Intraocular Pharmacokinetics and Safety of Subretinal Injection Compared with Intravitreal Application of Conbercept in Vitrectomized Rabbit Eyes

PURPOSE: To evaluate the ocular pharmacokinetic properties of subretinal conbercept injection in vitrectomized rabbit eyes and to compare them with those by intravitreal injection. METHODS: The following groups of New Zealand white rabbits received conbercept injections (0.5 mg/0.05 ml): a subretinal group (subretinal injection in vitrectomized eyes), an intravitreal group (intravitreal injection in vitrectomized eyes), and a control group (intravitreal injection in nonvitrectomized eyes). Drug concentrations in the aqueous humor (AH), the vitreous humor (VH), and the retina were measured by the enzyme-linked immunosorbent assay (ELISA), and pharmacokinetic parameters were calculated. Ophthalmic B-ultrasonography, electroretinogram (ERG), and hematoxylin and eosin (H&E) staining were performed to evaluate the safety of subretinal injection. RESULTS: On the 28(th) day after injection, the drug level in the subretinal group was significantly higher than that in the intravitreal group in the AH (0.90 ± 0.25 μg/ml and 0.11 ± 0.07 μg/ml and 0.11 ± 0.07 P < 0.001, respectively) and the VH (5.00 ± 3.86 μg/ml and 0.11 ± 0.07 μg/ml and 0.11 ± 0.07 P < 0.001, respectively) and the VH (5.00 ± 3.86 P < 0.001, respectively) and the VH (5.00 ± 3.86 P < 0.001, respectively) and the VH (5.00 ± 3.86 CONCLUSIONS: Our study indicates that applying conbercept by subretinal injection can reduce the drug clearance rate and sustain a long maintenance period in ocular tissue, which suggests that subretinal conbercept injection may be a potentially valuable treatment option.