Retinal toxicity of intravitreal ticarcillin

The retinal toxicity of the penicillin derivative, ticarcillin, was tested in albino rabbits by injecting the animals intravitreally with doses ranging from 50 to 3,000 micrograms, and monitoring them for 4 weeks. A second confirmatory study was performed by repeating the high-dose injections in a different set of rabbits and monitoring them for 3 weeks. Histologic examination and electroretinography of both groups showed that dosages up to 3000 micrograms produced no detectable damage to the retina. A dosage of 3000 micrograms of ticarcillin, which is 38 times the minimal inhibitory concentration for Pseudomonas aeruginosa, appears safe.