related macular degeneration (AMD). Bevacizumab has a longer half-life than ranibizumab after intravitreal injection in animal eyes; herein we use sequential macular volume and thickness measurements based on optical coherence tomography (OCT) to determine whether there is any significant difference in the relative efficacy and duration of action of ranibizumab versus bevacizumab in patients with wet AMD.
We retrospectively reviewed the charts of all patients who received intravitreal injection of either ranibizumab (July 2006 - June 2007) or bevacizumab (January 2006 - June 2007) for the treatment of exudative AMD. We identified 316 patients (202 ranibizumab; 114 bevacizumab) who received a total of over 823 injections (313 ranibizumab; 510 bevacizumab). We restricted ourselves to 75 eyes who had pre and post treatment OCT performed to determine macular thickness and macular volume.
Ranibizumab caused a reduction in central foveal point thickness (CFPT) (277.2 ± 11.7 vs. 226.2 ± 11.3 microns; p=.001) and macular volume (7.24 ± 0.14 vs. 6.69 ± 0.11 cubic mm; p=.001) between 30 ± 14 days post treatment. Intravitreal bevacizumab caused a significant reduction in CFPT (287.7 ± 18.9 vs. 220.2 ± 18.2 microns; p=.008) and macular volume (7.37 ± 0.22 vs. 6.50 ± 0.14 cubic mm; p=.001) at 60 ± 14 days post treatment. Thus, no difference was seen in the ability of intravitreal ranibizumab or bevacizumab to reduce CFPT or macular volume but ranibizumab appeared to take longer to achieve its effect; the average time required to achieve a minimum macular volume was 31.5 ± 5.26 days for ranibizumab vs. 51.0 ± 8.29 days for bevacizumab (p-value = .01; t-test). The average time until loss of physiologic effect was 57.2 ± 1.44 days for ranibizumab compared to 115.4 ± 31.69 days for bevacizumab (p = 0.035; t-test).
Our data suggests both drugs are equally effective at reducing CFPT or macular volume. Bevacizumab appears to take significantly longer to achieve the minimum macular volume and the effects of bevacizumab take longer to wear off, which is consistent with preclinical data on its longer half-life in healthy animals. Our data suggest that intravitreal bevacizumab will lead to a similar reduction in macular volume and thickness and can be given less frequently than intravitreal ranibizumab in the treatment of eyes with exudative AMD.
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