Predicted biologic activity of intravitreal bevacizumab.
OBJECTIVE
To create a time- and dose-dependent mathematical model that compares the intravitreal vascular endothelial growth factor (VEGF) binding activity of bevacizumab with that of ranibizumab.


METHODS
Intravitreal half-lives and relative equimolar VEGF binding activities of bevacizumab and ranibizumab were incorporated into a first-order decay model. Time-dependent bevacizumab activities (relative to ranibizumab) for different initial doses (1.25 and 2.5 mg) and reinjection intervals (single, weekly, and every 3 days) were calculated and graphed.


RESULTS
Twenty-seven days to 38 days after a single bevacizumab (1.25 mg) injection, the intravitreal VEGF binding activity would be comparable with that of ranibizumab at 30 days. Bevacizumab (2.5 mg) injections would need to be performed every 3 days for 1 month to equal the peak activity after a ranibizumab injection.


CONCLUSIONS
On the basis of this mathematical model, intravitreal bevacizumab maintains significant VEGF binding activity for 4 weeks to 5 weeks. More frequent bevacizumab injections increase the average binding activity but not to that seen with a single ranibizumab injection.
Stewart
Michael W
MW
Department of Ophthalmology, Mayo Clinic College of Medicine, Jacksonville, Florida, USA. stewart.michael@mayo.edu
D000042:Absorption; D020533:Angiogenesis Inhibitors / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000493:pharmacokinetics*; D061067:Antibodies, Monoclonal, Humanized; D000068258:Bevacizumab; D001682:Biological Availability; D006207:Half-Life; D006801:Humans; D007267:Injections; D008962:Models, Theoretical; D000069579:Ranibizumab; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D014822:Vitreous Body / Q000378:metabolism*
D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D042461:Vascular Endothelial Growth Factor A; D000068258:Bevacizumab; D000069579:Ranibizumab