title: Vitreous levels of unbound bevacizumab and unbound vascular endothelial growth factor in two patients.
abstract: BACKGROUND
  Vitreous levels of unbound bevacizumab (Avastin) and unbound vascular endothelial growth factor (VEGF) were determined in two patients. Patient 1 underwent repair of an 8-day-old rhegmatogenous retinal detachment 4 weeks after a single intravitreal bevacizumab injection, and Patient 2 underwent vitreous biopsy for endophthalmitis 48 hours after a combined bevacizumab and triamcinolone injection.
  
  
  METHODS
  The samples of vitreous fluid were analyzed for unbound bevacizumab and unbound VEGF levels using microsphere immunoassays targeted for bevacizumab and VEGF.
  
  
  RESULTS
  In Patient 1, the unbound bevacizumab level was 0.16% of the loading dose (or 500,000 pg/mL) and the unbound VEGF concentration was <41 pg/mL 4 weeks after the bevacizumab injection. In Patient 2, the unbound bevacizumab level was 53% of the loading dose (or 166,000,000 pg/mL) at 48 hours, with an unbound VEGF level of <41 pg/mL.
  
  
  CONCLUSIONS
  A single dose of intravitreal bevacizumab is likely to provide complete intravitreal VEGF blockade for a minimum of 4 weeks, with an intravitreal bevacizumab half-life of approximately 3 days.
authors.affiliation: Retina Consultants, PLLC, 1220 New Scotland Road, Suite 201, Slingerlands, NY 12159, USA. drbeer@retinaconsultants.org
authors.forename: Paul M
authors.initials: PM
authors.lastname: Beer
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Wong
authors.forename: Amjad M
authors.initials: AM
authors.lastname: Hammad
authors.forename: Naomi S
authors.initials: NS
authors.lastname: Falk
authors.forename: Martin R
authors.initials: MR
authors.lastname: O'Malley
authors.forename: Samira
authors.initials: S
authors.lastname: Khan
mesh_terms: D000368:Aged; D020533:Angiogenesis Inhibitors / Q000493:pharmacokinetics* / Q000627:therapeutic use; D000911:Antibodies, Monoclonal / Q000493:pharmacokinetics* / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized; D000068258:Bevacizumab; D001682:Biological Availability; D001706:Biopsy; D020256:Choroidal Neovascularization / Q000188:drug therapy; D004322:Drainage; D009877:Endophthalmitis / Q000175:diagnosis; D005260:Female; D006801:Humans; D007118:Immunoassay; D007267:Injections; D017075:Laser Coagulation; D008297:Male; D012163:Retinal Detachment / Q000601:surgery; D042461:Vascular Endothelial Growth Factor A / Q000276:immunology / Q000378:metabolism*; D014821:Vitrectomy; D014822:Vitreous Body / Q000378:metabolism*
chemical_list: D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D000068258:Bevacizumab