Pharmacokinetics of intravitreally injected bevacizumab in vitrectomized eyes

To compare the pharmacokinetics (PKs) of intravitreally injected bevacizumab in vitrectomized versus nonvitrectomized control rabbit eyes.

Twenty-five-gauge pars plana vitrectomy without lensectomy was performed in 17 right rabbit eyes (V) and 18 nonvitrectomized right rabbit eyes served as controls (C). After 1.25 mg/0.05 mL intravitreal bevacizumab (IVB) injections, eyes were enucleated at 1 h, 1, 2, 5, 14, and 30 days after the injection and immediately frozen at -80°C. Bevacizumab concentrations were determined after separation of frozen vitreous and aqueous humor (AH) compartments using indirect enzyme-linked immunosorbent assay. Bevacizumab concentration-time data were analyzed to obtain PK data.

Vitreous clearance of IVB consisted of 2 phases, the first fast distribution and second slow elimination phase. Clearance of IVB was accelerated in V eyes only during the first phase and not in the second phase. The vitreous concentration percent ratios between V and C eyes were 94.7% (1 h), 70.5% (1 day), 89.2% (2 days), 94.2% (5 days), 99.2% (14 days), and 79.1% (30 days). Overall vitreous half-lives were 6.99 and 7.06 days for V and C eyes, respectively (1.6-h difference).

Overall IVB PKs in rabbit eyes after vitrectomy without lensectomy are not substantially different from nonvitrectomized control eyes.