Penetration of piperacillin into the vitreous after intravenous administration.

Abstract

Penetration of piperacillin into the vitreous cavity after intravenous administration was investigated in humans. Forty-five eyes undergoing vitrectomy between November 1993 and December 1994 were included. Each patient received a single intravenous dose of piperacillin 4 g 2 hours before ocular incision. A 0.2-mL vitreous sample was aspired at the beginning of vitrectomy, a blood sample was obtained, and piperacillin level was assessed. There were no detectable drug concentrations in 25 eyes. Mean vitreous drug concentration in the remaining evaluable eyes (n = 14) was 2.33 microg/mL (+/-0.76). We divided samples into two groups: 23 uninflamed (Group 1) and 16 inflamed (Group 2) eyes. Mean vitreous drug concentration was 0.42 microg/mL in Group 1 and 4.95 microg/mL in Group 2 (P < 0.2). Piperacillin concentration was higher than the minimum inhibitory concentration for gram-positive bacteria in 13% of uninflamed and 69% of inflamed eyes (P < 0.001). Studies show that intravenously administered piperacillin can penetrate the vitreous cavity in rabbits. Our study suggests that a single dose of piperacillin can produce intravitreal concentrations sufficient to kill gram-positive bacteria in inflamed eyes. The poor intraocular penetration of systemically administered piperacillin in uninflamed eyes raises questions about its usefulness as a prophylactic agent in ophthalmic surgery.