Assessment of the safety of intravitreal injection of metoprolol tartrate in rabbits.

Purpose: To verify the safety of different doses of intravitreal metoprolol tartrate (MT) after intravitreal injection in rabbit eyes.
Methods: Animals were randomly assigned into 2 groups: group I received 50 µg of MT and group II 100 µg of MT. A volume of 0.05 mL of the drug solution was administered through an intravitreal injection, while the control eyes received an equal volume of saline solution. Safety was assessed by clinical observation, electroretinography (ERG) and histological evaluation.
Results: No evidence of clinical toxicity was observed. ERG waveforms from the MT treated eyes were similar to those recorded from the control eyes in dark-adapted state, amplitude and the implicit time are similar between the groups in light-adapted state, and their retinas had no signs of toxicity by histological evaluation 7 days after intravitreal injection.
Conclusions: The intravitreal use of metoprolol at 50 and 100 µg dosages does not cause short-term retinal toxicity in rabbits.