# Ocular pharmacokinetics of intravitreal conbercept in a rabbit model following retinal scatter laser photocoagulation

## TL;DR

This study finds that laser treatment before injecting conbercept in rabbits leads to faster drug clearance and lower drug levels in the eye.

## Contribution

The study reveals how retinal laser photocoagulation affects the pharmacokinetics of conbercept in rabbits, providing insights for optimal drug administration timing.

## Key findings

- Conbercept concentrations were higher in non-photocoagulated rabbits compared to photocoagulated ones.
- Photocoagulation increased drug clearance and reduced drug exposure in all tested ocular tissues.
- The half-life of conbercept was shorter in photocoagulated eyes across all ocular matrices.

## Abstract

The present study aims to evaluate the ocular pharmacokinetics of intravitreal conbercept after retinal scatter laser photocoagulation.

Thirty male Chinchilla rabbits (60 eyes) were used in this study. The control and photocoagulated animals received single bilateral intravitreal injections of conbercept, and the ocular tissues were collected and quantified for drug concentration using ELISA. Statistical analysis was then performed to compare the pharmacokinetic parameters between the control and photocoagulated eyes.

The conbercept concentrations were higher in the control rabbits than the photocoagulated rabbits and reached peak values in all ocular tissues 1 d after intravitreal dosing. The terminal t1/2 values in the vitreous humor (4.36 d), aqueous humor (4.19 d), retina (3.94 d), and choroid-RPE (3.84 d) of the control eyes were longer than those in the photocoagulated eyes (3.82 d, 3.69 d, 3.65 d, and 3.58 d, respectively). Conbercept exposure assessed using AUC0-t was lower in the photocoagulated rabbits than control animals in all four ocular matrices (p < 0.01). The clearance and volume of distribution were greater in the photocoagulated eyes than the control eyes, while the mean residence times were shorter in all four matrices.

Retinal scatter laser photocoagulation shortly before single intravitreal injection of conbercept enabled higher drug clearance and shorter half-life values, resulting in lower exposure in the ocular tissues compared to non-photocoagulated conditions. The distinct ocular pharmacokinetics of intravitreal conbercept observed in a rabbit model through retinal scatter laser photocoagulation is expected to enlighten further studies on investigating the optimal order of the combination of photocoagulation and anti-VEGF agents.