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Se Joon Woo, Jeeyun Ahn, Ji Hyun Park, Sunyoung Park, Kyu Hyung Park, Hyuncheol Kim; Pharmacokinetics of intravitreal bevacizumab (avastin) In vitrectomized eyes. Invest. Ophthalmol. Vis. Sci. 2012;53(14):483.
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To perform comparative analysis of pharmacokinetics of intravitreally injected bevacizumab in vitrectomized versus non-vitrectomized rabbit eyes.
Among the 35 eyes of 35 rabbits included in the study, 25-gauge pars plana vitrectomy was performed in 18 right eyes (vitrectomized eyes), and the remaining 17 right eyes served as control (non-vitrectomized eyes). Both groups received 1.25mg/0.05mL bevacizumab intravitreally. Eyes were enucleated at 1 hour, 1, 2, 5, 14 and 30 days after the intravitreal injection and were immediately frozen at -70°C. Bevacizumab concentrations were determined after separation of frozen vitreous and aqueous humor compartments using direct enzyme-linked immunosorbent assay. Bevacizumab concentration-time data were fit by two-compartmental analysis to determine half-life.
The vitreous concentration of bevacizumab in both groups showed two phases of clearance which are the fast distribution phase and the slow elimination phase. Bevacizumab vitreous concentration in vitrectomized eye showed 94.7% (1 hour), 70.5% (1 day), 89.2% (2 days), 94.2% (5 days), 99.2% (14 days), and 79.1% (30 days) of that of non-vitrectomized eyes. The calculated overall half-lives of intravitreal bevacizumab were 6.99 days for vitrectomized eyes and 7.06 days for non-vitrectomized eyes (1.6 hours difference). The clearance of intravitreal bevacizumab in vitrectomized eyes was accelerated only in the first phase but not in the second phase.
The increase of intravitreal bevacizumab clearance after vitrectomy is not substantial in rabbit eyes. This experimental data suggests that the therapeutic efficacy and duration of intravitreal bevacizumab in patients who previously underwent vitrectomy may be comparable to those without vitrectomy history.
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