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John B. Christoforidis, George H. Hinkle, Michelle M. Carlton, Michael V. Knopp; PET/CT Imaging Of Intravitreal Radiolabeled Bevacizumab and Ranibizumab In A Rabbit Model. Invest. Ophthalmol. Vis. Sci. 2011;52(14):938.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether the intravitreally injected anti-VEGF agents bevacizumab and ranibizumab are completely confined within the vitreous cavity after intravitreal injection and to determine the pharmacokinetic properties of these agents in the vitreous cavity by PET/CT.
Radiolabeling using I-124 was completed using a modified Iodogen method. After testing for radiochemical purity, intravitreal injection (0.05cc per agent) in one eye is performed. Three anesthetized Dutch-belted rabbits underwent intravitreal injection with I-124 bevacizumab and three with I-124 ranibizumab. All rabbits were imaged with a Micro PET-CT scanner on days 0, 2, 5, 7, 14, 21, 28 and 35.
The intravitreally placed radiolabelled agents were found to be contained within the vitreous cavity for the duration of the study with no extravasation seen into the central nervous system or elsewhere. I-124 bevacizumab was detectable to day 28 while I-124 ranibizumab was detectable until day 21. The kinetic model appears to be a 2-compartment model and the average retention times of bevacizumab and ranibizumab after correction for radioactive decay were found to be 4.2 days and 2.8 days respectively.
There appears to be no gross escape of intravitreally placed bevacizumab and ranibizumab from the vitreous cavity after intravitreal injection. After correction for radioactive decay both agents remain detectable until 28 and 21 days respectively with retention properties consistent with those reported in previous studies.
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