Safety of repeated intravitreous injections of antibiotics and dexamethasone.
OBJECTIVE
To determine the retinotoxicity of repeated intravitreous injections of vancomycin, ceftazidime, and dexamethasone in rabbit eyes.


METHODS
Twenty pigmented New Zealand rabbits were divided into two groups. In Group 1, the right eyes received repeated intravitreous injections with vancomycin 0.3 mg, ceftazidime 0.7 mg, and dexamethasone sodium phosphate 0.13 mg at three consecutive 48-hour intervals. Group 2 right eyes received three times higher dose of the same intravitreous drugs as used in Group 1, repeated at the same frequency. All left eyes served as control eyes. Retinotoxicity was monitored by slit-lamp biomicroscopy, indirect ophthalmoscopy, electroretinography, and light and electron microscopy.


RESULTS
No evidence of retinotoxicity was found in Group 1 eyes. Photopic A-waves were significantly elevated, and 30- and 50-Hz flicker fusion amplitudes were significantly depressed in Group 2 eyes. No changes were found by clinical or histopathologic examination in the retinas of either group.


CONCLUSIONS
Three repeated intravitreous injections at 48-hour intervals of a combination of vancomycin, ceftazidime, and dexamethasone in rabbit eyes at dosages that approximate drug concentrations recommended for human endophthalmitis were nontoxic. Similar injections at three times higher doses resulted in mild electroretinogram changes.
Yoshizumi
M O
MO
Department of Ophthalmology, The Jules Stein Eye Institute, Doris Stein Eye Research Center, UCLA School of Medicine, Los Angeles, California 90095-7000, USA.
Bhavsar
A R
AR
Dessouki
A
A
Kashani
A
A
D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000633:toxicity*; D002442:Ceftazidime / Q000008:administration & dosage / Q000633:toxicity*; D002452:Cell Count; D002511:Cephalosporins / Q000008:administration & dosage / Q000633:toxicity*; D003907:Dexamethasone / Q000008:administration & dosage / Q000633:toxicity*; D004338:Drug Combinations; D004596:Electroretinography / Q000187:drug effects; D005938:Glucocorticoids / Q000008:administration & dosage / Q000633:toxicity*; D006207:Half-Life; D007267:Injections; D009887:Ophthalmoscopy; D011817:Rabbits; D012160:Retina / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D012449:Safety; D014640:Vancomycin / Q000008:administration & dosage / Q000633:toxicity*; D014822:Vitreous Body / Q000187:drug effects
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004338:Drug Combinations; D005938:Glucocorticoids; D014640:Vancomycin; D003907:Dexamethasone; D002442:Ceftazidime