April 2011
Volume 52, Issue 14
ARVO Annual Meeting Abstract  |   April 2011
Translational Diffusion Of Ranibizumab As Measured By Fluorescence Recovery After Photobleaching (frap)
Author Affiliations & Notes
  • Nishanthan srikantha
    Ophthalmology, Kings College London, Worcester Park, United Kingdom
  • Timothy L. Jackson
    Ophthalmology, Kings College Hospital, London, United Kingdom
  • Klaus Suhling
    Physics, Kings College London, London, United Kingdom
  • James Levitt
    Physics, Kings College London, London, United Kingdom
  • Footnotes
    Commercial Relationships  Nishanthan srikantha, None; Timothy L. Jackson, None; Klaus Suhling, None; James Levitt, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 2325. doi:
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      Nishanthan srikantha, Timothy L. Jackson, Klaus Suhling, James Levitt; Translational Diffusion Of Ranibizumab As Measured By Fluorescence Recovery After Photobleaching (frap). Invest. Ophthalmol. Vis. Sci. 2011;52(14):2325.

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      © ARVO (1962-2015); The Authors (2016-present)

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Previous research by the group has shown a retinal molecular weight exclusion limit of 60,000 Dalton across the retina. It is thought that the 149,000 Dalton bevacizumab and 48,000 Dalton ranibizumab have similar therapeutic effects through clinical experience and small studies. It would be anticipated that ranibizumab is more effective as its lower molecular weight should facilitate diffusion across the retina.


We studied the diffusion properties of ranibizumab using FRAP (Fluorescence Recovery after Photobleaching), to measure the translational diffusion of fluorescently labeled ranibizumab. The translational diffusion coefficient was used to calculate an approximate size for ranibizumab.


It appears ranibizumab has a molecular radius of 5.5nm based on its translational diffusion characteristic. Preliminary results indicate this radius predicts the molecular weight to be much larger than the documented 48,000 Dalton.


Our results demonstrate ranibizumab to hold diffusion characteristics of a molecule with a higher molecular weight than expected. This may partly explain the reported similarity in the therapeutic effect of bevacizumab and ranibizumab although further studies are needed to validate this preliminary findings.  

Keywords: age-related macular degeneration • clinical laboratory testing • imaging/image analysis: non-clinical 

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