Comparison of the Effects of Continuous and Intermittent Systemic Administration on the Penetration of Gentamicin into Infected Rabbit Eyes

The effect of the mode of administration on the intraocular penetration of gentamicin in rabbits with bacterial endophthalmitis was examined. Animals were treated over a period of 12 hr either by intramuscular injection every 3 hr or by continuous intravenous infusion; both groups received the same total dose of drug. The mean peak and trough levels in serum with intramuscular injection were 11.4 and 1.6 micrograms/ml, respectively. Mean serum levels during continuous infusion were approximately 7 micrograms/ml. The area under the time-concentration curve for serum was approximately the same in both groups. Mean vitreous humor levels at the end of therapy were 2.8 micrograms/ml in the animals treated by repeated intramuscular injection and 2.6 micrograms/ml in those treated by continuous infusion (P greater than 0.2). In this model, the intraocular penetration of gentamicin was not influenced by the mode of systemic administration.